Dampening loudspeaker (woofer) frame

[pegwill]

Hi guys

Thought you might be interested in this. This follows the suggestion from Frank Van Alstine(link below) regarding dampening of speaker frames. If you remove your speaker part of your MLS hold it by the magnet and give it a tap with a screwdriver you will notice that it rings fairly well.

The idea behind this tweak is that you apply dampening to the frame - basket of the speaker. I used mortite. It is easy to apply and remove should you decide you do not like the affect. I applied to the drive unit of my Aeons, 8inch speaker. Just cut a strip and and apply to the frame wrapping it around the frame and up onto the magnet. I also applied some to the back of the magnet, encasing the strut in mortite. I remember reading about dampening the magnet years ago to reduce the reflections from the rear of the cabinet, this used a rubber material, can’t remember the name now though, something like derium.

Anyway you notice after the mortite application that there is no ringing at all. When I put the speaker back I used a single strip of mortite to make a gasket and it seemed to work well.

So, how does sound? well I was quite surprised it does seem to has made the bass more defined, less fuzzy around the edges of notes.

Mortite is cheap and available from most hardware stores, Lowe’s, Home Depot etc.

Has I say it costs very little, and is easy removed, returning the speak back to its original state.

Hope it helps
Regards to all

Frank Van Alstine wrote about damping speaker baskets way back in the January 1982 issue of Audio Basics Newsletter
http://www.avahifi.com/index.php?option=com_content&view=article&id=85&Itemid=181

 

[JonFo]

Interesting tweak. Reducing resonances, whatever their source is desirable. Besides your impressions, would you have any metrics (like REW measurements) of the before and after?

 

[pegwill]

Interesting tweak. Reducing resonances, whatever their source is desirable. Besides your impressions, would you have any metrics (like REW measurements) of the before and after?

Hi

No nothing like that, just my impression of before and after listening.

 

[Chops]

Not to bring up an old thread or rain on your parade, but if you bolt that woofer back into the enclosure, all of that ringing you just heard while holding it will be completely gone, since bolting it to the enclosure naturally dampens out any ringing in the basket.

Take a tuning fork, hold it by the base and strike it, it will ring. Lay it on a table and strike it, it no longer rings. Same thing, just a different object.

 

[pegwill]

Hi
I would suggest that the mortite approach of wrapping the frame (basket) is a quick and easy approach rather than messing around with bolts and bits of wood. It only takes a few minutes to apply and should you not like the effect is easily removed, but I guess each to their own.

 

[Peter Ward]

I used Deflex on the cone-facing surfaces of the woofer baskets in my previous speakers to reduce reflections. I felt this worked well. Perhaps part of it was a damping effect too. But as you say, it's quick, doesn't damage anything and it's reversible if you don't like it.

 

[Robert D]

Dont some woofers have a gasket that fits between it and the frame? Maybe there are some after market ones?

 

[Chops]

If you guys want to dampen anything and actually have positive, noticeable results, focus in the enclosures, not the driver baskets.

Yes, driver baskets will vibrate and ring in free-air, but that is nearly completely negated once mounted to the baffle/enclosure. What little vibration/ringing is left is going to be completely inaudible vs the vibrations coming from the enclosure, and even more so from the actual music coming out of the driver.

Focus on bracing/damping the enclosure itself.

I've played around with driver basket damping in the past several times, mostly of which were with open baffle designs. Even on those, where the rear of the driver and the basket are fully exposed, there was still very very little if any difference in sound before and after damping the baskets.