How to attentuate HF in AA crossover (La Scala) / horn deadening

[meagain]

Daddy Dee and/or 3dzap - would one put more than one layer of dynamat on the horns? 2?

[Ray Garrison]

re the dynamat -

My La Scalas had (past tense, sniffles...) the metal horns. I

damped them with DynaMat I bought at Pep Boys Auto Parts. It made

a significant difference on some music at loud volumes.

There are at least three kinds of DynaMat, maybe more now. Look

for the older, clunky-looking stuff with the brown backing on the

silver foil. The newer versions are more high-tech polymer for

high heat applications and lighter weight, important in auto

applications, but they don't damp as well.

The stuff adheres better when warm, but don't over do it. I cut

triangular patterns out - one for top, bottom, left side and right

side. Put them in a warm over for a few minutes. When I

took them out, they were warmer than they should have been.

Imagine sheets of heavy aluminum foil with (burning hot) goopy glop the

consistency of silly putty smeared on them. Damn near burned my

fingers off trying to apply it. Awful mess, smelly sticky droopy

sheets of hot sticky glop. Got them on the horns, let them cool

down. Prior to application, if I held the horn in my hand by the

flange where the driver mounts and rapped it with a hard object, it

made a "clang" kind of sound. Not like a bell, but definately

metallic. After application, it was a dull "thud". It was

also welded onto the surface of the horn to the extent that you'd've

needed a chisel to get (some of) it off. I was really happy with

the improvement in clarity at high levels, particularly on

voices. Of course, after going through the pain (literally) of

applying it, I was probably pretty much pre-disposed to like what I

heard, or I'd've been seriously bummed.

I doubt it would have made as big a difference on the polymer horns, but I really don't know.

[meagain]

I've been reading a bit about the dynamat stuff. The hammer/chisel comments scare me. I think I'm going to do modeling clay or rope caulk.

[cjgeraci]

"Hammer/chisel comments scare me."

Ok .......but original Dynamat is easy to use and it works. You can cut it with a standard pair of tin snips or even strong scissors. You are welcome to do modeling clay or rope caulk. I have gone the rope caulk route with Altec horns, but unless you really like spending some good time doing that - Dynamat is a much quicker and easier solution. I first got the idea from Al Klappenberger, and others have used it with success as well.

Ray's post is accurate. Back in the day when I ran metal horns with my Belles, I used one layer of the older (original) Dynamat that Ray posted about - and there was a noticeable difference in less ringing at high volumes.

No matter how much that reduced ringing, however, the change to constant imped networks was more significant though so I think Dean is correct with his comments.

Carl.

[meagain]

Is this 'older' style Dynamat still available or is it something one could only find on Ebay, etc? It does sound permanent though. I've only read one post where the owner didn't like the dampening and removed it. But that might be enough for me. Yet, it seems like 'everyone' else who's damped their horns says there's an improvement. I have a pair of Cornwalls here that are damped with modeling clay. They also have Dean crossovers (Jensen). There's something very smooth and comfy about the horn section. It's likely the crossovers, but hell - for not too much money, I really need to try this for my khorns. I found a stock pair of dec. corns at a house sale and their horn section isn't as sweet. I initially pegged the 'more comfy' sound to the corn horn, but when I got the 2nd stock pair... I knew it was either the crossovers or the clay. Prolly a combo. But I learned something.

Indeed, the clay or rope caulk sounds alot more tedious to install then the Dynamat. But if I go with Dynamat - I better like it?

[Ray Garrison]

http://www.crutchfield.com/S-IBB9S3yhQMk/cgi-bin/ProdView.asp?g=890&I=15410115&search=dynamat

The original DynaMat is still available.

If you put it on cool, it won't adhere as well, and you *might* be able to peel it off in sheets if you wanted to. It would probably separate over time, so if you liked it, you'd probably want to get around to re-applying it warm. But yes, if you put it on hot-ish like I did, it would be challenging to remove it.

To be honest, I can't image it having a negative impact. You might not think it made as much of an improvement as you were hoping, but I can't see any downside, other than cosmetic.

[BEC]

nevermind

[meagain]

BEC - Should I put a bit on the crossovers and wireing also? []

[cscmc1]

Man, guys (& gals), I just dunno... I fiddled with my squawkers (rope caulk and a light coat of rubber undercoating), and while they sound better (smoother) to my ears, I am still having a hard time tuning my ears to these things. I find that they sound pretty nice after an hour or so listening, but I hooked my Fostex full-rangers back up and they IMMEDIATELY sounded "right." The balance is there with the Fostex, while the La Scalas just sound too forward to me. I think maybe my room is too small for these speakers. I'm not sure which pair to keep! Letting both stay is not an option space-wise or conscience-wise. I am getting married this summer and have vowed to tidy up a bit, and the money I'll get from selling one pair or the other will pay for a chunk of the wedding, to boot.

My speakerphile side says "Get BEC to rework the crossovers and at least have a listen," but my Good Fiance side says "sell them as-is for what I've got in 'em and let the new owner make that call."

I feel bad, as I've all but promised to send the crossovers to Bob for a workover, but I'm just not sure now. Are a pair of commercial (read: black) LaScalas in solid shape (a few scratches and dings, but no structural issues) worth $600? Your thoughts are appreciated!

Chris

[pauln]

I'm surprized that so many try to damp the horns, and even more surprized that they claim results - some of the old papers relating to horn acoustics (even some posted to this forum) explain the physical theory of sound waves in horns and state that the horn wall's composition is irrelevant - it only has to be a substancial barrier and whether the horn wall is cardboard or concrete does not effect the sound... was this being overstated?

[Deang]

I think you prefer the sound of the full range drivers and should sell the LaScalas.

[3dzapper]

I'm surprized that so many try to damp the horns, and even more surprized that they claim results - some of the old papers relating to horn acoustics (even some posted to this forum) explain the physical theory of sound waves in horns and state that the horn wall's composition is irrelevant - it only has to be a substancial barrier and whether the horn wall is cardboard or concrete does not effect the sound... was this being overstated?

Could it possibly be that back then it was cheaper to cast horns with aluminum pot metal than injection molded graphite reinforced plastic? If moldable RP was even invented at the time.

Seems to me that the physics of sound wave transmission would not change no matter the material. What would change is any sound created by the resonance of the material used to cast the horn when excited by the sound pressure within the horn.

I used to have a standing joke I'd tell customers who complained of an unexplained vibration in their cars: "It's the front bumper." It was a joke until Ford issued a service bulletin and parts kit to address a vibration problem in some early Escorts. The kit comprised of a weight to be strategically bolted to the unit frame to cancel a resonance. The cause of the resonance? The front bumper!