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K 77 M Tweeters


Pstores
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The K-77 was an alnico magnet (round structure) until converted to the K-77-M "mud magnet" (rectangular ceramic) in the late 70's.  There SHOULD BE no differences during it's life time.

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I was asking just about the K77m. Not the K77. Some of the K77m have a gold square magnet. Then the color changed to a silverish. Just curious if there was any changes through the production years of the K77m’s. Late 1970’s-early 1990’s. 

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Magnet structure steel plates are typically plated with a "zinc chromite" plating.  I know of at least clear, yellow, and black.  There is no difference in magnetic performance, and the change might have been "environmentally" influenced.

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On 3/29/2022 at 8:41 PM, Pstores said:

Just wondering if there are differences in the earlier versions (late 70’s) and the 1990 versions of the K77m. See they have gold and silver square magnets. 

diaphragms  were definitely different  between the late 70's and 90's , some versions had Beryllium leads , and some did not 

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Environmentally influenced as in how? Factory change. The 1980 ones I have are gold magnet. The 1990 ones are more of a silver. So are you saying they should sound real same? I haven’t installed them into the Khorns yet. Khorns have the garbage Crites CT120 drivers. Wan to get them closer to original and better sounding. Need diaphragms for both. As each has one bad one. Just my luck. Lol…

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10 hours ago, Pstores said:

Khorns have the garbage Crites CT120 drivers. 

Wow-- we all have our opinions I guess. Since you have one good one of each why don't you install them and see if you can hear a difference? 

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I tested the tweeters and they aren’t close enough. Ordered new diaphragms. When I get those I’ll try both sets. See how they sound. Did take the tweeters from my Cornwalls and tried them. Gold square magnets. Made a nice difference. That’s what I am currently listening to. Be nice to put them back in the Cornwalls when I get the silver/grey magnet 1990 K77m tweeters fixed. 

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  • 1 month later...

Crites Speakers usually stocks replacement diaphragms, some pre-mounted so the replacement is an easy DIY job.  You DO want the later T-350/T-35 diaphragm with ribbon leads for it higher power handling capacity (5 cont/50/100 peak?).

 

I find the DE120 driver on a true tractrix horn to be silky smooth and natural sounding.  I like it better than my original K-77-Ms.  You should at least try to front mount your K-77s to get them out of the tunnel they fire through. 

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