Horn Damping

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#61
It's on roofing material isle .It's a weather strip , barrier or Ice& water shield and I think it's from GAF. Buy more expensive one. It's ticker and better quality. They sell it in 1 and 2 sg. lengths so it's either 3'x 33' or 3x66' . I think torch down is a better one but somewhat "dangerous" to apply. Hot bitumen and all... there is also a roofing felt in rolls which is what BBC used to damp their thin wall enclosures ,just stapling layers to the walls.
 
#62
This Eurodyn horn looks like bigger Klipsch square tractrix horns. I bet the driver is more responsible for good result that the horn or rather driver, horn combination. I read that there are very few neutral drivers suitable for tractrix horn and most is constructed with radial ,and other heavy equalised pro applications in mind i.e Tad td400 was made and optimised to perform well with TH 4001 horn
 
#63
The Klangfilm driver is pretty good, I am sure. There are field coil and PM Eurodyns with this horn.

jc morrison and I tried the horn with GIPs enhanced version of WE 594A. This was really really impressive.

Two years ago they had a horn shootout at ETF...I think this unit came in first or second.

It is a 2" throat so there are only a limited number of drivers that will bolt right up to it.
 
#64
I will probably be at Lowe's tomorrow and I will check out the "peel n seal" but 66' is enough to do all of my horns plus my car.

I just remembered another option that I saw once. A guy I met used stick-on rubber floor tiles to damp a 511.

Some flooring tiles are hard vinyl but they also make resilient rubber tiles. Some of the rubber tiles have jigsaw puzzle like edges to join one piece to the next.

This stuff is relatively cheap, you can buy only as much as you need, and it available in various designer colors that match the 511. I like the old 1950s style industrial flooring with flecks and/or swirls like a bowling ball.

The downside is that it is nowhere near as flexible and conformable as the "peel and stick" but it is an option, especially for a horn with wide near-flat surfaces like the 511s.
 
#65
The advantage of the roofing stuff is that presumably it is formulated to be able to adhere to a non flat surface, which is often found on roofs and horns... the premium brand is worth the price, and the stuff ain't that cheap either... should work pretty well for damping only, won't add stiffness, which is something that the sheet metal built multicells really want.

My kingdom for a very fast set thick contact adhesive - and not "construction" adhesive. All the construction adhesives I have tried are non spreadable, and give up sticking within a year or so... maybe they work ok on wallboard and the like, but they are no good on painted metal or bare metal surfaces...

I have experimented with the slower set "cove base" and wall tile and floor adhesives that can be spread and troweled, but they expect a flat surface going to a flat surface, so they won't hold enough to hold a layer to the outside of the curve of a square horn wall... not if the layer has any thickness or stiffness...

_-_-bear
 
#66
Adding surface damping can be an excercise in frustration. I've used a lot of the stick on tar-like pads (in your best British accent say "Bit-u-min") and they can help but they never seem to stick. On wooden cabinets you can staple them all over but not so good for horns. At KEF we found a two part resin called Polyoll, which was used in KM1s and 104/2s and other KEF products of that era. I also remember a dental molding compound that stuck well, went firm but not hard and had good characteristics.

If you really want to damp a surface effectivley then read up about constrained layer damping.

http://www.earsc.com/pdfs/engineering/CLD.pdf

Less Cowbell! The Unconstrained Truth About Constrained-Layer Damping

David
 
#67
Cal Weldon said:
Not necessarily good or bad but I did find that you need to damp only the lips of the 811/511 horns. That's where the ring is coming from. Damping material on the back behind the flange is IMO a waste.
Click to expand...

Actually the 511 is not dampable ,lips or no lips. This one honk.
I used it for years and it always sounded harsh. At the end I went for a conical horn ,Bill Woods type.
 
#71
Damping horns raises the question of what your expectations are. Many seem to think that horn sound is about structural resonances and some damping will transform a bad horn. The reality is that most of a horn's character is from its profile and not its material. Surely there will be a few structural resonances but most of a horns sound is due to the non-linear acoustical load it presents to the driver compounded by uneven directional effects.

Mounting is sufficient to damp most cast horns from any high Q ringing. I have seen some fiberglass horns pthat can benefit from mass or damping in the throat area where SPL is so great.

Still, it won't make a bad horn design sound good.
 
#76
Joe Roberts said:
Seriously doubt that Peavey would look to prewar German cinema gear for design, although both are square and black.

Must be a recent CD design. There is a guy on this thread using that horn and he says EV copy.
Click to expand...

They are both Tractrix horns or very close the Peavey is. The story I heard was that Peavey hired two ex Electrovoice engineers some time in the mid 1970's and that they had worked with Keele. I have no idea where that story came from so no way to know if it is true. The Peavey horns are very similar to the EV stuff. This all sound plausible enough and I can attest to the sonic quality of the CH-1 and ch-2 horns they sound excellent. Don K went from EV to Altec (had EV making the Manta Ray's for Altec) then to JBL , Klipsch Harmon others I think, setting them up with CD horn designs. The guy wrote the book and set up all the majors with his designs even won an Academy Award for technical excellence for one of his designs at JBL.
I seriously doubt that the math in the old Semens designs is as close to accurate as is Don's work many many decades later, that is possible but not likely. I look at the Peavey CH series as the poor man's EV horns. I recently compared the CH-2 Peavey to the EV original. Both are well made and the EV is the more expensively made as far as the complexity of the mold work goes. The EV would cost more to make and is a thinner wall horn as a result of keeping cost in line, I was surprised because my initial bias was that the EV would sound better but I liked the Peavey a little more than the EV. I would guess that the horn wall thickness had the most to do with my preference as the Peavey is much thicker than the EV. When you take a look at the measurements especially the polar response you can see the EV are the better designed horns. You get what you pay for. Still the big Peavey are serious quality for seriously little money. I would say that if you start out with the Peavey and you find another horn which betters it you have found a really good horn. It may take you a while and you will likely have to make the jump to large format drivers remember the Peavey are one inch horns. Best regards Moray James.
 
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#77
A good question is why do some cast aluminum horns mechanically ring and some don't?

I have an Emilar EH-200 and that doesn't ring. Western Electric KS-spec horns don't ring. The Eurodyn horn doesn't ring.

Here's a pic of late 40s KS-12025, which has a family resemblance to 511. I don't hear this one ringing:

http://www.audioanthology.com/images/ks12025+713 copia.jpg

The above mentioned horns have somewhat thicker walls than a 511, but I am not sure if that fully explains it.

Isn't there an overlapping set of mechanical design criteria where the shape, thickness, and dimensions of horns promote or retard physical vibration?

Further, I suppose every horn has a natural resonant frequency in the mechanical realm, which seems a potential source of headaches.

I guess I am saying that some horns are harder to damp because they really want to ring.

Often horns are the victims of cheap construction but it seems obvious that there is a tragic world of unintended consequences from the mechanical perspective related to their properties as mechanical resonators.
 
#78
I seriously doubt that the math in the old Semens designs is as close to accurate as is Don's work many many decades later, that is possible but not likely.
Click to expand...

I have high faith in the math capabilities of master Siemens engineers.

Know any German engineers?😀

Were there vast theoretical advances in tractrix horn design between 1935 and 1970?

The introduction of computer modeling and measurement was probably the major historical disjunction.

All I can say is that Eurodyn horn is mighty fine. I'd love to snag a pr of those Peaveys too. I'm looking for great 1" entry horns.

I don't care if a unit came from Berlin or Meridian, MS, 1928 or 2009, as long as it plays music.
 
#80
Norman: what is physically the largest horn that Peavey makes with the quadratic throat geometry? The CH-1 makes a lot of good sound over a wide band for very little money and the 22A is a big driver which sounds good too. I recently found a pair of these for $100.00, horns drivers and crossovers and that's cheap. I suppose that Don Keele's CBT work is the way to go to get the range and control in a domestic size package but I wonder about the system efficiency not to mention the cost and effort. Best regards Moray James.
 
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