It increases dialablity in pre stage gain and EQ and allows you to use that EQ at gain without flub or fizz.
Makes it sound and feel like my Mark III redstripe which is a dead ringer for IIC+ness.
Makes Channel 3 as brutal with rich low end as Crunch mode on Channel 1. Even on IIC+ mode. Massive increse in usable massive low mids and growl yet classy and smooth when you want it too. Makes Prescence more usable..
Mark IV and Extreme as ridiculously juicy and massive with a more increased fluidity and organic faster feel to em.
For this mod: I recommend:
V1: Tungsol 12AX7 Goldpin
V2: Mesa 12AT7 (the afforementioned gain stages)
V3: Tungsol silver
V4: Tungsol silver
V5: Mesa 12AX7
V6: Mesa 12 AT7 (Phase inverter slot)
So you can see a 12AT7 in Phase Inverter too, and that adds more vintage goodness, hugeness and 3D sound to it.
Demos recorded at high gain and moderate/low output level, (Where fizz or relative lack of guts would be expected to show up under those conditions, if ever.)
https://www.youtube.com/watch?v=r5F6_b2cLoE - V2 mod through 1x12 and 2x12
https://www.youtube.com/watch?v=fW8LQvpWFhM - V2 mod through single 1x12
https://www.youtube.com/watch?v=7epyD2QUm0E - V2 And V4 mod with Tungsols through 2x12
Just cam mic. No post not even so much as an Sm57 involved. But it sounds killer when mic'd too.
This was a line up something I went for after Apeman and Bandit's work in the Mark V 90w thread. The Phase inverter thing I added after massive positive change for the Mark III, after reading up on older models. And Tungsols are great always for these amps. The V2 slot in the 25 is equivalent in effect to the V4 mod in the 90w amp.
To help bring you up to speed: https://forum.grailtone.com/viewtopic.php?f=33&t=68808&start=30 (V25 mod in this thread)
https://forum.grailtone.com/viewtopic.php?f=33&t=73352 (The original saturation mod thread.)
Hope this helps.
