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PostPosted: Mon Apr 02, 2018 9:02 pm 
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Location: London, ON, CA
Here are a few pics of my dual 12" subwoofer build. The box is 2.6 cubic feet made out of 3/4" ply with a double front baffle. I left off tonight working on the bracing.


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PostPosted: Mon Apr 02, 2018 10:25 pm 
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Location: Port Moody, BC, CA
Cool, as any woodworker knows you can never have two many clamps!
keep the pictures coming.


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PostPosted: Tue Apr 03, 2018 5:19 am 
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Location: Newmarket, ON, CA
Looks good so far! what's going to power it?


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PostPosted: Tue Apr 03, 2018 1:43 pm 
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Soundemon wrote:
Looks good so far! what's going to power it?


All four coils (two x two ohm per sub) are going to be wired in series and run on an 800 watt 8 ohm amp. If that isn't enough, I will try something else :).

David.


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PostPosted: Tue Apr 03, 2018 2:58 pm 
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Location: Waterdown, ON, CA
DaveFred wrote:
Soundemon wrote:
Looks good so far! what's going to power it?


All four coils (two x two ohm per sub) are going to be wired in series and run on an 800 watt 8 ohm amp. If that isn't enough, I will try something else :).

David.

Is it sealed or ported? An 800 watt mono amp? will most certainly do the job.


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PostPosted: Tue Apr 03, 2018 4:35 pm 
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Good to see CSS back in action. Make sure you have tight coupling between the woofers to maximize the active force cancelation.

Image

Mine is a pair of push-push SDX10s, i powered them with a 4x100w Sure digital amp built for something like $100 USD.

dave

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PostPosted: Tue Apr 03, 2018 8:14 pm 
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planet10 wrote:
Good to see CSS back in action. Make sure you have tight coupling between the woofers to maximize the active force cancelation.

Image

Mine is a pair of push-push SDX10s, i powered them with a 4x100w Sure digital amp built for something like $100 USD.

dave


And what do you think of the sub you built?

I had several different ways in mind to use these two subs, an M&K style, front and down or push pull slot loaded. This seamed the easiest and took up the least space. :)


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PostPosted: Tue Apr 03, 2018 8:24 pm 
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I really liked them. The guy Chris sold them to when i was in th ehospital said they are the best he has heard.

I am a real fan of push-push. Properly coupled the reactive forces of each woofer cancels that od the other almost completely. This dramatically reduces the load on the box.

The cabinets for the SDX10 were made from well braced 15mm baltic birch ply. They could be lifted one hand (and the other with the other hand). With the woofers installed each was either a 2-man lift (or 1 beefy guy). I had to turn the woofers about 10dB past as loud as i typically listen to get the top moving (easily fixed with a layer of loosely coupled solid surface material) — every other panel was silent.

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an M&K style, front and down or push pull slot loaded


With good woofers, push-pull does little, as the woofers in & our are quite symetrical, and what it does is to remove some 2nd order harmonic distortion, but leaves the 3rd order. Not having 2nd order higher than 3rd order is usually not a good thing.

dave

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PostPosted: Wed Apr 04, 2018 8:39 am 
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Location: hawkesbury, ON, CA
are the 2 magnet touching that wood brace? if yes, don t you think it might make vibration


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PostPosted: Wed Apr 04, 2018 10:23 am 
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yes. It is important to get the fit just right. Solidly against the magnet but not so much as to stress the basket. We have built lterally 100s of boxes with this kind of driver brace and it has only brought benefits. In a push-push box it is quite important. An over the top implementation would also employ long bolt (like ready rod), that would pull the driver flanges tight to resist the movement of the driver baskets when the cone pushes in — the brace only realy works when the cone moves out.

dave

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PostPosted: Thu Apr 05, 2018 1:52 pm 
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planet10 wrote:
yes. It is important to get the fit just right. Solidly against the magnet but not so much as to stress the basket. We have built lterally 100s of boxes with this kind of driver brace and it has only brought benefits. In a push-push box it is quite important. An over the top implementation would also employ long bolt (like ready rod), that would pull the driver flanges tight to resist the movement of the driver baskets when the cone pushes in — the brace only realy works when the cone moves out.

dave


What about rigidly bracing the woofer baffles with some 1" dowels secured between them? Would that not brace for in *and* out stroke of the woofer?

That is what I am thinking of doing rather than wedging the woofers together for coupling only on the out stroke.

Thoughts?

Thank you,

David.


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PostPosted: Thu Apr 05, 2018 2:14 pm 
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Dowels are not a great brace, and it means that the connection berween woofers becomes “squishy” as the force has to travel thru the baffle, extactly what we are trying (and are) removing.

Not directly related, but of relevance:

Image

We have done a lot of experimenting with this kind of thing… here is an example of our standard bracing scheme:

Image

dave

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PostPosted: Thu Apr 05, 2018 3:15 pm 
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Location: London, ON, CA
planet10 wrote:
Dowels are not a great brace, and it means that the connection berween woofers becomes “squishy” as the force has to travel thru the baffle, extactly what we are trying (and are) removing.

Not directly related, but of relevance:

Image

We have done a lot of experimenting with this kind of thing… here is an example of our standard bracing scheme:

Image

dave


I don't know, I picked up 1-1/8" hardwood dowel today. Eight pieces, 16" long arranged in a circle behind each speaker flange, baffle to baffle, seems like it would be pretty strong. No?


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PostPosted: Thu Apr 05, 2018 3:51 pm 
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Maybe, but i wouldn’t count on it being as effective. A mechanics stethescope after the build will give you a good idea.

dave

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PostPosted: Thu Apr 05, 2018 5:29 pm 
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Location: Montréal, QC, CA
For a push-push design, speakers on the same axis must be one monolithic piece
to prevent vibrations. Using the backplate of the speaker is not good. Nothing
should touch the backplate and certainly not another speaker (via some brace).

Use some metal rods between both speakers.
This will dramatically lower force on the walls.
Attachment:
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