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175 litres - dual AV15X Push Pull Backfiring Sub

7082 Views 17 Replies 8 Participants Last post by  Moonfly
After a demo of my sub, a friend has asked me to build him one. Script is the same as it is for mine really, although the dims needed to be tweaked for his room, and he would like a backfiring version to mimic the M&K 5100sf. So, cabinet volume is around 175 litres, which will increase to around 200 for with stuffing. Power is a Behringer EP4000, and the drivers are 2 AE AV15-X drivers. Cabinet is made from 1"MDF and critically braced. I started this Wednesday night, put in about 3 hours a night (sorry Ive not been as busy on the forum guys) and by Saturday we had a cabinet ready for drivers and testing.

I need to resize the pictures of the build but will add them i as soon as I have resized them all. SWMBO lost my digital camera (left it in a bar for some lucky individual to find) so I apologise in advance for the poor quality phone pictures.

Ive also added the pictures of the sub at my friends house (we tested it last night). You'll notice the space between the centre and left M&K fronts. He plans to have a second sub in here. This is going to be his HT room (still plenty of work to do) and the screen is full width. When its brought down the bottom of the screen sits just above the sub and speakers, so it will be a nice install once complete.


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Hi Dan,

Are you using nails with that box instead of screw?


Cheers guys. Initial testing has been extremely impressive. In the next couple of weeks I will be getting round to doing the finish, which is going to be black gloss. I'll get a better camera and post the pictures when I get there :T
Great work Dan, interesting to see you are really into this now :). I like the way you wired the terminals, good forward thinking.
Looking good, HEAVY... eek. The only thing I would do before the box was totally finished would be to tighten the nuts on the inside of the binding post plate and cover them with either hot-melt glue or 5 min epoxy. I have had some loosen off, as well as bare wire on the outside, the nuts loosen off with vibration.

I only use Speakon connectors now for that reason, plus no fuss installation, drill one hole.
what have you used for stuffing and where did you get it as im in the uk to cheers andy
I used normal polyester fibre fill. There is a factory mill shop near me that does all kinds of fabric and cushions etc. It worked out less than £10 to fill that sub.

If you have nothing like that there are places you can order it from online, but it'll cost slightly more.

This may be of use
Is it best to stick the stuffing to the inner Walls or just fill the box ?
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I just fill the box, and the commercial subs Ive had a look in almost all do the same. I can really see a reason to stick it to the sides of the box myself. Theres no issue with it touching anything anyway, even if it does it wont do anything.

Thanks for posting this build and yours. It is very interesting to say the least. I am now contemplating doing one my self. I know you said it is 175L but what are the dimensions of this build?

In your build you said inorder to model a push/pull you just use sealed with 2 drivers. Anything else you have to do or change?

Also, is the other driver exposed to the outside of the box? Would it make a difference how this is oriented with the "sealed" driver? example: does it have to be a 90° like this build or can it be on the opposing wall from the first driver? Any advantage/disadvantage to either?

I want to get home and play with sketchup and winisd now!! You are trully inspiring!

Cheers for the kind words Joe.

The box is larger than its volume suggests. You can calculate volume using the EVC tools in the quick links drop down menu at the top. This cabinet is actually 1000 (w) x 700 (h) x 500 (d).

For push pull you need to have one driver firing out of the box, while the other fires into the box. You need to have the wiring reversed though so both drivers physically pull out of the box and push into the box together. Where you actually put the drivers is entirely upto you. A dual opposed alignment is probably the best for the cabinet as it helps cancel out cabinet resonance, but its difficult with push/pull due to have the rear of one driver outside of the cabinet. If you click the link in my sig, there is another build I did for myself that is also push/pull, and I did the second driver a slightly different way. Hopefully that should give you an idea of how I did things on my sub to get the overall size smaller.

How much does the cabinet vibrate, on this one or yours?
You say dual opposed is better for cabinet resonance. But does it help with cabinet vibration?

Would either be ok to put my TV on or is that not a good idea?

Neither obviously vibrate. The idea behind dual opposed is it stops the cabinet/subwoofer itself from moving at all. Its stays sturdy and doesnt move around your room. The drivers are very strong, and the pressure changes inside the cabinet cause the panels them self to vibrate. Good bracing is what helps eliminate this.

With this sub and mine, you can feel this vibration when you put your hand on the side, but there are no visible signs at all. You can put a drink on the sub and at full power it barely affects the drink.

I would quite happily put a tv on top of either and it wont fall. At full power you might be able to detect some movement up close, but I doubt you would from the viewing seat.

I'm going to take the fourth on this one though, as if you try it and something was to happen, there are to many variables in your construction for me to completely rule out it being a bad idea. Saying that, I know I wouldnt have an issue with my tv on my sub.

Hope that helps.
Thanks Dan!

I guess I will have to build one one now!!!

Sorry but I have one more question. Does the volume also include the area which is open to the room? Or just the actual sealed volume?

Thanks again,
The volume is just the area in side the sealed cabinet.
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