RCA BA34C Schems and pinout?

[Alistair]

I've just gotten my hands on an RCA BA34C- a germanium monitor amplifier w/ power supply from the mid-sixties (I think!).

I'd like to modify it to run as a mic preamp, so I think I'll need to bypass the poweramp section of the unit.  I've been unable to find a schematic for the BA34 though, or a pinout for the 2 8-pin connectors for ins/outs and power.  I believe the unit can be set up for 110/220v depending on where connections are made as well.

Does anyone have any leads on the 34C schems? 

 

[emrr]

Pointless exercise. 

 

[Alistair]

Hi Doug,

Thanks for the reply but I'm unsure if you're suggesting that the schematics are impossible to find, or that the unit isn't suitable for use as a mic preamp?

 

[emrr]

It's not suitable for preamp conversion in my opinion.  They will sort of work as a mic preamp, meaning they will pass a signal, but I don't understand why one would bother, when there's plenty of other suitable pieces that are meant for mics.    The input transformer is a 600:600, and it's loaded at 600 ohms.  I don't imagine how one would bypass the power section and be left with anything useful.

I don't find there's anything worth doing with 34/44/74 other than hacking them up for the iron.  The whole thing is meant for line level 600 ohm audio.    Ebay speculators calling them mic preamps are the entire reason for their overly inflated street value.  Not long ago they almost couldn't be given away at $25 a pop, and mostly for good reason.  A proper 31/41/71/72 or 33B/43 are the obvious better choice. 

I don't have the 34 or 44 manuals, only the 74 manual.  There are certainly going to be differences in the details.  The original document should be available on ebay at a reasonable price pretty much every day of the week.  I see it all the time. 

 

[Alistair]

Hi Doug,

Thanks for your reply, I appreciate it.  I can't find the schems on ebay, but I'm in Australia, so I'll check out US ebay to see if there are any there.

Yes, the person who sold it to me claimed it could be modded for a mic preamp but didn't have the time.  I don't really know anything about them, but the price seemed fair and a quick internet search revealed a couple of people happy with them as mic preamps.

I think I found some 31 schems on this site when searching the other day, so perhaps I'll consider removing the 34 circuit and building the 31 circuit in the case.
Or I might have a mono power amp for my Auratone!