Crites' Tweeter & Midrange upgrades - UPDATE

[davemac]

08/09/2017

 

I just finished the first third of my '80s Klipsch upgrade project that I mentioned in a couple other posts ("Smoothing Horns" and "WTB K-600 horns.") First third - two Cornwalls. Second third - two more Cornwalls. Last -  Heresys.

 

My recently acquired '84 and '85 Cornwalls got Bob Crites' B-3 crossovers, T120 tweeters, and A-55-G midrange drivers. The early '80s and up Cornwalls switched from the K-600 cast aluminum midrange horn to the plastic/resin K-601 with a midrange driver that bolts onto a flat flange at the horn's rear. The A-55-G upgrade driver from Crites (and I believe ALK) is threaded like the factory K-55 and requires the older threaded K-600 metal horn. 'K? I stalked Ebay for a couple weeks and nabbed me some K-600 horns.

 

The '84s are done. As recommended by many, I wrapped the plastic T120 tweeter horns and the metal 600s with rope caulk from Home Depot (found with the window insulation) to damp any unwanted resonance and added 1/16" rubber gaskets to the front mounting flanges. Of course the two mid horn styles have completely different screw-hole patterns so I made up a thin drill template to drill the new holes. The "new" side holes actually sat half-way on top of the existing holes so I filled the "stock" holes with epoxy, let them cure, and then drilled. It was really hard for me to hold the horn throat with one hand and try to screw in the A-55 driver with the other. Those last few turns were a b***h! So I installed the horns nice and tight and then screwed on the A-55 drivers. Oh, yes, much better. Now, the added front gasket and I guess some dimensional difference with the A-55 made the new horn assembly too long and the rear panel wouldn't fit (cue Maxwell Smart) by this much. The batting lining the rear panel was crushed flat by the stock horn/driver but still thick enough to keep the panel from fitting with the new driver so I just scissored out the compressed circle to reveal the plywood back and it fit fine.

 

 

OK, time to fire 'em up. I realized way too late that I should have listened to them without the caulk to give the new components a fair audition. It would have been relatively easy to open the backs and after a couple of deft razor slices, peel off the caulk, but . . . well, I didn't. I re-EQ'd my room to pretty darn flat and the new settings are a bit different than before. I had a long listening session with several of my go-to LPs (what a sacrifice!) and concluded "I really like this!" Whether I really, REALLY like it needs more time, but damn it sounds good! Audio memory is a lot shorter than we'd all like to believe but my overall impression is how much cleaner everything sounds. At first I didn't quite dig the high end but a nudge to the volume control and whoa now! There it is!

 

First up - Speakers Corner "Crime Of The Century."  Not the best choice vocally, Supertramp's lead singer has this high pitched nasal quality, but the band really kicks it on "School" into "Bloody Well Right." The deep, well defined bass I'm use to, and piano, guitar, and sax all sounded spot-on. No undue harshness or "edge."

 

ELP's first album, an old favorite, on a UK Island Pink Rim sounds fantastic. Even the built-in distortion in some of the organ stuff was less teeth-gritting. Lake's vocal and the piano in "Take A Pebble" sounded wonderful as did "Lucky Man."

 

Beatles' "Abbey Road," UK EMI/Apple, Both sides. Aside from a few inevitable clicks and pops the Boys sounded marvelous. Paul's bass is clean and clear, vocals are natural sounding (even the gravelly-shouty ones.) Paul sounds like Paul, John like John, Georgie like Georgie, and Ringo . . . well, he's always been very kind to his mother. The harmonies on side 2 are glorious and the closing medley never sounded better.

 

Dave Edmunds? Turn it UP!

 

"Dark Side . . ." is in the wings for tonight. Oh boy, oh boy, oh boy, oh boy!

 

These replacement drivers, the T120 tweeter and the A-55-G midrange are top notch. Bob Crites says they are the cleanest and smoothest that he's heard and tested. Just remember that the A55 mid driver needs a threaded horn. He told me that people like the 120 tweeter so much that his supplier can't keep up with his reorders. I had to wait about two weeks for mine. When I do the '85s I'll hold off on the caulk and give a listen first to "just" the drivers. I do recommend trying the caulk though. If you find you prefer the before to the after you can always remove it.

 

After all, caulk is cheap.  (Ha-ha-ha-ha . . . . .ha-ha . . . . . ha . . . . .hmm.)

 

Dave

 

EDIT :

I listened to the first pair of "upgraded" Cornwalls with the new Crites drivers and the damped horns and they sounded somewhat warmer and less fatiguing but still bright enough to be engaging with a variety of records. I found I could play them louder without needing to turn back the treble and still have very clean highs. How much of that is the damping and how much the new drivers?

 

Since they're already in place what I'll do next is switch the caulked horns in the finished speakers with the otherwise identical "un-caulked" ones and try to compare the sound. I suspect I might end up using a smaller amount of damping on the wide flare part of the horn instead of completely wrapping it, hoping to keep the new drivers' smooth response with a little bit more of the crisp Klipsch sound that I'm used to. Then again, maybe not.

 

I'm using a solid state Mac amp and, make no mistake, with the fully wrapped horns you can really crank these boys and maintain a clean, clear sound. I just owe it to myself to do what I should have done at first - check them out with the new drivers but without damping and then maybe with a little damping for a really fair test.

 

More comments about the horn damping can be found in "Smoothing Metal Horns."

 

 

Edited August 26, 2017 by davemac
clarification, spelling, re-direct