Rope Caulking Works!

[BEC]

Michael,

The rig below rings sometimes. Test is usually 1 watt into the driver testing drivers on a spectrum analyzer. Input is a sweep of 200 hz to 10 khz. That is pretty loud at one watt in front of that horn, but sometimes as the sweep starts back over at the low end, I can hear a "ring" of higher frequency. As I have said before, though, almost anything stops the ring, even placing my hand against the horn stops it. Also the ring is way below the horn output such that I can't really see it on the spectrum analyzer. In fact I have to be away from the horn mouth and with an ear close to the side of the horn to even hear it. But it is a genuine ring and I would say it is around 600 hz in the case of this hanging horn. Now, this test I am running should be the extreme of what could excite the horn to make it ring. That is a repeating sweep of frequencies. That is unlikely to happen with music anyway with any regularity and being able to hear it out of the front of the horn seems also unlikely to me.

As Roy has indicated recently in another thread, the fact that the midrange horn is exposed to the back side of the woofer output in the Cornwall (for instance), It might be more likely to ring or have a resonance. That I have definitely heard on a Cornscala when I did not have a midrange horn tightened up enough against the motor board.

[johnyholiday]

Ask Trey ,what PWK thought about it when he ask PWK about rope caulk ,before the 1st pilgrimage,because people were asking about it,Trey can be caught on video tape from the last pilgrimage, telling about PWK's response,to this question. it is a classic PWK response

[Dylanl]

Wait, he said rope caulk is BS; wrap it with lamp cord instead!

Why does klipch not use the metal horns now??? Its not that plastic is just cheaper. That's probably the biggest reason for Klipsch but it kills 2 birds with one stone. If I am correct they don't even use metal horns in the heritage lineup.

[BEC]

I think what Trey said was that when he asked PWK if rope caulking the horn would be an improvement, PWK threw him out of the house for suggesting that he would have missed something that simple in his 40 years of tweaking if it was an improvement.  

All the metal foundries that Klipsch once used to make horns are out of business.  And yes, the reason the metal foundries are out of business is that it is less than 1/10 the price to make the parts from plastics.  Main reason for the cost difference, and I have watched both processes, is that a plastic horn can be made about every 30 seconds.  With metal casting, the time is several minutes to half an hour depending on the type mold. Anyway, it took all day for a foundry to make 100 small metal horns for me with three men working and it took a plastic injection molding place all day to make 1000 of a similar size horn for me with 1 man working.

Bob

[jacksonbart]

sweet

[ka7niq]

I'm with Bob, just another version of snake oil. Course my ears ring all the time anyway so it doesn't really matter to me[D]

After hearing the difference in my Heresy's I will have to wholehartedly disagree. The difference in ny speakers is obvious. I did not start this thread for a flame war, only to report something that I felt was worthwhile.

I am not criticizing the goal, just the technique. If tightening up the horn did not work, you could try a gasket around the mouth flange. If more is still needed, how about a large package of rubber bands to put around the horn? Anything except that nasty rope caulk.

Bob Crites.

Actually, Bob, that is valuable information. Thanks! I did not know that rope caulk would deteriorate with time (and I plan on keeping my speakers for a long time). I will replace with Dynamat Extreme (the stuff with the silver backing) when I get the chance to do so. The important thing to know is that dampening the metal horns DOES make a difference.

Maybe the Metal Ones ?

But it mmade my CF 4's and CF 3's sound terrible.

Of course, they are plastic horns.

I also have 78 Cornwalls, is there a metal horn in there ?

Haven't had em apart yet

[marems]

I rope caulked my KLF-30's squaker last night, and I thought it made a big difference in the sound. The shrill has gone away. Hey Ka7nig, You tried it on the CF-3 & 4's??? I was thinking about getting a new pair of horns from Klipsch that are made with 20% glass and then applying some cascade damping spray to them. The version 1 horns are all plastic! So that can probably be improved.

[TBrennan]

"and I thought it made a big difference in the sound."

Yes, it seems it's always a big difference.

Like I said, I suspect Berenek's Law.

[Coytee]

How many miles of caulk would it take to rope up a K-402? []

[ka7niq]

I rope caulked my KLF-30's squaker last night, and I thought it made a big difference in the sound. The shrill has gone away. Hey Ka7nig, You tried it on the CF-3 & 4's??? I was thinking about getting a new pair of horns from Klipsch that are made with 20% glass and then applying some cascade damping spray to them. The version 1 horns are all plastic! So that can probably be improved.

My rope caulking experiences are limited to the CF 3 and CF 4 Horns.

I did it, and it did change the sound, and not to my liking either.

Transients seemed dulled, and there seemed to be a distinct coloration not there before.

I remove that stuff, and liked my speakers again.

That said, my 78 Cornwalls are gonna get caulked .....

Maybe it will improve them ?

[TBrennan]

"Transients seemed dulled, and there seemed to be a distinct coloration not there before."

I wonder if you heard what you expected to hear. You know, like people who think silver wire sounds "bright".

[popbumper]

I would tenure a guess that your '78 Corns have metal horns. My Corns are 1976, and they are definitely metal. You should be able to tell easily, at the front of the speaker - tapping on the horn will elicit the "snap" of metal or "dull thud" of plastic. Additionally, the metal horns are CAST, so they tend to have a somewhat rougher surface than plastic, which will be very smooth.

I have NOT tried this caulking method - YET.

Chris

[Colin]

I bet Bob is right and I would try his ideas first.

A few years ago, I wrote about my experience applying soft, gray window rope caulk (found at Home Depot for a few bucks) to my walnut-oiled Cornwall 1s, with their B2 crossovers. I loved the subtle difference the caulk made on my big ole horns. It helped to tame the savage harshness caused by the B2 crossover ringing (a sharp bounce at 5-9kHz). A few others here tried it on their big ole horns also. Some with the stiff black Dynmat, sold to dampen automobiles, applied by heating it first and some with the easy-to-apply and remove rope putty. Almost all reported liking the slight improvement. Even with newer, composite horns.

I have not yet tried it on my classic Klipsch corner Khorns. Their frequency response looks to be fairly flat.

BobG, a moderator of this forum, has recommended caulking and weighing down big ole horns to improve their sound. I followed his advice both times and liked the result:

Stereos as strenuous sport: Sand bagging the sound.

http://www.enjoythemusic.com/magazine/equipment/1299/sandbagging.htm

Try it you might like it.

[marems]

I agree with you too Colin, When I tap on the caulked horns it sounds like its not hollow anymore compared to the non caulked horns in the KLF-20's. (and those are next!)

[Dylanl]

Yeah I wouldn't think it would help plastic horns much but then again I never tried it so I cant say.

Wonder why there was no gasket material around the horns on both sets of Khorns & Belles I have owned? That may accomplish the same thing but the straight screws Klipsch uses dont help. My 1st Khorn the tweeter screws were stripped don't know why they just seemed overtightened. I could see using a gasket and T nuts that just might do the same thing as the caulk.

The fact that I can now listen without band-aids on my ears tells me that the caulk is doing it's job. Regardless I will be swapping out the mid horn soon for an Altec 511 and that will fix all. I will then be caulkless again.

[Good2BHome]

A few years ago, I wrote about my experience applying soft, gray window rope caulk (found at Home Depot for a few bucks) to my walnut-oiled Cornwall 1s, with their B2 crossovers. I loved the subtle difference the caulk made on my big ole horns. It helped to tame the savage harshness caused by the B2 crossover ringing (a sharp bounce at 5-9kHz).

Colin,

What year were the Cornwalls and did they have push or solder K-55's ?

Thanks,

Mike

[artto]

I will keep repeating this so all concerned will perhaps see it. I bought a pair of Heresys that had been someone had rope-caulked many years earlier. It was a pretty extreme case where the guy for some reason put that nasty stuff all over the tweeter, midrange horn and driver, the crossover and the woofer. The junk had been in there long enough that the rope-caulk had started to de-compose and the oil had dripped out of it and was all over the cabinet and even some of it on the woofer cone. When I tried to remove it, the sorry stuff had hardened and took all the paint off the horn and all other parts it had been applied to.

Anyway, now if I have a ringing problem with a horn, I tighten up the screws holding the horn to the motor board real good.

Bob Crites

Bob, I suspect that whatever you encountered was NOT "rope caulk", and/or the speakers were stored for a prolonged period of time under extreme conditions. I rope caulked the mid horns on my Khorns & Belle about 25 years ago and have not encountered anything like you describe. The rope caulk is still firm but pliable, there's nothing dripping or oozing out of it, nothing decomposing. It damps the metal horns very well. On the other hand I feel now that the K401 composite horns are available, these would be a better choice as they actually reinforce the horn structure as opposed to simply damping and they aren't that expensive ($50 each?)

[kaiser SET say]

Another material that works well is a bike inner tube cut to length and streched over the outside of your horn[] Completely reversible and leaves no residue[]

[vindeville]

i have been thinking about putting some kind of damping material on my Heresy II mid horn, not because of harshness though. i can feel some substantial vibrations when i touch the horn, especially the center channel heresy. i view it more as a weak point in the cabinet that could use some more solidity. i do detect a resonant quality from time to time on certain voices and suspect it is the plastic horn body being stimulated by the lower midrange frequencies. i would like to hear others thoughts on this. thanks

[BEC]

I once had a nasty resonance coming from a midrange plastic horn in a Cornscala.  Only heard it with some heavy bass notes on one recording.  I used a signal generator to find the frequency, (about 100 hz in this case) and was able to find that the resonance was coming from the flange of the horn where it attached to the motor board.  I tightened it up enough to stop that and was done with it.  I later put a gasket between the plastic horn and the wooden motor board and found that with the gasket, it did not even have to be that tight any more.

Bob Crites