Albis 502/59 Studioverstärker

[jensenmann]

A member of Franks nrgrecording.de forum sent me a pair of interesting tube amplifier modules. They are Swiss made by a company called Albis. At that time they obviously were a subdivision of Siemens and made ampmodules for any type of communication systems. Anyway I could not find any information about these modules at all, so I redrew the schematic and thought I´d share it with you since it looks pretty familiar compared to other firstclass tubeamps. Interesting part (for me as a tube-noob) is the feedback arrangement with a feedbackwinding in the outputtranny. Since one tube is missing I could not make them work upto now but I´m awaiting some E80CC which is the missing part. As soon as they are here I hopefully will bring that baby back to spec.

pictures:

 

[emrr]

Interesting looking modules.  I've never seen tertiary feedback connected to the same stage cathode as the plate to transformer primary.  Double check that part to be sure.  It would instead be more common to see that winding in the cathode of the first stage.  Please keep us posted on other performance aspects as you proceed.

 

[AndreasS]

The feedback winding works mainly as cathode feedback for the output tube (analog to the QUAD II amplifiers); the voltage feedback over the tubes come from the cathode of the output tube (with very low impedance).

Andreas