Identifying Strange La Scala Tweeters

[atriola]

I just purchased a pair of K-77 tweeters off of Ebay and

they look a little different than the "normal"

Alnico K-77 M tweeters. They are chrome and the magnet on the back of the tweeter is round and grey in color with a metal medallion of the Klipsch emblem on the back. You can see a picture of these tweeters on Ebay

Item # 1387962400.

One article I read in google stated that older Klipsch models had different type of tweeters (V's perhaps) that used ceramic magnets. If anybody knows anything about these please let me know.

If they are substandard to the "normal" K-77 M's I would like to know so that I can resell them and just have the diaphrams replaced in the original pair of K-77's taken from the 1984 La Scalas.

Thanks!

[Tom Mobley]

those look more like K77V, alnico magnets. I believe it is the K77M's that have the square ceramic magnet. I've been under the impression that the K77V round alnico magnet are the "preferred."

The K77V in my 77 Heresy's are all black on the horn part, the magnet cover is plain metal colored and has more rounded look at the back edge. That bluish-gray color is the exact shade my K55V's are painted.

Why not play them, see how they sound? That's what really counts. You could put one im one speaker and A/B them your hearts' content.

Tom

[HDBRbuilder]

Those are older model K77 tweeters...the alnico ones...K77M tweeters aren't alnico, they are ferrite mud magnets(ceramic), there should be no noticeable difference in the sound between these. The K77 was also known as the T-35 by its maker, Electrovoice, and was a production item for around 20 years or more. When cobalt became scarce in the late 1970's due to our government's apartheid stance against South Africa(where cobalt was processed and shipped out from), and Zaire's genocidal civil war(formerly the Belgian Congo, where it was originally sourced), magnet suppliers changed over to ferrite "mud" slurry ceramic for speaker magnets. Alnico magnets were aluminum/nickel/cobalt. Prior to that time, Alnico was the preferred magnet material for drivers.

[Malcolm]

Yep, early alnico K77s. These do not have quite the high end performance of the K77M. K77M output above 11 kHz or so is 2 or 3 or so dB better. Whether it is significant depends on your ears. Otherwise, timbre of the two flavors is essentially identical. The difference was covered in a Dope from Hope article. Maybe someone who has it can repost it.

[CaptnBob]

You might want to check the impedance. The grey magnet K-77s I've seen (both of them) were 16 ohm. Your LaScalas probably want the 8 ohm version.

Capt'n Bob

[JohnA]

Those are early T-35/K-77s. They may be 16 ohm, but if they are, the diaphragms can be changed by an experienced tech to make them 8 ohms. Experience is necessary because if the top plate is moved, the magnet dies. It would be expensive to remagnetize it.

John

[CaptnBob]

Boy, I sure wouldn't do that. The supply of 16 ohm replacement diaphrams is drying up, and someone with older Klipsches (or Electro-Voices, for that matter) might have serious need for them some day. Besides which, you'd be looking at spending another $35 - $70 per driver, and you probably don't want to do that, either. I'd put them back on ebay and look for a pair of the "square-back" K-77s. Or, see if someone here would be interested in a trade. Heck, I might be interested in a trade.

Capt'n Bob