Marshall JCM 2000 DSL 201 tubes

[na3d]

Can anyone tell me what are the V2 V3 and V4 for? The V1 is half for the clean and half four overdrive i realize that. So can someone explain me which one is for the reverb, or which one is for the fx loop, etc...
THX

[Reeltarded]

Turn the reverb control down and pull v4. Does the amp work?

Turn off the amp before pulling a tube!

If so, v4 is the reverb and effects loop. If that is so, 1 is two preamp triodes, 2 is a preamp section and a cathode follower, and 3 is the phase inverter.

[vibratoking]

I attached the schematic.

After a quick look at a busy schematic. V1A is clean preamp. V1B is OD gain stage. V2A is another OD gain stage. V2B is effects loop send which also feeds reverb circuit. The effects loop looks to be a parallel setup. The reverb circuit is an op amp based implementation and uses no tube. V3A is the return mixer for the effects loop and reverb returns. V3B is a cathode follower feeding the OD tone stack or the PI directly in the case where the clean is switched on - I think. V4A/B is the phase inverter driving the push pull output section. I didn't look long enough to figure out all the switching, but I think this is what is going on.

[Reeltarded]

omg what a mess

[vibratoking]

That schematic is busy and not well drawn IMO. There are relays and FET switches in many places, which make understanding it fully more of a challenge. I find the op amp reverb interesting. Also, the parallel loop.

na3d - tell us how the reverb sounds on that amp. Surfy, smooth, springy, brittle...?

[na3d]

Thank u so much! The reverb is the same one that I got in my Mesa DC3 (Accutronics) In the DSL 201 the reverb on clean channel is too low, you can even hear it and it's very smooth. On the OD channel it's a little better. In my DC 3 on clean sounds better then on the OD channel.

I am not happy with the reverb on the DSL 201 amp! Maybe it's a problem with some tube? What do u think?

[Structo]

Yes you should always suspect a bad tube if the sound quality changes.

Not to say it isn't a bad component but since tubes are so easy to check it's always worth a shot.

Take a known good preamp tube and substitute it one by one for the preamp tubes in the amp.
Turn on standby during each swap then give it a listen.

[martin manning]

The reverb circuit is an op amp based implementation and uses no tube.