switching between a 12ax7 and 6sl7 in a 5F2-A

[shay]

Hi all
I've built another 5F2-a type clone and have wired an octal base in parallel with the
regular 9pin pre-amp base so I can choose between them ,
Whats the best way to switch between them , at the moment i just swap them over.
Anyone tried it? any suggestions?

Thanks

[redelephant]

Have you tried them both at the same time? Which of the tubes do u prefer?
U could switch like u would channel switch. Kinda like this:

Oh, I drew a faulty switch, an unfaulty switch would have both poles go to the same tube...must be a chinese part;D

[shay]

not sure I prefer one over the other , the 6sl7 is warmer and more"lo fi" sounding
I haven't tried both together , would this be safe?

[redelephant]

Nothing will harm the tubes.

The 6SL7 is generally regarded as a better tube than the 12AX7 tho they are not exactly identical, I guess a 5751 is a closer noval version of the 6SL7? Most octal tubes supposedly have an edge on the 9 pin tubes. Not sure if this is related to tube life or other specs such as linearity.
I have some cheap russian 6SL7 and they are crap compared to the NOS versions I unfortunately have too few of. Have you tried tube rolling different brands?

[Wombaticus]

Nothing will harm the tubes.

The 6SL7 is generally regarded as a better tube than the 12AX7 tho they are not exactly identical, I guess a 5751 is a closer noval version of the 6SL7? Most octal tubes supposedly have an edge on the 9 pin tubes. Not sure if this is related to tube life or other specs such as linearity.
I have some cheap russian 6SL7 and they are crap compared to the NOS versions I unfortunately hav

e too few of. Have you tried tube rolling different brands?

The octal tubes are tonally nice, but I always seem to find they suffer more from noise and microphonics than the 12AX7...NOS and new alike. The Sovtek 6SL7 was especially crapalicious in that regard.