Musicians Roadhouse

Does anyone know for sure what the preamp tube functions are?

I checked out another Marshall forum site and even there it is inconsistent.

I would like to know what V1A/B, V2A/B, etc do and what is being used for each channel.

For example, does the Classic Gain channel go through V1A and V1B, then into V3A/B and V1A/B are gain dstages for the Ultra channel only? Or is V1A Classic channel and Ultra, V1B only affect the Ultra Gain?

Thanks,

GM

i was also wondering, if anyone knows, whats the LDR and opto coupler stuff in the schematic for??

The ultra gain channel uses all of the pre-amp tubes while switching to the classic gain channel takes the V1B out of the circuit.