Sudden loss of treble and presence...Mark IV B

[jwgreene86]

Amp's suddenly losing presence and treble...even dimed out, it's not biting like it normally does. New preamp section, but no idea how old the power tubes are. Start there? Using a Mark IV B widebody combo.

 

[topcat0399]

Put the old preamp tubes back in and see if behavior changes.
If not put new tubes back in and give all of your pots a good cleaning.

That would be my approach.

Good Luck.