How do you know if your K-77 tweeters are working?

[Corvette6769]

I know this may seem like a silly post, but am I correct to assume that a K-77 tweeter either functions properly or has no sound output at all?

What I mean by this is, I seem to hear a difference between different pairs of my speakers that have K-77 tweeters, and wonder if it is possible that the tweeters can become weak or partially damaged?

Can they be tested with a digital Ohm meter?

[yaffstone]

Shove your fingers in your squaker, or use a cloth, and put your ear right in the tweater. You will hear if it is working. If it's silent, you probably need a new diaphragm.

[3dzapper]

Vette, Your '79s have different tweeters than the '80s vintage. The '79 K-77 has the ALNICO magnet structure while the later have ceramic magnets. The earlier K-77s are a tad softer sounding and ever so slightly less extension.

Rick

[mikebse2a3]

I know this may seem like a silly post, but am I correct to assume that a K-77 tweeter either functions properly or has no sound output at all?

What I mean by this is, I seem to hear a difference between different pairs of my speakers that have K-77 tweeters, and wonder if it is possible that the tweeters can become weak or partially damaged?

Can they be tested with a digital Ohm meter?

In your case it's probably just a difference in model types.

But one thing that can happen on the K77 and K77M to cause the SPL Level to shift is a bad connection where the rivit and solder terminal contact each other on most models. Be carefull and don't wiggle the terminal much but if you can touch it and the SPL changes then you can fix this pretty easy if you can solder.

The voice coil wire is often just run through the rivit and soldered and the wire soldered hookup terminal just makes contact with the voice coil/rivit by the pressed rivit joint. Over years the pressed joint can become oxidized and not make good connection. I have fixed many of these by taking a very fine copper wire and wrapping it around the wire terminal and soldering this end and then leaving a little slack solder the other end to the rivit. By leaving a little slack if the terminal moves you want take a chance on breaking the voice coil wire as easily.

mike[]

[NOSValves]

Just place a piece of cardboard, pillow or whatever over the mid horn play some music and you should hear some hash like sound coming from the tweeter from close up. With the mid horn covered its should be easily heard.

Craig

[tigerwoodKhorns]

When I bought my Belles, I thought that the tweeters were blown. They just did not sound right. (I have "square magnet" K77's. I isolated them and they were playing, just very softly. I just figured that the crossovers (Type AB) were in need of a rebuild.

Which tweeter do I have?

Chris

[J.4knee]

K77M

[cjgeraci]

If one is bad, stay tuned for Bob's unveiling next year. Anyone know if he is taking pre-orders or has a waiting list formed?

Carl.

[BEC]

I think I will have plenty to go around of the "first pressing" of the tweeters, but any are welcome to email me to get on the list for the first group.

Bob Crites

bobcrites@centurytel.net

[WMcD]

The tweeter is only putting out the sound at the upper octave of our hearing range, maybe a little more, but not much. Also, there is not much content to music up there. Just the harmonics of bells and cymbals.

If you listen to it alone it will sound very tinny and distant.

In my view, it either works per the above, or it is dead. Measuring the voice coil d.c. resistance with a multimeter will confirm that.

Gil

[Corvette6769]

Measuring the voice coil d.c. resistance with a multimeter will confirm that.

I assume this means testing resistance from the + terminal to the - terminal on the tweeter. How many Ohms should a K-77 tweeter measure?

Should the resistance measure the same for K-77, K-77-M, and the K-77-V ?

[BEC]

With the tweeter disconnected from the crossover, should read about 6 ohms measured at the two terminals on the tweeter.

Bob Crites

[Timmikid]

I have heard the rumours about the new tweeter, can anyone enlighten me?

[Corvette6769]

With the tweeter disconnected from the crossover, should read about 6 ohms measured at the two terminals on the tweeter. Bob Crites

Should the resistance measure 6 ohms for the K-77, K-77-M, and the K-77-V ?

[Corvette6769]

What year did K-77 change to K-77-M and when did that change to the K-77-V, then the K-77-F, & etc..

Are there other versions of the K-77 in existence?

[BEC]

The K-77 alnico (round magnet) was used until about 1980. With the scarcity of the material to make alnico magnets, the K-77M ceramic (square magnet) tweeter came into use. Electrovoice built both of those tweeters for Klipsch. Both use the same diaphrgm. I think EV discontinued production of the K-77M sometime in the mid 1990s. Klipsch probably had enough bought up to continue production for some number of years. I think the K-77F (Philippine made clone of the K-77M) was developed around the turn of the century. It can use the same diaphragm as the K-77 and K-77M, although it is supplied with a clone of that diaphragm also.

Bob Crites

[Corvette6769]

Thank you Bob for that information. How does the K-77-V differ from the others and when was it used?

[Corvette6769]

Interesting notation in the description for this eBay auction: "when i tested this tweeter it had low output"

[BEC]

Also in that auction the guy said "so I removed the diaphragm". Usually when people do that they also throw away the gasket and that is not available as a replacement.

Bob Crites