Ringging in the K400 horn

[Bigal63]

Have been doing some reading about this and have seen where peple have put plunbers putty on the horn to stop some of the ring, What if you sprayed it with some truck bed liner paint???. I just got done cleaning mine up and painted them black but why not a few coats of bed liner!

[Chris A]

The following PWK article (see bottom of page 3) discusses the ringing of the K-400 horn. The solution: mount the horn in a baffle...

Apparently, putting rope caulk on the outside of the K-400 horn did little or nothing to reduce ringing:

http://forums.klipsch.com/forums/storage/3/445307/K-400%20Article.pdf

Chris

[kg4guy]

Have been doing some reading about this and have seen where peple have put plunbers putty on the horn to stop some of the ring, What if you sprayed it with some truck bed liner paint???. I just got done cleaning mine up and painted them black but why not a few coats of bed liner!

You can call Klipsch and they will sell you a pair of K-401's for $115. delivered if you have serial numbers of your cabinets that will correct the problem .

[Bigal63]

Thanks Chris

I read it but don't understand what they mean by mounting it in a baffle ????

And if they were looking at this back in 69 you would think they would have fixed it. I am rebuilding a set of 87 LS.

[CECAA850]

The face (large end) of the horn will stop vibrating if it is mounted to a baffle or motor board.

[Guest " "]

do you actually hear rining? when properly mounted in a lascala the requirement to mount the horn to a baffle is met. also, there is a rear l bracket under the driver area that should be mounted as well.

[Bigal63]

no I didnt hear any ringing, I have been reading several thousand differant post about anything to do with LS speakers and just remember seeing something about it. And yes my horns are mounted on the motherboard and has the rear bracket.

I am sure the only ringing will be between my ears, from listening to them way to loud after I get my new crossovers in!![H]

[Guest " "]

I wouldn't worry about the ringing . One thing to check for on your restoration.....see if you have solder terminal k-55's or push pin terminal k-55's. the solder terminal k-55's have dual phase plugs. the push pin k-55's have a single phase plug. when using an AA network, the push pin k-55 is known to cause a scretching sound in the 6 khz area. a lot of folks mistaken this for the ringing myth. if you have the push pin k-55's the issue does not exist if you are using an al-3 xover. some folks have modified the AA xover to unclude what's refered to as a P-trap. the p-trap shifts music in the scretch range of the mid driver to the tweeter.

[Panacea Engineering]

Also, just as an experiment, put some sand/lead shot in a couple of zip-locks and lay it on top of the metal horn. This should elieviate any perceived "Ringing" of the metal horn. Cost is about 39 cents.........

[Daan]

.....or buy a set of "FASTRACKS" from Dave and discover all the musical details the K400's hide from you.

[experienced first hand what I've been missing ,listening to the K400's for years]....

[coolhandjjl]

I read an article about a fellow who was using an Altec 511 horn and he built an enclosure around it that left only the compression driver protruding out of the rear. He then filled the enclosure with sand. He indicated that the ringing was pretty much mitigated.

[Panacea Engineering]

coolhand,

You certainly do not need to go to that extreme, to elieviate any perceived ringing in the horn.... That thing must have been a bear to move...!

I've probably got ten or so 400's around here, in various speakers, that get music pushed through them every day, from tubes to SS amps, and i have yet to hear any "Ringing"....YMMV

[coolhandjjl]

Right, overkill. Reminds me of those Wharfedales that had a dual cabinet filled with sand in between. []

But I do believe some can perceive a sort of resonance with horns due to their material. The guys that build Altec multicelluar clones and other horns out of wood may be onto something.

[Chris A]

But I do believe some can perceive a sort of resonance with horns due to their material. The guys that build Altec multicelluar clones and other horns out of wood may be onto something.

I've reproduced PWK's words from the referenced linked article (above):

"...Previous experiments with metal horns indicated an undesirable ring or hangover. The K-400 experimental prototype was of sheet iron, coated with damping compound on the outside. This did not prove satisfactory. A further experiment with cast aluminum exhibited the undesired ringing quality, but when the necessary flange was attached in the form of 3/4-inch plywood board, the resonances disappeared and no evidence of hangover was detectable by ear or measurement..."

I believe the point is to say that merely fastening the mouth of the K-400 horn to a piece of 3/4 ply was enough to damp horn ringing. No sand or rope caulk is required.

Can you clamp the mouth(s) of an Altec 511b or 811b horn?

Chris

[coolhandjjl]

That is an excellent and efficient solution. I believe Altec also had an open cell foam surround that was glued around the exterior of their flange. It was visible on the Altec 19, just as the circular foam surround is visible on those JBL LE25 tweeters.

So to quell anyones concerns, attach the flangs and put on a foam surround! []

[Marvel]

just as the circular foam surround is visible on those JBL LE25 tweeters

It would have to be visible on the tweeters for it to work. The foam rings on the tweeters aren't surrounds, per se, but are to stop reflections off the baffle.

[pzannucci]

Can you clamp the mouth(s) of an Altec 511b or 811b horn?

Chris

I found a little rope caulk and a small clamp (cheap small rachet bar clamps with rubber material from Harbor Frieght) on one of the rungs to the side in the 511 actually significantly dampens the 511s. Remove the one clamp and ringing significantly increases. It is just enough to stop the resonation and kill the "bell effect".

[Chris A]

It is just enough to stop the resonation and kill the "bell effect".

You know, all the pictures (some are really ugly, too) of rope caulk placed on acoustic horns that I've seen has most of the caulking material on the flanks of the horn, not on the mouth (or bell) end. If you think about it, the way that you mute a metal bell is to grab the flared end...or even just touch it. Interestingly, I haven't seen it documented in horn loudspeaker design practice except for PWK's article mentioned above.

Chris