1972 300 Series Technical Question

[Verdoliva]

Good morning.

My friend owns a 1972 300 Series bass amp that is constantly producing distortion regardless of the input (hi-lo) jack being used. He thinks the previous owner may have modified the amp for this effect but is unsure. I suspect their may be an issue in the pre-amp circuitry or with the input jack(s). It's my understanding that the High Gain input jack is used normally, but if distortion occurs then the Low gain jack should be used. However, in his case distortion occurs from both jacks.

Any and all suggestions are greatly appreciated.

Semper Fidelis
Ken

[studiodtk5]

Sounds to me like an issue with the amp. Have you made any visual inspections of the circuit yet?