# New 3-way build (AE woofers, B&C mid/tweet)



## Zeitgeist

I've started a new build recently... finally have all the parts, just need to do some more cuts and glue..

It's a 3 way, WCW configuration.. The AE TD12S are custom --- they have a fabric dustcap instead of phase plugs.

Just building a center for now - then going to build L/R.

Drivers: AE TD12S, B&C 8CXT, AE TD12S.
Amplification: Crown Microtech amps (2400/1200s) EDIT: Now, Emotiva XPA-1s, XPR-5 (hopefully), and UPA-7
Crossover: analog JBL M553 (for testing) - EDIT: Now, MiniDSPs w/4 way advanced plugin (3)
Dimensions: 16w x 38h x 14 deep
EQ: Undecided... I have a BFD 1124.... EDIT: MiniDSPs
Preamp: Onkyo PR-SC886 - RCA to MiniDSPs
Cabinet: 3/4" MDF 
Connectors: Neutrik Speakon (I've learned to like them more than banana plugs) (2, 1 for woof, 1 for coax)
Type: Sealed 
Stuffing: Thinking about 2lb of polyfill - would be about 16oz/cuft. Not sure if this is too much for a sealed speaker.
Driver mounting: Mounting woofers and coax flush with the front baffle..

Still figuring out crossover points... unfortunately the JBL unit doesn't provide much flexibility -- so just going to use as a starting point. Triamping it - in part to the substantially different sensitivities of the woofer and tweeter -- and the flexibility of changing crossover points on the fly. Sensitivities are 93.2 db for woofers, 94 for mid, 103 for tweeter. 

In my initial testing - I *LOVE* the 8CXT. I was listening to part of Despicable Me, and you could clearly hear the pluck of the guitar string (during the intro..). I was impressed. It took some time to get the TD12S woofers, but they are SOLID. Between the woofers and the coax - it's almost 60 lbs in drivers!!

Will hopefully get some pictures up tomorrow of progress..

Any questions?


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## bambino

I can't wait:sn:. I think the recommendation is 1lb. of fill per cu.ft. so your right in the ballpark weather or not it's all needed will need to be determined. Like i said before i can't wait to see these get off the ground. Do you have any pics of the drivers?


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## Zeitgeist

bambino said:


> I can't wait:sn:. I think the recommendation is 1lb. of fill per cu.ft. so your right in the ballpark weather or not it's all needed will need to be determined. Like i said before i can't wait to see these get off the ground. Do you have any pics of the drivers?


I've always heard that recommendation for subs - just wasn't sure how it translated to woofers..

I just took some driver pics... somehow I managed to make these drivers look ugly! 
AE TD12S:
   

B&C 8CXT


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## bambino

Those look like some serious drivers now i'm really excited to see your build progress!:T


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## zero the hero

That is going to be one awesome set of speakers! Have you considered using the MiniDSP for XO use (you'd actually need a pair)?


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## Zeitgeist

zero the hero said:


> That is going to be one awesome set of speakers! Have you considered using the MiniDSP for XO use (you'd actually need a pair)?


Thanks!

I've actually thought about them a great deal... They seem to be pretty good and very modular. Any clue if they allow mixing plugins - so that you can use them for XOs and for parametric EQ?

I'm just trying to keep from putting too many devices in the chain.

I think my only minor gripes about the MiniDSP is the $35 or so for shipping from China... and the fact that I wish there was some more elegant rack mount solution. All my other gear is racked - so trying to avoid having "boxes" that sit around..


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## Zeitgeist

Actual cabinet w/bracing dry fit. Hard to see - but the two 1" holes are for Neutrik Speakon connectors. I am using two - one for woofer and a second one for the coax. Each of the connectors has 4 conductors.
 

Still need to cut holes in the bracing that sits behind the woofers


Front baffles - the primed one is the forward most -- cut to recess the woofers. Also has an (approx) .4" deep recess cut for the B&C. That was fun to route! Polyfill sitting next to the baffles... and part of an enclosure -- to chamber the midrange. 


Amps, amps, and more amps. On top is crossover and an EQ. EQ is not currently hooked up.


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## bambino

Wow! Nice job man. Got a close up of the cutout for the woofer? And what are all the amps for, your starting to remind me of myself, (can't ever have enough) LOL! Your doing some exellent work.:T


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## Zeitgeist

I'll get some close ups...

Well for LCR 3 ways that's 9 channels or 5 stereo amps right there. Sounds crazy right? I might bridge a couple so for 9 channels its easy to use 6 amps!! 

I should just buy stock in an amp company...  I would have bought integrated Digmoda amps but that's some serious money there too.


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## bambino

Let me know when you buy that stock i'll join you.:bigsmile: I guess when i think about it you need all those amps, wait a minute.... does that mean i need all 17 channels of amplification i have? What are we to do with all that power. 
Oh, i know build more speakers:devil::T.


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## Zeitgeist

bambino said:


> Let me know when you buy that stock i'll join you.:bigsmile: I guess when i think about it you need all those amps, wait a minute.... does that mean i need all 17 channels of amplification i have? What are we to do with all that power.
> Oh, i know build more speakers:devil::T.


I've thought about building surrounds with the B&C drivers... but then I'm looking at another 8 channels of amplification.

So I should just stock up on Emotiva multichannel amps then... :flex:


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## bambino

Zeitgeist said:


> I've thought about building surrounds with the B&C drivers... but then I'm looking at another 8 channels of amplification.
> 
> So I should just stock up on Emotiva multichannel amps then... :flex:


Better get the Emotivas before they go up in price again or wait and hopefully they will go on sale again soon.:spend:


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## Zeitgeist

Agreed!


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## Zeitgeist

Test fitting the speakers before gluing the front baffles together..
 

Closeup of B&C recessed cutout.


To do:
Paint
Glue bracing in
Drill holes for hurricaine nuts... and install
Glue cabinet
Cut 45 degree 1.25" bevel on front baffle
Put polyfill in
Install speakon connectors in rear
Install and wire drivers


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## bambino

Exellent job on the octagon cutout!:sn: Did you use a template or was that done freehand?


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## Zeitgeist

Freehand  I stuck the B&C in the hole... and then traced around the flange w/a sharpie... and then cut within the sharpie. 

The lines are actually straight.. for some reason in the pic there was a reflection or something weird. The B&C fits like a glove on the cutout..

When it's all black, should be pretty good.


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## bambino

Well executed, for freehand work the lines look perfect and like you said any imperfections will disapear once it's painted.:T


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## vinculum

I'm just going to blurt it out here...

Wow, a Seaton Sound Catalyst clone! Drivers, dimensions, ect. 

Looks great so far! I wish we would see more DIY coaxial projects. What do you project your final cost per channel will be?

For surrounds you could stick to just the coax in a ported box and get down to 80hz, if that sparks your interest.


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## Zeitgeist

vinculum said:


> I'm just going to blurt it out here...
> 
> Wow, a Seaton Sound Catalyst clone! Drivers, dimensions, ect.
> 
> Looks great so far! I wish we would see more DIY coaxial projects. What do you project your final cost per channel will be?
> 
> For surrounds you could stick to just the coax in a ported box and get down to 80hz, if that sparks your interest.


I have no idea what you're talking about... :whistling:
Don't they say that imitation is the sincerest form of flattery?? onder:
But.. I don't have a rear chamfer on mine... I just beveled the front of the baffle over the weekend.. 

I think weight probably came out to 110-120 lbs. All the MDF and then the driver weight (probably 60 lbs for drivers).

Lets see.. cost... 

$45 - Wood:
Well, each speaker is about 1.5 sheets of MDF (plus or minus) -- so that's 45 for wood.

$840 - Drivers:
B&C - about $240 shipped (I think it was free shipping)
AE drivers - about $600 shipped

$5 - Connectors:
Maybe $5 for the Neutrik Speakon connectors

So, lets say that's maybe... $1000 for drivers, wood, wire, etc. Maybe even including cost for DuraTex (that I have yet to buy)

Then there is:
Cost for amps (3 channels of amplification per speaker...)
Cost for crossover ($200-250 for DCX or $400 for DBX Driverack PA+) --- need 2 of them for 3 channels
Speaker Wire (I think it was $70 or so for 500 feet, I can't believe I used 450 feet (50 feet per channel) just for 3 speakers)

Not sure how to quantify the cost for amps and crossovers yet - since I'm using what I have on hand.. 

IF I were to go the Digmoda route - I think I'd hit the $1500 price point pretty quickly. Integrated amp modules aren't cheap.

Needless to say - when I started pricing everything out - in terms of crossovers and amps - I was surprised - it really adds up!

Why yes - that does Spark my interest! The B&C coaxes are really amazing drivers.


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## vinculum

I'm sure Mark would be flattered. Who wouldn't? He's probably even following along to see what crossover parameters you select. I'll be curious myself to see what methods you use to arrive at the crossover frequencies and slopes. Keep up the good work!


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## Zeitgeist

vinculum said:


> I'm sure Mark would be flattered. Who wouldn't? He's probably even following along to see what crossover parameters you select. I'll be curious myself to see what methods you use to arrive at the crossover frequencies and slopes. Keep up the good work!


Using the primitive JBL M553, it only allows gain and crossover frequency selection. No slope, no good stuff.

I've only built one speaker so far, need to save up some $$$ to build the other 2. Building LCRs.

I'm not sure when a DCX/PA+ is going to be purchased, but needless to say - sometime!! I'll definitely post when I get one and can fine tune it. Looking at the FR of the B&C there are definitely some peaks that need to be tweaked.

Right now, I chose 400hz and 2000hz for the points. I just picked them because they seemed "safe". Takes a few minutes to run tones - and set the gain... since you're setting the gain on THREE channels and trying to get them all at the same level. I can only imagine how time consuming it must have been for Mark to fine tune his settings and EQ.

I had it resting on a coffee table while adjusting levels......and I could hear the coffee table shifting under the weight. Not good!! 

In the few minutes that I've had a chance to hear it - it's impressive! Being so big - you need to be back a few feet to really appreciate it. But the woofers and the coax seem to blend so nicely. It makes me feel like I've been listening to muddy speakers all these years!


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## Zeitgeist

Still need to do some sanding and paint... but all the cutting/assembly is done.


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## vann_d

That looks really cool.

I was looking at those coaxial speakers when I was thinking about a JTR clone. Never pulled the trigger on that project though.

How far off axis are you vertically from the tweet / CD?


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## Zeitgeist

vann_d said:


> How far off axis are you vertically from the tweet / CD?


Hmmm. Good question. I don't really have it in place yet. I would guess it'll come out to 15 degrees or so - much further than I'd like for the time being. I've read mixed things about the off-axis performance of the 8CXTs -- but I think that the quality of the driver was more than enough reason for me to not worry about that too much. I know the AE woofers are highly regarded but the coax has really impressed me.

Since I don't have an AT screen - I really can't put them at the height I want. They have to sit below the screen.

Part of the problem is that it probably weighs 100-120 lbs. The size of these has me thinking about an AT screen again, so I can mount them higher - but at 100+ lbs, that's going to take a little planning.


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## vinculum

Once you go AT, there's NO going back! 

There is an immediately noticeable improvement in the soundstage once you are able to place the LCRs where they are "supposed to be" rather than where they "have to be". Trust me, you won't regret it! Material is cheap and it's easy to build a frame..


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## vann_d

Tilt stands maybe?


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## Zeitgeist

vinculum said:


> Once you go AT, there's NO going back!
> 
> There is an immediately noticeable improvement in the soundstage once you are able to place the LCRs where they are "supposed to be" rather than where they "have to be". Trust me, you won't regret it! Material is cheap and it's easy to build a frame..


My only reluctance has been that I wish I had more space! But looking at fabric prices, I know it's not expensive - so it wouldn't be an expensive if done as a DIY screen.

I keep telling myself... SOMEDAY I'll have my CIH 2.35 AT setup.

In the meantime, I'm just going to keep building subs and speakers and getting gear!


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## Zeitgeist

vann_d said:


> Tilt stands maybe?


Hmmm.. Not a bad idea, just need to build some beefy stands!


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## GranteedEV

Looks sweet 

I bet your dynamic capability just flew through the ROOF :yikes: with that choice of drivers.

Have you measured these things yet?


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## Zeitgeist

I haven't measured it yet! I keep meaning to... and keep running out of time.


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## TD10XGUY

Hmm sounds like the project is coming along nicely. Interested in the coax's myself. Have some TD15Xs in my mains, and to say that the coaxs impressed you more than the TDs really sparks my interest. Looking forward to the results


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## Zeitgeist

TD10XGUY said:


> Hmm sounds like the project is coming along nicely. Interested in the coax's myself. Have some TD15Xs in my mains, and to say that the coaxs impressed you more than the TDs really sparks my interest. Looking forward to the results


Thanks. Hopefully with a little luck I can get some measurements this weekend.

You like TD10X drivers?


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## TD10XGUY

Well truth be told I've never heard the TD10x drivers. I was planning a build with them when I first joined this forum. Shortly thereafter, I decided to go with the TD15Xs instead  Have them crossed over at 750hz to a JBL 2446 on a 2380 horn crossed to a Beyma CP21/F tweeter. The TD15 sounds great up that high so I assume the smaller woofers would as well.


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## vinculum

I've been invited to a Catalyst installation this Saturday, so I'll finally get to hear this coax. Mark Seaton will be doing the install so it should be optimized as good as it can be. After that I'm off to hear some Triad Platinums at a friends house. It's going to be a fun day!


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## GranteedEV

I am pretty sure the current catalysts do not use any OEM availavle drivers... all custom. The B&C coax was used in the first generation but since then Mark Seaton has switched to fully custom drivers as far as I know. Plus he's using advanced DSP tri-amp XOs.... so you won't really be listening to the driver.... just the speaker in all its glory as one cohesive piece.


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## Zeitgeist

Just to clarify.. I never titled this thread Catalyst clone........ 
I'm aware that Mark uses custom drivers for most of his products..... 

My intention was to build a similar speaker - since I don't have access to the custom drivers... nor the OEM DSP/amps. From a couple posts that I've seen Mark mention DIY - it sounds like he doesn't have objections to people attempting to build similar speakers. Most people just balk at the driver cost -- and I chose to spend the money.

I have no doubt that the Catalyst speakers sound excellent and are worth every penny (and having priced out similar components - I know that the component cost is high). I just don't have the budget for them - and I'm not going to any time remotely soon. If budget wasn't an issue, I'd already own a set of them.

The time to build the cabinet, get the drivers, the amps, crossover, tweak the gain, tweak the EQ and cable it.. is the price that I'm paying for a 3-way solution that I think I'll be happy with..


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## vinculum

No worries Zeitgeist. Your custom speaker has all the ingredients to be great sounding.  I'm glad to see someone finally doing a build like this!


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## Zeitgeist

vinculum said:


> No worries Zeitgeist. Your custom speaker has all the ingredients to be great sounding.  I'm glad to see someone finally doing a build like this!


Cool - Thanks!

I'm glad to hear it! 

When you get a chance to hear a Catalyst.. please post your comments. Always curious to hear more about them.. 

:T


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## GranteedEV

I agree, your custom speaker has a ton of potential.

One thing I do think you will need to do is really do many measurements, parametric EQ, and perhaps mess around with both crossovers if you want to get this sounding its best, especially since the B&C coax does have some raggedness in its response from what I recall. the DCX or whatever it was that you're using is a good reason an ambitious endeavour like this could work out.... any time your crossover is going to be in the most critical region of voices you really need to be able to adjust over and over until you can get phase and response smooth


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## Zeitgeist

GranteedEV said:


> I agree, your custom speaker has a ton of potential.
> 
> One thing I do think you will need to do is really do many measurements, parametric EQ, and perhaps mess around with both crossovers if you want to get this sounding its best, especially since the B&C coax does have some raggedness in its response from what I recall. the DCX or whatever it was that you're using is a good reason an ambitious endeavour like this could work out.


Yeah, I've seen the FR of the B&C and it's rather ragged. I chose to go with it - because it seemed to be a very good driver - despite it's ragged FR and less-than-perfect off-axis performance.

I recall reading that Mark said that the DCX lacked some of the precision in setting the Q value of the filters. So it's not ideal. I was looking for a "step-up" from the DCX and started reading about the DriveRack PA+ - which seemed to be better quality but doesn't necessarily allow more precision. I'm not sure about the MiniDSPs and whether they'd give enough flexibility to get a better result. 

Either way I'm looking at $200+ (used DCX) or $400+ for a PA+, times two.

I've also thought about relying on Audyssey to some degree - which is probably a bad idea. I guess in my head - I don't understand the importance of making the speaker FR flat - and then putting it in a room that's going to require EQ on top of it? Wouldn't Audyssey flatten the response out... in room?

I don't mean to start a long winded Audyssey discussion - I've read too many of them! I was just curious why EQing a speaker to flat is so important when it'll change in the room?


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## Zeitgeist

GranteedEV said:


> ...any time your crossover is going to be in the most critical region of voices you really need to be able to adjust over and over until you can get phase and response smooth


What do you consider that region? I've read a few different answers..

Last time I was toying with it, I thought 400 seemed like a safe-ish (new word) value?

Hmm...... The more I think about it, the more I feel like I need to find some good content to play to fine-tune the crossover points. Sure, REW or a RTA can help get the FR flat.. but I don't think that there is a good way to fine-tune crossover points... without just playing content and listening. Maybe someone can correct me.


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## GranteedEV

The region i refer to is _roughly_ 200hz - 4khz, and our ears are most sensitive to sounds between 1 and 6khz i believe. 

The woofer-tweeter crossover is going to be smack dab in the middle at around 1-2khz unless i'm mistaken, so you don't want to hear crossover artifacts. Not saying it won't work, but it'll take some work. :T

P.S. I'm not a believer in using your ears to tune a crossover. You need anechoic measurements, and many different types. Everything you can measure. If at the end of it all it doesn't sound right, there's a fundamental flaw in the design concept. Remember, unless you've got a live, unamplified reference _right next_ to the speaker, how do you know what a recording sounds like?


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## Zeitgeist

I couldn't even remember what crossover points I wrote.. I had to read through my old posts!

I could probably go to 300hz from 400.. 

Yeah, looks like the crossover for the mid/tweet needs to be somewhere between 1-2K. Not too much wiggle room there... Maybe 3K would be OK.

FR for the 8CXT:


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## GranteedEV

The MiniDSP with the biquad filters is extremely powerful. I own one and I'm amazed at the amount of things you can do with it in such a small box. I can highly recommend it. 



> I've also thought about relying on Audyssey to some degree - which is probably a bad idea. I guess in my head - I don't understand the importance of making the speaker FR flat - and then putting it in a room that's going to require EQ on top of it? Wouldn't Audyssey flatten the response out... in room?
> 
> I don't mean to start a long winded Audyssey discussion - I've read too many of them! I was just curious why EQing a speaker to flat is so important when it'll change in the room?


It's an interesting approach, I guess. :dontknow: 

I will say that on-axis response aside, the crossover much determines off axis response, and this is a huge factor in what we hear in a room. you can have an awful sounding speaker EQ'd flat. Don't think of audessey as a reason to neglect a great crossover, even if it can response-shape on axis. 

Now if audessey is doing the active crossover, that's another thing. The only speaker I can think of where audessey is a big part of the crossover as a whole is the Phase Tech DARTS. That's a very different design concept though. The closest you can get to that is to drop $2000 on a DEQX.

Anyways regarding the crossover, try to use the natural acoustic rolloff of the driver as much as you can to shape the response. Don't just go with symmetrical electrical slopes.


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## Zeitgeist

I don't know much about biquad filters... probably time to learn!

Thanks for the mention of the crossover and off axis response. Good to know.

I'm not planning on being lazy and depending on Audyssey... was just a thought.

I've only built one speaker so far, so probably going to scrape together the money to build the other 2 in the next few months - before picking a crossover and fine tuning it.. Having a single speaker really makes it hard for anything to sound right... :heehee:


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## GranteedEV

Zeitgeist said:


> Thanks for the mention of the crossover and off axis response. Good to know.


Coaxials are a good idea in that the cone of the woofer does double as a waveguide for the tweeter, so the dispersion/directivity is somewhat consistent.


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## Theresa

Yes, of course they can do equalization at the same time as crossovers. It also does delay, reverses polarity, and levels in and out. Go to the site and read the data sheets. They are the best thing to ever happen to my speakers. I would get the "miniDSPs in a Box" with one of the advanced plugins, I use the two way advanced which has eighteen PEQs and can import from REW.


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## Theresa

I only need 10 amp channels for actively crossed over fronts and two subs and my surround speakers use passive crossovers so they only need one amp channel per surround speaker. 10 does seem like a lot though. What are B&C mid/tweets though?


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## GranteedEV

Theresa said:


> I only need 10 amp channels for actively crossed over fronts and two subs and my surround speakers use passive crossovers so they only need one amp channel per surround speaker. 10 does seem like a lot though.


Because there's no insertion loss, even 60 watts becomes a lot of power. So something like 

http://classicaudioparts.com/store/...Channel-x-60-Watt-Amplifier-B-Stock-120V.html

or

http://classicaudioparts.com/store/ATI-AT1806-Six-Channel-x-180-Watt-Amplifier-B-Stock-(120V).html

is all a person needs IMO. Like you, I too think that passive surrounds are okay.



> What are B&C mid/tweets though?


B&C 8CXT Coaxial 8" Midrange with Compression Driver tweeter

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-653

B&C is a professional audio driver company, so their drivers edge more towards high sensitivity, active crossovers, and high power handling rather than deep extension and "easy" passive crossovers. Some PA drivers can sound extremely "hi fi" actually.


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## Mark Seaton

Zeitgeist said:


> Just to clarify.. I never titled this thread Catalyst clone........
> I'm aware that Mark uses custom drivers for most of his products.....
> 
> My intention was to build a similar speaker - since I don't have access to the custom drivers... nor the OEM DSP/amps. From a couple posts that I've seen Mark mention DIY - it sounds like he doesn't have objections to people attempting to build similar speakers. Most people just balk at the driver cost -- and I chose to spend the money.
> 
> I have no doubt that the Catalyst speakers sound excellent and are worth every penny (and having priced out similar components - I know that the component cost is high). I just don't have the budget for them - and I'm not going to any time remotely soon. If budget wasn't an issue, I'd already own a set of them.
> 
> The time to build the cabinet, get the drivers, the amps, crossover, tweak the gain, tweak the EQ and cable it.. is the price that I'm paying for a 3-way solution that I think I'll be happy with..


Hi Zeitgeist,

I only just recently saw this thread. Very nice work in what you've shown. I very much appreciate your acknowledgement of all that's involved in making such a speaker come together and sound its best. You have as similar drivers as are available to DIYers, but as you say, getting them to optimally play well together takes a good deal of work, and measurement is really required. For the DIYer, I think one of the better solutions would be to use 3 MiniDSP modules with one for each speaker. This keeps channel separation to a maximum while also giving you 1 in and 1 output from each module you can use for subwoofer channels or other speakers.



Zeitgeist said:


> I've also thought about relying on Audyssey to some degree - which is probably a bad idea. I guess in my head - I don't understand the importance of making the speaker FR flat - and then putting it in a room that's going to require EQ on top of it? Wouldn't Audyssey flatten the response out... in room?
> 
> I don't mean to start a long winded Audyssey discussion - I've read too many of them! I was just curious why EQing a speaker to flat is so important when it'll change in the room?


You can get into matters of debate with subwoofers in this approach, where I still find that you hear the fingerprint of the anechoic response in the power response driving the room. Without a flat reference, it is very easy to completely miss tilted subwoofer or speaker responses which sound obviously different, but are insignificant visually amongst the peaks and dips created by the room. Consistently I find separating the problems of the device from the room to yield better results, especially above 30-40Hz.

The exact frequency response of the speaker at a given location can always be adjusted with various EQ efforts. What cannot be changed is how the drivers integrate. The on/off axis integration, total radiated power and location of any off axis lobes cannot be changed by any device correcting the speaker as a single channel/entity (Audyssey, ARC, etc). These correction systems can alter the frequency response or even the time domain, but those changes are equal at all locations. This is where crossover frequency, slope and implementation can create very different sounding real world results, even when the on axis response looks about the same. 

Fortunately the coaxial mounting of the tweeter makes life much easier in this regard, as off axis lobing between the mid and tweeter are mostly eliminated. The integration of the parts can also be largely driven my measurement, with observed behavior or limitations accounted for such as driver overload or breakup. With a 120 lb speaker of significant size, the bigger hurdle is often figuring out how to take useful measurements without an anechoic chamber or crane available. :scratch: In general you will be splicing measurements useful for different ranges which will overlap plenty to give all the info you need. Once you think you are on track, it's also very useful to just throw some pink noise on the speaker and walk around. With any coaxial speaker be very careful in getting too caught up with any single measurement, as the wiggles in the response need to be looked at for trends, not absolutes.

Take your time and keep testing. The time put into measuring and even damping internally will pay out big time.

Enjoy,


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## Zeitgeist

Mark Seaton said:


> Hi Zeitgeist,
> 
> I only just recently saw this thread. Very nice work in what you've shown. I very much appreciate your acknowledgement of all that's involved in making such a speaker come together and sound its best. You have as similar drivers as are available to DIYers, but as you say, getting them to optimally play well together takes a good deal of work, and measurement is really required. For the DIYer, I think one of the better solutions would be to use 3 MiniDSP modules with one for each speaker. This keeps channel separation to a maximum while also giving you 1 in and 1 output from each module you can use for subwoofer channels or other speakers.


Thanks Mark, I really appreciate it! I realize that I've just shown the early work... I still have yet to paint the speaker, and I still need to build two more. Glad to hear that the drivers are similar and that I'm not totally off base . From the little testing that I've done, I love the B&C. The AE drivers seem pretty good too. No idea how I'll come up with a crossover point that I like, I figure looking at FR, educated guesses and just plain listening.

I'm glad you mentioned the MiniDSP modules, because that's exactly what I decided that I'm going to do. They seem to be the best fit that I can find in terms of features/flexibility.

Previously I was going to tri-amp with some old Crown pro-amps, but I'm now hopefully going to get an Emotiva XPR-7 to drive 7 of the 9 channels. Hoping it provides enough oomph for the woofers without being crazy overkill on the tweeters. I figure under-utilizing some of the channels won't hurt. 

Really appreciate your advice on the testing too. It's been on the back of my mind for a while on how to get the best measurements. I really like REW, and I think that I can probably get the measurements that I need/want in order to smooth out the response. But as you said, bigger hurdle is how to do it without a chamber or crane. I keep thinking about building a temporary chamber of sorts with copious amounts of acoustic fiberglass to prevent reflections and room interactions but that might cause more problems than it would solve.

It's funny how easy it seems to be to stray from easy to what feels like unchartered territory! Seems like the average joe just does testing outside..


----------



## Theresa

I've actually found my speakers to sound best with a 24db/octave symmetrical crossover between midwoofers and tweeters at 1700Hz. I've tried 12db on the midwoofer and on the tweeter (at the same time (symmetrical) and asymmetrical). Did some testing and the crossover area is smooth without any suckouts with this setup. Tried 48db too and that just didn't sound right as didn't a 12db symmetrical and asymmetrical as didn't ones with 36db/octave. Sometimes symmetrical works out depending on driver, phase, and crossover frequency. The miniDSPs are wonderful for the ease with which these things can be experimented with.


----------



## Zeitgeist

Theresa said:


> I've actually found my speakers to sound best with a 24db/octave symmetrical crossover between midwoofers and tweeters at 1700Hz. I've tried 12db on the midwoofer and on the tweeter (at the same time (symmetrical) and asymmetrical). Did some testing and the crossover area is smooth without any suckouts with this setup. Tried 48db too and that just didn't sound right as didn't a 12db symmetrical and asymmetrical as didn't ones with 36db/octave. Sometimes symmetrical works out depending on driver, phase, and crossover frequency. The miniDSPs are wonderful for the ease with which these things can be experimented with.


Thanks for your comments.. I was about to ask what drivers you had, but just found an earlier post of yours. Looks like some nice drivers!

Yeah, I was thinking that the miniDSPs would allow me to try a whole bunch of crossover selections in a relatively short period of time. I've always thought that potentially 12db is too narrow and 48db is too wide, so I figured I'd start with 24 when I get one.

I'm planning on finishing the other two speakers later this year, and then probably buying 4 miniDSPs, so I don't have to repeatedly pay shipping. 3 for LCR and 1 for LFE.


----------



## Mark Seaton

Zeitgeist said:


> Thanks Mark, I really appreciate it! I realize that I've just shown the early work... I still have yet to paint the speaker, and I still need to build two more. Glad to hear that the drivers are similar and that I'm not totally off base . From the little testing that I've done, I love the B&C. The AE drivers seem pretty good too. No idea how I'll come up with a crossover point that I like, I figure looking at FR, educated guesses and just plain listening.
> 
> I'm glad you mentioned the MiniDSP modules, because that's exactly what I decided that I'm going to do. They seem to be the best fit that I can find in terms of features/flexibility.
> 
> Previously I was going to tri-amp with some old Crown pro-amps, but I'm now hopefully going to get an Emotiva XPR-7 to drive 7 of the 9 channels. Hoping it provides enough oomph for the woofers without being crazy overkill on the tweeters. I figure under-utilizing some of the channels won't hurt.
> 
> Really appreciate your advice on the testing too. It's been on the back of my mind for a while on how to get the best measurements. I really like REW, and I think that I can probably get the measurements that I need/want in order to smooth out the response. But as you said, bigger hurdle is how to do it without a chamber or crane. I keep thinking about building a temporary chamber of sorts with copious amounts of acoustic fiberglass to prevent reflections and room interactions but that might cause more problems than it would solve.
> 
> It's funny how easy it seems to be to stray from easy to what feels like unchartered territory! Seems like the average joe just does testing outside..


I applaud you trying something that isn't already mapped out for you. Not as many are willing to give that a whirl.

I believe another program you might want to check out is ARTA and a program HOLM. I believe there may be a few others as well, but the one limitation with REW, is that as far as I know there is no time windowing capability (it may be possible now, but I haven't tried). Your best bet for measurement is a calm day outdoors. The best way to measure the midbass crossover will be to stand the speaker upright on the ground or a small stand, and tilt the speaker forward to aim the tweeter at the microphone about 3-6' away, placed on the ground. Boundaries are your friend, where this measurement eliminates the problematic floor/ground reflection which will fall in your crossover range if you just set the speaker up and start measuring in the air. A program which can window a measurement can allow you to get useful measurements down to 500Hz or lower when up in the air. Some creativity will give you plenty of information to insure each crossover is integrating well. For the woofer-mid XO you can even set the speaker on its side and measure at about 5-8' away on the ground. The response will tilt/shelf up sooner due to the effectively double width baffle, but it allows you to insure that there are no cancellations or weird interactions in what is normally the vertical axis as there are no reflections to be concerned with.

One key bit to the process IMO is to first smooth the driver, then apply the crossover. If you apply the crossover first, it becomes easy to ignore out of band issues which are audible and measurable, but only make for small ripples in the summed response. By far, smoothing major peaks in the compression driver's response is the most critical.

The high pass on the 8" mid will require some tinkering, and will be different from what I use, as the Catalyst midrange differs from your box. For the mid chamber, be sure to not leave it empty else sound quality will be greatly compromised.

For amplification I don't see much concern with the big Emotiva, and think it will work nicely, even if under powering the woofers a bit. The compression driver will take the peaks at higher frequencies just fine while you have to watch lower frequencies.

Lots of fun still ahead.


----------



## Zeitgeist

I've read about ARTA but never downloaded it before, I'm looking at it now. Thanks for the recommendation! By HOLM, do you mean HOLMImpulse? I've seen it mentioned plenty of times in horn build threads. 

Thanks for the recommendations on measurements, I'm sure your advice will prove invaluable when I start doing measurements. Appreciate the comments on smoothing before picking crossover, I would have probably fought with the crossover first before EQing. I knew that the one challenge with the 8CXT would be smoothing it out since the response on paper looks pretty peaky. 

For the mid chamber, you mean make sure to use some damping? The mid chamber is very small, so I probably need to spend some time tweaking that too.

I'm not too worried about underpowering the woofers right now, because my 10x20 room won't utilize half of the capability!  I'd love to get a set of XPA-1s down the road to power the woofers (but that's another $3K).

At least I have a (Cross Spectrum Labs) calibrated EMM-6 now, so at least I can get some good measurements down the road.

I think my one concern is a limited number of EQ points w/the MiniDSPs.


----------



## Theresa

Zeitgeist said:


> Thanks!
> 
> I've actually thought about them a great deal... They seem to be pretty good and very modular. Any clue if they allow mixing plugins - so that you can use them for XOs and for parametric EQ?
> 
> I'm just trying to keep from putting too many devices in the chain.
> 
> I think my only minor gripes about the MiniDSP is the $35 or so for shipping from China... and the fact that I wish there was some more elegant rack mount solution. All my other gear is racked - so trying to avoid having "boxes" that sit around..


I would use the four way advanced plug-in for the miniDSPs if your speakers are three way. It has both crossovers and many bands of PEQ. You will need three probably or else get the "2x8" which is actually "4x8" if you get it with the miniDIGI. The trouble with the "2x8" is you can't get it mounted in a box. I use three of the miniDSP "2x4 In A Box" but with the two way advanced plugins. Two are unbalanced and the one for the sub is balanced. If you are going to use pro-amps for all drivers than get all balanced. They will accept an unbalanced input. Read the manuals on the miniDSP site. I don't have a single complaint about the miniDSPs.


----------



## Zeitgeist

Hi Theresa, 
Thanks for the advice. I was planning on the 4-way advanced. I looked at the 2x8, but I didn't think it was as cost effective. I thought it was something like $300, whereas 2 4ways would be $200 total.

I think I'm planning on getting 3 unbalanced - as I'm now hopefully going to go to Emotiva amps, and then getting 1 unbalanced for XLR/sub duty. I'm hoping to not do pro-amps for the speakers. The pro amps that I have now don't have DC protection on them, and that just makes me nervous. It doesn't make sense to build/buy protection circuits for 9 channels either.

I used to be very skeptical of MiniDSPs, but I have to say that I'm impressed that they've actually listened to what the users want, and they allow EQing below 20hz for example.

Now I just need to get $1100 more for woofers, $500 for mid/tweets and another $400 for MiniDSPs.  

Maybe it would have been easier to just start saving up for Mark's speakers...


----------



## gperkins_1973

Mark's catalysts are $3500 each but the specs look awesome. I guess you may be thinking off the sparks which are $1500 each. Mark has a great reputation that's for sure.


----------



## Zeitgeist

gperkins_1973 said:


> Mark's catalysts are $3500 each but the specs look awesome. I guess you may be thinking off the sparks which are $1500 each. Mark has a great reputation that's for sure.


Not sure who you are responding to?

I was just thinking out loud about parts cost for building two more speakers and the other parts I need for all 3 speakers.


----------



## Theresa

Well the miniDSPs "in-a-box" are more like $160 after you pay for shipping. That comes out slightly less than the "2x8" which is really 4x8 with the miniDIGI. I'm perfectly satisfied with the 2x4s though and already have them so I won't be getting a 4x8. The one balanced I have goes between the Emotiva UMC-1 balanced sub out and a EP4000. I have to admit that's overkill for me, I don't need that much power. Sounds great though. I am in complete agreement with getting the 2x4s especially if you need to get them already in an enclosure.


----------



## Zeitgeist

It's 125/ea for MiniDSP 2x4 RevA in a box..... and $145 for the balanced.

Shipping is $25, even if you buy 4. I figured I might as well wait, and buy em all at once.


----------



## Zeitgeist

If anyone happens to have Catalysts or other Seaton speakers in Ohio, I'd love to come listen to them......


----------



## gperkins_1973

I'd second that one. Only trouble I would have to travel about 4000 miles to find that out. LOL.

I bet they sound fab!


----------



## Zeitgeist

Welllll. Looks like I'm moving forward with purchasing the 4 TD12S and 2 8CXTs that I need to build the other two speakers I need to have a complete LCR.

I kept hoping that the Emotiva XPR-7 would be out soon but from the looks of it, it won't be out any time soon. So, rather than saving that money to take advantage of a presale that I thought would be soon, I'm going to get drivers and worry about an amp later.

I'm starting to rethink how I'm going to amplify all 3 speakers. First I thought some Crown pro-amps, then I decided I wanted consumer and was going to use an Emotiva XPR-7 and my Emotiva UPA-7 - so I could get some serious wattage to the woofers/mids from the XPR-7 drive the tweeters with the UPA-7.

The XPR-7 was tested at one point with 465 Watts into 8 Ohms and 690 Watts into 4 Ohms... (rated at 400/w at 8 ohms)..... so I thought that would be a perfect fit, but it's hard to find high wattage multi-channel amps, and I don't think I want to buy 6 single channel amps (takes up room and ends up expensive).


----------



## zero the hero

i can't help but think that you're out of your mind if you really think you need that much power for EACH driver, especially knowing they're high-efficiency drivers! How big is your stadium??


You realize realistically you could probably drive your mids/tweets with 30 watts each and never run out of headroom... sure more power for the woofers might be called for, but geez....


----------



## Zeitgeist

zero the hero said:


> i can't help but think that you're out of your mind if you really think you need that much power for EACH driver, especially knowing they're high-efficiency drivers! How big is your stadium??
> 
> You realize realistically you could probably drive your mids/tweets with 30 watts each and never run out of headroom... sure more power for the woofers might be called for, but moowee....


Yeah yeah yeah, I know, overkill right? I don't have a stadium   .

I'm not that worried about the tweets or even so much the mids, but would really like to have more than enough power for the woofers... and would like to have more than 100-200 watts..

For comparison, Seaton Catalysts (some similarities with mine) have in the neighborhood of 1000w into woofers, 350 into mids and 150 into tweets (If I've read Speakerpower's spec sheets correctly and chosen 4ohm/8ohm wattage correctly). 

Not saying that I need 1000w for each 2 woofers, but I'm definitely a fan of using a portion of an amps total output capability, since distortion rises dramatically when the amps do get pushed.


----------



## robbo266317

The other reason to use larger amps is that peaks can be 10x the average value. So if you are running 10 watts the peaks can be at 100 watts.


----------



## Zeitgeist

robbo266317 said:


> The other reason to use larger amps is that peaks can be 10x the average value. So if you are running 10 watts the peaks can be at 100 watts.


Or 100W to woofers, 1000w peaks


----------



## GranteedEV

if you ever watch the spectrograms of music, you find that the biggest power demands are from around 60-400hz, and peaks can be a good 10-20db louder than peaks higher in frequency


----------



## studiotech

Great looking project! For the mid and woofer chambers, look at using some Bonded Logic(it looks like shredded blue jeans), it works better than anything else I've tried for broadband absorption. Do not waste your time with plain old eggcrate foam or a little bit of poofy, loose fiberglass. Search around because some of the DIY resellers have it or some similar other brand names in smaller quanitities. I've been getting big bundles from an A/C contractor supplier for making sound panels too. If you need some, I could send some your way for not much $.

These active, multichannel projects add up real quick. I'm actively tri-amping my open baffles as well. I ended up getting Digmoda units directly as a small OEM, but even with my price, they are a little expensive. There is another compant from Italy called Powersoft that i'm considering using next time. And, you can almost never have too much power. With dynamic, uncompressed soundtracks and music, peaks can really push short term power needs through the roof. Better to have it than not. 

Greg


----------



## Zeitgeist

Thanks! Appreciate the compliment and advice.

The mid chamber right now is rather small, and I'm thinking about making it smaller, but I'm not sure. I think I'll have to build a couple prototypes and compare how they sound. Thanks for the suggestion of bonded logic, I'm always on the lookout for other damping materials. I have some OC 703, but I'm sure that that is denser. I'll have to look for it. Right now I have 1 cu/ft polyfil in the woofer chamber but that's subject to change.. 

Glad to hear that I'm not the only one tri-amping. Bi-amping seems common enough, but tri-amping seems more rare! I'm familiar with Digmoda and Speakerpower but Powersoft is new to me. 

I have a strong preference for rack-mounted amps over plate amps and the like, and I thought that having all the amplification in the rack made sense until I started making cables!! I think that the pricing for the speaker-integrated amps wouldn't have been affordable for me, regardless. I think I was looking at $1500-2000 per speaker.

Still hoping the Emotiva XPR-7 comes out eventually. Apparently some of the delays are rumored to getting it to operate efficiently on 120v (400W x 7 channels). Might get 3 XPA-1s eventually for the woofers. Now that would be TONS of power (and a bajillion farads of capacitance).


----------



## studiotech

Zeitgeist said:


> I have a strong preference for rack-mounted amps over plate amps and the like, and I thought that having all the amplification in the rack made sense until I started making cables!! I think that the pricing for the speaker-integrated amps wouldn't have been affordable for me, regardless. I think I was looking at $1500-2000 per speaker.


Funny you should mention that. I really wanted a simple, clean setup, so I chose not to get Emotivas and seperate processor, just so I didn't have the nightmare of so many cables all over the place. I'm using some heavy gauge 8 cond. speaker wire with Neutrik NL8 connectors from the amp to the back side of the speaker. I am doubling up on the conductors for the woofer.

Greg


----------



## Zeitgeist

studiotech said:


> Funny you should mention that. I really wanted a simple, clean setup, so I chose not to get Emotivas and seperate processor, just so I didn't have the nightmare of so many cables all over the place. I'm using some heavy gauge 8 cond. speaker wire with Neutrik NL8 connectors from the amp to the back side of the speaker. I am doubling up on the conductors for the woofer.
> 
> Greg


Yeah.......hind sight is 20/20. I never realized just how much gear I'd end up with by not using a cabinet mount amp.

I'm making slooooooooooow progress.


----------



## Zeitgeist

For anyone interested, this is still a work in progress.

I bought 3 XPA-1 amps a couple months ago - and have been waiting for Emotiva to get properly designed rack ears in stock. I'm also waiting for the class-H amps to come out since I need 6 more channels to be fully active.

Planning on buying Mini-DSPs later this year.

I have all 3 B&C 8CXT drivers.... just waiting for the AE drivers. It's been about 10-11 weeks since I placed that order...

I met Mark Seaton on Friday - which was pretty cool. Also got to hear the 12-C (Catalyst) and 8-C drivers as well as Submersives. Impressive demo. Mark is an exceedingly nice guy - and the quality and price for his speakers is exemplary (Especially compared to all the manufacturers that do not sell direct!). Perfect fit and finish. The Submersives are awesome for what he managed to pack into a cabinet that's not the size of a fridge!

Hopefully I'll get my AE drivers soon and the MiniDSPs in a couple months and I can work on crossovers, EQ... and eventually get some more amps!


----------



## GranteedEV

Zeitgeist said:


> It's a 3 way, WCW configuration.. The AE TD12S are custom --- they have a fabric dustcap instead of phase plugs.


What advantage is there to the fabric dustcap? Is it purely aesthetic?


----------



## Zeitgeist

Yeah - pretty much.

I just can't get used to the appearance of big shiny phase plugs.. I dunno what I would have done - if I could do it all over.


----------



## Zeitgeist

Got tracking number for AE drivers. Finally.
Unfortunately took 11 weeks for them to ship...


----------



## taloyd

AE is build-to-order (almost entirely in-house, with minimal staff), and really, really high quality. Imagine it's some supercar (a fair analogy), and you'll be more than pleased with only waiting 3 months.

cheers,
-Tal


----------



## Zeitgeist

taloyd said:


> AE is build-to-order (almost entirely in-house, with minimal staff), and really, really high quality. Imagine it's some supercar (a fair analogy), and you'll be more than pleased with only waiting 3 months.
> 
> cheers,
> -Tal


I've always been happy with the build quality, this is my second order. It's just him (John) and one part time (maybe full time? whomever it is seems to come and go) person.

I was OK with 5 weeks on the first order, 3 months is a long time though.

I received the 4 woofers last week which was sweet. Now I just need to find time to build 2 more cabinets. 

So, still to be done, build 2 more cabs, get MiniDSPs (December?) and then buy more amps.


----------



## penngray

Subscribed!!


Im a huge fan of AEspeakers.com and Johns work ( I own many TD12S, TD12M, AV15X)

Many of us are definitely waiting for the Coax DIY project that is similar to JTRs or Catalysts. Its great to read you have all the drivers now.

FWIW, I created a simply HOLM "HOW TO" on AVS awhile ago (http://www.avsforum.com/avs-vb/showthread.php?t=1236094&highlight=holm) that might help you get upto speed if you choose to use it. I wanted to go through ARTA too but I just didn't have the time 

I read through your thread but I didnt find what XO software package you are considering using ?? PCD, Speaker workshop??

Awesome stuff....you are going to love those driver choices!!!


----------



## Zeitgeist

penngray said:


> Subscribed!!
> 
> 
> Im a huge fan of AEspeakers.com and Johns work ( I own many TD12S, TD12M, AV15X)
> 
> Many of us are definitely waiting for the Coax DIY project that is similar to JTRs or Catalysts. Its great to read you have all the drivers now.
> 
> FWIW, I created a simply HOLM HOWTO on AVS awhile ago that might help you get upto speed if you choose to use it.
> 
> I read through your thread but I didnt find what XO software package you are considering using ?? PCD, Speaker workshop??
> 
> Awesome stuff....you are going to love those driver choices!!!


Thanks penngray! Appreciate the comments. I've followed a lot of your postings on AVS and you definitely have more experience than I do. Wish that AE drivers were easier to get, some AV15 drivers would make some excellent fill subwoofers.  

I might have even stumbled upon your HOLM HowTo before - I'll have to check it out again. 

I actually don't know what package I'm going to use. I was planning on doing a lot of listening and tweaking, but I'm not really familiar with Speaker Workshop or PCD. I shall have to read up! If you have any suggestions - I'm all ears. At least with the MiniDSPs I can change it on the fly...

I'm anxiously awaiting buying 3 MiniDSPs (4 way advanced plugins) - but that's going to be probably around the new year. Need to pay off some bills first. Same goes for getting some more amplification for the mids/tweets. Hoping that Emotiva releases their XPR line next year. Still seems like a good fit (I THINK).

Hoping if I get some down time I can work on the cabinets this weekend. I finally bought some new router bits (solid carbide) - so hoping they last longer.


----------



## penngray

One time I did a build, measured the drivers then just listened to the drivers/dialing the XO on the DCX. I enjoyed the speakers for over a year by just doing the minimum measurement effort.

Its a great educational experience, You can change the MiniDSP on the fly hearing what a 2nd order buttworth sounds like vs 4th order LR!! Then you can change phase/delay and hear differences. Look can tilt the HF down to get a better bass response, tweak until you love what you hear.

Cool stuff.


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## Zeitgeist

I'm planning on definitely spending some time trying to get the response flat... but I know that might be a challenge with it being winter time when the DSPs come.. 

I guess I'll see what kind of measurements I can get done indoors.  

I figure once I get the cabinets built and the amps that I want - I'll have plenty of time to do the crossover work and EQ tweaking. Regardless - I'll have some real nice drivers as a starting point.


----------



## penngray

Zeitgeist said:


> I'm planning on definitely spending some time trying to get the response flat... but I know that might be a challenge with it being winter time when the DSPs come..
> 
> I guess I'll see what kind of measurements I can get done indoors.
> 
> I figure once I get the cabinets built and the amps that I want - I'll have plenty of time to do the crossover work and EQ tweaking. Regardless - I'll have some real nice drivers as a starting point.


I do all my measurements in doors. If you have atleast 5 feet in any direction you can get easily down around 4 to 6 ms. I also have 2'x4' 4" OC703 panels I can place below and beside speakers to further reduce early reflections.

Remember you are designing an active speaker for your room so measure it in that room, no reason to measure outdoors at all.


----------



## Zeitgeist

Good to know. From what I read it seemed like the common answer seemed to be towards an anechoic chamber (who has one??) or doing it outside..

Glad to know that in room measurements are still usable.


----------



## penngray

You have to look at the impulse response and see where the room starts to effect the response.

I think HOLM is the best tool for disecting the IR plot since it allows for simple zooms and other functionality to see the exact number of milliseconds it takes before we see the first reflection from the room.

We can measure anything in the room if we undertand/control the issues from doing so.


----------



## Zeitgeist

I never noticed that HOLM shows you the FR *AND* the impulse at the same time. That seems like that is a nice design - so you can see them both at once.

I was planing on using REW quite a bit - since I really like the interface and I find it pretty intuitive. The fact that it integrates with the MiniDSPs is pretty cool too. 

I feel like the more I read about testing the less I know. At least I have a calibrated mic.. 

I'm still glad that I'm going this route - I'm enjoying learning. I picked up Dr. Toole's book "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" which has been a fun read so far.


----------



## penngray

Yeah, its nice to move the gating on the IR and see how it changes the FR plot. HOLM has one screen that shows everything. It shows distortion/phase overlaying the FR. You can easily do up to 3 different measurements, showing the summed response.

Its the best free measurement tool I have used for speaker design.


----------



## Zeitgeist

Progress! Need to do a couple more cuts, install bracing... primer some more... paint.. wire/install drivers...

OK, so maybe more than just a few more mins 

1. Partially completed cabs, 2 AE TD12S, 1 B&C8XCT. 
2. 4 more AE drivers, 2 more B&Cs.. 
3. Framing square. These speakers aren't small!

Please excuse the cell phone pics.


----------



## Zeitgeist

I bought a gallon of Duratex too. So have high hopes for a durable coating. I've used regular primer and some automotive primer (The auto primer seems to be a lot thicker).... even though Duratex says it's not required. I just figured it would minimize the amount that was soaked up by the MDF.

I keep chewing up the corners too, so I keep thinking about buying corner protectors from PE. 100-120 lbs isn't great for MDF corners. 

Maybe some day I'll do nice chamfered rear corners, but I can't cut angles accurately with the dreadful table saw I have now.


----------



## bambino

Nice project. On the chipped edge thing, have you tried round overs using a router?


----------



## Zeitgeist

bambino said:


> Nice project. On the chipped edge thing, have you tried round overs using a router?


You know, I haven't. I keep trying to come up with excuses on new router bits to buy. Perhaps I should round it over.

From what I can tell, almost all corner protectors need a 3/8th roundover to fit snug anyway.


----------



## bambino

Zeitgeist said:


> You know, I haven't. I keep trying to come up with excuses on new router bits to buy. Perhaps I should round it over.
> 
> From what I can tell, almost all corner protectors need a 3/8th roundover to fit snug anyway.


So there is your exuse, you need roundover bits for the corner protecters anyways so.....

I've gotten some great bits on ebay and amazon. i prefer freud bits of all others but there is several great brands out there.:T


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## Zeitgeist

I've had good luck with MLCS (http://www.mlcswoodworking.com/).

I'm sure that Freud bits are good though. You get what you pay for


----------



## bambino

Freud blades and router bits have been great to me over the years but i checked out your link and think i may have found somemore nice bits worth trying.:T As you said yo get what you pay for.:sn:


----------



## Zeitgeist

OK, some progress. Not as much as I wanted (thanks family!) 

Pics of how I ended up doing mid chamber, finished baffles, bracing, finished speakers (sans paint, drivers).


----------



## studiotech

Looking good! I think the chamber you made for the mid looks a little small. You are going to need to stuff it well with some bonded logic or similar acoustical cotton, not standard fiberfill junk. You want to really attenuate the rear wave for clear, precise sound.

Greg


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## Zeitgeist

Yeah, I realize the chamber is small. Part of it - is I wanted the rear of the horn - in the coax driver - to pass through the chamber. 

I have some OC703 that I was going to stuff in there to pretty much fill the dead space, and have some PE speaker gasket that I was going to use to seal it.


----------



## Zeitgeist

LCR woofer amplification.....done!
3 Emotiva XPA-1s, 1000w/4ohms each.

Now on to amplification for mids/tweets and MiniDSPs. I think 2 XPR-5s would fit nicely in there (2 5U amps with ventilation). Hopefully they're released next year.

And thank you Emotiva for understanding that 4U = 4U. Fits perfectly. Gear that doesn't fit properly bugs me. The blanks that are filling up the rack are just a smattering of blanks I've had sitting around. Some M/A, some generic, some mesh.


----------



## studiotech

Lots of power and pretty looking amps...I like! If I hadn't used the Digmoda stuff myself, I would have had a rack full of Emotiva gear too. Great stuff for a very fair price.

Your local home depot may have this stuff in stock:

http://www.homedepot.com/webapp/wcs...on;202710055-_-202709974-_-N&locStoreNum=6367

Or look here for a distributor near you:

www.bondedlogic.com

I use the 4" stuff myself.

Greg


----------



## Zeitgeist

In hindsight I might have gone the Digmoda route (or SpeakerPower since they're selling some to the public now) --- because good amplification takes up loads of space and needs lots of cabling. Should look pretty awesome though! And provide lots of flexibility if my long term plans change.

Some people talk smack about Emotiva which I don't always get. No product is perfect but from a technical performance point of view the Emotivas seem to hold their own (even compared to gear costing 2-3-4 times more)

You speak so highly of the bonded-logic stuff - I'll have to check it out! I see the HD page says online only - but in my experience that doesn't mean anything. Does the bonded-logic (denim insulation) perform better at HF absorption than rigid fiberglass? or do you prefer it because it's easier to fill a cavity? I have a couple scraps of 2" 703 so just curious.


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## studiotech

If you believe the absorption coefficients on their site, it absorbs just as well if not better than rigid fiberglass, does not leave a nasty, itchy crumble behind and can be wedged in anywhere. We have used it in all speaker projects for the last 2 years and all over the place at the studio. I also have it in all of the panels in my listening room.

I just realized that I posted some picts of it on the third page of my open baffle thread. You can see the thick stuff inside my servo subwoofer tubes.

Greg


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## GranteedEV

studiotech said:


> If you believe the absorption coefficients on their site, it absorbs just as well if not better than rigid fiberglass, does not leave a nasty, itchy crumble behind and can be wedged in anywhere. We have used it in all speaker projects for the last 2 years and all over the place at the studio. I also have it in all of the panels in my listening room.
> 
> I just realized that I posted some picts of it on the third page of my open baffle thread. You can see the thick stuff inside my servo subwoofer tubes.
> 
> Greg


This appears to be the same Ultratouch stuff that Bob from CSS sells, so its use in speaker cabinets is not unprecedented. :sn:


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## Zeitgeist

I'll have to stop by HD. I found that the closest distributor is Menards - which it looks like all they carry is 5 roll batts -- which is more than I need. I'd buy it - but I don't have a good place to store that volume of insulation! I've read about it before - I just figured that by now it would have gained some more popularity in terms of easily finding it.

I'm not crazy about 703/705 anyway so happy to look for something else.


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## studiotech

GranteedEV said:


> This appears to be the same Ultratouch stuff that Bob from CSS sells, so its use in speaker cabinets is not unprecedented. :sn:


Well, now that you mention it, I have a whole bundle left over from my projects. Pieces are 2'*4' and 3.5" thick. I'll sell off a few if anyone wants some. $20 per piece plus whatever shipping comes out to. Bob's is only the 1/2" stuff.

PM me if interested.

Greg


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## Zeitgeist

studiotech said:


> Well, now that you mention it, I have a whole bundle left over from my projects. Pieces are 2'*4' and 3.5" thick. I'll sell off a few if anyone wants some. $20 per piece plus whatever shipping comes out to. Bob's is only the 1/2" stuff.
> 
> PM me if interested.
> 
> Greg


I've actually talked myself into stopping by Menards and maybe buying the huge package. I always seem to be building big projects -- so probably makes sense to just keep it on hand.

I was planning on doing 1lb polyfill per 1 cuft in the sealed woofer chamber. You think that makes sense? I'm probably going to have to try different fill percentages with freq sweeps...

I just started rethinking whether lining or filling made more sense - when I was thinking about the bonded logic... although I know common logic is sealed=filled, ported=lined.


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## Zeitgeist

I'm now the proud owner of a ton of bonded-logic/ultratouch insulation. It's 80 sq ft of 3.5" insulation (8 batts total!)

Should be perfect for the EVX-180B subs I want to rebuild.










I found out that Menards only started carrying it 3 days ago.. nifty!


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## studiotech

Excellent! How much does Menards get for that bundle?

Greg


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## Zeitgeist

It was $60? Didn't seem like a bad price considering the huge volume.


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## studiotech

! That's quite a bit less than we are paying directly from a construction supplier. That IS a good price! Got no Menards down here, too bad.


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## Zeitgeist

Sounds like with the green-building boom it should become more and more accessible. The Menards here only opened a couple months ago - I had never been in one/seen one.

Glad to hear it's a good price - for anyone else who's looking for it. Thanks for recommending it.


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## Zeitgeist

I have the cabinets painted - all but bottoms. I used Duratex - which I have to say is sweeet! I used roller grade -and it's the perfect consistency. Sticks on anything and holds it's shape. I used a 4" foam roller - and maybe I should have used a short nap roller instead to get a smoother coat. It has some texture - which I'm cool with too. I couldn't decide if I wanted it very smooth or a little texture!

Since these speakers are going to end up behind an AT screen (eventually) - and going to be moved around a little bit - durability is important to me. Duratex seems really tough. I'm a fan of the durable-functional black appearance - perhaps because I'm partial to pro-gear.

Absolutely going to use Duratex on my future sub builds. Low VOC and water clean up... and quick curing too!


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## studiotech

Duratex is great stuff. Used it on those studio monitors. Nice, even loss gloss finish.

Make sure you've got a really sharp pair of good scissors or fabric shears for the insulation. It can be a real PITA to cut.


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## Jstslamd

Buy a cheap electric turkey knife they are incredible when cutting things like that. Second would be a bread knife


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## Zeitgeist

Jstslamd said:


> Buy a cheap electric turkey knife they are incredible when cutting things like that. Second would be a bread knife


I actually already have one from the last time I bought one for cutting fiberglass for a super-chunk trap. Should be fun!


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## nottaway

Those look "catalyzmic"...... 

*edit made typo


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## Zeitgeist

Obligatory cabinet and driver shot (something like $2500 worth of drivers. weeee!). I think that the AE drivers totaled around $1700 and the 8CXTs were about 800 total. The one on the right has some insulation in the mid chamber, I ended up using less because it wouldn't fit well. Used PE speaker gasket material to try to give a good seal to the coax drivers.

And the finished speakers. The one on the left soaked in quite a bit of the paint, it's barely noticeable - but looks pretty glaring in the picture. I need to fix that. touch up the paint on the baffle near the woofer too. In the back is 2 recessed Neutrik Speakon connectors (1 for woofers, 1 for Coax). I'll get a picture later. 

The cabinet weight w/o drivers is 54 lbs. I imagine with drivers, it's up around the 110-115 lb mark. Going to weigh later - now that they're assembled. Takes a few minutes to drill pilot holes for 72 holes and get screws in.  EDIT: Weighed... 108.9 lbs each. 

You might notice that the dust caps on the L/R speakers are slightly bigger. John didn't have the identical dust-caps at the time that he was trying to ship those 4 out, and I was too impatient for him to wait to get them. I had a hard time waiting for the drivers (sorry John!) but I have to say the build quality on the AE drivers is awesome. I felt like I was hiding them by putting them inside a wood cabinet.

Other ramblings:
Electric turkey carving knife on that Bonded-Logic insulation..... didn't work whatsoever! Really surprised me. I actually wondered if I put the blades back in the carver correctly. 

Next on the to do list is buying some MiniDSPs - then some more amps. By the time this project is done, it's going to be in the ballpark of Catalysts - but it's been fun. Can't wait to get all the gear and get it done.. then next on my list is to give Mark some of my business (I can't resist the Submersives. too cool).

Planning on 3 Emotiva XPA1s (1000w into 4 ohms)) for woofs, likely XPR-5 for mids (400w into 8ohms) and a UPA-7 (125w into 8 ohms) for tweets.

Unfortunately didn't have the cabling I needed to fire these up to play yet! I have a JBL analog 3-way cross-over, but it's all XLR. I ran 1 speaker with it a while back for a few minutes - but i can't bring myself to use the old Crown amps that I have right now (No DC protection). So its either get XLR/RCA cables to use the crossover for a week or two -- or just wait for MiniDSPs and do all RCA.


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## studiotech

Sweet dude!

Why not just used the Bonded Logic in the woofer chambers too? After all, you bought the big bundle. Maybe you can use a bunch a room treatment...

Greg


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## Zeitgeist

studiotech said:


> Sweet dude!
> 
> Why not just used the Bonded Logic in the woofer chambers too? After all, you bought the big bundle. Maybe you can use a bunch a room treatment...
> 
> Greg


Thanks!

I might - I had 2 storage tubs of poly-fil (10 lbs of it) that I took out of a 8cuft sub that I'm going to rebuild - so I figured why not use it? (OK, so part of it was trying to keep from storing 2 huge tubs of poly-fil). I'm going to have to tweak the stuffing when I get around to EQing/measuring - so I might go that route. 

I'll have to do some testing to compare results from poly-fil and bonded-logic. I almost wonder if the bonded-logic might be too dense.


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## bambino

Nice work man they look great!:T Just a thought and something i did with my EMO mono's was take off the alluminum trim pieces on either side of the amps and reinstall the screws, promise you'll like the look and they'll match your build perfectly and make the EMO's much cleaner looking.:T


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## Zeitgeist

bambino said:


> Nice work man they look great!:T Just a thought and something i did with my EMO mono's was take off the alluminum trim pieces on either side of the amps and reinstall the screws, promise you'll like the look and they'll match your build perfectly and make the EMO's much cleaner looking.:T


I might do that. Right now i have the XPA-1s sitting in another room (not the HT room)... so not super concerned about cosmetics quite yet. I'll have to take em off and see what it looks like, I've read that others love the look too - but I'll need to see it first hand.


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## Zeitgeist

Well, purchased 3 MiniDSP Unabalanced models.

Unfortunately, I thought that the 2v input translated to 2v output, but it doesn't. It attenuates 2v down to .9 regardless of the input sensitivity (selectable between .9 and 2v). So, Despite the typical input sensitivity of 1.5v of Emotiva gear, the .9v output doesn't quite cut it.

Which is........ frustrating.


----------



## Zeitgeist

Looks like gain probably won't be an issue. I FINALLY had a chance to do my first frequency sweep today and look at the levels for each driver. I had the mid apparently set WAY too low. Once I corrected that, the sweeps and overall gain looked much better. Pink noise sounds correct too (doh!)

Next up is going to be doing some sweeps on individual drivers so that I can EQ their individual response, then adjust crossover points. I can also do some overall EQ which is pretty cool. The MiniDSPs are extremely flexible. 

Right now, I think I have 500/3000 as crossover points with 48/db LR types.

I think even with the gain limitations, I can still hit 120db (which is crazy loud)


----------



## GranteedEV

Zeitgeist said:


> Looks like gain probably won't be an issue. I FINALLY had a chance to do my first frequency sweep today and look at the levels for each driver. I had the mid apparently set WAY too low. Once I corrected that, the sweeps and overall gain looked much better. Pink noise sounds correct too (doh!)
> 
> Next up is going to be doing some sweeps on individual drivers so that I can EQ their individual response, then adjust crossover points. I can also do some overall EQ which is pretty cool. The MiniDSPs are extremely flexible.
> 
> Right now, I think I have 500/3000 as crossover points with 48/db LR types.
> 
> I think even with the gain limitations, I can still hit 120db (which is crazy loud)


3000hz sounds way too high for the 8" B&C. I'd wager it's operating into its breakup and starting to aggressively narrow directivity. Drop that down to as low as the tweeter can handle cleanly at your max SPLs - IMO.

48db/oct also sounds a bit high for the mid/woofer crossover. I think you'll get better coherency with something like 2nd order @ 300hz - to start. The overlap will help smooth the blend between the drivers.

Don't forget to time delay the coax as its voice coil isn't as deep as the AE woofers.

Make sure all your drivers are well in phase - take a good look at the reverse nulls. If it's not deep enough that's IMO a big problem.


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## Zeitgeist

I have no idea why I was using 3000. I never intended to set it that high. I've been planning on something closer to 1800-2000. I'd have to look at the B&C spec sheet again. I think I was just playing around with the MiniDSP software (disconnected)- and set that without thinking. I had a feeling that 48 db/oct was way too high as well for the mid/woofer. I've struggled with the mid/woofer point as well. I'll try 300. I was originally thinking 400, but there has been no real science to that choice. 

I know that I need to adjust the delay in the coax.. Need to decide by how much. Not sure where the horn is in relation to the woofer VCs as well (might need to look at some drawings -- or do some measurements). I looked briefly at phase in REW and it looked wonky. I know that's going to need a little work.

Thanks for your suggestions, I know I have a lot of work to do - but glad that I'm FINALLY getting to the fun stage.

It's so nice to be able to make changes with MiniDSP and hear the changes in real time. Currently have the XPA-1 driving the woofers, and 2 channels of the UPA-7 driving mid/tweet -- seems to be a workable solution for the time being.


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## Zeitgeist

Here is what 300/24db and 2000/48 db looks like in MiniDSP


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## GranteedEV

...is that factoring in the acoustic transfer functions too?...otherwise the lowpass on the bass looks way off with -6db @ 100hz... double check every filter being applied on the woofers every step of the way. barring acoustic behaviour they should be -6db @ 300hz (and maybe less if they're filling in the baffle step)...? I would import the gated in-baffle measurements into miniDSP's software for starters.


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## Zeitgeist

GranteedEV said:


> is that factoring in the acoustic tranafer functions too?


Nope.. not yet.


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## Zeitgeist

GranteedEV said:


> ...is that factoring in the acoustic transfer functions too?...otherwise the lowpass on the bass looks way off with -6db @ 100hz... double check every filter being applied on the woofers every step of the way. barring acoustic behaviour they should be -6db @ 300hz (and maybe less if they're filling in the baffle step)...? I would import the gated in-baffle measurements into miniDSP's software for starters.



Gah. I'm hopeless today. I must have had something set wrong when I took that.

I'm planning on importing the measurements later - once I get the individual drivers tweaked a little bit. I really wish that you could import FR data for EACH output/driver, rather than FR for the single input. Would make EQing each output much easier (since you can EQ both the input and the individual outputs).

Today was the first time I've really had a chance to do individual driver sweeps and look at it for more than a couple minutes. I realized that my laptop sound card is *terrible*, but thankfully had a USB one that performs much better with a calibration. I keep tossing around the idea of getting a serious sound card that's flat without calibration.

Anyone happen to know what the best measuring distance is? I know 1m is common for sensitivity measurements but not sure I've ever read a recommendation for measuring FR.


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## Zeitgeist

I know I'm pretty much talking to myself, but I can't help but laugh.

I was looking at some sweeps and starting to question the reliability - so I started looking at the sound card loopback calibrations. The internal laptop audio was something like 10-12 db +/- from 20hz-20khz. The iMic that I had kicking around is +/- 7db. 

Time to shop for a USB solution with flat response... Was looking at the E-MU 0404.

I love this hobby. It's like every purchase leads to 10 more.


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## GranteedEV

Zeitgeist said:


> Anyone happen to know what the best measuring distance is? I know 1m is common for sensitivity measurements but not sure I've ever read a recommendation for measuring FR.


It has to be far enough away for the drivers to acoustically sum properly. 3m would be recommended but room reflections begin to dominate heavily. Try 6ms gated 1.5m measurements.


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## Zeitgeist

Yeah, I figured it was exactly that. Need the drivers to sum. I feel like the acoustics in my room are terrible (I need to add more broadband absorption). so I'll need to find some compromise between 1-3m. 

I've been using REW. What would you recommend for gated measurements? I know that REW allows a gate width setting (default of 500ms). I believe other alternatives are ARTA and HolmImpulse?

I've been planning in getting up to speed with HolmImpulse, it's just a little less user friendly.


----------



## GranteedEV

Zeitgeist said:


> I've been using REW. What would you recommend for gated measurements? I know that REW allows a gate width setting (default of 500ms). I believe other alternatives are ARTA and HolmImpulse?


It's the first roughly 5 to 10ms are what form our timbre/clarity perception, though bass takes longer to properly sum (which is why the 500ms window is fine for bass). Beyond that 10ms window, there's still some perception of balance that we hear that is introduced by the room. REW at its core is a room program so it uses a long gate but I think it's still fantastic either way. I do like the ability of ARTA and Holm to do polar contour maps though. 

Anyways we know that if the nearest boundary is x distance away from the speaker/mic it will take (2x) / 340m/s for the reflection to arrive at the mic. 

We also know if the mic is y distance away from the speaker it will take y/340m/s for the direct sound to arrive. 

So in REW the "left window" should be less than y/340m/s (to make sure the mic is capturing all the direct sound) 

The right window should be near or less than (2x + y)/340m/s (to make sure the mic isn't capturing too much reflected sound). 

The difference between the windows is your gate time and so IMO it should try to cover somewhere between 5 to 10ms because for a crossover that's the region we're concerned with. 

The crossover shouldn't try to fix the room, though it should try to minimize the audible effect of speaker's interaction with the room (the power response)

If the nearest boundary is 1m away, you can do a 5.6 ms gate and still get accurate results at least down to the cutoff frequency. (Frequency Resolution in REW). Generally the floor bounce will still manage to leak into the measurement. You can choose to ignore it or put your crossover there to maximize/smooth out its excitation. Up to you.

All of the above may be wrong.:whistling: :clap:


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## Zeitgeist

GranteedEV said:


> The difference between the windows is your gate time and so IMO it should try to cover somewhere between 5 to 10ms because for a crossover that's the region we're concerned with.
> 
> The crossover shouldn't try to fix the room, though it should try to minimize the audible effect of speaker's interaction with the room (the power response)
> 
> All of the above may be wrong.:whistling: :clap:


Thanks for your explanation. I've never heard gating explained so well! Makes perfect sense now. lddude:

I'm just trying to address the drivers themselves, and trying to keep room interactions totally separate. The mid/tweet response of the 8CXT is a little ragged. If the weather wasn't so nasty I'd probably be trying to do this outside (Still planning on doing it in Spring).

I figure I'll let Audyssey Pro deal with the room itself addle:


----------



## Zeitgeist

Zeitgeist said:


> Well, purchased 3 MiniDSP Unabalanced models.
> 
> Unfortunately, I thought that the 2v input translated to 2v output, but it doesn't. It attenuates 2v down to .9 regardless of the input sensitivity (selectable between .9 and 2v). So, Despite the typical input sensitivity of 1.5v of Emotiva gear, the .9v output doesn't quite cut it.
> 
> Which is........ frustrating.


I was apparently wrong about needing the extra output. I've done some SPL calculations and played with a voltmeter quite a bit. I calibrated to 75db - and played some content that peaks up (I think) around 0dbfs. Needless to say, I can hit frightening output levels without clipping the MiniDSP (thanks to the sensitive gain structure of the amps, sensitive drivers, etc). 

I played the shoot-out from Open Range a few db ABOVE reference. I'm glad my neighbors didn't call the cops  It was peaking somewhere above 100db.

I should be getting a Tascam US-122mkII in the mail tomorrow so I can get some accurate sweeps. Supposed to be pretty flat (http://www.ab-weblog.com/en/usb-audio-interfaces-with-good-frequency-response/). Hope it wasn't a bad choice. I might have bought an M-Audio if I wanted to spend some more money, but FR looks pretty good with this model.


----------



## Zeitgeist

So, very happy with the Tascam. Accurate to within +-.5 db. Using it with Cross Spectrum labs calibrated EMM-6. I've done a boat load of sweeps and learning a lot. I've been alternating between REW and HolmImpulse. 

I was leery of HolmImpulse for a while - due to lack of understanding, but I'm feeling much better about it. I understand why so many people like using HolmImpulse. I love the fact that you can change the gating on the fly and see the FR. Very powerful software, now I just need to get around some of the quirks that I've run into. When I do sweeps of the mid or tweeter sometimes the phase is just a squiggly mess. Almost like feedback. Not sure why. Right now I have the drivers time aligned based on the VC distance. I've compared some impulses as well, and they seem to be almost dead on. 

Crossover is set to 400hz and 2000hz. I got smoother response with 400hz instead of 300hz.

I've also used REW quite a bit, once you know what gating you want, it gives very good results. Very comparable to HolmImpulse.The ability to EQ, tweak it and dump it into biquads - and import into MiniDSP is unbeatable. I started using a pair of super-chunk traps I built on the left/right of the speaker and some OC703 above it - which did a remarkable job taming reflections. Makes gating a lot less important. (Building an anechoic chamber would be so sweeet, albeit super costly). I'm planning on doing some outdoor testing in spring. 

From 100hz-10khz, I think I have it pretty close to +- 2db. Looks VERY good (to me anyway!). I haven't paid as much attention to 10k-15k, looks pretty close though. The FR of the tweeter is a little challenging - since it's all over the place. 

Finally got to do some actual listening and thrilled so far. Going to upgrade mid amplification to Emotiva XPR-5s if they come out. It would result in XPA-1 for woofers (1000w), XPR-5 for mids (400w) and UPA-7 (125w). Right now I have 1000w (XPA1) for woofers, 125w (UPA7) for mid, 125w (UPA7) for tweets. It's overkill, but I love it. Even with 3750 watts on tap, running normal content is only around 100w. Not much. 

Planning on building 4 smaller MTM surrounds w/Dayton RS225s and 8CXTs. Hopefully next year. Another 11 drivers to buy.
Might eventually upgrade to MiniDSP 2x4 balanced to get the extra gain - but somewhat low on the list right now.

Enough of the techy talk and buy buy buy.... On to the enjoyment part!


----------



## GranteedEV

> The ability to EQ, tweak it and dump it into biquads - and import into MiniDSP is unbeatable. I started using a pair of super-chunk traps I built on the left/right of the speaker and some OC703 above it - which did a remarkable job taming reflections. Makes gating a lot less important. (Building an anechoic chamber would be so sweeet, albeit super costly). I'm planning on doing some outdoor testing in spring.
> 
> From 100hz-10khz, I think I have it pretty close to +- 2db. Looks VERY good (to me anyway!). I haven't paid as much attention to 10k-15k, looks pretty close though. The FR of the tweeter is a little challenging - since it's all over the place.


The only problem with what you're doing, is that some of the on axis dips and peaks might be related to the coaxial.. things like the reflection off the mouth /axial holes/ diffraction/. These are things you don't want to equalize IMO. If you can get rid of them acoustically that's preferable. The big thing is to see what's going on not only on axis but off axis. It might be a 4db broad dip on axis but actually "clears up" @ 30 degrees maybe. In these situations you need to recognize that and kind of "pretend" it's flatter than it is. This is where shooting for flattest possible response on axis might not get you the best results.

Generally there's a few different measurements i'd recommend taking... 

0 degrees.

0, 5, 10, 15 degrees on/off axis averaged both vertically and horizontally (listening window - obviously most important because the most power is focused on axis). Focus on general trends and getting resonances out of the drivers' passbands. Bare in mind the coaxial might create some response issues and try to identify them specificially.

15, 30, 45, 60 degrees off axis (starting to gradually lose radiated power so it shouldn't look as flat, but it should give you signs of any mistakes you might have made EQing the on axis response... watching out for ugly peaks (or nulls I suppose) off axis caused by your EQ filters... it might make some frequencies "jump out" off axis Not flat (because there's less power compared to on axis, especially above 10khz) but nothing that stands out as bad frequency response either. The dispersion is a big factor in the subjective soundstage/Tonality. It should help you analyze your crossover a bit too. IMO, even though we call "on axis" the listening window, 15 to 30 degrees tends to more closely represent the "listening window over our two ears most of the time. Toe in is another factor of course. Some speakers sound best NOT toed in. IMO a speaker's 45 - 60 degree behaviour tells a lot about how it sounds.


~75, 90, 135, 180 degrees off axis - this should start to look pretty attenuated at this point, at least above 1.5 to 2khz or so where the 8" cone is narrowing directivity and modulating the tweeter off axis response. If there's a spike at any frquency it might be work making note of.

Also remember 100-400hz or so is dominated by the room.... You know as well as the rest of us how annoying the room can be so it would be best to measure this general region at the averages of the seating positions instead. Also a good argument for 2nd order acoustic slopes in this region... throw as many different sources at the room as you can.



> Planning on building 4 smaller MTM surrounds w/Dayton RS225s and 8CXTs. Hopefully next year. Another 11 drivers to buy.


Rather than the 8CXT, what are your thoughts on the KEF Q900 coaxial? 

http://reconingspeakers.com/products-page/pro-audio/kef-8-q900-coaxial-driver/

Tweeter Frequency response'll be a lot easier to pull off... be done passively as long as you hit the metal cone breakup. For a surround I would do a single 8" woofer only however in order to maximize dispersion... Pity that Audiotechnology drivers are so pricy because that would be my choice


----------



## Zeitgeist

Thanks for the recommendations on looking at response at various angles and comparing EQ at those angles. I've seen plenty of graphs of off-axis performance - but never really considered EQing based on the off-axis performance. I know that the room dominates down low - which is why I've not spent too much time worrying about those frequencies. I'm sure that the FR will look very different with the speaker in position.

I think the FR and quirks of a coax more or less require a DSP for EQ. That's been the most surprising thing for me - especially when comparing extremely flat performance of some tweeters.

I'd like to become more proficient with HolmImpulse, but I'll need to do some more reading... 

I've barely had a chance to listen to my current settings for more than 5 minutes, so I'm planning on enjoying some first - before I get back into measurements and possibly tweaking the fill in the coax chamber.


----------



## GranteedEV

Zeitgeist said:


> Thanks for the recommendations on looking at response at various angles and comparing EQ at those angles. I've seen plenty of graphs of off-axis performance - but never really considered EQing based on the off-axis performance.


Treat it as a wholistic approach. :sn:

On axis should of course be as flat as possible - but don't EQ things that will mess up/are filled in by the off-axis response. Your crossovers - both frequency and slope - will also affect off axis response both vertically and horizontally. That also applies to driver integration. If you think at any point your ears can hear a shift from one driver to another, then you're probably too aggressive with the slopes... if the drivers aren't very similar in character then you'll hear the difference between them without enough overlap... If the off axis response at any point seems to "pinch" or "bloom" you might be crossing over too high, or too shallow. 

Taken as a whole - on and off axis and plenty of other stuff - you will end up with a speaker that radiates sound evenly into the room, where the soundstage seems somewhere behind and outside the speakers, with dynamic contrast between nothingness and every note, truly never drawing undue attention to anything, yet never muting anything that's there... with a calm but definite instrument placement that feels real, tight accurate powerful bass, and sweet extraction of almost every last detail... :T


----------



## runitca

Zeitgeist said:


> Thanks for the recommendations on looking at response at various angles and comparing EQ at those angles. I've seen plenty of graphs of off-axis performance - but never really considered EQing based on the off-axis performance. I know that the room dominates down low - which is why I've not spent too much time worrying about those frequencies. I'm sure that the FR will look very different with the speaker in position.
> 
> I think the FR and quirks of a coax more or less require a DSP for EQ. That's been the most surprising thing for me - especially when comparing extremely flat performance of some tweeters.
> 
> I'd like to become more proficient with HolmImpulse, but I'll need to do some more reading...
> 
> I've barely had a chance to listen to my current settings for more than 5 minutes, so I'm planning on enjoying some first - before I get back into measurements and possibly tweaking the fill in the coax chamber.



Hi Zeitgeist,
I am thinking about trying to build a passive version of your speaker but can't seem to be able to get the AE TD12S I was just wondering if you considered any other drivers for this application? Any help would be greatly appreciated . Thank you


----------



## Zeitgeist

Building a passive version would be difficult with a B&C 8CXT and most woofers. The varying sensitivities and frequency response make it very difficult to integrate.

For the 8CXT:
(LF) 94 dB, (HF) 103 dB 1W
For the TD12S (this is assuming 2 TD12S):
96.4 dB

It might be possible to build a passive crossover, but it would require some wizardry. The 8CXT's response is far from flat.

I'm using a MiniDSP to EQ the wacky FR.


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## sub_crazy

The HTS Newsletter is great, without it I would have missed this build completely.

Awesome work Jim, any updates?


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