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Dual Opposed AV15H Subwoofer Build

post #1 of 802
Thread Starter 
Okay, time to start the official build thread as I'll be working on the boxes and have the drivers in next week (hopefully!!). Basically a continuation of this thread (where I was debating back and forth between going DIY or not, then what driver to use, etc)...


http://www.avsforum.com/avs-vb/showthread.php?t=1208220

My family room HT "history" thread ...

http://www.avsforum.com/avs-vb/showt...9#post17758909


I've ordered 4 AV15H's in 4ohm impedence (per a recco from JJ) from Acoustic Elegance ...



Purchased a used QSC RMX-5050 which will drive both subs providing 1600 to 1800 watts per side ...



Put together a design on Google Sketchup (took my forever and no, it's not perfectly to scale!) ... dimensions to be 18w x 22h x 24d



The napkin math ...



Had 2 4 x 8 sheets of Birch 3/4" Ply cut at Home Depot ...


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post #2 of 802
Thread Starter 
The WINISD "stuff" ...




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post #3 of 802
Thread Starter 
One box "mocked up" and placed next to my unit to see how it would look size wise...



The Hometheatershack volume calc ....



My current PB13's response in sealed tune taken with the sub at both the right and left side of the room (no EQ) ...

Left side:


Right side:

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post #4 of 802
Thread Starter 
Thought I'd use this post on the first page to list out the tools used, tips and "lessons learned" etc. as I go through the build being my first time. I'll update it as I go along.

Note, this obviously was not a "how can I build a subwoofer as cheap as possible to beat out X commercial sub", i.e., I didn't try to build the sub with 1 or 2 tools, bought a relatively expensive amp, did some roundovers etc.

Tools/materials Used:

3/4" Birch Ply

1" Dowel rods (for bracing)

Bosch 1587AVSP-1 Jig Saw (great jig saw once you learn the blade release mechanism and comes with several blades)

Bosch T244D TShank blades (for the round over cuts)

Battery Powered Drills - I actually have 2 plus an electric drill. It's great to have more as you can use one with a drill bit to drill pilot holes (see tip below) and another to drill the screws in. Obviously not required, but hey, I had them so ....

Various drill bits (buy one of those cheap wood drill bit sets)

RYOBI Router and 1/2" Roundover bit - only used for the roundovers, though could have used for the circular cuts. This router came with a bunch of bits (borrowed it from my father in law)

Husky 55" Saw Guide - GREAT tool for the jig saw, saved me numerous times!

Black & Decker Mouse Sander (all I had) and numerous sand grits (80/120/150/180/220)

320 Finishing Sanding "sponge"

Titebond II glue and Lepage Wood Glue - used both, but mainly the Titebond II as it had better initial tack which helped out at times.

1/2" Chisel - for recessing the Terminal Cups

Knife/Blade

1" deck screws (for screwing in internal wood blocks which were used as guides when gluing)

Square

Work bench - mine wasn't the greatest as it was too small and the handles were annoying (it's some Fatmax bench that doubles as a trolly). I really don't see how anyone gets by without one though!

Level

Wood filler

1" Spade bit (to recess the dowel rods into the inner baffles)

#8 Wood Anchors

2 Large bags of poly fill from Fabric Land (5lbs each) - $29 each


Lessons Learned:

Jasper Model 200 Circular Guide - Grrr ... doesn't fit the RYOBI router even though it says it does, and can't return the darn thing!

Practice, practice, practice EVERYTHING on scrap pieces of wood if you are a first time DIY like me. E.g., using the round over bits.

Drill pilot holes before putting any screws or anchors in. Repeat after me "Drill pilot holes before inserting screws into wood". Say it 10 times. Great to have 2 drills for this reason.

Don't do any roundovers until you've glued most pieces on as in my case I noticed I was about 1/8" too large in terms of width (which was okay as if I was too short it would be trouble!) and having already cut the roundover it was a bit more of a pain to shave this off and redo the roundover.

When gluing - keep a wet rag by you at ALL times and a flat head screw driver to help clean out the glue. Clean out the excess glue immediately (don't wait thinking you'll just sand it off!).

Wood Anchors - thank you Joe for that tip ... very easy to drill into the wood. MAKE SURE you drill a pilot hole first though and put them in with a screw driver, not a drill, to try and prevent the wood from breaking.

Buy square terminal cups unless you're confident in your ability to make circle cuts. I started out with circular ones and ended up buying square, way easier to work with and easy to chisel into the wood to reset it a bit.

When staining, MAKE SURE you wipe off excess stain after 10 minutes or so per the instructions. Leaving it on just causes headaches!!
post #5 of 802
Nice amp! I have the 4050hd, great sub amps.
post #6 of 802
Thread Starter 
Quote:
Originally Posted by jeff76 View Post

Nice amp! I have the 4050hd, great sub amps.

I know, you're the one who's giving me the trepidation on fan noise!! Any issues with the 12V fan you're using?

BTW, did you put rubber feet on the bottom of your amp? I can remove and replace the black screws on the back end of the amp but can't seem to "unscrew" the two gold screws with washers on the front (see this pic)?


LL
post #7 of 802
Why not just get some stick on little rubber feet for the bottom of the amp, thats what I did before I put them in my rack. Worked just fine, 1 in each corner, only added about 1/4" to the full height.

Find them easily at target.
post #8 of 802
Quote:
Originally Posted by pbc View Post

I can remove and replace the black screws on the back end of the amp but can't seem to "unscrew" the two gold screws with washers on the front (see this pic)?

The gold screws are holding down the transformers inside the unit - you've loosened the nut at the top of the screws and now they're just spinning freely.
post #9 of 802
Thread Starter 
Quote:
Originally Posted by Oklahoma Wolf View Post

The gold screws are holding down the transformers inside the unit - you've loosened the nut at the top of the screws and now they're just spinning freely.

Well, that doesn't sound good. Do I need to open her up?
post #10 of 802
Thread Starter 
Quote:
Originally Posted by Warpdrv View Post

Why not just get some stick on little rubber feet for the bottom of the amp, thats what I did before I put them in my rack. Worked just fine, 1 in each corner, only added about 1/4" to the full height.

Find them easily at target.

Just figured on a 75 lb amp they may just fall off? Plus, couldn't find them at Home Depot! (note we have no Targets in Canada).
post #11 of 802
I'd pull the lid off and at least tighten those nuts up again... the transformers are heavy. Be careful not to let them slide around in there while you're doing it.

Good choice in amps BTW - I have an 1850HD

Mine's not fan modded - it's in another room from the home theater.
post #12 of 802
Thread Starter 
btw, I purchased this cup from Solen.ca.

http://www.solen.ca/pub/cms_nf_catal...2=2&niveau3=44

Curious, I assume drilling out a hole into the wood is fine to install this? I noticed some have simply drilled two holes and inserted the terminals directly into the wood, then added a face plate on top?
post #13 of 802
I don't see why not - just seal it off to make sure there are no leaks.
post #14 of 802
Quote:
Originally Posted by Warpdrv View Post

Why not just get some stick on little rubber feet for the bottom of the amp, thats what I did before I put them in my rack. Worked just fine, 1 in each corner, only added about 1/4" to the full height.

Find them easily at target.

I used rubber feet or thick felt stick on pads for all of my components, easy and cheap.
post #15 of 802
Quote:
Originally Posted by jpmst3 View Post

I used rubber feet or thick felt stick on pads for all of my components, easy and cheap.

Agreed..... the weight of the amp on them will keep them on just fine.... when I put the amps in my rack, I had to peel those rubber feet off, and it was a chore. The glue set on the sticky and I "Almost broke a NAIL !!!" trying to get them off.... hehehhe

Any home store should have felt pads or little rubber feet for protecting furniture type thing....
post #16 of 802
Thread Starter 
Quote:
Originally Posted by Oklahoma Wolf View Post

I don't see why not - just seal it off to make sure there are no leaks.

Weather stripping I assume?
post #17 of 802
Thread Starter 
Next Q, it appears on the QSX they have a 30hz or 50hz low pass filter (or off). Should I keep that puppy "off" or some other setting until I get a DCX or equivalent (assume I should keep it off when I get the DCX or other EQ)?

Also, I assume the sub should be set to "stereo mode" and not "parallel mode" (obviously not bridged)?

Page 5 here is what I'm referring to ...

http://www.qscaudio.com/pdfs/manuals...al_EN_revF.pdf
post #18 of 802
Quote:
Originally Posted by pbc View Post

Weather stripping I assume?

Glue or silicone around the hole is what I'd use.

Quote:
Originally Posted by pbc View Post

Next Q, it appears on the QSX they have a 30hz or 50hz low pass filter (or off). Should I keep that puppy "off" or some other setting until I get a DCX or equivalent (assume I should keep it off when I get the DCX or other EQ)?

Also, I assume the sub should be set to "stereo mode" and not "parallel mode" (obviously not bridged)?

Page 5 here is what I'm referring to ...

http://www.qscaudio.com/pdfs/manuals...al_EN_revF.pdf

Turn the amp's SSF off completely - even 30Hz is too high for sub duty.

Use parallel mode if you only want to make one connection to the amp - that way both channels get the same input signal. Stereo mode you'll need a signal input on both channels.
post #19 of 802
Thread Starter 
What's the advantage of using one vs the other? Parallel vs stereo I mean? I assume given my AVR only has 1 sub out I would use Parallel?

Sorry if that's a stupid question!
post #20 of 802
Its just a switch that will send the incoming signal to both outputs when in parallel, or separate signals in stereo mode.

If you want to just run 1 RCA out of your receiver connect to the single input and set the switch to parallel, both subs will receive the same signal from both outputs.
post #21 of 802
Thread Starter 
Guess what I was asking is what are the advantages of one over the other (outside of the need for a splitter and two RCA cables versus one RCA cable and no splitter)?
post #22 of 802
No need for all that extra, its built in.... one cable and done with it...
post #23 of 802
Quote:
Originally Posted by pbc View Post

I know, you're the one who's giving me the trepidation on fan noise!! Any issues with the 12V fan you're using?

BTW, did you put rubber feet on the bottom of your amp? I can remove and replace the black screws on the back end of the amp but can't seem to "unscrew" the two gold screws with washers on the front (see this pic)?



I took the top off of mine. I think those gold screws hold some of the parts inside the case. The fan seems to work fine so far. The amp hasn't even got warm during a movie. I put small felt pads on mine so it would slide in my cabinet without scratching the wood.
post #24 of 802
Quote:
Originally Posted by pbc View Post

Next Q, it appears on the QSX they have a 30hz or 50hz low pass filter (or off). Should I keep that puppy "off" or some other setting until I get a DCX or equivalent (assume I should keep it off when I get the DCX or other EQ)?

Also, I assume the sub should be set to "stereo mode" and not "parallel mode" (obviously not bridged)?

Page 5 here is what I'm referring to ...

http://www.qscaudio.com/pdfs/manuals...al_EN_revF.pdf

Leave the low pass filter off. That is to protect main speakers. Obviously you don't need it for subs. Parallel mode is fine since the amp will only see a single signal.
post #25 of 802
Thread Starter 
Curious. If I were to go with a Marchand Bassis, would a DCX still be required? Or would the bassis be able to do phase adjustments as well as EQ?
post #26 of 802
Quote:
Originally Posted by pbc View Post

Curious. If I were to go with a Marchand Bassis, would a DCX still be required? Or would the bassis be able to do phase adjustments as well as EQ?

Hey PBC,

Nice build.

I used single 4 ohm VC drivers. Each sub wired in series to 8 ohms and 2 subs wired in parallel to 4 ohms at the amp which is in bridged mode. That would give you the best short term performance.

I understand you're using dual 4 ohm coils, so you'll have each sub at 4 ohms and use the amp in dual channel mode. That'll work fine and only be a couple of dB less capable with very short transients.

The phase can be adjusted by using the SW distance setting in the preamp, but the DCX having separate delay settings for each output gives you an ability you won't have with preamp/Bassis.

I would probably lean toward the DCX with multiple subs vs the Bassis if I had to choose one over the other. The best situation would be to have both because they each can do things the other simply can't do.

Either way, you should have more than enough low end with this system. Looking forward to the details.

Bosso
post #27 of 802
Thread Starter 
Hmmmmm ... so how are people making such perfect circles for their drivers, window braces etc? I've been trying on scrap with my Bosch jig saw to cut out a circle for this stupid terminal cup (don't know why I purchased it now!) and couldn't cut a decent circle to save my life. God help me when I need to do a few that matter on the baffle.

http://www.solen.ca/pub/cms_nf_catal...2=2&niveau3=44

Was actually thinking of "recessing" the cup a tad so the lip didn't show, but after staring at the tools I had in the basement I can't figure out how to do it.

Starting to regret this DIY build and have barely even started!!
post #28 of 802
They use a router and a circle jig. link
post #29 of 802
Thread Starter 
Great, now to find one of those in Toronto ...
post #30 of 802
Quote:
Originally Posted by pbc View Post

Great, now to find one of those in Toronto ...

Go to your scrap pile. Pull out a piece of 1/4" or 1/2" of plywood/MDF/HDF that's as wide as your router's base and is slightly longer than the largest radius you want to cut measured from the router center plus a bit. Trim it down to size if it'll be unwieldy.

Mark your router's mounting pattern and the center where the bit ends up. Draw one or more lines from the center point along which you'll drill the centers for the circles you cut. Note that you'll get half a bit diameter larger than the radius for cut-outs, and half a bit diameter smaller for circles. For instance, there should be 2 7/8" between the center of the router bit and center of the six inch inside diameter hole.

Drill holes (I like a piece of 1/8" drill rod, although you could size for a finishing nail) for circle centers and router mounting. Drill a clearance hole for the bit. Counter sink or counter bore the router mounting holes as appropriate.

Should take you all of 10 minutes.
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