# 7 speaker home theater DIY project with active crossover...would love discussion



## cobyh (Jun 7, 2006)

I’m currently in the process of figuring out the replacement/upgrade for my living room home theater setup. 



The room: I’ve got a 9 ft wide screen I’m projecting onto, hanging from the ceiling. The screen is about three feet from the back wall, and directly above a halfwall about 3.5’ high (there’s a stairway heading downstairs behind the screen). Acoustically, the room is really, really bad. Vaulted ceiling (peak perpendicular to line of sight to screen, thankfully), open to kitchen and dining room to left, open hallway to bedrooms and bath on right, huge volume to fill, assymetrical reflecting surface profile. The living room area is about 15’ x 25’; the back wall has a fireplace in one corner and a baby grand piano in the other, so the seats are ahead of those. Currently, I’ve got a set of Acoustic Research 312HO’s as mains, with an AR center and little bookshelf AR’s as surrounds. There’s suckouts in the room and the bass has serious nulls in various places and the waf of room treatments isn’t high, but I’m working on that. (luckily she wasn’t too upset with the 7 foot tall 24” diameter subwoofer…but she doesn’t like her miniature piano collection flying off the shelves in her music studio several doors down because of the vibrations…that kinda annoyed her when they broke).



The project concept: I want to have 7 identical speakers (sonically anyway) in the living room, and they don’t have to have extension below 70hz because they’ll be crossed over into the sub. 

Some of the constraints include:

1. Form Factor: there’s about 12 inches below the screen and above the halfwall, and it’s right around ear height when seated for a movie. The part of the speaker with the drivers needs to fit in that space. 

2. Output: Lots of it. Design goal is to get to 110db cleanly. I like dynamics. I like something that sounds good low AND high. The AR’s were good for that, with a high sensitivity, but the towers just don’t fit into the layout for the room.

3. Cost: Like most folks, I’m not made of money. So, >$1000 per speaker is out. I’m trying to get under $300 per speaker if possible for materials, not including amplification.

4.  Clarity: I’m looking to use drivers that are quick, and to minimize anything that’ll make them muddy

5. Voice intelligibility: I’ve heard that crossing over in the 300hz to 3600hz range is to be avoided in a setup that does a lot of HT, however, it’s tough to do a 2way without violating that rule. And for the #3 criteria, a 2way is more attractive. 

6. Dispersion/Sweet Spot: I’m looking to have excellent off axis response so that more than one person can have excellent imaging for movies and multi channel music. This also makes it tough to do a 2way.

7. Phase coherency: A must. I want this acoustic lens to be sharp. 



Current direction for the design: Unless I go with three centers across the front, it’s almost impossible to satisfy the criteria stated above, and using centers on the walls to the side and rear is impractical. So, I need to roll my own, as it were. I’ve looked and looked and looked at various DIY designs, and one thing has become apparent…it’s silly to go with passive crossovers. With the Behringer DCX2496 as inexpensive as it is, active electronics is the best fit to the criteria. So…we’re going active. I’m planning on some fairly nonstandard enclosures as well. 

1. Active crossover: Using multiple DCX2496’s for the seven speakers. Either 3 if 2ways, or 4 if 3way design is chosen. This will buy me phase coherency, time alignment, 48db/octave slopes, static and dynamic equalization, EQ profiles for various recordings, and the ability to iterate changes to the crossover to decide on best voicing. Downside is massive amount of time spent dinking with it, and the learning curve for using it. Cost is about a wash; good crossovers (passive) are similar in their cost per speaker especially if going with a 2way setup, where I can use one DCX per three speakers. If I’m able to implement one of my secondary goals (keeping the signal digital from source to amplifier…hard to do inexpensively) then it’s only 2 speakers per DCX, as that unit has one stereo AES input. Also, this solution will enable me to get a fairly flat FR in room, instead of just anechoic, which is important given that my room isn’t ideal by any means…

2. Enclosures: 12” diameter, probably 18” long (driven by driver requirements), and haven’t decided between sealed or vented. Won’t tolerate large group delay numbers, and will likely go sealed, but not locked into that yet. The cylindrical enclosure will be capped by wood on either end, and will have a tube either coming out the bottom with a 90deg mandrel bend the diameter of the woofer or normal to the surface of the tube. Tweeter (and mid, if 3way) will be mounted on a ring faceplate around the tube holding the woofer and be rotateable to accommodate various orientations of the main enclosure tube. I’ll model it in Pro/E and put up pics if anyone’s interested and can offer criticisms. Risks of standing waves will be mitigated. Material for tube will either be aluminum, pvc, cardboard (sonotube) or carbon fiber…haven’t looked into resonance yet.

3. Amplification: External, likely several 7 channel amps



Questions….man, I’ve got tons of them as I work through this exercise. Here’s a couple I’ve got right now that I’d love some feedback on:

1. Driver selection and orientation- I’ve looked at Peerless, Vifa, Hiquophon, Dayton, etc., etc. If there’s a two way setup that’ll work well, then that’d be my first choice. I just don’t know if that’ll work well…I need to settle that aspect before I can move on. And do I do dual woofers with the tweet in a 2way? Can I get away with a single woofer? Where do I put the crossover point….with the steep filtering the DCX provides, can I get away with putting that crossover point in the critical human voice range and not suffer deleterious effects? How about some open ended discussion on this?

2. Amplifier selection-I won’t need an uber expensive amplifier rack, as the load will be resistive due to the use of the active crossover. I’d love the LPA-1 from Emotiva if the last amp wasn’t split. Grr. For the tweets, I was thinking of something like a Panny receiver run in direct mode; they won’t need a ton of current to drive to high volumes cleanly. What are some suggestions for 7 channel amplification for low cost, given the modest requirements?



Once I settle on the drivers and layout, I can proceed with the rest of the design. I welcome any discussion on it; whether it’s in relation to the two questions posted, or anything else in the project described above. Thanks!



I may post this in several of the forums dedicated to DIY speaker design as well, so I apologize if you see this more than once. I'd love some discussion and feedback on this if you've the time.


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## F1 fan (Jul 6, 2006)

Wow coby , it sounds like you want to build a very serious and complex system.I thought I was getting carried away by running fully active LCR's but you want 7 active channels.I can say from expirience that great gains in dynamic capabilities are possible when going with the active approach for the front 3 channels.But IMO it is not worth the effort or expense of doing active surrounds.

If I understand correctly you are limited vertically at 12" ?You might want to consider building a horizontally oriented 3way WMTW or a WCW using the SEAS COAX driver.( See discussion on AVS about this idea someone is considering).
The SEAS unit is nice because it has a controlled vertical and horizontal directivity which helps dialog intelligability as well as stereo imaging ,also the woofer and tweeter are time aligned regardless of listener axis,and with appropriate xover design the off axis response will be very good.All in all it is a great driver choice for HT.
Anyway thats my $.02


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## cobyh (Jun 7, 2006)

I don't think it's all that much more complex than one with passive crossovers and I think the gains will be worth it, especially for 7 ch music. Tell me about your LCR setup; what was used, why, problems you ran into, design goals.... Which components did you use? (drivers, active crossover unit, signal processor...)

I'll look at that Seas unit...right now I'm leaning towards a TM in a vertical orientation, and I'm up in the air on something like dual 6.5's for woofs arrayed horizontally under the TM, or a 10 or 12" woof on the side of the TM array. The Morel mid is looking attractive, though it's pricey.


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## F1 fan (Jul 6, 2006)

Here is an updated list of my setup and my almost completed centre channel. 

http://www.hometheatershack.com/forums/home-theater-equipment/1830-my-ht.html#post13925 

http://www.hometheatershack.com/forums/diy-speakers/2800-active-center-channel.html#post30271


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## cobyh (Jun 7, 2006)

Ok....interesting setup. For curiosities sake, why did you choose to crossover as low as you did to the tweeter? Also, the active crossover you used...those are analog? 
And where are your woofers in relation to the MTM setup you've got for the center channel?


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## F1 fan (Jul 6, 2006)

I crossed the tweeter over at 2k for a couple reasons.

1. It has much better dispersion at 2k than the 6.5" midwoofer so the combined system off axis response will be better than if the xover was placed higher.

2.The midwoofer has some roughness in its response above 3k so the lower xover point and steep 24db slope will mean these irregularities will be much reduced in level.

Yes the active units are pure analog.I knew the exact xover response (slope and frequency)I wanted to achieve so other than level adjustments the need for tweaking crossover points etc.was not a necessity.
Also I like the fact that the signal stays in the analog domain instead of being sent through different stages of A-D and D-A conversion.But I will add that the Behringers are absolutely wonderfull units for those who want to do alot of tweaking.

Im now mixing the bass below 80hz of the center channel with the LFE subs.


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## reed.hannebaum (Apr 21, 2006)

Coby,

If your goal is to create an "acoustic lens", then you probably want to use identical amps all the way around, or at least amps with the same circuit design. As I am sure you know, the phase/frequency response of amps can vary widely.


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## cobyh (Jun 7, 2006)

reed.hannebaum said:


> Coby,
> 
> If your goal is to create an "acoustic lens", then you probably want to use identical amps all the way around, or at least amps with the same circuit design. As I am sure you know, the phase/frequency response of amps can vary widely.


Absolutely. Intention is identical amps exactly for each level of driver, for all 7 channels. I'd love to use something like the Emotiva LPA-1 if it was actually a 7 channel amp instead of a 6 channel with the last channel being able to be a stereo amp at a much lower wattage. 

I'm just starting the search for amplification. These will not be hard units to drive, since there will be no passive crossover. A rack of Audiosource amps might be an affordable way to go for the mids and lows, and still not sure about the tweets yet. Suggestions? I'm trying to keep the amplifier budget between $1500 and $2k tops...hopefully less. I"ll be scouring Ebay.
Gain control and balanced inputs would be a bonus.


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## cobyh (Jun 7, 2006)

F1 fan said:


> I crossed the tweeter over at 2k for a couple reasons.
> 
> 1. It has much better dispersion at 2k than the 6.5" midwoofer so the combined system off axis response will be better than if the xover was placed higher.
> 
> ...


So you're extending the mids down to the 80hz point and then rolling off to the subs for a 3 way instead of a 4way?

Can you hear the difference if you crossover above 3500hz or well below it, in human voices? I guess if you match the dispersion, phase and have a flatish FR, you shouldn't be able to tell the difference, right? Life would be easier if I could live with a 2way (3way when the sub is taken into account)


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## F1 fan (Jul 6, 2006)

cobyh said:


> So you're extending the mids down to the 80hz point and then rolling off to the subs for a 3 way instead of a 4way?
> 
> Can you hear the difference if you crossover above 3500hz or well below it, in human voices? I guess if you match the dispersion, phase and have a flatish FR, you shouldn't be able to tell the difference, right? Life would be easier if I could live with a 2way (3way when the sub is taken into account)


It is only with the center channel that I let the midbass drivers extend down to 80hz because it has 2 of them therefore it has the volume displacement to handle it.So yes when combined with the sub it would be a 3 way.

My main speakers have only 1 midbass driver so I cross it over to an 8" woofer at 300hz then the 8" passes off to a 10'' woofer at 50hz to make it a 4way.


Generally it would not be advisable to crossover a 6.5" midbass to a 1" dome tweeter above 2500hz because the off axis response will be poor due to the narrowing dispersion pattern of the cone as frequency rises or in other words it becomes directional or beamy.And yes if the system has poor off axis response it will be audible. 
A smaller diameter cone like a 4" or midrange dome could probably be successfully crossed over at 3600hz.

Most high performance 2way speakers on the market have crossovers that are well within the human voice range 1.8-2.5k so it is not a problem as long as it is done correctly.It depends on the actual drivers being used.


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## cobyh (Jun 7, 2006)

F1 fan said:


> It is only with the center channel that I let the midbass drivers extend down to 80hz because it has 2 of them therefore it has the volume displacement to handle it.So yes when combined with the sub it would be a 3 way.
> 
> My main speakers have only 1 midbass driver so I cross it over to an 8" woofer at 300hz then the 8" passes off to a 10'' woofer at 50hz to make it a 4way.
> 
> ...



Yea....I was assuming that poor offaxis response would be noticeable; I wouldn't try to use a 6.5" as a mid. I'm looking at the Morel dome unit right now as a midrange. My question was more along the lines of whether or not you could hear your crossover in that range; i.e., can you hear the effects of it when people are speaking through the speaker...

thanks for all the responses, btw


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## cobyh (Jun 7, 2006)

thylantyr said:


> You mentioned "The AR’s were good for that, with a high sensitivity, but the towers just don’t fit into the layout for the room."
> 
> If I understand correctly, you have space limitations and you want to build
> smaller speakers than those?


Sort of....I've got space behind the screen and halfwall; the enclosure volume can go there, or in between the drivers. I'll model up the enclosure I'm thinking of and post it; it'll be a lot clearer then. I'm pretty sure I can best the AR design by a LONG shot in terms of dynamics, power handling and especially dispersion, as the dispersion on the AR's was not what I'd call adequate.




thylantyr said:


> Have you considered building already published designs from cyberspace
> using passive crossovers?
> 
> You should examine designs from here to give us a better idea on what
> ...


Actually, I've been to all those sites, and more. And I've looked at every project once, twice, 10 times. Had my heart set on the 340SE's for a while, but there's just too many compromises. About the only way I can satisfy my criteria is to roll my own. It's frustrating. 

I'm really rather surprised that more folks aren't using active digital crossovers. As far as I can tell, they're comparable costwise with a good analog crossover, and have few of their compromises. Is it just that there's not as many folks out there already using them and they scare people? I don't get it....

Right now I'm looking at the Morel dome midrange for about $82 to do the bulk of the work, between 350ish and 3500ish, and the Dayton Quad 8" sub might work well for the 30 to 350 point, and I haven't decided on a tweet yet at all. One driver of each simplifies things a bit; I can likely do a vertical alignment of the TM and offset it's midrange center to the 2 Oclock position relative to the center of the 8" woofer. Any suggestions for a tweet (not a horn....I dislike the sound of those I've heard) that only has to do from 3500 up? 20k isn't even a necessity....my hearing goes to around 15k before almost completely losing the sensation (I'm 38). 


What are some of your experiences with the DCX? Are you bringing in signal digitally or through analog? Have you made use of the dynamic EQ options?


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## cobyh (Jun 7, 2006)

thylantyr said:


> re: $1500 - $2000 amp budget
> 
> If passive crossover loudspeakers.
> 
> ...


Those are way more power than what's needed. What I'm looking for is 7 channels of 50-100w at 8ohm for the tweets (which should be an order of magnitude more than I need), 7 channels of 125w ish at 8 ohm for the mids (also likely much more than I'd need), and 7 channels of 300w ish for 4 ohm for the woofer (adequate). The amps for the tweets and mids don't need to be designed for 2 ohm loads; in fact, one of the advantages of not using a passive crossover is that it creates very easy to drive speakers...I'd like to take advantage of that fact and not pay more than is necessary for this system. 

As far as many active crossovers....it'd require 4 DCX's for threeway all the way around and 3 DCX's if I went 2way all the way around. If I can find a pre/pro that has digital AES out, even better, though then I'll definately have to do 4 DCX's. The DCX can be had refurbed for $200....which is $100 per speaker for an active digital crossover. Definately not the major expense here. The amps are what make it pricier....but should provide gobs of headroom for 'effortless' dynamics (btw, I'm not a fan of flowery speech, hence the quotes)

Right now, the Audiosource 5.1's from Ebay look like a good deal for the tweets, and I think I can get 7 channels worth for less than $500 (possibly less than $400 but I doubt it. For the mids, either the Emotiva monoblocks or the Audiosource 5.2's or 5.3's. For the low end, the Emotiva 7ch or the Outlaw Audio 7ch units might do well. 

Are there some good pro amp monoblocks I should be considering? 

Love the pro amps as compared to the consumer amps...and a class D amp would probably work great for the woofer channel. I'm using a Mackie M-1400 bridged at some 1400watts for my LLT sonotube sub right now; worked out great.


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## reed.hannebaum (Apr 21, 2006)

cobyh said:


> Absolutely. Intention is identical amps exactly for each level of driver, for all 7 channels. I'd love to use something like the Emotiva LPA-1 if it was actually a 7 channel amp instead of a 6 channel with the last channel being able to be a stereo amp at a much lower wattage.
> 
> I'm just starting the search for amplification. These will not be hard units to drive, since there will be no passive crossover. A rack of Audiosource amps might be an affordable way to go for the mids and lows, and still not sure about the tweets yet. Suggestions? I'm trying to keep the amplifier budget between $1500 and $2k tops...hopefully less. I"ll be scouring Ebay.
> Gain control and balanced inputs would be a bonus.



If you go 2-way at say 100 Watts/ch @ 8 ohms then you are talking about $1.40/watt. This is not very much. You definitely want to look at good used equipment and don't overlook professional equipment; its usually more band/buck, but you may have to put up with fan noise. I have a Carvin DMC600 that I use to drive (bridged) my sub and it works great. I bought it used/mint for $200 => $1.25/watt @ 8 ohm. It has great specs, gain control & balanced inputs, and the fan is very quiet. When I first got it I tried it on my main speakers and it sounded great. With a 100 db S/N this amp is quiet as a church mouse. Also, it runs very cool, so I keep it in a closed cabinet and no heat problems.


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## reed.hannebaum (Apr 21, 2006)

Sorry, I just now noticed your post above. You are obviously aware of pro equipment. I agree with your comment of relegating class D equipment to low frequency assignments. I may be old school, but I can't help but believe that the switching noise of those mosfets would result in listener fatigue.


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## cobyh (Jun 7, 2006)

First off...thank you for the time you've all put into this discussion; it's greatly appreciated. It's a somewhat largish project.

Driver selection...definately one of the first things I'm agonizing over, and a decision that is complicated by the fact that I've not heard 99% of the drivers I'm contemplating buying. Complicated further by the fact there's no way I *could* hear the drivers, together, in the configuration I'll end up putting them in, and in my particular room. That being said, I'm going about it the best way I know how...reading reviews and opinions, sifting through them, looking at the compromises made, and relating it to my own experiences. That being said...

You asked what was the best sound I've heard. So far...a set of Final Sound electrostats, last year at CEDIA (it's in Denver so I took off four days and was there from the time they opened to the time they closed). They were simply gorgeous. Clear, sharp....stunning. And I like tight bass...fast, clean...sealed designs usually. However...this room is primarily home theater for more than just one person. I'm saving the 'real' clear setup for my audio room in the basement, which I'll begin planning the build on later this year. So, one of the big things I've been trying to keep in mind is dispersion, which is why I'm leaning more and more towards a 3way system.

I know I don't like horns. I have heard dome midranges before and didn't dislike them, though I've not heard the Morel midrange itself. The LDSG gave a thumbs up to that particular driver, and I like the specs...it's small (2 1/8, if I remember right), has excellent off axis response, would work well from 500 to 3500, and has high sensitivity as well as power handling. In fact, I'd like all three components to have above 91db sensitivity, if possible, and I think it's possible. Am I married to this midrange? No....if a cone will do, and go a little lower (say to 300) but still have good characteristics at 3500, I'd be happy...just haven't run across one yet that struck me. I also like having the mid and tweeter come with their own enclosure...the enclosure I'll build should be for the woofer only.

As far as as skimping on amps....come on. Most amps are expensive for several reasons...they have to drive a wide variety of impedences. They're an order of magnitude cleaner than is audible. They've got this or that fancy only useful in the marketing world function...blah. I have auditioned a few amps over the years...most of them are unnecessary given how they're used. Headroom; big power supply...definately worthwhile. THD improvement from .010 to .001....no. I don't hear that. 
I'm not talking tube amps; I want more power than that. But really....how much energy is needed for ear bleeding crystal clear sound from 3khz on up? 5 watts? That much? 
I've wondered about using one of the Panny class T amps as the 7 channel tweeter amplification....might not be a bad idea, and not too expensive. Don't know if they've got a direct path through to the amp though...need to research.

Good point on the volume for the digital out. I can't even begin to put the energy into the pre/pro until I at least have the drivers sorted out and the design begun. I'd like to settle on something and then pick up a DCX and the drivers in question, enough to make one speaker that I can listen to and play with. Should minimize risk a bit.


Why do you like tweeters that have to go down that low? (2k) What's the basis for the crossover point preference? 

How is the DAYTON QT255-4 10" QUATRO SERIES SUBWOOFER 4 OHM...been looking at that for the lower end reinforcement. Crossover with something shallow around 300, run it sealed and eq it flat. Possible? Not adviseable?

What are your recommendations for true mids? (not mid woofers)

And what was that last post referencing? I got a bit confused...don't recall seeing the post you were quoting from?

BTW, I've been looking at some of the stiffer material for cones for exactly the reason you mentioned...I like the fact you can get a nice steep slope with the DCX without some of the negative traits that are introduced with passive crossovers. This makes the stiffer coned drivers more attractive as a solution, as well as the ones that require notch filters for nasty li'l spikes in their FR graph.


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## cobyh (Jun 7, 2006)

Oh, and I'm familiar with monoblocks....first one I used was over 20 years ago. I didn't mention them for name dropping...just for the fact they were coming across as some of the lowest dollar for watt deals I've been able to see yet, for quality units. And dual monoblock design couples the power supply to the individual channel, so the two channels don't share a power supply. Not a huge deal, usually, but it can have an impact. Can't do much if you're limited.

Just took another look at the MPA's from emotiva....they're two channel units that are 75w at 4 ohms, not 8. And I'm not sure from their specs if they can drive 4 ohms when bridged. 

Right now the Audiosource and the Marantz monoblocks are looking to be good deals. I'll keep looking though.


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## cobyh (Jun 7, 2006)

you wrote: If it's a 3 way design, that implies tweeter, pure midrange [not midwoofer],
and woofer(s), either a couple of 8" - 10", single 12" - 18". Problem with this
design is that there are only a few good pure midrange candidates and I know
of one vendor that makes great product. The next obstacle is to find a woofer
solution that plays well up to ~ 300hz because pure midrange drivers lack bass
extension unless you port the midranges. I'm fond of a certain 15" woofer
design that do this job well, hard to source these drivers as they are hand
made by one person. They come in 12" and 15" size. There are some
alternatives, not as good, but might cost more, lol.

my comment: I think this is true only if you're thinking of a fullrange speaker. Technically, these aren't necessarily fullrange speakers. The intention is to cross over all channels to the sub, so I'd like to go down to the 50-60hz range cleanly for a bit of overlap, but really, anything lower is icing on the cake, and unfortunately it's very expensive icing. Finding a woofer than can go down to 80 flat with some content in the 50-60 range doesn't seem to be hard at all but trying to get a 12" to do up to 300-400hz without beaming does seem like a challenge...hence the crossover points that I've been thinking of.

I've got a big sub and I'm prepared to use it. (grins) :devil: 

As an aside...what's the story with the Davis drivers that it seems that PE used to carry but doesn't anymore? Any history on that?

BTW, I have looked extensively at the Dayton drivers...seem to be a really good deal and they've certainly got a following.


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## cobyh (Jun 7, 2006)

Any diy'ers that are in Colorado that wouldn't mind letting me listen to their system? I'm north of Denver in Loveland. 

I'll definately return the favor once this project is near completion. (I'm an engineer...very few projects are truly 'complete')


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## cobyh (Jun 7, 2006)

Excellent info...I'd been pretty attracted to the PHL lineup and the additional info on them is priceless.

What if question....been looking at a lot of WMTW cc setups. What happens dispersion-wise if you brought the W's together side by side, as close as possible, and then mounted the TM vertically arrayed centered between the woofs, obviously above them, but as close horizontally as possible? I'm picturing it looking rather like a small willy on a couple of huge balls, basically...I think I might be able to fit that in the space allowed, and if I'm correct, should limit problems with spacing for the woofs and not limit horizontal dispersion quite so much....right?


Still haven't decided on a tweet...read through all the Zaph tweet stuff earlier tonight, including the HD graphs. That's a wonderful thing he did, btw; much appreciated. 

The vifa ring radiator looks interesting, and has a following. I'll explore more of the drivers you just listed and see how they could work out. Thanks again for the typin' time.

(ps....I just avoided crackin' a joke about designing a speaker that'd remind me of our President...but I think I hurt my wrist pattin' myself on the back for it):jump:

(pps...my wife just told me she'd prefer I didn't make 7 speakers for the living room that resembled male anatomy.)


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## cobyh (Jun 7, 2006)

Line arrays....would love to do one; definately not in the plans for this problem. If I can do it as a twoway I can come up on the budget per speaker, since I won't have the additional $100 to $200 per speaker it'd cost for the amplification (minimum). I'll look and try to find some drivers that could work. 

Remember, one of my firmest criteria is the form factor...picture three big center channels across the front, and similiar drivers for the sides and rear (but those can be oriented more vertically. I'm picturing using aluminum tube...like a 20" long 12" diameter for the woofer chamber. (I know...resonant...that'll be addressed). I've got access to a waterjet table and full CNC mills and lathes, and possibly a complete carbon fiber shop (need to talk to the shop manager and see what kind of access I can get).

Here's a couple of pics (if I can get the posting a pic part right):

btw, the enclosure1.zip is not a zip. rename the extension from 'zip' to 'edrw', then you can view it with eDrawings (there's a viewer available on the web for free). It's a pretty handy li'l tool.


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## cobyh (Jun 7, 2006)

Here's some shots of the room. Don't mind the mess; all the electronics just got relocated and the new PJ went in. Most of the electronics will be housed in the basement, so amps with fans on them are no worries. You can see part of the reason I need some oomph...it's a huge area to fill, and I took the shots from inside the dining area, which isn't shown, as well as the pass through kitchen.

Note the area between the screen and the halfwall. That's thankfully about ear level when seated. I have to fit my drivers there. The chamber can go behind it, either on it's side, or behind the screen pointing upwards, or downwards...there's some options.


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## cobyh (Jun 7, 2006)

Ah, I'm glad you brought that up, though I think you might be looking at his example of a circular baffle, where right now this has no baffle other than the edge of the driver itself. I can emulate the spherical transition pretty easily with this, without changing the enclosure design at all. That was an informative site; I'd bookmarked it some time ago, with respect to baffle effect. It's part of what is driving this design concept.

RE: art....I'm not about art. I'm really a function over form kinda guy; these will likely offend the sensibilities of a few folks. I'm just hoping my wife'll buy into them.

One advantage of this type of enclosure design lies in the fact you decouple the baffle design from the enclosure. As is, there is no baffle. The case that produces the most ripple is a circular baffle; these don't have any baffle to speak of; just the driver's edge itself, and the effect from the other drivers in close proximity as well as the effects from the screen above and the halfwall below. However, with this design, you can change the baffle out at will, since it's separate from the enclosure. Picture a baffle with a star pattern centered on each driver, or some organic shapes....I can make several of them and then test to determine it's effect on the FR. ****, we can even tailor the FR curve acoustically, at least on paper, by swapping out various baffle designs. They'll attach to a ring around the driver tubes; flush mount, change a coupla screws and Bob's your uncle. Material can be changed for the baffle as well, since with access to a waterjet table, I can quickly cut out complex designs in just about anything (except MDF...those don't like water too much. Go figger..)

If I have some extra time tonight I'll model up what I'm talking about so it's more apparent. I'm expecting a much smoother curve than from a rectangular baffle, since a cylindrical housing is nearly ideal, but I'm betting it'll change quite a bit once it's in place. Another consideration I had was building one continuious baffle across all three front speakers (LCR) and mounting the screen onto it so it's flush, and fairly flush with that halfwall below. Then I have one baffle that's 9 feet long and 10 feet high or thereabouts, and contigious with the floor on the bottom and within inches of the angled ceiling on the top. I'm a bit scared of how that'd sound; that's basically an inwall application.

Some other advantages of this enclosure design are
1. Less in the way of standing waves
2. Much lighter weight to acheive the same rigidity
3. Very little in the way of panels that are acting as transducers 
4. Easier for fabrication (at least for my situation)
5. Can be made very durable


I've been looking at 2 WR125ST's as a midrange, crossing over around 2800 with an XT19, with a 10" woofer to handle 60 to 400-500. Two 8" woofs might be a better choice but a single woof simplifies construction and affords more configurational options for the wall mounting of the other 4 speakers (surrounds, r,l,rears)
Thoughts on that? I'm concerned about getting them to the 110db mark cleanly, but I need to start modeling drivers and see what at least looks good on paper.

Positioning the tweeter under the midrange as shown....most alignments I've seen have it above the mid. I've seen some that have it below. I'm assuming there's some effect, possibly directing the HF at a slight downward angle if I did it as shown? (from the boundry reinforcement of the driver above it). Is that correct?


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## Guest (Apr 11, 2007)

Coby,
d I am in a similar boat as yourself, although I don't expect to make up my mind on anything soon. I have too many other honey-do projects to complete before I get to play with building speakers.

I too am amazed at the lack of active designs that have been published for the DIY.

I am currently looking hard at implementing an active crossover for one of the TMWW 3-way designs using Dayton RS drivers at HTGUIDE, or doing my own active crossover on a GR-Research AV3, which is a 2.5-way speaker. Some the RS designs on HTGUIDE give you the individual driver crossover functions, so all you have to do is implement those!

After reading a ton about this, it appears that the biggest sonic benefit in going active is in separating the woofers from the rest of the speaker, and an active between the mid and tweeter doesn't buy much over a passive corssover. However, if you are going active anyways, especially if you are going to build your crossover with discrete opamps (my plan), you might as well do the whole thing.

I keep waiting for a GR-Research design that uses the new M-165X driver in a 3-way design. Perhaps I'll just email Danny there, explain what I'm planning on doing, and see what he suggests. He's great about that sort of thing from what I've read.

At any rate, good luck in your quest, and I look forward to reading about what you end up with. The only difference between the two of us is in our speaker size limitations - I intend on building 7 towers, with the center tower being perhaps smaller to fit underneath a future screen. I'm curious to see how well this works out, and how easy it is to implement a good design, or at least a new implementation of an existing proven design.


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## Guest (Apr 11, 2007)

> Active designs don't really need to be published because they are so flexible. You can mismatch
> drivers on purpose and still come out sweet. Everything I do is all active, it's too easy to get
> great sound if you know how to turn knobs and use your ears
> Today 2:50 PM



I suppose that's true. But it wouldn't take that much work to write down someone's optimal settings for their crossover design. Discrete implementation would be very cheap too. The entire design cycle would be much quicker than for a passive crossover as well.

If I ever get to the point where I'm going to build 7 identical tower speakers, I will undoubtedly buy a 2496, or whatever the rage at that point in time. But hopefully, I'll be able to use that to translate the optimal crossover settings into a discrete Op-amp design that can be replicated less expensively. Maybe I'm really in a minority by wanting to do DIY active AND build my own boards and amps!

Well, if I ever get there, I'll be certain to document the journey - there has to be someone like me around!


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## cobyh (Jun 7, 2006)

thylantyr said:


> 110dB[c] spl goal. From what distance? What frequency range?
> It's easy to hit higher SPL from those 1m reference points but harder to do
> from a greater listening distance. It's easy to hit those numbers with bass,
> but it becomes harder to reach playing midrange and even harder with
> ...


Sorry, I thought it was obvious; I meant 1 meter away, and full frequency of course. The one meter measurement is the only one that gets published with any consistancy; it would be a bit hard for manufacturers or other DIY'ers to publish numbers of spl levels experienced in my Lazyboy, and I don't think my wife would like the constant stream of people coming into the house bearing drivers to do that test. 

I disagree with the comment disregarding the 3/4" dome tweeters. They fit my criteria better; the dispersion is more uniform and they're more effective crossed over higher than you like. If I remember right, the XT19 is around 91db efficient, crossed over at 2,500, and with my crossover being a tad higher than that, I doubt it'll be more stressed than that test case. 

Anyhow, I'll see if I can round up a couple for the test speaker and see what it sounds like. What else is out there that's similiar to the CSS WR125? A bit more efficiency would be nice, but the distortion and off axis performance looks great.


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## cobyh (Jun 7, 2006)

ssabin said:


> I suppose that's true. But it wouldn't take that much work to write down someone's optimal settings for their crossover design. Discrete implementation would be very cheap too. The entire design cycle would be much quicker than for a passive crossover as well.
> 
> If I ever get to the point where I'm going to build 7 identical tower speakers, I will undoubtedly buy a 2496, or whatever the rage at that point in time. But hopefully, I'll be able to use that to translate the optimal crossover settings into a discrete Op-amp design that can be replicated less expensively. Maybe I'm really in a minority by wanting to do DIY active AND build my own boards and amps!
> 
> Well, if I ever get there, I'll be certain to document the journey - there has to be someone like me around!


I think the other aspect is folks can find tons of material on passive designs from those in the know and basically ride their shoulders, whereas there's nowhere as much as on designs using active crossovers and that's intimidating. It's new (well, not really) and it's not readily apparent how easy it is, or how inexpensive. I don't think most folks would shirk at the idea of spending $70 to $100 a speaker for a good quality crossover, and you can do the DCX for that much these days. But they don't know that...Need pictures and screenshots and stories and cost analysis of finished projects and test results....there's just not much out there. You can help with that. 

I love the what if aspect of it....I want to hear for myself what the numbers mean; I want to change things and just listen. Good stuff...:R :T 

Love your idea of building your digital active crossovers yourself. What kind of cost per speaker (threeway) do you envision?


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## Guest (Apr 12, 2007)

> Love your idea of building your digital active crossovers yourself. What kind of cost per speaker (threeway) do you envision?



I'm thinking, $10-20 per speaker is attainable for the active crossover for a 3-way, depending on how much is needed. Probably a bit more if you have to also figure in a power supply per speaker for the amp and crossover, but that's more allocated cost, and depends how all the electronics get packaged.

I used to design Bessel filters for accelerometer data processing on combustion engines, and although I haven't done that in quite some time, it doesn't seem like it would take much to put together a cookbook of active filter designs using op amps all in a single Excel workbookl. Just plug in the target frequency and spit out the resitor and cap values. To keep it simple, just have seperate sheets for different types of designs (LR2, LR4, BW2, BW4, etc). Throw in an all pass stage and some baffle step compensation, and designing the thing would be pretty straightforward. Not only that, but 1% resistor tolerances make it easy to ensure the frequency points are right where you want them. The speaker designer could pluck out which stages are necessary and have a complete crossover done. 

I still think you'd want a more flexible active crossover to get through the design stage, but once you're there, go discrete!


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## cobyh (Jun 7, 2006)

thylantyr said:


> I still don't see your vision exactly. Your CAD drawing shows tweeter, ~ 5" midrange,
> and dual ~ 7.5" woofers. Is the large tube airspace for the 7.5" drivers or is this another
> isolated chamber for the 10" woofer(s)? If so, this is a 4 way module ?


Don't worry about the driver arrangement in the drawing; it was something created in about 10 minutes to give a general idea of the enclosure and a possible option, and to help you understand that a 6 foot tall tower of drivers won't fit here. Dual 8's, a 5" mid 'n a tweet under 3" for outer flange isn't what I'd hoped for...if I can do it with a single woofer and use a mid and tweet that have their own chamber, life's easier. But that'll be what it'll be. what part of the criteria are confusing? I can restate some of it...it's a 7 channel equal amplification, equal speaker system, direct radiating, +/- 3db from at least 80 to 18k hz (lower is nice, higher is probably entirely unecessary), low distortion (linear and non linear, harmonic, im), excellent! dispersion characteristics for a wide and clear soundstage, using active digital filtering and eq'ing, and able to produce the same tonal quality across all 7 units while conforming to at least two distinct packaging requirements (lcr vs the 4 onwall units). That leaves quite a bit up in the air, I know, but as decisions are made more will be nailed down. Part of the reason I'm leaning towards a threeway is dispersion related...much easier to have consistant dispersion characteristics with three sizes of transducers across that frequency range. 

BTW, all of these speakers actually will be four way's....all will be rolled off to a LLT sonotube subwoofer using a single Avalanche 18" driver. But each individual unit will be a threeway on it's own.

Any of ya'll readers have any experience with the CSS WR125?


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## Guest (Apr 12, 2007)

thylantyr said:


> If I gave you $250 to mimic a DCX in performance and build quality, it's hard to do.



The whole point is that once you are done using a 2496, you really don't need all of that flexibility. $250 is a lot to some folks for the crossover function for a pair of speakers. Most of use here are focusing on speakers pairs, but the OP and I are thinking about 7 identical speakers.

I'm not saying I am right and you are wrong, but despite the increasing value and power in modern DSPs, there is still a (shrinking??) place for DIY electronics too.


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## cobyh (Jun 7, 2006)

ssabin said:


> The whole point is that once you are done using a 2496, you really don't need all of that flexibility. $250 is a lot to some folks for the crossover function for a pair of speakers. Most of use here are focusing on speakers pairs, but the OP and I are thinking about 7 identical speakers.
> 
> I'm not saying I am right and you are wrong, but despite the increasing value and power in modern DSPs, there is still a (shrinking??) place for DIY electronics too.


I think you're dead on with your assessment. You're in a unique position though, with the comfort level of designing your own setup, and if you come up with something good you can contribute to the other folks that are willing to melt some solder but aren't comfortable with the design process. Could save some bucks for a few folks, and give that satisfaction that comes from sayin' "I built it". Not to mention, if you document your project, it'll provide some understanding of the process and awareness of it to a LOT of people.


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## Guest (Apr 17, 2007)

How are you getting along on this, Coby?

I've been doing some thinking about this more and more, and am really intrigued about these speakers: http://www.gr-research.com/kits/ob-5.shtm

If one were to design and build their own active crossover, you save a lot of cash on the passive crossover parts. Driver cost would be less than $200 per speaker, and you'd probably be able to get some discount if you bought 7 speakers worth of drivers. The enclosure design looks like a TL design, although it only extends to about 45 Hz for F3. I considered making my own bass box and use the M-165X drivers from GR instead of the two M-130-16s, but I wonder if it would be worth it. I've heard that the quality of the bass from TL enclosures is superb, even if the extension numbers look rather ordinary.

For amps, get two of these:
http://www.outdoorspeakerdepot.com/pgmuam.html

Even if you bought 4 DCX2496s, that would be less than $4K for 7 nearly full-range OB ribbon speakers!
And you could always spend more on the amps for the front channels, at least for the bass cubes.

That's where my mind is going now, but I won't be building for awhile. Maybe somebody will try this. Maybe I'll just get the full passive kit myself someday, who knows.


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## Guest (Apr 17, 2007)

cobyh said:


> Any of ya'll readers have any experience with the CSS WR125?


I have played a lot with the CSS drivers. I picked up 16 a few months back and have built a number of different designs. Last year I built a couple of speakers that use them too.

What do you want to know?


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## cobyh (Jun 7, 2006)

ssabin said:


> How are you getting along on this, Coby?
> 
> I've been doing some thinking about this more and more, and am really intrigued about these speakers: http://www.gr-research.com/kits/ob-5.shtm
> 
> ...



I'm makin' slow but steady progress. Been researching drivers till my eyes have poppped out. I've also been looking at some different cad packages; it looks like Soundeasy is worth the buy, but folks have complained of it's non linear approach. However, it does integrate with the DCX well, from what little I've read. 

Right now I'm narrowing down the midrange choices, since that's the driver that'll determine the woofer 'n the tweeter (even though someone else keeps saying to start with the tweeter...that doesn't seem to make sense, since there's much more to choose from in tweets than there is in midranges). On the radar most prominently is two B&C mids...first off, the 6NDL38

6NDL38
Nominal Diameter 170 (6.5) mm (in)
Nominal Impedance 8 Ohm
Minimum Impedence 6 Ohm
Nominal Power Handling 150 W
Continuous Power Handling 300 W
Sensitivity (1W/1m) 92 dB
Frequency Range 70 - 6000 Hz
Voice Coil Diameter 38 (1.5) mm (in)
Winding Material Copper
Former Material Kapton
Winding Depth 12 (0.5) mm (in)
Magnetic Gap Depth 6 (0.25) mm (in)
Flux Density 1.15 T

and second from BC, the 6MDN44
6MDN44
Nominal Diameter 170 (6.5) mm (in)
Nominal Impedance 8 Ohm
Minimum Impedence 6.5 Ohm
Nominal Power Handling 150 W
Continuous Power Handling 300 W
Sensitivity (1W/1m) 96.5 dB
Frequency Range 150 - 6000 Hz
Voice Coil Diameter 44 (1.7) mm (in)
Winding Material Aluminium
Former Material Glass Fibre
Winding Depth 9.5 (3/8) mm (in)
Magnetic Gap Depth 6 (0.25) mm (in)
Flux Density 1.45 T

The first plays lower and has lower efficiency, the second isn't as low, but very nice efficiency. NO idea how the distortion is...I'm trying to find that data. If you might know someone that's tested it, let me know? I think it's worth getting some samples in to test.

I'm also interested in that WR125, but that efficiency is sooo low. I was thinking I could put two in a vertical array and mount the tweeter on top, and have the lower unit with a passive rolloff for the higher freqs, then have the woofer on the side. They're cheaper, and that bullet is just so phallic. (grins).

I'm still interested in going up to at least 3k for the upper crossover, and use a 3/4" dome tweet. Alternately, I'm dreaming up how I can do a oblate spheroid waveguide but still maintain close spaceing between the acoustic centers of the tweet 'n the mid. I really like that idea. I'm going to check into some contacts and see if I can get some time on a rapid prototyping machine. I think I can emulate the waveguides that are gaining favor now and shape it such that the woofer intrudes into it a bit, shaping the polar response a bit in the process. 

The physical layout is taking more shape as well. I think I'm going to make a 9' wide front panel and connect the screen above to the half wall below. I'm contemplating using a TC Sounds 1000 sub up front for the 100 'n below info, and I'm considering using only two for the three channels. I think I can set it up such that the left uses one, the right uses the other and the center uses both of them up front. Then for the rears I'll use one sub for each pair of speakers. It's a thought. I'm not sure how that'll affect localizeability; it'll depend on how low I cross over. I'll still use the Atlas Ava 18 for the really low stuff. It excels at that. 

Next steps...I'm bidding on a set of amps on ebay right now, for the tweets...might just get away with a bit of a steal. I saw that amp you posted; I think I'll be alright with using something like 7 a500's for the woof 'n mid, depending on which drivers I choose. That makes the overall amplification around 
$140 per speaker (three amps per speaker) which is ludicrously cheap for decent power. Of course, someone will probably drive the price up on this auction at the last second, and the country will experience a sudden dearth of a500's, or my driver choice will require 1000w per channel....never know.
Todo: order in one of those B&C drivers, or both, and likely at least one more. Settle on two or three tweets to try. Find the woofer. Buy my mic and make some noise. Measure it...

My basement is unfinished...or more accurate, partially finished. The walls are all framed out and have fiberglass between the studs. However..no sheetrock up yet. It's DEAD acoustically down there. Sounds weird...outta be good for doing measurements. I've told the wife we can't finish the basement till I get this done.


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## cobyh (Jun 7, 2006)

hardman said:


> I have played a lot with the CSS drivers. I picked up 16 a few months back and have built a number of different designs. Last year I built a couple of speakers that use them too.
> 
> What do you want to know?


How low are you running them, and what kind out output can you get at the levels you're tuning to? How's the distortion? How's the beaming at the upper ranges?


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## cobyh (Jun 7, 2006)

Oh, and on the subject of the planers 'n ribbons....I've liked what I've heard before (maggies 'n a pristine set of Final Sound...stunning) but the dispersion and the distortion scares me. I feel more comfortable going with a dome tweet of decent output. I'd like to experiment more with planars or ribbons in the future, for my 'audio' room, but for this I think I'll stick with domes and possibly experiment with waveguides. I'm not even sure about doing the waveguide experimentation right now; it's a big enough project without it.:duh:


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## Guest (Apr 18, 2007)

cobyh said:


> How low are you running them, and what kind out output can you get at the levels you're tuning to? How's the distortion? How's the beaming at the upper ranges?


When you say “how are you running them” I assume you mean how have they been implemented in the speakers? I have built the following speakers for other people, but I spent a good amount of time with each speaker prior to it leaving. Currently, I am working on some PC speakers that also use the WR125 that I am keeping for myself.

Exodus Audio 2641 and LCR which uses the CSSWR125 as a mid range. The WR125 is running about 700 to about 3000 in this design. See this link for more info on the Exodus Kits http://www.diycable.com/main/default.php?cPath=24_92 . SPL is not an issue with this desing.

I built a bipole MLTL using only one WR125 and a FR125 per speaker. This a great design if you want to see the amount of bass these babies have. While you can’t drive these speakers to supper high levels, they were able to carry their own in my 18’ X 20’ room. Side note…shortly after I built these speakers for my friend he decided he wanted a pair of the Exodus 2641’s and so he sold the MLTL's. To this day he still is trying to get back something he feels is missing in his current speakers. Just the other day he dropped of some Hemp Acoustic speakers in hopes of finding what he believes is missing in his current setup. If you can’t tell this guy is struck with the full range bug.

Recently I built a small 7.1 setup using WR125ST and FR125 drivers. I just posted a thread about this design the other day. See the thread for more details.

As you noted the efficency isn’t supper high on these drivers, but when implemented correctly they can hold their own. They have a very good midrange with less distortion than some of the other drivers out there (see www.zaphaudio.com site for some actual measurements on this driver).

Regarding beaming, I found I prefer about 3500 Hz. Originally, I did some testing at about 6000 Hz and I did not like the results. This is not to say that possibly someone with more experience than myself couldn’t pull off a higher crossover. I also don’t remember beaming to be much of an issue with the bipole MLTL, but it has been over a year since I listened to that speaker.

I am also aware of a line array that uses these drivers that is reported to be very good. I can get more info on this design if you are interested.

All in all I really like this driver. I plan to order more as I seem to almost be out of them.


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## cobyh (Jun 7, 2006)

Actually, I was asking how LOW you run them...what crossover freq you choose on the bottom end. (I do that all the time...read something quickly and miss a word that turns out to be key). I'm looking to crossover much lower than 700, if possible. And what kind of output levels are you getting with low tuning, or whatever tuning you're doing (at 1 meter)? 

My space is close to 8000 cu ft; the area they're in is open to other areas and there's a very large volume. Bass gets sucked up faster than a golf ball through a garden hose in the seedier side of town. And, I'm looking to build my 7.1 setup to have some real dynamics. 

I've looked at that exodus, and seen your thread on the speakers you built. Dipoles sound like fun but not something to give decent dynamics, at least affordably, from what I've read. I don't just want 'pretty decent for their size', I want, "Oh, my GOD, that car just blew up and there's something mushy in my panties". I want to hear the guns go off in the 1812 overture and feel my chest getting hit with grapeshot. I love passages that are soft and build into a serious crescendo that carries with it your emotions and whole soul. I want to FEEL like I'm only three rows back from the stage of a 135 peice orchestra. (I used to play in one...upright bass..I miss those days). 

So...yea....I'm trying to figure out how to get good spl without sacrificing purity in reproduction, while still maintaining excellent dispersion. Can two WR125's serve that up in midrange duties?

I saw Zaph's measurements; they looked pretty good. 

Some of Thy's suggestions have proved to be pretty decent so far, as well.


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## Guest (Apr 18, 2007)

Yup missed that one (LOW), sorry. To answer your question, no I do not think two WR’s will “leave mushy in your panties”. Will the WR reproduce good bass that mates easily to a sub, no problem, but not at 110 db? The pro drivers Thy recommended are good choices.

However, if I had your space and a big budget I would build these http://www.creativesound.ca/details.php?model=BETALS (yes it uses WR125 – a bunch of them) and then build some serious subwoofers (both sealed - music and LLT - movie).


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