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Horn mods


NBPK402

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I saw in a DIY forum where people were wrapping the exterior of the horns with a white cloth like substance... I am assuming this was to dampen the resonance of the horns. Has anyone tried this on the Klipsch Horns? I was thinking maybe some dynamat.

tia,

Ron

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I saw in a DIY forum where people were wrapping the exterior of the horns with a white cloth like substance... I am assuming this was to dampen the resonance of the horns. Has anyone tried this on the Klipsch Horns? I was thinking maybe some dynamat.

tia,

Ron

The only way this would be a problem is if the horn was not attached and even then? Screw down a bell and does it ring?

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What you're seeing may be Moretite window caulking. You can Google. Out of the box it looks like a roll of ribbon cable (though bigger). When used as caulking you unwind a single "wire" of the ribbon cable and have a string of caulk about 1/8 inch in diameter which can be pushed into the gap between a sliding window and the larger frame, or any long, thin gap. It is probably made of clay and some sort of low volatility oil or glycerin. Probably like modeling clay.

The idea that the Klipsch mid horn needs damping, even more than provided by screwing the mouth to the front plywood board, has been around for a while. People would apply Moretite in strings or multiple width strings (strips).

I did not put any credence in this. Modifications are like belly buttons; everyone has one. And the modifier always finds that their mod was an improvement. They never find the mod was worthless or did harm. Cynical me speaking.

You should look at the four-part tour of the Klipsch museum with Jim Hunter on YouTube. Near the end he shows the mold used to cast the K-400 aluminum horn. Very impressive.

In 1987, Don Keele (big name in audio engineering) was working for Klipsch and designed the K-401 horn which is made from structural plastic (or resin perhaps). I've never read the reasons for the re design. Was it cost, or performance, or both?. It does feature some large rings of material which should increase strength and maybe damping.

Look at the History or the Klipschorn on the main site. These technical articles are easiest to find on the website map. There is a lot of interesting material.

https://2d73e25b29782b6d6766-9c8af5cbfef16739445bc76457060528.ssl.cf2.rackcdn.com/KhornTimeline_635116436015580000.pdf .

In any event, there is reportedly a slight improvement in distortion in the K-401. (I'm sure a lot of people cried, "What are you doing with cheap plastic.) Now whether that is related to resonance the history does not say. But cynical me has to backtrack and say that maybe there is a corresponding slight improvement in distortion when material is added to a K-400. So it is not just a belly button modification. Smile.

Best,

WMcD

Edited by William F. Gil McDermott
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I've read many articles relating to people damping horns, whether they be Klipsch, Altec, etc. I read one article where a guy was coating the exterior of his Altec 811's with a heavy mix of bondo and sand.

Perhaps that is why MDF has become such a popular choice for DIY horn designs. Horns are easily made in slices via a CNC machine, and its resonant frequency is so low, it's inaudible.

(Dave H, I don't mean the designs, prototype, or testing is easy. Based on what I have read here, it's apparent that you spend countless hours perfecting your horns before someone like me can buy a kit.)

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Horns are easier to make in slices versus CNC?

I'm not buying that one... repeatability alone warrants digitization.

Perhaps i didnt get the meaning accurately... which wouldn't be the first time

No, not versus, via. The CNC machine is programmed to cut according to Dav'es tractrix horn shape. The CNC machine cuts out a series of progressively smaller sections on a 3/4" sheet of MDF with registration holes in the corners of each slice. They go together very easily. Dave's horns are very consistant. Don't know why they wouldn't be.

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Ron,

What horn do you have? The 400 or the 401? If it is the metal horn, you can place a small bag filled with sand on the top side of the horn flare. Won't hurt anything and it would help to damp any ringing on a large portion of the horn. Or put in a bag of ball bearings. Any mass to damp the horn. You find out quickly and easily if it makes a difference and it's easily removable.

Bruce

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Ron,

What horn do you have? The 400 or the 401? If it is the metal horn, you can place a small bag filled with sand on the top side of the horn flare. Won't hurt anything and it would help to damp any ringing on a large portion of the horn. Or put in a bag of ball bearings. Any mass to damp the horn. You find out quickly and easily if it makes a difference and it's easily removable.

Bruce

Hi Bruce, I have the 400 horn I believe (it is aluminum). Sounds like a good little project to try out! Thanks.

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When I first started investigating horn damping that a suggestion was to wrap the horn with electrical tape to see if it was something worth while. This seemed easy enough and reversible. so I tried it on some Fortes with the resin horn. I wrapped about 4 layers of tape on the midhorn. There was a difference in the sound. I believe it reduced what is referred to as honkiness. The midrange seemed slightly quieter but the added clarity was a benefit IMO. I have since removed the tape and applied 1 pound of nondrying modeling clay to each midhorn. The clay can be removed to restore the horn to original where as dynamat or other products would be most likely impossible to remove. when I tap on an installed horn with the damping it sounds deader than an undamped horn. I understand that a bell sitting(or bolted) on a table rings less than a suspended bell. But if you put your hand on the bell it will ring less whether it is mounted tightly or suspended.

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Does the modeling clay fall off with time or does it stay intact forever (until you remove it). Do you have any pics of it after you put the clay on it? I wonder how many pounds you would need to do 1 horn in a LaScala....

Edited by ellisr63
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I did this mod in January or February and the clay has been holding just fine. It is a Crayola brand clay. I have had the driver out several times trying different mods and I see no sign separation. The clay claims to be non-drying so I am thinking it will hold. I don't have any estimates on how much clay to damp those larger horns. I just kept adding clay until it was nearly level with the stiffening runners that are molded into the horn body. Of course I stayed away from the mounting flange as not to interfere with mounting. The forte horns mount from the front of the baffle. I also stayed about an 2 inches from the driver so I could change diaphragms later.

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I used dynamat. I cannot claim it made an audible difference, as I made quite a few other mods at the same time (k-52 and k-79-k). Of course, after all the mods, the speakers are much improved but cannot quantify the dynamat effect.

Since I had the speakers apart, I couldn't see that the dynamat would do any harm and I certainly did have the "honky-ness" at louder volumes.

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Dynamat is easy to apply, but I don't know if it makes much difference in the sound. I did apply it to my K400 horns shortly after I got the speakers.

I've read that casting the aluminum horns was difficult, and there was an issue with the molds. Some of the horns are a bit rough-looking, even in the inner side that's visible in assembled speakers. The K401 horns cost less, look better, and sound better.

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The damping mods are going to be in the range of hard to hear a difference, if at all....the real fix is to replace the entire horn with a modern design. That's something that would be easy to hear.

I seem to recall sometime mentioning something about the out-gassing of Rope Caulk possibly interacting with something in the crossover? Anyone else remember that?

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