New to me AU-777a !!

The Fuxtor

Addicted Member
Finally got myself one of the best cap coupled amps ever!! Just hooked her up and she can sure sing! Wow.... Sure as hell seems a heck of a lot more powerful than its rating?? Just mulling over some of the features like dual phono inputs with one having pick up impedance selector and another goodie which I'm not completely sure about? Next to the preout / main ins is another input labeled " high cut" ?? What's this all about??P_20170407_183008.jpg P_20170407_182937.jpg
 
Mroboto is right on. The 777a can run a 3 channel scheme. From the high cut you connect an amp that drives the 3rd channel, a center channel that only receives freqs under 159hz.

I highly recommend you restore it. Changing out the 16 2sc458's to ksc1845fta's will drop the noise floor and bring about even more detail. Also get a 10k supply in there and uprate the 4 output coupling caps. It's a beast of an amp and one of the most musical sounding I have ever enjoyed once restored.
 
Mroboto is right on. The 777a can run a 3 channel scheme. From the high cut you connect an amp that drives the 3rd channel, a center channel that only receives freqs under 159hz.

I highly recommend you restore it. Changing out the 16 2sc458's to ksc1845fta's will drop the noise floor and bring about even more detail. Also get a 10k supply in there and uprate the 4 output coupling caps. It's a beast of an amp and one of the most musical sounding I have ever enjoyed once restored.
Yes! Very good.. I plan to do all of the above... Very good....... I like very much....
 
Mroboto is right on. The 777a can run a 3 channel scheme. From the high cut you connect an amp that drives the 3rd channel, a center channel that only receives freqs under 159hz.

I highly recommend you restore it. Changing out the 16 2sc458's to ksc1845fta's will drop the noise floor and bring about even more detail. Also get a 10k supply in there and uprate the 4 output coupling caps. It's a beast of an amp and one of the most musical sounding I have ever enjoyed once restored.
Not sure if this unit has had a running change or if someone else has already switched the 458's...? Looking inside last night reveals c632 all over the unit? They have gold plated legs and I don't hear any noisiness. I'll check with some headphones to determine.
 
Very likely that there were changes during production. That's why It's hard to get religious about original transistors lol

The 632's are also in the Eight phono amp, in two positions out of 6. They are probably dedicated low noise transistors. If they are quite, then ofcourse no need to replace.
 
Very likely that there were changes during production. That's why It's hard to get religious about original transistors lol

The 632's are also in the Eight phono amp, in two positions out of 6. They are probably dedicated low noise transistors. If they are quite, then ofcourse no need to replace.

Can't remember if it was you, but I read an older Post saying you had a recap list for a 777a? If so could I bug you to post it??
 
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Well, I've recapped this baby, and installed new trimmers!! Sounding really good!! Finished adjusting bias, but can anyone enlighten me about how to adjust the center voltage without a scope?? I know I should be dialing in half of my power supply voltage to be in the right ballpark, but I don't know where to take the reading from??
 
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