Horn Dampening--811B

[Gary L]

In my quest for the optimum performance from my speakers I keep hearing from many that the first thing is to dampen the 811B horns.
I don't hear any ringing but I do listen in the nearfield and have some time to mess around.

Lots of info but what I need to know is where do I concentrate the dampening on the horns? Does it go on the back side behind the baffel, on the front side part that protrudes out, both? What is best.
Also I have heard alot about what to use but would like some advice from those who have found what works and is relatively easy to put on/get off.
Do I mix some tar type concoction, by sticky backed material, spray undercoating or what?
I do not wish to destroy my horns by cutting fins, nor do I want to destroy the looks of them by gooping up the exterior visible portion.
Don't know if others feel this way but at times I like to remove the grills and watch the speakers work while I listen, usually when I am getting loud, just seems to add to the pleasure.

Any help on this subject.

Thank you

Gary

[doclamb]

Gary, I recently refurbished a pair of 19's. To dampen the 811's I used Evamastic, a sound vibration dampening material that comes in 32" x 54" sheets and is .079" thick. I believe it's used to reduce vibration for mechanical ducts. One sheet covers both horns. I purchased the material through McMaster-Carr for $22/sheet shipped. One side of the material sticks to the metal on the horn well enough but it seemed that if you wanted to remove it at a later date, it wouldn't destroy the horn. The material was easy to cut with a utility knife to the shape of the 811 and I applied the mastic to all external surfaces of the horn except where the flange meets the cabinet. There I used double sided weather tape. The results were that when I tapped on the horns prior to mastic it would ring like a bell. After application there was a dull thud and it sounded close to wood. It smoothed out the horn and was definitely worth the $22 and 2 hours of time.

[edgewound]

Another material you can use is Dynamat sheet. It's a sticky-back asphalt sheet loaded with mica for vibration damping. Clean all the surfaces with rubbing alcohol, then cover the inside bells of the outer horn, and the inner flare that lives in the cabinet. It focuses the upper mids and highs from the fatiguing ring that happens at around 1000hz.

There's other brands of the sound deadening sheet, too...you can find a few different types at Parts Express:

http://www.partsexpress.com/webpage....ectGroup_ID=37

[Gary L]

Thanks for the links and advice on this. Do either of you have photos of the finished horn so I can see the resulting look?

I have been considering useing the goo they sell for dipping plier handels in to renew the insulation but I am not quite sure of what properties the dampening material needs to have.
A friend used Great Stuff, the insulation in a can for filling cracks and crevices. It looks like $hit but his horns do Thud now instead of ring and sound a bit less shrill then mine.
Some have even mentioned that Rhino Coating stuff they spray as bed liner in PU trucks. I could get this done easy enough and it would look just fine if you think that would work.

That's because you listen to your music so loudly that your ears are already ringing!

Thanks Widget but you might be right!!

Gary

[edgewound]

Hey Gary...
I don't have any pics of a dampened Altec horn, but if you do it like I said in the previous post, you won't see it from the front. You said that you want something reversible and this solution is just that. Once you start spraying stuff on, it's a MUCH bigger chore to remove it if you choose to do so.

Rhino Lining, etc, might work fine, but it's a bitch to cut and peel off, and is for the most part permanent....and pretty expensive. You can get the same type of bedlining material in a spray can at the auto parts store now...if that's what you want to do.

I'd go with the Dynamat type stuff.

[Gary L]

Think you are right Edgewound. I am sitting here right now with some brown paper cutting and fitting the pieces for patterns. Whats behind the baffle doesn't matter how it looks but up front I really want to keep them looking right.

I am a bit of a Perfucktionist with this stuff so it takes me a while to get R done.

Should have just built wood horns while I was building the cabs but thats yet another future project.

Gary

[Mr. Widget]

In my quest for the optimum performance from my speakers I keep hearing from many that the first thing is to dampen the 811B horns.
I don't hear any ringing but I do listen in the nearfield and have some time to mess around.

That's because you listen to your music so loudly that your ears are already ringing!

Sorry... I couldn't help myself. Many times there are "problems" with speakers that we filter out with our onboard computers. After fixing the problem your listening experience should be a bit more open and relaxed... the sound will be slightly more true. The improvement will be subtle but well worth it.


Widget