Dynamat

Yes, won't hurt at all to put in the Dynamat. Put the speaker foam or stuffing on top of that. You'll likely enjoy the result.
 
Seems pointless to put an expensive material known for reducing ringing and reverbrations in METAL surfaces
(Car doors and such) into a WOODEN BOX which is not a medium generally known as having Ringing problems.

Seems like a BIG waste of Money ...
What am I missing here??
 
Seems pointless to put an expensive material known for reducing ringing and reverbrations in METAL surfaces
(Car doors and such) into a WOODEN BOX which is not a medium generally known as having Ringing problems.

Seems like a BIG waste of Money ...
What am I missing here??

Probably nothing. It might cut back slightly on enclosure resonance. Would it be worth it, probably not. Would it harm it? Cant see how. Bob
 
Probably nothing. It might cut back slightly on enclosure resonance. Would it be worth it, probably not. Would it harm it? Cant see how. Bob

Never said it would hurt them - just seems like a big waste of money.

Again, Westlake monitors used a custom tar and fiber goop and painted the inside of their studio monitor cabinets to deaden them.
Then again, they are ENGINEERS, have designed the speakers for this treatment, and get paid HUGE MONEY for their technique.
Telling someone to put tarry sheets of dynamat in some off the rack pair of speakers is just encouraging them to waste their money.
If you must, load then up with polyfill, or build braces to stiffen the panels ...
 
Seems pointless to put an expensive material known for reducing ringing and reverbrations in METAL surfaces
(Car doors and such) into a WOODEN BOX which is not a medium generally known as having Ringing problems.

Seems like a BIG waste of Money ...
What am I missing here??
I'm just curious to see the experiment performed at somebody else's expense! :D

Also, as pointed out earlier in the thread, if you hang around at a car audio store (if you can still find one) you might be able to access Dynamat scraps.
 
Well Im not for the idea of using it. Id probably use a significantly cheaper product called Peel and Seal for roofing were I inclined to experiment in such a way. Bob

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One of, if not the most effective methods of combating enclosure resonance is the use of cross bracing between the enclosure panels.

Being on a budget, I used some hardwood flooring from a past employer, with 79 cent L-brackets that I had modified.
Side, back, and top panels have center bracing screwed and glued to the panels. I used 3/4" (polyethylene?) foam pad to line the side, top, bottom, and back panels. I suppose it isn't the best material for the purpose, but it works to me. I split a one pound bag of fiber-fill batting for each speaker, and spread most of the batting behind the driver.
 

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Cabinet wall damping is a very different thing than internal damping of the air cavity. One, dynamat, Black Hole 5 etc., deals with resonances of the cabinet panels and the other, wool, fiberglass, polfill etc. with the internal standing waves and the cabinet Q. Removing the polyfill is not needed or advisable if you decide to stiffen the cabs with an acoustic mat. One thing, you only need a few strips on the cabinet. often with BR designs folks will place a sheet of it behind the woofer.
 
I haven't used dynamat, mainly because I could not source any. I also knew it's pretty expensive, so I used a different but similar material.
I found that several of my KEF loudspeaker enclosures have pieces of bitumen like sheets covering parts of the inside panels. Small rectangular pieces, the size of an 8" woofer each. Of course, after 30+ years they had been altered to a form more brittle than elastic, so I consider them gone.

I found nice rolls of bitumen sheets in construction suppliers. There are two kinds of sheets. The ones with small grain gravel encased on one side (these are no good) and the more suitable ones with plain bitumen material. They are heavy and somewhat elastic, more plastic I should say.

I made an experiment enclosure, around 200lt big by external dimensions, using 3/4" plywood. I enclosed a small enclosure in that with a 12" woofer in that. I then did experiments of measuring the output at various frequencies. I should not be getting any output (as the outer enclosure was fully closed) but of course I did get a slightly muffled version of the output of the woofer.

I made three main tests by applying up to three layers of 3" thick sheets along all internal sides of the panels. Not on some places but all around.

The results was very good. Each new layer decreased the "parasitic" output by a couple of dB, more at the resonance frequencies of the enclosure. The third layer decreased the overall output by about 20dB, more at the resonance points that showed a slight drop in frequency as well as new layers were added. I attribute the drop in resonance frequencies to the increased mass of the enclosure.
I stopped at the third layer as it showed a decreased effect compared to the second layer which in turn showed a relatively smaller effect compared to the first layer. And three layers increased the weight by a lot so I had to stop, really.

This lining is not meant to replace the fiberglass or mineral wool stuffing. The lining is there to reduce panel resonance and emission through the panels. The stuffing is there to tame standing waves (which also helps reduce parasitic emissions) as well as increase the effective volume of the enclosure as a load to the woofer. Enough stuffing can achieve up to 25-30% increase of the effective load volume. However, when treating a product loudspeaker, you should observe the stuffing added by the manufacturer as they probably have considered how much was needed.

Apart from the test enclosure mentioned above, I treated my pair of KEF R105, a pair of Calinda and Carlton III. Of course after removing the original few pieces of sheets that were mounted there that broke into pieces.

One thing I should mention is that I didn't use just staples, (like KEF originally used) but applied contact glue to the entire surfaces to be glued and then mounted the sheets, applied pressure with a roller and finally staples using a staple gun. That was done to ensure full contact between the two and to make the wooden panel and the bitumen sheet act together as one lump.

The results have been great in terms of sound quality. The sound is clear, transient response (kick drum and upright bass strings) sounds cleaner and I also realized the loudspeakers in their original form had some element of boxiness in their sound. Nothing I noticed before but once you listen to the difference it's something that's easy to identify as ... missing.

There is a caveat however. Three layers of bitumen sheets on the 200lt box made for a really heavy box. The 105s have become a lot heavier as well, but manageable. The 50lt Calinda / Carlton are much more easy to handle after being treated. Also, measuring and cutting the bitumen sheets to properly fit into the "compartments" created by asymetric and diagonal braces is a small challenge but I used paper to create templates so it was doable.

If you add three layers (i.e. 9mm thick) you should also consider they take up some space that was meant for loading the woofer, so in turn I increased the stuffing density with some more baf material to compensate.
 
Jeez, it's a few sheets of Dynamat.

Cheapskates in an audio forum? We've all wasted a lot more money than what it costs for a bit of Dynamat to treat the inside of those bookshelfs.

It can't hurt, and it may help. I've placed similar materials inside of speakers, inside of TT platters and plinths with perceivable dampening effects.
 
If you add three layers (i.e. 9mm thick) you should also consider they take up some space that was meant for loading the woofer, so in turn I increased the stuffing density with some more baf material to compensate.

Yes, any volume consumed should be countered for with additional "stuffing"
 
I have a pair of MachOne speakers, not good. So, I lined them with peel and stick aluminum face rubber sheets left over from another project. No other changes were made. The inside of the box must be primed or it won't stick.
It didn't fix what comes out the front of the speakers but it did stop the cabinet from broadcasting junk around the room that I was not aware of.
So yes, good idea.
 
Dang, still kicking around your BS "theory" of "why not, it can't hurt."
Why spend money on BS stuff like that - just buy better speakers to begin with!

Dynamat is one of the more expensive materials going. It has a function, its used by Car Audio folks for deadening METAL area - like inside door panels, under the carpets - generally to cut down excess road noise so you can hear your tunes better.to tone down rattles and ringing in metal areas.

That has NOTHING TO DO with deadening a WOODEN BOX! That kind of wood does not ring!
Use roofing pitch or the sticky sheet another member mentioned.

If you want the box to act "larger", or to play lower, add some polyfill in stages, experiment, until you get the results you desire.

I just used a comparable material called QPads to deaden the metal ALTEC 811 Horns in my Heath AS101 speakers - to stop any potential ringing!
($36 shipped from Amazon for a box of 6 sheets of 12" x 12" material - its a tarry material with LEAD mpregnated - MUCH cheaper than Dynamat.
https://smile.amazon.com/Fibreglass-Evercoat-FIB116-Q-Pads-Deadener/dp/B000KEDUE4/

Insulting people because they are being frugal/sensible is outrageous!

QPad.jpg
 
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My Mach boxes were ringin a plenty.
Are those "thrusters" or some such? What are "Mach boxes"?
Besides, I asked the original poster where he heard ringing on HIS speakers and he did not answer.

Its not hard to track down ringing - take a cardboard tube, like from paper towels, put one end on your ear,
and use the other end to move around your speaker while its playing and see if you hear ringing.
If you don't any part ringing, there is no point in using Dynamat to stop ringing.
 
Are those "thrusters" or some such? What are "Mach boxes"?
Besides, I asked the original poster where he heard ringing on HIS speakers and he did not answer.

Its not hard to track down ringing - take a cardboard tube, like from paper towels, put one end on your ear,
and use the other end to move around your speaker while its playing and see if you hear ringing.
If you don't any part ringing, there is no point in using Dynamat to stop ringing.
The infamous Realistic MachOne. A much loved but known to be not so good speaker sold by RadioShack in the 70's.
No cardboard tube needed. Place hand on side of box.
 
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