Inherited amp


I have inherited two tube amps but there is no schematic diagram. It came with two sets of seven matched 6550 tubes (yes, seven). This is my first posting on the forum and I am not sure how to attach a picture.Any suggestions?
oldaudiofan

Showing 3 responses by oldaudiofan

Unfortunately, there are no markings of any kind on the two amps. They are incredibly well constructed made out of 5mm sheet aluminum screwed together. There are two transformers either end of the chassis. The power transformer is a Hammond 278cx and the output transformer is also Hammond 1650t. Either side of the power transformer are banks of Four J J 100-100 500v capacitors. There are a total of 9 tube sockets 8 are the 8 pin octal as used with the 6550 tubes the other socket is a miniature 9 pin (12AT7 type base). Three sockets are either side of the output transformer and three between the two transformers.This may be a home made amp but the quality is remarkable if it is.
For anyone interested I have solved the problem of identifying this amp.It is based on a DIY design published in 2000 by Glass audio. It is a design by Joseph Norwood Still and goes under the title 100W Triode Amplifier. Luckily the article includes schematic so I was able to identify the the missing tubes. My amps have been extensively modified with additional circuitry including timers and relays.