# SDX15 - Quick Build - 5.5 Cu.Ft. Ported - First DIY



## Fishtank

After harassing Mark and Mike P. for a few weeks I decided to just go ahead and build something already. Mike tweaked my final crack at box design so I took it and ran!

I know next to nothing about subs, my previous subs were small commercial 8-10" subs, so I'm not even sure what to expect once I finally plug this in. I really just wanted to get something built, get my hands dirty and hear some results. If I have to tear it down and start over that's not really that much of an issue to me.

I wanted to build this quickly and easily... partly because I might be destroying it at some point to try again. I hope I do a good enough job to keep it, but we will see.

Build tools/material:
Table Saw
Router
Cordless Finish Nailer
Few different power sanders
7 - 2' x 4' x 3/4" MDF panels
Glue
1 1/2" 16gauge finish nails (might be a bit big)
Hurricane nuts/bolt set (have a question at the end about those)

Size etc:
25.5"h x 24"w x 25.5"d
5.5L
44" Port tunes to 18hz
3 db boost at 20hz
HPF at 15hz
Reckhorn B-1
EP4000
SDX15!!!

So I got started yesterday, I spent a bit more on the 2' x 4' panels because it gave me less cuts, and more straight edges, since I'm not a pro with the table saws.










Basically I just cut 3 boards in half, created the bottom/top, sides, 2 internal braces. Cut 3 board's to 25.5" for the 2 front plates, and the back, the rest of the bracing and ports comes from the left overs of those boards. Some trimming after the fact to get the boards flush because of the saw blade etc but wasn't bad.










Cut the center braces out with a router, put in the bottom 1/2 of the port.










Here you can see I have the back part of the port on, some more bracing. The bracing is pretty simple, I feel it will be more than enough, but we will find out!










Front view with the sides and bracing and ports in place.










Cut the center holes and port openings out with a router, and then routed all the straight edges. I will smooth out the port edges some more, however I liked the look of the straight edge router bit quite a bit.










You can't see it here, however the top is attached, and the sub bolt holes are drilled. The front isn't attached yet, neither is the back. I don't have a great router bit to countersink the sub... I couldn't bring myself to tack in that 50lb SDX15 into one piece of mdf and just run the 2nd piece around it. I didn't think of a good way to do it before I had the front boards together, so I decided to mount it on the outside. Sitting here tonight I've figured out a way to do it, so I will probably still sink the sub in 1/2 ", so it still gets 1/4" of the second piece of MDF.











So I'm about 10hrs into it, and I need to sort a few things out. I don't actually know how to wire it yet :dontknow:. I'm terrible with watt's etc. Would I wire the dual voice coils in series or parallel for best results with an EP4000? I don't see any reason to not wire it in series so it receives the 2000w @ 2ohms... that's what I've always planned on, however I thought I should float the question since I'm about to do it and I'm not 100%.

Also I gave a hurricane nut a go, but I was having some issues getting it to dig into the mdf it would slide in a bit and spin with the bolt... and I was stressed out about it splitting the mdf...there isn't a ton to work with there. Do you guys countersink the the hurricane nut? I can't see it just forcing into the wood... however counter-sinking the nut seems to negate the reason for it to have teeth... I was planning on countersinking them pretty snug and using epoxy as well... Is there a better way?



Thanks for any and all help... if you want to see how this came about check out the my "noob thread".

All questions and comments are welcome, if you think something is wrong let me know!

http://www.hometheatershack.com/for.../26227-looking-some-answers-css-products.html


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## mwmkravchenko

> Do you guys countersink the the hurricane nut? I can't see it just forcing into the wood... however counter-sinking the nut seems to negate the reason for it to have teeth... I was planning on countersinking them pretty snug and using epoxy as well... Is there a better way?


You already have a marking of the legs of the hurricane nut. So drill some small holes to let them sink into the MDF. Practice on some scrap and you will quickly figure out what size holes work best. Then when you have it all down use some polyurethane adhesive to lock them into place if you want. If your fit is tight enough you probably don't need adhesive.

Nice build. You won't be sorry with what you are building.

As for your amp and the wiring question you probably want to series. That's connecting to one coil and then jumping from that coil over to the other. Stick with your plan to bring out both coils into a bi-wire cup and you can do whatever you want from the outside.



Mark


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## ironglen

Nice job thus far:T

I just used hurricane nuts on my project- loved them. I practiced on scrap to find the following: I drilled a hole the diameter of the 'tube' outside diameter, that would allow the nut to fit flush with the material, snugly. I then drilled using a barely-larger bit to allow the outer flanges to fit, though they dug in and held. I then found the depth at which I need to drill that second, wider time to allow the flanges to fit nicely. I used a rubber mallet to smack'em into place addle: I didn't use glue, but that's probably not a bad idea, just be absolutely sure not to get it in the threading.

PE REALLY should give the bit sizes needed to do this in the package :foottap: (and I really should have taken notes to share:doh


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## Mike P.

Nice cabinet! As for wiring, are the coils 2 ohm? I can't remember.


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## mwmkravchenko

I had to look to!

1.8 + 1.8 Ω

So yep you most definitely have to wire them in series. I don't know of to many amps that will be happy into a 0.9 ohm load and cost less than a good used car!

Mark


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## Fishtank

mwmkravchenko said:


> As for your amp and the wiring question you probably want to series. That's connecting to one coil and then jumping from that coil over to the other. Stick with your plan to bring out both coils into a bi-wire cup and you can do whatever you want from the outside.
> 
> Mark


Awesome thanks, I was bouncing back and forth between just wiring it inside because I have 1 cup already with a single set of posts, I have to order a second one or a bi-wire cup and wait for the shipping... my amp isn't here until this weekend anyhow so I may as well wait it out I suppose!

Mike P. Yes they are 2 ohm voice coils. 

Edit: Also from what I've read today if I wire it in series which it looks like I have to, it's going to be at 4 ohms (or 3.6 to be exact I suppose).

Thanks for the tips on the Hurricane nuts, I know what you guys mean, just seemed a little counter intuitive to me a the time and I didn't want to shred any holes. If I had to rotate the speaker and redo holes, I would run into problems with how close the bracing is to the side of the speaker, the nuts wouldn't fit.


Another 2 questions, I was going to email the guys at CSS, but you guys may know. 

Is it a good idea to "break" a speaker in before i set it in the box? My friend has some spare 300w Carver amps sitting around i could use. I'm fine downloading some sinewave sweeps and all that, but if it doesn't actually do anything I don't really want to bother. I won't be playing this sub loud enough to properly push any boundaries in normal usage, so it may never get a serious workout while it's in the box... People seem to banter back and for with the pro's and cons so I'm wondering what you guys think.

Also I was planning on using some polyfill. After reading more, most people say it's not needed in a ported sub. To eliminate some standing/back waves people sometimes used Eggcrate foam, however lately it would seem that most people don't think it does very much. Which leaves me with fiberglass/rockwool. I'm not thrilled about using fiberglass or the rockwool in a vented enclosure...I picture millions of particles floating through my movie room! I can still quite easily put in some rigid fiberglass along the sides, even after the sub is built. So my plan right now is to use nothing...and then if I feel I need it I will try some rigid fiberglass. Is this ok or should I be doing something about this now?


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## Mike P.

The suspension will loosen up on most subs, you can break it in in free air or just use the sub when it's built.

As for lining the sub, try it first without anything and see how it sounds.


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## Fishtank

Mike P. said:


> The suspension will loosen up on most subs, you can break it in in free air or just use the sub when it's built.
> 
> As for lining the sub, try it first without anything and see how it sounds.


Alright, sounds good.

It sounds like I'm stressing out on minor details a bit too much!

I found a dual binding post wallplate for $12 in town at lunch, so I think I'm pretty much ready to finish this thing off tonight.

I changed my mind on counter-sinking the driver again for now. I read what I could find today, the decision really seems to be split on whether it's needed or not. The majority of people who said it was needed mentioned the frequency spikes came when you pushed the sub hard, lot's of people just seem to prefer the look.... So I decided to wait and see for myself.

I'm not going to finish the exterior of the sub until I know I'm happy with it, so if I need to counter sink it, I will still have the ability to do it without trashing the finish around the driver.

I had quite a bit of fun building this, I expect to be building another smaller box in the near future, then I will just move the driver over to hear for myself how a different build affects the performance.


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## mwmkravchenko

> It sounds like I'm stressing out on minor details a bit too much!


Hey make music not worries!

And yep you will get all the boom boom you want want.

as for the dual post cup. Well you could force some more power into the driver using your pro sound amp and a channel to each coil. But I doubt that you will ever need that kind of volume. Your gonna be a very happy camper!

Mark


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## Fishtank

I got a bit further through.

Again I changed my mind about countersinking, so I chewed up an hour and a half doing that. I didn't have a bit that I could just run around the outside edge, it wouldn't take enough off, and the one that does is over $100 at home depot. So I had to set up another jig to find the dead center of a 15" hole and then I ran around it twice with a larger cutting bit.











Then I got the front and back glued on without issue, and cut out the hole on the back for the binding post plate. I had to quit it was getting very dark. I have to do all of this at my friends house since I'm still in an apartment, and he doesn't have a shop. Construction is done other than routing down the top edge's from front to back. Hurricane nuts are in without issue, very tight, I also got a strip of the foam down for under the speaker bracket.










I'm pretty confident this thing is rock solid. I can't see any gaps, used a ton of glue and it's nailed solid. 

I have a bad nick in the port you can see, where I manage to lift the router a bit, but I should be able to fix that, other than that it should be pretty easy to sand this out and paint. I just used a matt black textured Tremclad paint on my stands, so I will probably go ahead with that. It matches my speakers almost perfectly. I will probably build a mesh grill to cover the entire front section that sticks out as well, I have a few easy idea's for that already.

Also the amp is ordered, I will have it on Saturday. Is it a bad idea to give it a try with my buddies 300watt carver? The only risk is the amp clipping and cooking the driver correct? If I'm careful to watch for it and I'm reasonable with the levels it should be fine right? If I'm happy with what I hear, and I think I will be I will finish it up this weekend.


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## mwmkravchenko

> Is it a bad idea to give it a try with my buddies 300watt carver? The only risk is the amp clipping and cooking the driver correct? If I'm careful to watch for it and I'm reasonable with the levels it should be fine right?


Yep and yep

No problem doing what you are talking about.

Mark


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## Fishtank

nice, I will probably turn it on tomorrow then!

And yeah, I don't need that much power to wire a channel per voice coil! I'm still planning on using the other half of the amp for some transducers eventually.


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## Mike P.

You should prime the box before you paint it as the end cuts of MDF really soak up paint.


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## bambino

Looks like away nice build, sure that is your first? I like that you decided to countrsink the sub a little even though it was a pain looks like you pulled it off quite well. As for your nick in the port with the router, if your gonna paint the sub just fill it with wood putty and sand it out you'll never see it or i like to use Bondo, seems to stick to the MDF better. Anyways your the only one that will know it's there (except for all of us shackers that is).


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## Fishtank

Mike P. said:


> You should prime the box before you paint it as the end cuts of MDF really soak up paint.


Ha yeah...I learnt my MDF painting lessons on some stands I built 2 weeks ago. My first stand was a painting nightmare, it was cold out, I used some cheap black oil paint as a first coat... it didn't settle at all. Globs/streaks everywhere...I sanded the out of it, to the point where the routed corners were bare again but most of the sides still had paint...then I went ahead with the $10 can of spray paint and the corners just drank it all in...while the sides looked great. Eventually it even's out with enough paint, but I picked a proper primer for my center stand and it worked much better.


As for the nick on the port bambino, I've never used it before but my friend has some "plastic wood" i was going to try. If it's no good I will try the bondo next.... because it will be the ONLY thing I see when I look at it if I don't fix it!


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## Fishtank

So I screwed in the sub(only 5 of 8 hurricane nuts took  ), wired it and fired it up.Sorry I was in a rush I didn't get any pictures, I'll grab some next time.

The countersink around the sub is so tight still i don't think the hurricane nuts are an issue. I think I'm going to need meat hooks or something to dig into the bolt holes on the basket to get that thing out!

Again I was short on time, we just flopped it in the center of my friends living room. No time to really set it up. It's a 1500 sq foot bungalow that is basically open concept, there isn't a door in the place other than his bedroom and bathroom.

The smaller amp seemed fine, I wasn't giving it a hard workout with some heavy bass music or anything just some explosions and rumbling...however I was a little stressed out! I've never seen a speaker move like that! It didn't make any mechanical noises or seem to bottom out, but I swore it was going to just explode or fall apart... I guess I'll get used to it, but I was a bit shocked! I youtubed some other sdx15 video's and I guess it's normal... pretty cool.

It was pretty loud for the large open area and sitting in the middle of a room, and you could feel the vibrations through the floor and into the couch...probably partly because I've yet to put any legs/spikes on the sub. A few explosions pushed air into my pant legs from 7-10' away!

Decent amount of air coming out of the port most of the time, not a sound from the cabinet, the only vibrations I heard where various things on the coffee table. So I think the cabinet is fine. I didn't hear anything sound off/wrong like port noise etc, however it doesn't have 1400-2000w behind it yet.

I only had 15 mins with Call of Duty, my buddy didn't have a single dvd or blu-ray in his place...or any 5.1 tracks for that matter...I think something is wrong with the guy but that's a different story. I'm impressed, it's pretty exciting over-all, I don't have any real impressions yet, it's not really fair to rate it based on 1 level of CoD, and it's only getting about 250w, without the reckhorn/boost added in yet!

I'm going to finish it off soon, I'm happy with it already, I'll post some more pics and impressions shortly.


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## mwmkravchenko

It's all Mikes fault. I take no responsibility what so ever!

He's bigger and ....

Mark


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## Fishtank

haha yeah... look what you guys made me do...

nah this is pretty awesome. I'm definitely going to finish this one up, thenI'm going to build another once I move... probably after I give sound treatments a try.

This A/V hobby I've acquired seems to have a never ending stream of ways to chew up time and money!


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## mwmkravchenko

So where to Kaboom! There's supposed to be a Kaboom some where?

MArk


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## Fishtank

Ha, it's loud that's for sure... I still haven't picked up my amp yet, hopefully saturday I can go get it.

I have only had about an hour or 2 with it since I built it, still sitting at my friends house. He's watched a bunch of movies and seems to like it. 

If the weekend is nice I will take a day to sand it out and get some paint on it. I'll probably bring it home after I get the amp and painting done, but I can't really push it like I can at his house so it might stay there for a bit.

I still don't have a good opinion on the sub, I need to spend some more time with it!

I know it's lots of fun though!


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## mwmkravchenko

Good to hear from you!

Sometimes it's best that a speaker doesn't jump out and grab you at first. I almost always find that a speaker that jumps out and grabs your attention immediately has some underlying flaw. My first encounter with Thiele speakers was like that. They did not sound good or bad. BUt whenyou used the right program material on them. WOW!

My guess is that you have created a rather neutral sounding sub that will show off the good recordings with gusto. The lesser ones that depend on poor performing subwoofers to give that mid-bass bloom will fair badly. Unfortunately there are a whole bunch of lesser recordings. The better our systems get the more critical we can become.

But this is to listen to music right!

Mark

Mark


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## Fishtank

Yeah, it is hard to nail down right now. 

I'm used to small subs in my small rooms. Right now I have a:

-huge sub in a huge room 
-no consideration to placement or configuration
-not running with the amp I had designed it for and without the boost etc. design with the reckhorn
-haven't tried putting any filler inside
-haven't tried raising it off the floor
-haven't tried music or any material I'm familiar with

I already like what I hear, but I need to fiddle around for a while before I can get a good understanding of what I have. Once I think I know what I have,I probably will build another sub that's significantly different just to see what happens with the same driver and amp in a different box.

Until I do I'm always going to have a little ? in the back of my head saying, "what if you built it wrong!" " what if you can do better!".

Very fun though!


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## Fishtank

well I got an OK day to do some work so I spent a few more hours.

I didn't mention my gorilla glue lesson, I thought I would try it out on one side, turns out it's a mistake! Once you scrape that off from using too much it leaves a bit of a gap in the join if you had one, which I did have a small one. I'm sure it's sealed fine but I had to fill the some shallow holes.










Anyhow patched all the nail holes and covered the driver before I sanded.










I forgot to take a picture after I sanded, as you would imagine it looked the same, just sanded. Sanded easily with a little orbit sander with 3 small pads that can angle individually...not even sure what you call it. After that I had to hand sand the port, chewed it out with some 60 grit to make it even, then some 200, then I ran some 500 over the hole thing and it felt pretty good. The patching on the port went smooth, can't even tell there was a bit of a gouge there.

Few cans of spray paint later I arrive at the picture below. Just a quick coat with some cheap matt black krylon, then 2 cans of Tremclad textured matt black. I chose it because it matches my actual speakers very very well... I also sprayed my speaker stands with it. I actually really like the textured paint in person, but it might not be for everyone.










I didn't get to actually finish it today unfortunately. It was getting cold, and there was a decent breeze, I had to hold the spray can so close it was impossible to keep it even. So I settled for 2 coats of the cheap black and 4 coats of the tremclad, then I soaked the corners and joins with paint to really let it set in. I have to wait for the right conditions to do a light sanding and a few more even coats.

So I put it back behind my friends couch for now, STILL don't have my amp, it's waiting for me just across the border, just waiting for a good time to go grab it.










I do expect to make a cloth grill yet, to really blend this in with my speakers. But I might change my mind. I'll make sure to post some final shots with my room and other speakers when I get a chance. I'll try to get some close-ups of the paint as well once it's decent. Maybe it give a better idea of how it looks.

My wife finally saw it today... she doesn't care about the size because the movie room is my own... however she was a bit surprised. She has not heard it yet though... That might be a bit more of a hard sell. I don't think we share the same enthusiasm!


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## mwmkravchenko

Lookin good:T

I personally use PL Premium to glue up cabinets. It is a construction grade thick as in caulking thick polyurethane glue. Tenacious with a capital T and it does not let go. It also expands as it cures and fills gaps well. As to how tenacious. The two boxes that I have had to take apart were done with a sledge hammer and crow bar. My 4 foot crow bar. I literally peeled of layers of veneer on the plywood horn, and layers of MDF on the MDF horn. Great stuff. But like any polyurethane make sure you like it a lot. If you get it on yourself you will be wearing it for about a week!

I like your paint job. God testimate to proper methods and patience. Well done.

As to your better half. I have been making speakers for people for over 20 years and I have always found that inthe end everyone appreciates good sound. I had one guy unplug his subwoofer because his wife said it made no difference. Then a week latter she kept asking what was wrong with the stereo? So persevere Fishy ( hey do we ever get a real name here? ) . Your efforts will work out well in the end.

Mark


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## Mike P.

I'll be waiting to hear your impressions of the sub and your new amp.


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## Fishtank

Alright so I finally got that amp on Tuesday. I went to set it up Tuesday night, and I didn't know I would need one of those 1/4" TRS adapters for the sub cable, so I had to wait another day! :hissyfit:

Anyway I found one yesterday at lunch, so last night I finally got it all hooked up. I may or may not have something setup wrong... because I was slightly underwhelmed! Also I guess I'm doing the fan mod on that amp because it's quite loud. I guess will go through some of my beginner observations... keep in mind I have very little reference to what it should be doing!

I played that intro to Lord of the Rings where the "bad guy" gets his finger cut off, there is a quick sweep in there and some decent bass. I played it repeatedly changing some settings etc, I'll try to recap it a bit below. Also when I say it "clipped" I'm referring to the "clip" light on the amp lighting up. I can never actually hear any problems in the bass... and it seems to keep playing through the clipping light fine....

Immediately after taking off those 2 bridged carvers the output with the EP4000 was significantly less. I didn't change how the sub was wired... and I'm 99% sure I have it right. I was just using 1 channel of the amp. Literally it pretty much cut in half. Also that LED clipping light on the EP4000 lights up quite a bit if it's on full output, and I wouldn't even really consider it very loud...I definitely wouldn't need to turn it down. The bass was there...I could hear it, but if I dialed the output down a bit so it doesn't clip, the speakers would almost start to over power the sub... something I never had an issue with the other 2 carvers.

I tried using input 2 and output 2 right after and had identical output so I'm thinking the amp is ok, and doesn't have any problems with a certain channel.

So I bridged the amp, and it seemed to make a small difference in the output, and it definitely could run a bit harder before it clipped...however it still would clip even with the "rated" 4000w peak amps. maybe that's normal, however I guess I assumed the amp wouldn't be a bottle neck in that mode. It was loud enough to rattle his old windows a bit on the really big bass notes, but again it still seemed to really lack some output compared to what I was getting used to.

Near the end I upped the SW channel from the receiver 6db, and it started to approach what I was used to previously.

So a couple questions:

My 1/4" TRS adapter is a cheap piece of junk. Could this be a problem? It definitely seems like it could be a weak link to me! I've never used an XLR cable but I went and found some places to order RCA->XLR cables, not sure if it's worth it... but that adapter is the only link in the chain that is different from when the carvers were running.

When the "clip" light on the amp comes on and I don't hear any problems, do I really need to be worried about it?

Repeating the same section of a single movie isn't a great way to get used to a sub, but I was just trying to figure out why the output seemed to be diminished. I think i will find some decent music to test with next time I'm over there. A few posts ago I mentioned I was shocked at how much the cone moved... sometimes more than 1" for sure.. That was when I was only running 1 of the 150W carver amps. When I bridged the carvers it moved less, and now it really only seems to push out 1/4" at the most, even at the loudest scenes and running some of the same content. I'm assuming it's a good thing, but can you guys clarify that and why for me!

If you guys have any suggestions based on my ramblings above let me hear them! I'm not disappointed with what I have at all. In a smaller closed room I know I will have more than enough bass. I definitely need more time with it, I was however a bit surprised that the output dropped when I got this new amp!

After writing this I'm starting to think that adapter could be an issue... It's sitting at the end of a 25' monoprice sub cable. My amp is just sitting on my sub across the room. I'm thinking I should shorten up all those analogue cables and put my gear close together, and get that adapter out of the equation... and just run the speaker wire to the sub. That will be my next step anyhow unless you guys have better idea's than me!


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## mwmkravchenko

Hi Fishy

Well you may be up against signal loss or different amp sensitivity. Your amp is new right?

I'll check it out quickly.

Here is a usefull little signal generator to check out what is going on:

http://www.dr-jordan-design.de/signalgen.htm

Mark


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## mwmkravchenko

There are quite a few settings that could mess you up. 

Input impedance. Signal gain. Low cut.

Check these out.

Most consumer recievers will not like to see a 10k Ω load. 20k is better.

2 and 3 should be off
8 and 9 should be off

Unbalanced on this amp is the 1/4 inch mono input. You might want a balanced to unbalanced converter. Choose wisely. Some have a built in 30hz high pass. Alternatively you can make your own cable from an RCA line and an XLR connector or an RCA and a stereo 1/4" conector. Not to hard. Look up the pin out on page 10 and I'll nudge you along.

Mark


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## Fishtank

mwmkravchenko said:


> Hi Fishy
> 
> Well you may be up against signal loss or different amp sensitivity. Your amp is new right?
> 
> I'll check it out quickly.
> 
> Here is a usefull little signal generator to check out what is going on:
> 
> http://www.dr-jordan-design.de/signalgen.htm
> 
> Mark


I guess it makes more sense to run a signal generator instead of movies to get a clear idea of what is being output. I keep meaning to find one, so thanks for handing me one!

I'll play with it a bit next time I'm over there.


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## Fishtank

mwmkravchenko said:


> There are quite a few settings that could mess you up.
> 
> Input impedance. Signal gain. Low cut.
> 
> Check these out.
> 
> Most consumer recievers will not like to see a 10k Ω load. 20k is better.
> 
> 2 and 3 should be off
> 8 and 9 should be off
> 
> Unbalanced on this amp is the 1/4 inch mono input. You might want a balanced to unbalanced converter. Choose wisely. Some have a built in 30hz high pass. Alternatively you can make your own cable from an RCA line and an XLR connector or an RCA and a stereo 1/4" conector. Not to hard. Look up the pin out on page 10 and I'll nudge you along.
> 
> Mark


Missed this one while writing my last reply.

The low cut filters are absolutely off, that much I managed on my own!

Unfortunately I've never heard of balanced or unbalanced before...:scratch: I looked it up a bit makes some sense. 

I'm a little confused by your statement though...

EDIT: actually I just read page 10 of the manual and it would seem both inputs are 20k balanced unless I change something for the XLR input and make it unbalanced.

So now I'm not sure why you said 20k is better, but I might want a balanced to unbalanced converter!

EDIT #2: On page 11 it's starting to look like my 1/4" adapter might be unbalanced. I didn't buy this adapter and it was given to me by my friend, so i didn't see any labeling on it. I'm 90% sure it looks like the unbalanced tip. So at least it gives me something else to try.


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## mwmkravchenko

Hi Fishy

The pics below are the Mono Stereo versions of the 1/4" jack. The stereo version can be wired up for balaced input as it has three conact points just like an XLR plug.

There is still something wrong with there being such a difference inbwtween the two amps. You sure the Carver stuff does not have it's own gain settings to? Because that will throw the comparison way off as well.

THe point you probably already know is that the box delivered. You just have to set it up in a like manner so that the settings are an apples and apples comparison.

Mark

If you want my phone number send me a PM. I can talk you through what you need much faster than typing it!


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## Mike P.

The issue sounds like a voltage mismatch between the amp and receiver, a common problem when mixing pro audio and home audio gear. The solution is a Samson S-Convert:

http://www.samsontech.com/products/productpage.cfm?prodID=1699


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## Fishtank

Mike P. said:


> The issue sounds like a voltage mismatch between the amp and receiver, a common problem when mixing pro audio and home audio gear. The solution is a Samson S-Convert:
> 
> http://www.samsontech.com/products/productpage.cfm?prodID=1699


If I can avoid buying another box to put in the middle I am going to! I didn't even mention that reckhorn yet... I tried it a few times and had some poor results as well! I barely even fiddled with it though.

In the end it's possible that the amps are just that different, those carvers are 20yrs old.

I can still get enough output from the behringer to be quite happy, it's just we were quite surprised by the difference. I do have 2 other friends with their own pro amps, one of these days I can probably coordinate a time to try some of theirs out as well, to see what happens.

I appreciate the offer for more in-depth help Mark but I will probably just go take a look and see what I can pick up tonight or tomorrow.

Anyhow thanks for the response's. I will probably get a few hours with it tomorrow, so I will make some changes and play with some more media or that generator and see what what happens.


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## mwmkravchenko

Great post Mike. Solution in a nut shell.

Someone else has been down this road before:

http://www.hometheatershack.com/for...s/8235-samson-s-convert-alt-art-cleanbox.html

Solution here:

http://www.mcmelectronics.com/product/SAMSON-TECHNOLOGIES-S-CONVERT-/555-7574

Keep on plugging and you will get where you want with something like this box. 

Mark


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## Mike P.

Mark, I forgot he had a Reckhorn which is supposed to be able to boost the input voltage. 

Fishtank, which Reckhorn do you have, the B1 or the B2?


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## mwmkravchenko

I'll bet that even with the Rekhorn's gain he won't be where he was before. Interfacing home to pro equipment starts with proper level matching. From there you can play with the Rekhorn. Otherwise your just banging your head against the wall.

There are more things afoot than are apparent...

The impedance mismatch is at worst 4 to1 or at best 2 to 1 . Which means the recievers output signal stage will be called upon to throw out 2 to 4 times as much current as is normal. They are happy into a 48k ohm load not 10 or 20 k ohm load.

The Rekhorn will face the same problem.

The Samson box is purpose designed to mitigate this prooblem.

Mark


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## Fishtank

uh oh, I'm starting to feel like I need it! As for that reckhorn Mike, it's the B-1. It's impact seemed quite limited on everything but cutting out lower frequencies. But again I only tried it out a few times.

It's only $50 and if it's going to make my $600 invested and few hundred hours of reading and building more worthwhile then I suppose it should happen! Besides when you guys agree, who am I to disagree!

Edit: I deleted a question here, it's starting to sink in why it's needed. I don't fully understand it all, but there were a few more threads on the shack here that helped me out a bit more.


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## Fishtank

Ok, so it is ordered. Can you guys just quickly help me verify what cables are proper, so I'm not caught waiting again when it does arrive in a week or so. 


So now I have:

Denon -> Reckhorn -> S-convert -> EP4000 

RCA(out)-> RCA(in)/RCA(out) -> RCA(in)/XLR(out) -> XLR(in)


Is there anything you can think of that might trip me up at this point?


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## Mike P.

If you're in Canada then Axe Music is the place to go.

http://www.axemusic.com/product.asp...artPosition=1&strSearchCriteria=any&PT_ID=all


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## Mike P.

Did you try the B1 with the Main Level control turned all the way up?


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## Fishtank

Mike P. said:


> Did you try the B1 with the Main Level control turned all the way up?


Yeah I assumed that would be the correct setting. I didn't see any reason why I would want it to limit the signal with the reckhorn.

I think I know what my problem was with the Reckhorn now that I was looking at the dials again, I believe I had the subsonic frequency too high, when I consider the range is 10-150hz. I don't think I can effectively set that dial by hand to the 16hz the sub was modeled too. I should be able to set it properly with that signal generator that Mark linked me yesterday. If I'm way off on my thinking let me know, but I'm pretty sure that was my problem. I think I was close but I might have had it at 25hz or something. So during that scene in LOTR where the bass sweeps down low it was cutting out way too much. I guess since my 3db boost is supposed to be at 20hz, if I did have the dial in the mid 20's it wouldn't have been accomplishing anything at all! 

I already ordered that s-convert from the states. Depending on what Canada post does for duty it will be a bit cheaper, but take a bit longer. I would have just ordered it from axe if I knew about it. Oh well, keep it in mind for next time!

Thanks for all the help again guys, I'm feeling confident you sorted my problems for me again!


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## Mike P.

The B1 is not accurate at all, with the 10 hz filter setting and boost applied at 20 hz you end up with 2nd order HPF at 15 hz. So turn the filter setting down to 10 hz and only increase it if the sub complains. See post #4 here:

http://www.hometheatershack.com/for...devices/21838-reckhorn-b1-b2-differences.html


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## Fishtank

Mike P. said:


> The B1 is not accurate at all, with the 10 hz filter setting and boost applied at 20 hz you end up with 2nd order HPF at 15 hz. So turn the filter setting down to 10 hz and only increase it if the sub complains. See post #4 here:
> 
> http://www.hometheatershack.com/for...devices/21838-reckhorn-b1-b2-differences.html



Ah that's too bad... I knew it wasn't as accurate as the B-2 when I bought it. But I figured it was good enough, maybe it's not!

I can always ebay it and try the B-2 I suppose if it doesn't work out properly.


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## mwmkravchenko

Hey You can measure it to!

If you want an audio frequency Osciliscope program you can use it to measure where you have set cut off. Don't give up so easy!

We are here to push you to audio heaven!

MArk


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## Fishtank

mwmkravchenko said:


> Hey You can measure it to!
> 
> If you want an audio frequency Osciliscope program you can use it to measure where you have set cut off. Don't give up so easy!
> 
> We are here to push you to audio heaven!
> 
> MArk


Ha yeah I was planning on trying that generator...i've never used one before but I assumed I can send just a 16hz or a 20hz etc. signal and find out if it's cut off or not.

I'm not really sure about the frequency osciliscope program... I guess if I used the frequency osciliscope I could find out _how much_ of the signal it's cut out at that frequency? 

Since you said "program" i assume I can just run the signal into the input on my laptop? I'll give it a shot, shouldn't be too hard!


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## mwmkravchenko

An osciliscope is just a voltmeter with a TV set that lets you see what the voltage is over a time base. That's the basics.

Any freeware program that you will get from me or find will run off the same sound card that will be generating the signals through the function generator. 

Mess with them a bit and things will start to become intuitive. Remember when the creek gets a bit thick you can either post questions or give me a call. You are so close to getting what you want. I'd be very happy to see you get to where you were planning. THat's why I post on this forum. I do enjoy giving back what I have learned. THis kind of thing was not available 25 years ago. Boy do I wish it was. But then again Whatsamattayou is kind of good sometimes to. THat's where I got my BscEng QBE from.

Mark


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## Fishtank

Well the s-convert finally showed up today! 

I was ready for it this time, had my wires all ready to go! I had to make the XLR one out of some parts I wound up finding and initially it had some troubles, but I just readjusted the end I had soldered on and all of the sudden the signal cleared up and I got to finally try out the sub!

Soooo... it's loud! yeah works like you would expect now! I had the receiver's output at a comfortable level and I wound up with the EP4000 at around 2/3's gain without being bridged and my buddies old windows were shaking pretty good. The couch during some of the parts had a significant amount of vibration to it, it was pretty fun. The amps clipping light would light up here and there, however some parts were really thumping and it wasn't lighting up at all so I figured it was pretty good.

I've never had a sub like this before so unfortunately I can't compare it very well. I think it is possibly a little boomy, so I will probably try to get some material inside to see if I can pick up any differences. Also I'm quite certain it's not placed in an optimal position. It's up front now, however it's on the left of even the FL speaker. It's a pretty big sub and it's my buddies living room so I can't really re-arrange his house!

Thanks for all the help from the both of you, my friend and myself are pretty pleased with the results. For a first attempt that isn't quite complete yet I think it sounds pretty amazing even right now. 

I still need to fire up that reckhorn and see if I can get anywhere with that, I was having so much fun watching some movies that I just left it out of the equation tonight.


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## mwmkravchenko

Great news!

Happy everything is working out as you planned.

Mark


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