NAD Guild Thunderstar Bass - PICS + Questions

[andy]

Hey all, first post here.
I picked up this Guild off of a friend of mine a few weeks ago. All I know about it is that it is 40ish watts and it's from the late 60's.
I was hoping someone here could help me date this thing and tell me some facts about these heads.

PICS!

 

[Default]

Pretty cool amps! Like you said, about 40-50 watts from a pair of 6l6's. Each tube has it's own bias control pot by the sockets, the test jack is located on back of the chassis. It came with a 1 - 15" cabinet. If you check this thread, you can date your amp to an approximate time by the cosmetics. Your Thunderstar is a late sixties early seventies model. Nice score!

<Edit to fix links and misspelling, thanks Ralf>

 

[andy]

Thanks! Any clue what the "Hum Balance" knob does?

 

[Default]

Just that! It replaces the 100 ohm resistors that go from ground to the heaters on other amps. Turn the amp all the way up and adjust it for the lowest background hiss. Guild did some really cool things with their amps, it's criminal that they had such low market penetration.