Early Cornwall xover w/ later Cornwall?

[JonM]

Here's one for Al Klappenberger:

Can the crossover (B type) from an early Cornwall II (the one with the vertical horns) be used with a late production (1985) Cornwall I (the one with the K57K squawker and K77M tweeter)? I'm looking at a pair of Cornwall I's with the early xovers and the later drivers, and I'm wondering if this is an okay combo.

The K57 ws used in the later Cornwall II (mid-late 1980's) along with the K79 tweeter. I seem to remember reading the K79 was less efficient than the K77, which makes me think/guess that the original xover in the later Cornwalls (B3 type) might have dropped the level of the K77. Can I just change the autoformer tap that's used to drive the tweeter to drop its level? (This tweak that works well with the Heresy does seem to work real well with these particular Cornwalls - yes, I've already tried it, and I like the results.)

Is the impedance of the K57 similar enough to that of the K55 that no other xover changes are needed? I.e., is the xover freq to the squawker (600 Hz, I think) unchanged with the K57 in place of the K55?

Or is it better just to order B3 xovers from Klipsch?

Thanks!

[Al Klappenberger]

JonM,

The K55 and K57 have the same sensitivity. That says to me you can put a "B", "B-2" or a "B-3" network in one with a K57 squawker. The incompatible combination is the later Cornwalls that have the K79 tweeter. The K79 has lower sensitivity and the speaker will lack highs if a network intended for the K77 is used with it.

Changing the taps on the transformer is NOT a good idea because it changes impedance levels which also requires changes in the values of other parts.

AL K.

[JonM]

Thanks! Is there a better way to drop the tweeter level? The stock config is considerably brighter than my K-horns (K55V/K77M, 1976 vintage, stock), which I find more listenable.

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Well, maybe I spoke too soon. I reconnected the Cornwall tweeters their original way, and moved the Cornwalls directly in front of my K-horns (so that the fronts of the K-horn and the Cornwall were parallel, facing the same direction into the room). Ta daa! The highs are extremely similar now. The extra brightness had been because I had the Cornwalls facing more forward, toward my listening chair, on the tweeter axis. The K-horns have no choice but to face diagonally, nowhere near on axis to my chair.

Ahh, the importance of room placement and angling!

The K-horns have a bigger sound, less distinct in the mids (the Cornwalls are crystal clear in the mids - that K57 squawker, or that angling off axis again?) but with a big, explosive low end the Cornwalls can't touch. I like them each for different music, but overall, the K-horns win. Now is that any surprise?

This message has been edited by JonM on 09-21-2001 at 03:36 PM

[Colin]

I live with a big old pair of Klipsch Cornwalls Is (serial # 32x57 and 32x58) rated at 100 dB/w/m with horizontal horns. Label says they are type CWO. They include the K-33-E woofer, K-51-V metal mid-range horn and K-77-M metal tweeter horn. They have the B-2 crossover, so I guess that makes them 1 and 1/3 models. They are bright and can be harsh sounding. The cross-over definitely needs upgrading.

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horns, tubes, subs, leather couch & female vocalists

[mopar dave]

hi al, i have a simular question. i'm building a pair of cornwalls, and i plan on using k77,k57 with a B xover. is this a good combo? between the k55 and k57, is one brighter than the other? thank you dave