Marshall pre PI MV to Post PI

[JammyDodger]

Hey All,

Is it worthwhile changing the pre P.I. Master Volume on my Marshall 2204 to a Post P.I.? This is a simple change but I was wondering if there would be enough tonal difference to make it worthwhile.

Any thoughts?

Cheers, Mike

[Rich M]

Yes. Much of teh tonal characteristics of a Marshall come from the PI being overdriven.

[topbrent]

Do both.

Keep the Pre PI MV and add the Post PI MV.

2203 + LarMar PPIMV. =

It is the current fun to play favorite over at metroamp.

"Rockstah" sets his 2203 up this way, uses plexi era filtering and calls it the "mod 5"

[M Fowler]

Man I love the 2204 the way it is.

Are you looking for more bit in the gain with lower overall volume?

Mark

[Ian444]

As you said it is a simple change, why not just try it out?

[rockstah]

yes, do both.
Mark

[rockstah]

Do both.

Keep the Pre PI MV and add the Post PI MV.

2203 + LarMar PPIMV. =

It is the current fun to play favorite over at metroamp.

"Rockstah" sets his 2203 up this way, uses plexi era filtering and calls it the "mod 5"

the thing I did was understand that you need to get the volumes up loud in a cascaded gain stage amp to have it sound good.

While guys were doing one or the other( pre or post master) i did both masters in one amp. of course there is still some tweaking to do after that but thats was what I did.

If your 2203/2204 sounds like this you got it right - http://www.youtube.com/user/RockstahAmp ... 5sco_gLFas

Mark

[topbrent]

Do both.

Keep the Pre PI MV and add the Post PI MV.

2203 + LarMar PPIMV. =

It is the current fun to play favorite over at metroamp.

"Rockstah" sets his 2203 up this way, uses plexi era filtering and calls it the "mod 5"

the thing I did was understand that you need to get the volumes up loud in a cascaded gain stage amp to have it sound good.

While guys were doing one or the other( pre or post master) i did both masters in one amp. of course there is still some tweaking to do after that but thats was what I did.

If your 2203/2204 sounds like this you got it right - http://www.youtube.com/user/RockstahAmp ... 5sco_gLFas

Mark

That tone is awesome.

[Rooster1]

HOW DO i change A master volume Marshalls from pre PI master to post PI master. everyone here says its easy ,I dont knkow where the phase invertor tube is - I'm not an Amp builder just on that quest for Tone -, my amp MArshall Jtm 30 ,whats the first thing I do ? does it requier Physically adding another tube /and tube mount or is it just moving tubes around ? Any help appreciated

[Bob Simpson]

Ruh-roh...

[Reeltarded]

You just move the MV to after the PI.

[xtian]

Rooster1, do you know how to read a schematic, safely discharge capacitors, solder, etc.?

Reading required: http://ampgarage.com/forum/viewtopic.php?t=9023

[Smokebreak]

Do both.

Keep the Pre PI MV and add the Post PI MV.

2203 + LarMar PPIMV. =

It is the current fun to play favorite over at metroamp.

"Rockstah" sets his 2203 up this way, uses plexi era filtering and calls it the "mod 5"

Wow. Just did this along with the mod5 specs I could find and I think I am done with my plexi mods, for now. This is amazing. Amp sounds really big. Thanks a bunch!

[iknowjohnny]

In this diagram... http://metroamp.com/wiki/index.php/Imag ... PPI-MV.jpg

what are the 2.2M resistors for, or better yet what if i don't use them? I ask because i did this type of master before and didn't care for it, but i didn't add those resistors so i'm curious what the do. Looks like they just mod the taper, huh?

[xtian]

NO, those resistors allow there to be a bias voltage if the pot fails.