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post #1 of 19 Old 07-22-2014, 08:34 AM - Thread Starter
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Rate my DIY box...

A friend and I made our first attempt at a DIY home theater box. Everything before this has been <2cuft for car audio.

I had this sub laying around.
http://www.crutchfield.com/S-MQmq3T5...n-AW1206T.html

3/4 birch plywood
double front faceplate in the 'sub' section
~5.5cu.ft
2inx14inx 12in port + 4inx14inx6in angle.
About 200 screws and a full 11oz tube of liquid nails.

It should be tuned to ~26-27hz

I haven't really 'tested' it that much because I only have a crappy ~80w amp. My yamaha M-45 is waiting on some mica insulators.

Next weekend is some TLC with a router, filler and stain


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post #2 of 19 Old 07-22-2014, 03:53 PM
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Quote:
Originally Posted by whitrzac View Post
It should be tuned to ~26-27hz
Most people around here aim for 15hz or at least 20hz; why so high?

Cars have like 40db of room-gain below 100hz, but room-gain in a house starts at like 25hz. So expect it to be 40db quieter.
So expect the sub to sound very weak-sauce compared to in a trunk of a car; especially true if the floor is cement at ground level.
In a home it's all about displacement, it is not uncommon to see 4 18's with 10kW on dual 30amp breakers being used for a mid-sized HT because of the lack of room-gain and/or the 10-20hz requirement.

4 18's and 10kW sounds like a lot for a car, but that wouldn't even place you in the top 30 DIY AVS HT systems unfortunately.
Me personally I run 20 subs and 35,000watts (and I still want MORE BASS...) You can never have too much bass it seems.
The physics of houses, suck.

Last edited by BassThatHz; 07-22-2014 at 04:00 PM.
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post #3 of 19 Old 07-22-2014, 04:14 PM - Thread Starter
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Quote:
Originally Posted by BassThatHz View Post
Most people around here aim for 15hz or at least 20hz; why so high?

Cars have like 40db of room-gain below 100hz, but room-gain in a house starts at like 25hz. So expect it to be 40db quieter.
So expect the sub to sound very weak-sauce compared to in a trunk of a car; especially true if the floor is cement at ground level.
In a home it's all about displacement, it is not uncommon to see 4 18's with 10kW on dual 30amp breakers being used for a mid-sized HT because of the lack of room-gain and/or the 10-20hz requirement.

4 18's and 10kW sounds like a lot for a car, but that wouldn't even place you in the top 30 DIY AVS HT systems unfortunately.
Me personally I run 20 subs and 35,000watts (and I still want MORE BASS...) You can never have too much bass it seems.
The physics of houses, suck.
See also: home audio beginners.

The theory was long ports = delay, small ports = distortion/noise. 27hz seemed like a good compromise, car audio subs are usually ported to ~40hz.

It was a good experiment, I'm out $50 in materials and an afternoon of hanging out. I could probably sell the box for what I have into it...



I have 2 of these subs and a yamaha m-45 amp(125x2 at 8ohm, 180@4)

What would you suggest?
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post #4 of 19 Old 07-22-2014, 04:54 PM
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You might be able to extend the length of the port all the way over to the brace and get the tune in the low 20s. The brace might cause some weirdness with the airflow. You could chop out that part of the brace. You have enough cubic feet for a lower tune.
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post #5 of 19 Old 07-22-2014, 05:26 PM
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Quote:
Originally Posted by Samps View Post
You might be able to extend the length of the port all the way over to the brace and get the tune in the low 20s. The brace might cause some weirdness with the airflow. You could chop out that part of the brace. You have enough cubic feet for a lower tune.
I'd cut the brace and extend the port.
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post #6 of 19 Old 07-22-2014, 06:00 PM - Thread Starter
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I was planning on building another/different box... plywood isn't that expensive...

I have 2ft x10ft under my screen where I could put a larger box.

I have 2 of these subs. What box should I put them in?
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post #7 of 19 Old 07-22-2014, 06:07 PM
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I don't believe the box is the problem just the length of the port. Model out how long that port needs to be for 20hz and if the airspeed is acceptable, let it rip.
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post #8 of 19 Old 07-22-2014, 06:32 PM
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Quote:
Originally Posted by whitrzac View Post
What box should I put them in?
Download WinISDPro, it'll tell you the specs.
http://www.linearteam.dk/?pageid=winisdpro

You could probably salvage that box easy enough.
If the braces are only held by glue then some good hammer blows near the seams will pop them off easy.
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post #9 of 19 Old 07-22-2014, 06:50 PM
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Quote:
Originally Posted by whitrzac View Post
I have 2 of these subs and a yamaha m-45 amp(125x2 at 8ohm, 180@4)

What would you suggest?
Assuming you stick with the yamaha amp, I suggest you look at a more efficient 15" driver.

For example....not bad for the $$$....you can spend much more.
http://www.parts-express.com/dayton-...4-ohm--295-470

....and you can always add a killowatt or 3 of power later.

Good luck!
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post #10 of 19 Old 07-22-2014, 06:50 PM - Thread Starter
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Quote:
Originally Posted by BassThatHz View Post
Download WinISDPro, it'll tell you the specs.
http://www.linearteam.dk/?pageid=winisdpro

You could probably salvage that box easy enough.
If the braces are only held by glue then some good hammer blows near the seams will pop them off easy.
The entire box is glued together, with contractor grade liquid nails.
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post #11 of 19 Old 07-22-2014, 08:11 PM - Thread Starter
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Originally Posted by mobeer4don View Post
Assuming you stick with the yamaha amp, I suggest you look at a more efficient 15" driver.

For example....not bad for the $$$....you can spend much more.
http://www.parts-express.com/dayton-...4-ohm--295-470

....and you can always add a killowatt or 3 of power later.

Good luck!
I know there's better out there. But I have these, it would be nice to use them...

I just picked up another yamaha amp(mx-600)
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post #12 of 19 Old 07-23-2014, 04:45 AM
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I just picked up another yamaha amp(mx-600)
Very nice amp but that isn't big power by modern subwoofer standards. Curious about what you plan to run for your mains if you are considering using the MX-600 on the subs...

Back to the driver, you can only get so much displacement out of a 12" driver (more power helps) so I would at least plan ahead to make it easy to modify the cabinet by making the front baffle removable (too late?) so you can later add a second (or third) 12" driver or go with 15" drivers in the future.
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post #13 of 19 Old 07-23-2014, 05:30 AM - Thread Starter
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Originally Posted by mobeer4don View Post
Very nice amp but that isn't big power by modern subwoofer standards. Curious about what you plan to run for your mains if you are considering using the MX-600 on the subs...

Back to the driver, you can only get so much displacement out of a 12" driver (more power helps) so I would at least plan ahead to make it easy to modify the cabinet by making the front baffle removable (too late?) so you can later add a second (or third) 12" driver or go with 15" drivers in the future.
The Yamaha M-45 I have... Or I'll just keep using my RX-A2020 for power

I'm looking at building another box from scratch using both subs.
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post #14 of 19 Old 07-23-2014, 01:51 PM - Thread Starter
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I've spent the afternoon looking at various sub box designs...

How good/bad would a cube design work for these subs? I would build 2 and use the MX-600 amp at 2ohm.

2 x 12in, 500w(dynamic) each, ported to???
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post #15 of 19 Old 07-23-2014, 03:36 PM
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I have the RX-A2010 and have had little interest in getting more power.

Checking the link you posted up top I found this....

Recommended Ported Box Volume: For best response and sound quality, Audiobahn recommends a ported enclosure with an internal volume of 2.3 cu/ft with one 4" diameter x 7.25" long port, so that is the enclosure recommended by Crutchfield. If box space is lacking in the vehicle, Audiobahn suggests a "Space Saver" box can be used with an internal volume of 1.3 cu/ft with one 3" diameter x 6.75" long port. For high performance applications, Audiobahn's "Ultimate SPL" box design has an internal volume of 3.2 cu/ft with two 4" diameter x 12" long ports.

Being lazy, I would take your existing big cabinet and use it with 2 drivers in it since that puts you pretty much right between the 2.3 and 3.2 ft^3 designs. Not sure what tuning was used in the designs above (38-39 Hz)...your best bet is to model it if can find the T/S parameters.....here they are.

http://audiobahn.com/phocadownload/A...6T-rev.2.0.pdf

Looks like a big peak at the tuning frequency for those designs. You really need to model it to see if anything will take out the boom. Last resort is using DSP or a parametric EQ to try to fix it. YPAO might help...not sure how much effect, if any, it has on the LFE channel other than level/distance/phase. Easy enough to test.
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post #16 of 19 Old 07-24-2014, 06:05 AM - Thread Starter
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The sub was 'made' for car use. That's why the manufacturer specs a small box and 40hz tune.

The A2020 has a 4 band parametric EQ on both sub channels.


I'm going to attempt to take apart the box this weekend, otherwise I will probably build a pair of 'cubes' ported in the mid teens.
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post #17 of 19 Old 07-28-2014, 06:32 AM - Thread Starter
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v2.0

5.1cf
1.25in x 14.5in port, ~40in long
Tuned for ~15hz

It sounds much better


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post #18 of 19 Old 07-28-2014, 06:44 AM
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Quote:
Originally Posted by BassThatHz View Post
...it is not uncommon to see 4 18's with 10kW on dual 30amp breakers being used for a mid-sized HT because of the lack of room-gain and/or the 10-20hz requirement.
Actually, it's very uncommon; it's just not uncommon HERE.


Did you really need to quote that entire post in your reply?
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post #19 of 19 Old 10-26-2014, 05:32 PM - Thread Starter
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Made another one... Pics incoming tomorrow.


Same driver, I have 2..

Box is ~24"x 15in x 15in. It's tiny
~2cu/f
2x 3/4" x 6" x 44" ports
Tuned to 16hz

With the single 12, I get no port noise with my 500w amp above 12hz.

I probably wouldn't make a box with 3/4" ports again...
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