3 ch = transistors?

[eet fuk]

I'm one of the few who actually prefer the 3 ch to the 2 ch rectos.
In looking at the schematic of both, I've noticed that the 3 chs have two transistors between the 1st and 2nd gain stages, the 6426 and the J175. Are theses use for gain or switching or both? The 175 in particular looks like it's in the signal path bypassing the second stage grid load resistor. But the 175 seems to play the role of switcher. The two chs don't have those in the signal path. This is the only difference between the 2&3 that I could find besides the gain pot ohms and 3 cathode R/C differences.

To those who would respond in such typical fashion: "Who cares? Just play your **** amp, who cares if it has transistors or not, it only matters if it sounds good to you."
Well, I care, that's why I'm asking, but it does already sound good to me. Second, I like boost pedals anyways, so I like transistors and diodes. Third, I'm just curious, being a newb at electronics and I am just studying the circuitry. Forth, I'm gassing for another 3 ch recto again. :mrgreen:

 

[jvk]

Hey eet,

The 2ch rectos were closer in terms of design principles to the Marks in that they used LDRs (light dependant switches) which are pretty much noiseless when switching - whereas the 3ch rectos use cheaper electro-mechanical switches (relays) that are noisy as sh1t and produce a popping sound when switching. And hence most of the transistors in the 3ch recto are there to mute and eliminate the pop. The transistors eliminate the pop (although not completely) by acting as a momentary switch, grounding and muting the audio signal for the duration of the 'pop' (around 10-30ms) and then releasing it again.

Hope this answers your question.

 

[eet fuk]

Sure does, thanks mate. If I am understanding you right, the transistors are there in the signal path as short moments of mute during the relay pop, like a quick noise gate. I was thinking that the transistors were somehow used like diodes in jcm900 and jubillee marshalls, but I guess this is not the case.

So the extra grind I'm hearing on the 3 chs must come from the different cathode R/C arrangements. The resistors vary in value (from 2 to 3 ch) that are in series with the cathode R bypass caps, also the second stage has a second switchable bypass cap added. Does this sound right, that this would produce more trebley grind?

I keep listening to tunes which have dual recs on em, just to hear the tone.

 

[stephen sawall]

This is a interesting thread.

I have wondered about what was making the tone differences of the 2/3 channel amp. I have a Tremoveb and have played a most of the new ones from the recto family.