Bias probe question

Matt300ZXT

Member
Messages
412
I want to retube my new tube amp (yes it does have a trim pot on the board), and a couple of my other amps once I get around to it and I am looking at the Euro Tubes probes. To get right to the point, for a 50 watt amp with 2 EL34s, do I need just the 1 probe? I'm guessing since most amps are push/pull I just need the 1 probe and put it under either tube and it tells me the readings for that pair of tubes.

I'm curious though, when I go to rebias my other amps that are 100-120 watts with 4 power tubes, is there a better option so that I'm not having to go back and forth between the 2 sets of tubes, letting them warm up/cool down just to get them set correctly? I have seen the one probe, though I forgot where I found it, that has 2 probes on it with a box in the middle that switches between the 2 probes so that 1 multi meter can read both sets of tubes.
 

candid_x

Silver Supporting Member
Messages
9,676
They come with 1 to 4 probes. I like not having to yank probes from tubes and tubes from sockets anymore than I have to, so I use a two probes, when using a probe method, because my amps use 2 output tubes. That said, once you find the hottest of the hopefully well matched set, you only need to bias using that one tube. But checking how they are matched would initially require measuring each tube.
 

Matt300ZXT

Member
Messages
412
Oh to hell with that, I'll start looking for 4 probe kits so when I go my 100-120 watt amps I don't have to change a bunch of stuff out lol Thanks!
 

smolder

Platinum Supporting Member
Messages
14,365
Get a two probe unit from Amp-Head... You'll be glad you did. Even when buying matched tubes it's a real convenience.
 




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