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FDP Forum / Amp Mods, Repairs, and Projects / Newbie FIrst time biasing

Power Trio

Long Island

Mar 21st, 2017 07:47 AM   Edit   Profile   Print Topic   Search Topic

I have the Euro Tube probe and a fluke

my 69 Vibrolux (3/69) was converted to AB 763. also the balance pot was converted to a bias pot by a tech.

my question is can i safely use 5881 vs 6L6 in this beast or should i just stick with the 6L6

Contributing Member

American Patriot

About as ordinary as you can get.
Mar 21st, 2017 08:33 AM   Edit   Profile   Print Topic   Search Topic

I am not a tech but I say yes you can.

Power Trio

Long Island

Apr 4th, 2017 08:57 AM   Edit   Profile   Print Topic   Search Topic

well that went easy. I used 6L6s from Euro Tube.

Their probe worked great and was a sinch to use

I asked for a set of tubes on the clean side so they are a tad cold. 427 PV was only able to bias at 36ma not 39

amp sounds really good anyway.

just for a tests I put the old set back in and was able to bias up to 44ma so I know there is nothing wrong with anything internally or the probe

im building confidence with mild amp work, next job is to change the filter caps in my JCM 4500 which are 25 years old now.

FDP Forum / Amp Mods, Repairs, and Projects / Newbie FIrst time biasing

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