Peavey 5150 owners and amp techs problem question??

[Rod]

Hi!

I have notice a problem in my peavey 5150, the possible problem is the following:
when i choose the clean channel with the pre gain almost at zero, and then when i rotate the post gain knob from zero to the maximum value i ear a noise like the one from the attached mp3 file.

this noise happears bettween the 4 and 6 value of post gain, Is this normal?

I also have notice after i have done this, that the lead channel sounds way better, the bass is more tighter and sound is more clear and defined.

Do i have some kind of problem in the power amp of this amp?
The other owners of this amp, have this problem?

[Amp Kat]

Unfortunately that is pretty normal for this amp. It's one of the only amps where the master or Post as it's called effects the tone of the amp. Even if you use the preamp out you need to crank the post to about 3 or it gets very thin. I guess it's a preamp/post cross master volume.