Which tubes go where in Sano guitar amp

[plumsolly]

I have a pair of 60's Sano amps that I have been restoring. They each have one 8" and one 15". The power section uses a pair of el34s. The preamp section is 6sn7s and 6sl7s. I have not been able to find a schematic, and there are no markings at the tube sockets, so I am guessing a little as to which tube goes where. The preamp section tubes go something like this:

V1: Tremelo. The cathodes from both sections are tied together, and the plates from both sections are tied together. 1 grid connected to oscillator and other grid connected to signal. Cathode out. 

V2:
Section A: Input for guitar and instrument (they are tied together after respective volume pots, which is first thing signal sees). Plate out, cathode bias (2.2K)
Section B: Input for treble side of accordion input. Plate out, cathode bias (2.2K)

V3:
Section A: Oscillator. Plate out to grid of V1. Cathode bias (2.2K)
Section B: Input is summed preamp section after eq. Last stage before preamp volume and power section. Plate out, cathode bias (2.2K)

V4:
Section A: Input for bass side of accordion input. Plate out, cathode bias (2.2K)
Section B: 2nd stage for bass side of accordion input. Plate out, cathode bias (2.2K)

Heres how I think it goes:

V1: 6sn7
V2: 6sl7
V3: 6sl7
V4: 6sn7

Does that sound right? Any guesses?

Thanks,

Ben

 

[CJ]

6SL7's amplification factor is 70, according to the 1959 RCA tube manual that I have. The 6SN7's amp. factor is 20,

so the first tube should be the one with the most gain to get the git signal up off it's feet,

now the phase inverter can be either/or in fact some freaks pop in a tube with more gain so they can try to be hendrix or somebody, but that is rude distortion at that location in time, so i am going wit a gain of 20 which is the sn7.

now where does that leave us?

probably my guess, oh, no phase inverter,just effects, so

v2 has to be 6sl7 and unless accordian bass inputs are line level, i would say stick a 6sl7  in that slot too, v4 i believe.

you could check some old ampeg circuits, they used the same tubes and have accordian input,

the amp will work with any combo, so you could also just mix and match for the best operation, might be different than stock, same pinout for the base so you can not blow up anything, cathode resistors might get hot,

ok, that is another way to tell, the 6sl7 will have a higher value cathode resistor, the low gain of the 6sn7 will mean more current, smaller value resistor needed to get a negative bias, correct? or is my ass full of bacon? 

nuthin against bacon, as long as you moderate and don't cook in the buff,
nitrates should be limited, so figure 1 lb of bacon a day should be your limit, unless you work for the police dept.  those freaks are under stress so they eat, or drink, liquor in the mail box, you bet,