Another germanium preamplifier of the past - the SR Hh63

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5v333

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this is vital info about feedback. i have much to learn about the different variants.
would you say that one path decreases voltage gain while the other does not?
 

5v333

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Conviction said:
Tuffa grejer indeed! But even more so if it was the Hh61.

I found it in a top secret location at the SR Stockholm headquarter  :-X ;) I think I've had it in my storage for about 10 years. But seriously. Got it - like a lot of other stuff I have - from a tech whose boss demanded him to do that final clean-out.

PS: I see you're in Gothenburg too!

Yes!
Living in Kortedala.
 

Conviction

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FknTYi1.jpg
 

abbey road d enfer

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5v333 said:
this is vital info about feedback. i have much to learn about the different variants.
would you say that one path decreases voltage gain while the other does not?
They both decrease overall voltage gain, but have different effects on input and output impedances.
Voltage-to-voltage increases input Z, voltage-to-current decreases it; boith decrease output Z.
Current-derived NFB increases output Z.
 

hans a

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Im the one who took the crappy photos haha. And probably who sold your friend his HH63. I will try to scan something a little more readable. My unit is not working sadly. I´m just beginning to feel secure enough with reading the schematics to go trough it.
Glad I found this thread. Conviction.. do you happen to know anything about the solid state SR units?
 

Conviction

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hans a said:
Im the one who took the crappy photos haha. And probably who sold your friend his HH63. I will try to scan something a little more readable. My unit is not working sadly. I´m just beginning to feel secure enough with reading the schematics to go trough it.
Glad I found this thread. Conviction.. do you happen to know anything about the solid state SR units?

Haha! I think I got them from Daniel (A). The photos work but I would love a scan if you have the time! I collect everything-SR and have quite the archive of docs. My friend is an ex-SR tech and has heaps of stuff from the past. Quite provoking.  ;D Wish he had all the schems too.

Have you tried your unit recently? Remember the Hh63 runs on positive ground, like most Germanium gear.

What other SR solid state units are you thinking of?
 

hans a

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:) Nice

Ok, i will see if i can do something better. I tried with my phone but will need a scanner and do some vectorizing i think to get all the detail.

Ok i, that really nice. I have one working Ha 54 line/mic amp. 32dB gain.. But no schematic. One has no markings and one is called Hb 66. No clue there. I would really like to get them working, but would need something to aid in "felsökning" :)
Best regards Alex

 

Whoops

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I wonder if I can make this into something useful, say, four stand-alone germanium preamplifiers.

Using an 2520 Opamp Plus 2503 transformer would probably be a good output stage for each of those preamps.
That's what I would probably pursue, but might be big enough to fit into that case
 

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