I like my Class 5, but with Humbuckers and even P90's I find it lacks trebble and can be a bit muddy at low volume, less than 3.5 on the volume Pot. If you crank the Class 5, this is less of an issue, but I don't really want to crank mine, I love it when it just reaches the breakup point, and it's not too loud.
The problem for me is that the topend is just not enough at these volume settings, it is further complicated by turning down the guitar volume which then really reduces the trebble and really kills off the clean tones of a Start or Tele, even my PRS Custom 22 when in Single coil mode suffers.
Elsewhere people have complained about the same problems, I have changed the Input impedance on mine which really helps solve some of these issues, along with a couple of minor mods elsewhere. Most of the mods came from the Les Paul Forum, there was a post which was to be fair, rather unkind to the Class 5 as it's not as bad as they made out; it really does depend on what you want from it and your Guitar, Marshall have tried to make this amp for all players, Plexi and new more modern players, in doing so, they must of course make some compromises, so it suits some and not others.
Heres my mods based on a combination of different posts - I'm not trying to turn mine into a Plexi or anything else, it's already a good amp, but I just felt it lacks something at lower volumes. If you have a high output guitar, or crank the amp, these may not be for you.
Change the Input Impedance to 1Megohm - by changing R20 to 1M Ohm, remove C10 (Steve from Marshall has commented on removing this capacitor, but to me it did make a difference on single coils).
Change R18 to 1.8K and change C8 to 4.7uF (you may wish to go lower possibly to 1uF, might be worth experimenting).
From other posts there are some more radical changes to the Tone stack that I have not yet tried as I feel this amp does not need too much tweaking, but I may decide to try these in the future, I'll post something if I do end up doing them and they have a good effect or not.
One last comment on the top end, with my Class 5 in original condition, through the internall 10" the sound at lower volumes is quite muddy and gives rise to many of my comments above, through my Marshall 4x12AV with the GT75 whatever Vintage speakers (don't remember the exact details), it is much, much better and needs almost no changes, but I don't want to carry about the 4x12, the little combo is just the perfect size, so tweaking is the way to go, but I do wonder if the standard speaker is a little dark and muddy at low volumes, maybe I'll try a different one if any one has any suggestions, remember, when the thing is cranked, it's fine, but I don't crank mine like some.
All tone and settings are subjective and I respect each and everones opinion, these are just what I have found and done to mine which I think improves it, you may or maynot agree.
Good luck if you try these mods, but remember to ensure it is fully discharged before attempting such changes as there are dangerous voltages present within the amp.
Cheers all
