Name:    Steve Kennedy
Email:   steve@pacair.com  
Subject: Music Man RD-65 112
Thread:  154
Time:    Sat, 1 Sep 2001 19:36:19 UTC

You can peruse the schematics on-line here to help you make this determination. The 2165 and 2100 RD series schematics clearly show that the GD-1 and GD-2 chassis of both the 65 & 100 watt models used the 6CA7 (EL34).


The later GD-2A chassis used the 6L6, but by the time they went to 6L6 it is highly likely that the 65 watt model had been dropped from the line.


The problem is knowing which chassis you have. Some amps will have this information stamped on a plate on the rear of the amp and some will only have the model number and not the chassis identification.


If you can't identify the chassis number, then you might have to see which version of the schematic most closely matches your specific amplifier (by visual verification of circuitry components).


The early GD-1 models used a relay (labeled RY-1 on the schematic) to switch which set of gain and volume controls to use (simulating a two-channel amp). The later models used solid-state CMOS switches and more sophisticated gain and switching topologies.


Steve