#1
I am planning to create a second channel on my blues Junior using the spare triode, and I notice that I will need a total of 4 switch point for true by pass, and 2 for "normal" bypass.

So I have the three options. As far as I know, there is no "QPDT" physical switch, despite having the symbols for it. I am worried that transistor is unable to handle the high instense signal (for switching purpose, it will go from collector to emitter instead of base to collector/emitter, thus should not color the sound), while relay is large and thus may not fit with in a blues JR chassis.

The better question is: do I really need true bypass for an amp channel? I notice that quite a lot of even good amps does not use true bypass (at both ends), but just disconnect one side.
Ibanez SA-120 (ed.2006)
BluesJr 1996-B + cathode follower + texas Heat
Crate CPB150
Homemade 4 x 10 cab Bass closeback
Metal Muff
#2
Quote by Jestersage
I am planning to create a second channel on my blues Junior using the spare triode, and I notice that I will need a total of 4 switch point for true by pass, and 2 for "normal" bypass.

So I have the three options. As far as I know, there is no "QPDT" physical switch, despite having the symbols for it. I am worried that transistor is unable to handle the high instense signal (for switching purpose, it will go from collector to emitter instead of base to collector/emitter, thus should not color the sound), while relay is large and thus may not fit with in a blues JR chassis.

The better question is: do I really need true bypass for an amp channel? I notice that quite a lot of even good amps does not use true bypass (at both ends), but just disconnect one side.
1 - True bypass is only important when you can't have control over what happens at the inputs. In the case of pedals, you could literally have dozens of them connected in parallel, if you had dozens of pedals daisy chained together. This would create a low pass filter, when combined with the series inductance of the pickup(s). ie: tonesuck. You have much more control over what gets connected in parallel in an amplifier. More importantly, you can design to compensate for it.

2 - NEVER use BJTs for switching in a tube amp. The leakage currents and non-linearities are intolerable. FETs are acceptable.

3 - QPDT? Yes, but it's called 4PDT.
Meadows
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#3
I see. thank you. 4PDT may just be what I need.

Also, what is the usual voltage and ampage for a signal path of a preamp, and how should I measure it? (important for transistor switch)
Ibanez SA-120 (ed.2006)
BluesJr 1996-B + cathode follower + texas Heat
Crate CPB150
Homemade 4 x 10 cab Bass closeback
Metal Muff