tubes blend, question

[Xplorer]

hi,
i think i read several times that in the past, roadies, or guitarists would swap tubes into their amps, and could replace it with no care. there's also a picture of another topic that i'm reposting here.

my question is : would that be dangerous or something , will something burn if i switch some el34 nto an amp with some 6550, not even trying to rebiase it or something ? my bias pot is on max anyway.
i'd like to try with 2 el 34 and 2 6550, or 1 el34, 3 6550 or the opposite, and see ...
i just don't know about that. i wonder what this experimentation, doing like some guys , 50 years ago, would do.

again, still in bog test, off course i'd like to try 4 6550 and see. and change what i should change, again i don't remember, i should check on the forum for some answers i received, that i didn't understand , deeply ( what's behind this result you know ...why changing this or that ... i don't have the experience yet ) .

so i'll get a set of new matched tung sol 6550 somewhere.

as it's difficult for many to choose between el34 and 6550 , why wouldn't jimi have some amps with el34 and some others with 6550 ? you know, doing a nice blend with the daisy chaining, also with the stacks filled with mysterious speakers, and the sunn cab fed by i don't know what amp between the three heads. and how ...

[HTH]

If you have dual bias supplies for each half of a 100w amp, I don't see why you couldn't have a pair of EL34s in the inside pair and a pair of 6550s on the outside pair. The 6550s will of course need more bias voltage than the EL34s though.

[Xplorer]

Thanks, so now i hope that there are some layouts that work fine. I didn't know that there was an onside and an outside for tubes .

[Roe]

its a little complicated: you need two bias supplies and two pairs of bias splitters (usually 220Ks) - on to each pair of tubes. this means that you also need four independent wires to pin 5.

I've tried it and went back (except for the dual bias). but I dont have a layout

[Xplorer]

thanks.
i've contacted a nice shop , the guy seemed serious and heard the samples of the band of gypsies i've send to him, as well as billy batz clips. and he advised me some GE 6550 A , NOS. Expensive but why not, after that my amp would be deep BOG. i'll see later for NOS Mullard 12Ax7. expensive too.
he kept saying that new or reissue of 6550 are shit. i prefer to do a good choice for the tubes. i took my time to decide and now i forget my idea of a blend. he also told me that it wasn't a very good idea.
Roe, i think you told me what caps or resistors i should change, with the 6550. i'll see that then.
my amp is ready, but i'll have to be patient.

[Roe]

lower the 220Ks to no higher than 150k (100k would be safer). increase NFB a tad (move from 8ohms to 4ohms)

[Xplorer]

ok, i'll do that. i'll have to check into the build guide what was the NFB again cause i don't remember what's this.

[Xplorer]

lol, i see under my profile : "born to bias", ; ) but i insure you : i don't know doing this. i think i necessarly did it once, but i'm really not a master !