Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Misc Schematics and Layouts => Topic started by: Milnoque on March 08, 2011, 08:40:40 am

Title: Old AA5 based amp
Post by: Milnoque on March 08, 2011, 08:40:40 am

I've got a little Airline amp that uses : 50L6, 35Z5, & 12BA7. This one has an isolation transformer. Does anyone have a schemo for one of these? I can find some similar ones but nothing that uses the 12BA7 pentagrid. I don't understand anything about pentagrid tubes. Any help would be appreciated.

Some sites that talk about old AA5 based radios say nice things about the tone from this type configuration. I'd like to see for myself, but I'm not above changing it out for a 12A?7 if need be.

Title: Re: Old AA5 based amp
Post by: bobmc on August 11, 2012, 02:30:57 pm

Wow 12BA7 pentagrid or Heptode (or 7-tode)! Its listed as a frequency converter for radio receivers but I have seen them use as an audio preamp in early FM receivers.  If have to change it, you could use something like the Magnitone Starlet, but Keep the isolation transformer.
Good luck!