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Post subject: Late 60's Bassman Amp
Posted: Fri Jul 13, 2012 1:03 pm
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Is there a way to determine if my Late 60's Bassman 50W Amp has the 165 circuit or something else. What are the major differences to look for?


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Post subject: Re: Late 60's Bassman Amp
Posted: Fri Jul 13, 2012 1:32 pm
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WOW :!: Is that ever a technical question! :idea: Go to facebook and look up David Hayes. He's a Fender tube amp expert. He restores and also builds his own. :arrow: He'll know. I hope this helps.


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Post subject: Re: Late 60's Bassman Amp
Posted: Fri Jul 13, 2012 1:43 pm
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You look for AA165 or AB165 ?

Shortly , before AA or AB 165 Basman use only 20 MFD filter electrolytic ( like 6G6-B ) . AA and AB use 2 X 70 MFD filter electrolytic.

After , ( like AA270) it have a small capacitor , 2000 PF, on pin 5 to ground on each 6L6 output tube.


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Post subject: Re: Late 60's Bassman Amp
Posted: Fri Jul 13, 2012 6:06 pm
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The AB165 chassis will be wired using cloth-insulated push-back wire. This was changed to neoprene-jacketed wire when the Bassman circuit was revised in mid-68 to become the AC568. As mentioned by our good friend stratele, small "snubber" caps were added to the power tube sockets of the later silverface versions. As well, a pair of large, square "concrete" resistors accompanied these snubber caps (they're instantly recognizable when the chassis is exposed). The EIA codes found on the amp's major electronic components will help reveal precisely when the amp was assembled. From there it's easy to determine what circuit revision is extant.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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