Anyone Damp the insides of your Speaker Cabinets?

Interesting that some say they use resonance as part of the design. I seem to recall comments elsewhere these types of speaker builders used real wood instead of mdf. I’d like to see the way they estimate a standard for the vibration factor. Anyone who does a bit of woodworking can tell you that no two pieces of wood are the same. The density and hardness can change along just a few feet in a single piece! I prefer the efforts of those who work with materials that can provide a better consistency: and the efforts of those like Rockport where crossovers are hand tuned to bring the output of the speaker to spec. 

I diy’d my speakers-bass reflex and a front loaded horn.  Generally, with a ported design I line the walls with .5” wool felt pad and avoid stuffing the enclosure.  A sealed design usually utilizes stuffing.  Transmission line designs use a very specific amount of stuffing based both on the length of the line and the density of the stuffing.  In all cases, bracing is necessary to break up cabinet resonance.  As mentioned in another post, some speakers utilize cabinet resonance as an integral part of the design.   I think Viking Acoustics does this with their Berlin-R. 

Ported has alot to do with as well. Most ported JBL I have had just had an inch or 2  on all 6 pannels. All sealed boxes were full of foam or fibeglass or polly. Sealed Celestion for example uses foam and stuffs the box other than if there is a passive radiator. You need the airflow between the woofer and the radiator for it to work properly. 

Ptss, would you please start the thread? I start a new thread every other day, and don't want to be labeled "that guy".

In all honesty, this is the only site I've ever participated in, in any way, so its a learning experience all the way around for me. I've said a bunch of things I regret (it's on here forever, for all to see...) and a bunch of things I wish I never said, lol.

I agree though, time to start a new thread. Damping (huh, huh, notice I didn't say dampening??) has run its course... Black hole, maybe some plasticide on the drivers, etc.

I think damping is more of a way to fine tune. A strong, sturdy enclosure that is braced well should be step one... or steps 1-10!

There are many ways of bracing, but introducing anything that affects the internal reflective properties of an enclosure may result in acoustic changes that are undesirable.

Shelves with hole(s) are used often, but it is calulated and incorporated into the enclosure design.

The technique in a prior post about using table legs to brace the sides has a lot of merit, in that it has the least impact on internal soundwave reflections or the possibility of creating standing wave traps.

Installing large diameter (1" - 2") wooden dowels in a finished enclosure can be probelmatic, but not unsolveable.

They would need to apply a little bracing pressure on the sides of the cabinet , which will be key in the success of this project. Fastening the dowels in place can be accomplished using epoxy on the ends.

Using seasoned wood is key, since it could shrink.

I have seen round aluminum bars and is worked very well, but in that case the enclosure had double sides and the bars were held in place with bolts hidden by the outer layer

Regards

B_limo. Interesting tough question that companies like Wilson, Rockport, Magico, Focal, YG, B&W, Dynaudio and others never stop working on. Of course as businesses they must concern with trade-offs. Your question-the best-need not consider trade-offs. I think this question is worth its own thread. I believe there are many knowledgeable, educated people who we hope would contribute. (Will you start the thread?-or shall I, as it interests me greatly as well.) I still have a pair of 1985 JBL 250Ti's whose sound I transformed-in all ways for the better- with bracing, mass and damping (all done with minimal effect on internal volume.

Ptss, if building a box from scratch (or even retrofitting), whats the best way to brace it? I was thinking it would be most effective to put shelves throughout that fit snug on all corners of the cabinet and then either cutting a bunch of small circles out of the shelves or even perhaps just one big one in the center of the shelf (to allow air to pass through). Also, would this approach impede free air flow and degrade sound quality?

All loudspeakers sound best when they are as close to inert as possible. Vibrations just cause "fuzzy" sound. Before you go stuffing the insides--1st seriously consider reducing/eliminating vibration by bracing the walls.
Adding stuffing material will affect the bass response whereas bracing simply eliminates resonances. I have used "well seasoned" i.e.- old- coffee table legs of oak and mahogany to excellent effect. Use PL Premium glue and a snug fit. You can't go wrong by minimizing vibrations this way. It's well worth it.. You will end up smiling with the enhanced clarity and dynamics.

I own a pair of Allison CD8s. I have always liked the way they sounded. I read in an issue of Audio Basics Magazine about applying plasticine to the interior of the speaker housing and to the speaker frames. I figured 'why not' if I didn't like the results, it was easy enough to remove. I am pleased with the results as I notice an improvement in the bass response....the bass had been tightened up a bit. I have since left it in the speakers.

If you want to add material to suppress vibration one of the better materials to use is polyester batting.

It comes in different thicknesses and can be found on the web or at a local haberdasher.

It will hold it's shape and thickness compared to other materials.

Google fatt batt :-)

There's damping of a speaker's interior, like adding wool or fiberglass insulation. If judiciously done it really helps a speaker resolve itself and avoid ringing. If overdone it is readily audible as a lack of micro dynamics.

There's damping of a spekers internal cabinet walls to reduce cabinet vibrations, generally using Dynamat or automobile door daming materials. This can make much sense overall, but there's no replacement for a sturdy, thick, well braced cabinet to starty out with.

Then there's Black Hole 5, which effectively damps the cabinet walls while making the interior of the cabinet seem larger to the speaker, enhancing bass and mid-bass characteristics. However this too can be overdone.

Any or all of these might require an adjustment to the crossover to compensate for the different Q you will achieve, perhaps as easy as altering the tweeter resistor value, but it could need more tweaking. No way to know for sure unless you try it and listen.

Uh, I feel stupid...lol.

Thank you RW for nipping that in the butt for me ;-)

Correct term is "damping". Damping reduces resonances, dampening wets something. I'm pretty sure you'd never want to wet the insides of your speakers...

-RW-

I added dampening to my wine tonight; it tasted awful, but it does sound better;-)
Sorry Mapman, my jokes get worse as I get older, lol.

I've been reading a little bit on-line and trying to educate myself a little more on the topic. I'll report back as I learn more and experiment with my own speakers (frankensteined in wall speakers mounted in a phase tech speaker box).

If anyone has done this, and achieved a good result please chime in and let us know where you applied the dampening material and what you used.

Thanks everyone!

I suppose one way to look at it is that resonances always occur and a designer can chose their approach on they are managed or controlled as needed to get the desired results. How much is right or best is something of a subjective determination, part of managing the science in order to deliver the art in a pleasing manner. But there is no single one piece of art that works best for everyone all the time. Like most things audio, in the end, it all depends. There is no single right answer. Like wine, ice cream, and all that. If you buy a nice bottle of wine and are not 100% happy with the flavor, there are many ways to tweak it to make it "better".

"Do most speakers sound best in cabinets that resonate as little as possible?"

I'd say the answer is yes.

Most but not all. Some speaker designs (Tonian comes to mind and a few others that I recall investigating) make cabinet resonances (as opposed to minimizing same) an integral and key part of the sound design along lines analogous to how a string instrument does the same.

My opinion is that designing a speaker and designing a string instrument are not analogous so I am not sure how well the analogy stands. I do not doubt however that speakers designed this way can sound very good indeed, at least in subjective terms at a minimum. its one way to get something more and/or different out of a similar box compared to others. Is it better or worse though? Dunno. I suppose it depends on the talent and ears of the designer more so than anything else.

"The thinking is that most dampening simply smears and delays the resonate behavior without truly eliminating it."

I tend to think of it strictly as what it says, ie damping material in the textbook sense of the meaning of the word Damping.

Yes, it may sound worse or better than otherwise, or not much different at all. Par for the course for "tweaks". At least its an easy, inexpensive, fairly harmless and easily reversible one to try if one is so inclined.

I've done some DIY speaker maintenance projects on older speakers where I changed the volume and distribution of internal damping material as part of the repair and tuning process, but have never felt the need nor been sufficiently inclined to just muck with the damping of a new pair in good operating condition, especially if still under a warranty of any kind.

Some manufacturers factor the resonate nature of the enclosure into the overall sound of loudspeaker. The thinking is that most dampening simply smears and delays the resonate behavior without truly eliminating it. Having a cabinet that quickly releases rather than storing energy is thus seen as an advantage.

Applying additional dampening material will definitely change the sound of a loudspeaker, but it could just as easily sound worst.

Speakers are usually voiced for a cabinet. Placing dynamat or any other similar material can change the sound and not for better.

Probably would help a lot of inexpensive speakers sound better and not a hard or expensive tweak to try in most cases.

Everything has a price point. Manufactures come out with new and improved products all the time. What is wrong with trying to make your gear sound better?

Well-made is all relative. Maybe you have in mind shipbuilding standards of construction, like Rockport speakers.

If the speaker is well made you should not have to do anything.

I used dynamat on the mid range and mid bass boxes inside my speaker.