swapping el84's

[hitchcaster]

hi.. ive got a trainwreck rocket 4 X el84's and wanted to swap el84's and see how the matching and unmatching and different brands mix effects the sound.. would it hurt anything to pull one el84 out while the amp is on and put in another one at a time in its place? some people say matching sounds better, some say mismatched sounds better.. some say mixing brands sounds better.. so i was going to try and its easier to roll tubes without having to power on and off every time. anyone think of a reason this might hurt something?
thanks!

[Phil_S]

Yeah, I can think of a few reasons.

Edit: I want to apologize for yesterday's snarky reply. You were reaching out for help and what I said wasn't constructive. The question caused me to shake my head and wonder. I should have simply taken it at face value and given an appropriate answer. I'm sorry for my bad behavior.

[Stevem]

You can swap yes, but to do so turn the amp off and then swap the tubes, then while playing do so in a dark room with the rear of the amp facing you. While playing look for any signs that the tube you swap in has is plate structure starting to glow a reddish purple.
If you see the beginning signs of this then the output stage bias will need to be adjusted to keep the tubes out of melt down and possibly doing harm to the output Transformer.

[martin manning]

I'd say don't turn the amp off, rather place it on standby. That will remove the high voltage and avoid over dissipation on the tubes remaining in the circuit, but keep the reservoir caps fully charged. If you switch main power off and on you risk damaging the rectifier.

[hitchcaster]

I'd say don't turn the amp off, rather place it on standby. That will remove the high voltage and avoid over dissipation on the tubes remaining in the circuit, but keep the reservoir caps fully charged. If you switch main power off and on you risk damaging the rectifier.

thats a good idea. thanks martin. yeah and this amp has 80uf on the gz34 so its already going thru enough.

[hitchcaster]

Yeah, I can think of a few reasons.

Edit: I want to apologize for yesterday's snarky reply. You were reaching out for help and what I said wasn't constructive. The question caused me to shake my head and wonder. I should have simply taken it at face value and given an appropriate answer. I'm sorry for my bad behavior.

no worries! yeah i built this clone and el84's seem to have different rules. i like matched on octals though.. but ken fisher and many others talk about mismatching on el84's so i was going to try some experimenting and see if i can hear the difference and find out what i like better. i tested all my el84's on a matcher so i have readings marked just need to roll them tru the amp. some also say if you have 2 matched pairs, you put one matched pair on one side and other pair on the other side.. some say you put one matched pair on the inside, and other pair on the outside tubes (that makes more sense to me). you never know till you try, so i was thinking about what the best way to try is. its harder to hear/remember changes if there is long breaks between.

[martin manning]

some also say if you have 2 matched pairs, you put one matched pair on one side and other pair on the other side.. some say you put one matched pair on the inside, and other pair on the outside tubes (that makes more sense to me).

The second scenario would be essentially equivalent to a matched quad. In the first, the two sides are as miss-matched as the two pairs.

its harder to hear/remember changes if there is long breaks between.

Absolutely!