Have you found any decent mods for harp yet?
I have a Masco MA-25PN on my bench right now which could use a little more "drive" and grind. At least that's what the owner requested.
I'm thinking about leaving MIC1 as is and lowering the pre amp voltages on MIC2 a bit to get a little more overdrive on this channel. The guy likes playing harp with a tube screamer..... Not my first thought, 'cause I really like the "clean" kind of harp overdrive.
Anyway, the guy also wants to play blues guitar on this amp, that why I thought to scrap the line input and convert this channel together with the MIC3 input to a Fender 5C3, with 6L6's as power stage. Ted Weber has also done this with his 5C3P kit. The paraphase PI and power stage are already into place, Now I only need to scrap on 6J7 and replace it with a 6SC7 or 6SL7 as pre amp section.
It would be nice to hear what you've done to your amp as it comes to harp mods.
The speakers which came with this amp are (home build by the owner) one cabinet with two 8" Jensen Bluetone AlNiCo's (2x 4Ohm in series) parallelled with another cabinet driving a 12" Jensen (8 Ohm) speaker.