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Multi-Way Conventional loudspeakers with crossovers

Speaker baffle interface and cabinet resonance - Getting that last 10%
Speaker baffle interface and cabinet resonance - Getting that last 10%
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Old 14th September 2020, 04:07 PM   #1
johnp98 is offline johnp98
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Join Date: Jun 2020
Default Speaker baffle interface and cabinet resonance - Getting that last 10%

Hello,
I am about to built a pair of DIYSG HTM-12 speakers was wondering if there were potential ways I could maximize the quality of the speaker build. Reading around it does appear there are some potential things that could help but I am just wanting to make sure they are correct and ask for feedback.

1) I was wondering about the speaker driver / baffle interface. I have read that having some dampening material (such as weather stripping or neoprene etc) can help reduce the transmission of vibrations to the speaker cabinet. I could not get it to be a fully floating driver but I was wondering if instead of the driver being simply screwed into the MDF if this design would be beneficial:
Speaker driver -->
Dampening material -->
MDF baffle (drilled through, so no direct contact with the bolts)-->
Dampening material -->
1 plywood with T nuts for bolting the speaker to (the plywood could either be cut around the whole speaker cut out, or could be in smaller pieces for each individual bolt hole)

Do you think that would help isolate the driver from the baffle and be worth doing? Any room for improvement?

2) I was looking to minimize cabinet resonances and so I have read that the main way to do this is through adding more mass to the walls, adding more bracing to the walls, adding dampening material, absorption.

Mass: I have looked into constrained layer dampening and using green glue, and so I could potentially put another layer of MDF on the back wall. Would this be beneficial? Any other options / thoughts?

Bracing: I certainly can add more MDF bracing to the cabinet. Are window braces most effective? Any places that I should avoid putting bracing (i.e. right behind the main driver)?

Dampening: This is where I haven seen lots of opinions yet have not figured out what truly would be best. I have heard of people using dynamat, roofing felt, industrial floor tiling, rubber gym mats, memory foam, bubble wrap, etc. Would all of these be options? Any personal preferences people have? Also how does this affect the effective volume of the cabinet, like can one go too overboard with this stuff?

Absorption: The speaker design is a ported design and calls for ~3inches of absorption on the back wall and 1.5inches on the side and to keep the ports clear. I have read that the maximum velocity of standing waves is in the middle of the cabinet, so then hanging the absorption material way through the cabinet would be most effective would it not? But are their down sides to this? Also if it was in the way of the direct path from the speaker to the ports would that change the port tuning, or is that all about the internal volume and should not be a problem? Also, more absorption would change the effective volume and thus change the port tuning so maybe not changing the absorption would be ideal? I have also heard that there are significant downsides with over stuffing a speaker yet I have not personally made any speakers so what should I be looking for if that occurs?

Ok, I think those were the main things that I was looking into to try and squeeze that final 10% of performance out of this DIY build. I would appreciate any feedback on the proposed alterations and also let me know if there are any glaring ways I could further improve on the cabinet making.

Thanks!
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Old 14th September 2020, 04:16 PM   #2
Bill Coltrane is offline Bill Coltrane  Netherlands
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For speaker mounting, you could attach the magnet to the rear wall of the speaker.
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Old 15th September 2020, 01:28 AM   #3
johnp98 is offline johnp98
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Quote:
Originally Posted by Bill Coltrane View Post
For speaker mounting, you could attach the magnet to the rear wall of the speaker.
Yeah, I have just not seen an elegant way to do that. Humm.
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Old 15th September 2020, 10:40 PM   #4
johnp98 is offline johnp98
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Join Date: Jun 2020
Quote:
Originally Posted by johnp98 View Post
Yeah, I have just not seen an elegant way to do that. Humm.
Could you make the cross bracing line up and support the driver magnet? Would that add extra support to the driver as then it would be anchored to the front but also resting on the cross bracing (I would put dampening material between the bracing and the magnet just so it does not rattle)?
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Old 16th September 2020, 12:07 AM   #5
Richard Ellis is offline Richard Ellis  Argentina
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Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
There was a thread on the Eminence Beta 12LTA...in an effort to optimize the "last few percentages", he had tightly wrapped the basket structure in a foam absorbent material. This guy kept running those "waterfall" tests...& this was a tiny percentage improvement. The structure a few inches from the cone, he theorized, was actually reflecting pressure waves to re-energize, imparted unwanted cone vibrations.








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