Preamp valve positions

[jmpman]

I know this has been posted, but need clarification. Is the below specifications listed mean from left to right if looking at the amp from the back or from the chassis taken out of the head box and turned upside down? Thanks.

Q: What do each of the preamp valves do?
A:V1 is the first gain stage included in the signal path on both dynamic ranges.

V2 is an extra gain stage, which is included only on the high dynamic range.

V3 is the tone stack

V4 is the phase inverter.

[surfnorthwest]

Go to the FAQ part of this forum the information is there.

http://marshallvintagemodern.com/viewto ... =28&t=2771

[jmpman]

That's where I got the copied info from. Just want to make certain if V1 starts on the left side if looking from the back of the amp or the right side? The FAQ section did not specify, it just listed the purpose of each position. Please elaborate. Thanks

[SteveD]

Welcome to the forum jmpman.

Looking at the banner at the top of this page, V1 and V2 are the ones with the metal shields covering them. So, from right to left, preamp valves are V1, V2, V3 and V4.

[jmpman]

SteveD. Thanks for clarifying. I just bought mine yesterday and still exploring all the tonal nuances. The only thing weird was I had to put a ground lift plug on the power cord because it would hum some and that seemed to cure that, not sure why it did that because it did not do that at GC. Any idea?

[jmpman]

SteveD, any idea with the hum part of my previous post? Like I said I isolated it by just putting a ground lift plug on the power cord. But should I try something else? And thanks for the warm welcome!!

[SteveD]

It would usually only do that if you had a ground loop. Have you got something else in your signal chain that uses mains power like a floor controller, stomp box or rack effect?

[jmpman]

It would usually only do that if you had a ground loop. Have you got something else in your signal chain that uses mains power like a floor controller, stomp box or rack effect?

Oh yeah, I sure do. I did not have time to isolate but will try to eliminate by trial and error this evening. But in the meantime it won't hurt to do the ground lift plug method on the VM, correct? Also, once I find the weak link in the chain, would you just put the ground lift on that?

[SteveD]

If you have other mains operated equipment try it on them rather than the amp. I always prefer an amp to have nothing in the way of it's safety earth.

[jmpman]

Will do. Thanks again!