Junction
Well-known member
I have a JTM45 (guitar amp) which sounds really sweet, but I don't like the way it breaks up when you drive the input gain beyond about 5. I want the break up to start at about 8 so I have better volume control range when it is clean.
Have checked with a CRO, the distortion (squaring off) is introduced at the phase splitter, so have tried lower MU tubes to replace the high MU 12AX7, tried a 12AT7 and a 12AV7, they both kinda improve it a little, but the higer freq tone and definition just dissapper, making the amp sound quite flat.
Have searched many forums but can't find anyone who has addressed this. Any ideas??
Does anyone know how or if you can adjust the gain in a phase splitter? Also how can I increase the headroom?
Link to schematic, have linked the Fender 5F6 as the 45 schematics are really hard to read, same circuit except 45 has KT66 instead of 5881 tubes.
http://www.drtube.com/schematics/fender/bassman-5f6-a-schematic.gif
Thanks
Michael
Have checked with a CRO, the distortion (squaring off) is introduced at the phase splitter, so have tried lower MU tubes to replace the high MU 12AX7, tried a 12AT7 and a 12AV7, they both kinda improve it a little, but the higer freq tone and definition just dissapper, making the amp sound quite flat.
Have searched many forums but can't find anyone who has addressed this. Any ideas??
Does anyone know how or if you can adjust the gain in a phase splitter? Also how can I increase the headroom?
Link to schematic, have linked the Fender 5F6 as the 45 schematics are really hard to read, same circuit except 45 has KT66 instead of 5881 tubes.
http://www.drtube.com/schematics/fender/bassman-5f6-a-schematic.gif
Thanks
Michael