Artiste to Artiste JCM

[GraemeSP]

I'm converting a Marshall Artiste 2040 to a JCM 1959 - they use the same PI and PA sections so there's only the preamp to modify.

I can isolate the valves into sections - input, 2nd stage, cascade , reverb drive/recovery and use relay switching to bypass the 2nd stage for clean/boost channel. Where in the chain would I put the reverb? after the first stage? 2nd stage or the MTB tone stack (pre-PI)?

[GraemeSP]

I've sorted this out myself. Cancelled the JCM idea and gone back to basics with a plexi type preamp instead - much neater. I had a problem with the reverb going directly to the second stage - it whistled when the reverb pot was increased. sounded like feedback - aha! there was more signal going through the reverb bypass resistor and this was causing the feedback.

I added a 1Meg resistor to the reverb output and bobsy uncle it worked.

Now I have the amp set up so that on boost channel the second half of the input triode is in series with the first half. So far it works, I just need to sort out the pot values to get levels under control.

I like this site. There is a wealth of information available on all things electronic and it gets me thinking on ways to get out of my own amp problems. More power to you all.

[GraemeSP]

AND I've managed to do it without getting zapped by B+ - so far......

[GraemeSP]

Ayyy , I've finished and it works and it sounds great. Har Har.

[drewl]

I know these supposedly got a bad rap (from Jim Marshall even) but obviously they can be easily modded into a standard screaming marshall amp!
I have an Artist cab I found on EBay a while ago that houses one of my 18w clones.

[RogerWilco99]

AND I've managed to do it without getting zapped by B+ - so far......

This is always a big plus!

I have always liked to have the reverb just before the tone stack. But just after the tone stack may works as well. You can either shape the reverbed signal or reverb the shaped signal. I like the sound of the former over the latter.

I usually use the reverb circuit from the AA1164 which uses a 1M to ground on the input to the 12AX7 driver tube. I've always thought that was there to prevent oscillations (feedback) witin the reverb circuit. It does take 1.5 12A?7 tubes to run that reverb. But it sure does work well.

And Fender puts that reverb in after the tone stack right on the input to the PI.

Glad you've got it working. Put up some sound links if you can so we can hear what she sounds like.

Cheers,
Bruce

[GraemeSP]

Audio file for my Marshall Artiste/JCM

Shove this into your browser -

SoundClick artist: GSP Instrumentals - Guitar Instrumentals , acoustic and electric.

I recorded this with a Boss micro thing (I really must read the manual). A bit too long to upload to the forum, so I put it on my soundclick page - Noodling.
The guitar is my best lady - Les Paul Custom 57 (ok its a VOS but it's got Tom Murphy all over it and it even smells 50 years old). I Peter Greened the pups and I love everything about this guitar except the weight.

In true Rock Style, all the amp knobs are at set to max - except the Master 'cos I like my windows in place. This is set about a third and the result is a comfortable room level. Guitar straight into the amp, no effects.

Start with clean, both pups, guitar volumes down to around 3 each.
At 00:37, I wind up the guitar vols to max. The sound builds and there's a slight breakup on hard notes. Change to OD channel at 01:10 and off we go. Bit noodle up and down, few bends, reverb off at 02:21, back on at 02:43. The amp will feed back on notes and chords with very little effort. This is the amp I've wanted for years - and I had it all along - she just needed a bit of careful work.

I think this amp sounds great. I hope you agree.

[gayler]

Very nice playing, and nice tones from the amp as well!