Preamp Tube Functions

[Wizard of Ozz]

I. JVM Series Amps:

JVM410, JVM210 & JVM205:

V1A: 1st gain stage
V1B: 2nd gain stage
V2A: 3rd gain stage
V2B: 4th gain stage
V3A: Cathode Follower: Drives Tone Stack
V3B: Cathode Follower: Drives FX Loop
V4A: FX Loop Return
V4B: Reverb Mix
V5A/B: Phase Inverter

The reverb circuit is digital, and is not tube driven or buffered. As long as the reverb is off, the JVM series amps have an all-tube signal path.

II. JCM2000 Series Amps:

DSL 100/50 & TSL 100/60/122/601/602:

V1A: 1st gain stage (active on both channels)
V1B: 2nd gain stage (active on both channels)
V2A: 3rd gain stage (active on Ultra Gain channel only)
V2B: 4th gain stage (active on Ultra Gain channel only)
V3A/B: Cathode Follower
V4A/B: Phase Inverter

Both the Reverb and FX loop circuits are totally solid state, no tube buffers or drivers.

Classic Gain / channel A:

Signal goes into V1A, then to gain knob, then to V1B, then to reverb, then to V3A&B (cathode follower), then to tone stack, then to master volume, then to V4, then to power tubes, then to output transformer, out to speakers.

Ultra Gain / channel B:

Signal goes into V1A, then to gain knob, then to V1B, then to V2A&B (gain stages), then to reverb, then to V3A&B (cathode follower), then to tone stack, then to master volume, then to V4, then to power tubes, then to output transformer, out to speakers.

Note ~ pushing the "crunch or lead 2" button in for either channel does not change the above signal paths... it just engages a bypass to a resistor, thus allowing more gain into the respective drive control knob.

DSL 401/201:

V1A: Both Channels
V1B: Lead 1/2 only
V2A: Lead 1/2 only
V2B: Both Channels
V3A/B: Cathode Follower
V4A/B: Phase Inverter

~(Courtesey of RJGTR, Swarty, and WhiteRam)~

III. JMP 1959/1987 Series:

V1A: 1st Gain Stage Normal Channel
V1B: 1st Gain Stage Bright Channel
V2A: 2nd Gain Stage Both Channels
V2B: Cathode Follower
V3A/B: Phase Inverter

Click here for a flow diagram

IV. JMP 2203/2204 & JCM800 2203/2204 Series:

V1A: 1st Gain Stage
V1B: 2nd Gain Stage
V2A: 3rd Gain Stage
V2B: Cathode Follower
V3A/B: Phase Inverter

(Use of the low input on the JMP & JCM 800 2203/2204 amps bypasses V1A to V1B).

Click here for a flow diagram

~(Block diagrams courtesey of Clay Finley)~