"Smoothing" inside of metal mid-horns?

[JohnA]

The wavelength of a 20k Hz tone is 0.68 inches.  How much disruption do you think a 0.010" peak to valley roughness (pretty rough) would make? 

[davemac]

On 8/18/2017 at 1:05 AM, davemac said:

 

And here we are.

Side by side A/B-ing is not doable for me so my head-first leap into damping is modify, listen, modify, listen  . . . . I went with rope caulk instead of researching further because it was suggested, it's cheap, and Home Depot is 10 minutes away. Baby steps. I really did like the fully damped sound but it felt like something was missing. (Again, maybe I'm just too used to the original brighter sound.) So tonight I pulled the caulked horns and installed the undamped ones to get back to square 1. Well, Square 2 -- new drivers. Re-EQ the room. It does sound very bright and frankly a bit harsh in the vocals on Abbey Road. OK, add a hand-sized patch of caulk to the top of the mid horn. Re-re-EQ the room (some subtle changes.) Hm-m-m-m. Sounds quite bit nicer.

 

A little bit of recap there.

 

And here we are again.

 

OK, so I listened to the undamped drivers and horns and decided they did indeed need some damping. I went a little beyond the "hand-sized patch of caulk" and found what I believe is the sweet spot. But still, something was not . . . quite . . . right.

 

A long time ago in what feels like a galaxy far, far away I drank the Equalizer Kool-Aid and never looked back. Until now. Back in those days any self proclaimed "stereo nut" (not "audiophile," that was a totally different galaxy) was almost required to have an equalizer. My (same) room was more crowded and overstuffed with . . .stuff . . .  back then and it honestly benefited from a room EQ. Over time the room got less and less crowded and I just kept re-EQing. Didn't think twice about it. It was necessary. The other day, after I messed about with the damping (pull the backs, add some caulk, reattach the backs, pull the backs, add some caulk, reattach the backs, pull th-- you get the idea -- thank God for electric drills!) I fired things back up and GREAT GOOGLY-MOOGLY AND WOWIE ZOWIE, GIRL!! What the hell happened? That sounds so go-o-o-o-d!

 

Well, it turns out that for some reason known only to the Gods up on Mount Stereo I inadvertently switched off the EQ! Bass extension and decay? Smooth and crisp mids and highs without a trace of harshness -- no matter how loud? Seems that my newest room configuration, though still kind of small, is open enough for the Corns to sing to (my) hearts' content all on their own without the need for any EQ life support. How come I never realized before how limiting the EQ really was? Button in, button out, button in, button out. Damn. The difference makes me feel like such a fool. "Ain't nothing like the real thing, bay-bee!" I'll still keep the unit hooked into the system if only to use the Real Time Analyzer to visually compare different records' studio EQ to what I'm hearing. Besides, the bouncing blue bars look kinda cool.

 

I sat back and listened to Who's Next (UK Track,) Abbey Road (UK,) Dark Side (30th Ann.,) Roxy Avalon (UK,) and, well, gotta have me some Dave Edmunds! 5 albums -- 10 sides. I haven't done that in years. But you can bet your a** I'll be doing it again. Same Bat-time, same Bat-channel! The combination of the new tweeters, A55 mid drivers, horn damping, and cutting out the now unnecessary EQ is truly nothing less than astounding to this re-energized listener. I think I can safely swear that my system has never sounded better. Finally, the true glory that is Mac and Klipsch. I'm not discounting maybe someday a new cartridge or whatever, but for now I ain't touchin' nuthin' else for fear of screwing it up. God, I can't wait for a bigger room.

 

 

So this is where I ended up with the damping. Moray James and others suggested Dynamat (expensive!) Duct Seal and other stuff but honestly the rope caulk seems to work just fine for me. It will close to never dry out and at $5-$6 a box from Home Depot a couple boxes will do a set of Cornwalls or Heresys or whatever. And who knows, you could even use some on your windows! Both the A55 mid driver and the Crites tweeter are reported to have much smoother frequency response than the factory originals. Sounds pretty right to me. Even so, the horns on the tweeters feel like a cheap ABS type plastic and I'm sure they benefit from the damping.

 

Well, that's my story and I'm sticking to it. It's been an interesting few weeks messing around with this stuff and I'm really happy with the results. Especially the unexpected one! A big hearty handshake to everyone for your comments, insights, and the whole discussion. So, in the immortal words of Hound Dog Taylor, "les has some fun!"

 

davemac

[JohnA]

LOL!  Only problem, the place I found vibrating the most on my K-400s was right in front of the K-55.   

[davemac]

4 hours ago, John Albright said:

LOL!  Only problem, the place I found vibrating the most on my K-400s was right in front of the K-55.   

 

Ha! Really! That's interesting. In pics I've seen it looks like the K-400 has a longer throat than the 600. I assume (and we all know what that means!) because the cabinet is deeper than the Cornwall. Do you think the material is thinner in front of the driver because of the extra length and more prone to resonance? Are you going to try any damping around that part?

 

Before I damped the 600s the whole horn rang like a bell when tapped with a fingernail. After my "half-damping" the undamped part just kind of "ticks." I just checked the pair I caulked today for my '85s and found that both mounting flanges ring when tapped, even after the damping and with 1/16" rubber gaskets stuck on them. And one flange rings with an obvious lower frequency than the other! Different densities in the castings I guess. I didn't think to check the flanges on the '84s but I really love their new sound so that's moot. (Or should I say "mute?")

[JohnA]

I thought I could find pics of mine, back when.  The current Forum doesn't do back that far.  I wrapped my K-400s from throat to mouth with 2 layers of old, brown Dynamat, heated and mashed in well.  This has been an old subject, but is always worth the effort for us OCD nerds. 

 

 

[Marvel]

On 08/22/2017 at 10:17 PM, John Albright said:

The wavelength of a 20k Hz tone is 0.68 inches.  How much disruption do you think a 0.010" peak to valley roughness (pretty rough) would make? 

 

The ridge inside of mine was at least 1/16 inch, and could make a difference if closer to the throat. Roy said it couldn't hurt to file it down/smooth it out.