Harsh, grainy distortion

[bluesguitar]

I finally decided to replace all of the resistors in my '67 Super Reverb that were out of spec to see what it was designed to sound like. I replaced about 16 in all. Everything was fine when I did a play test, until I got the volume above 5. Then, I was getting a harsh, grainy, high pitched distortion. I knew it was a clipping issue. I play with no V1 tube in the amp, which gives me earlier breakup. I put a tube in V1, and that solved the problem. I could dime the amp without the unpleasant distortion that I experienced before. However, I know that I should be able to play the amp without a V1 tube, because I could before changing the resistors. I changed the V2 tube and tried it again without a tube in V1, but still have the same problem. I don't think it is an issue of vibration. I think it is more an issue of voltage or current. Any ideas what would be causing the problem?

[vibratoking]

If you replaced all the resistors with the correct value, then there should not be a problem. My first guess would be a cold solder joint. Why V1 insertion would fix it? Maybe a coincidence that the joint made a better connection after you manipulated the amp? I would double check all the resistor values and all the solder joints including any and all wired that should be electrically connected to the eyelets.

[bluesguitar]

[quote="vibratoking"]If you replaced all the resistors with the correct value, then there should not be a problem. My first guess would be a cold solder joint.
I appriciate the feedback, and my thinking is the same as yours. However, I have play tested it numerous times now with the same consistent results. It plays fine with the volume at 5 or lower. This is plenty of volume to vibrate the chassis. If it were a cold solder joint I think it would create the same unwanted distortion. I don't think it's an issue of vibration causing intermittent connection. And it never happens with a tube in V1 no matter the volume and amount of vibration.

[martin manning]

Perhaps you disturbed some leads and you are now getting a parasitic oscillation?

[tubeswell]

Or perhaps you cooked the replacement resistors when soldering them in (if they were CCs)?

[Randall]

Or perhaps you cooked the replacement resistors when soldering them in (if they were CCs)?

I've done that! ^

[Milkmansound]

Perhaps you disturbed some leads and you are now getting a parasitic oscillation?

this was my guess - leads in the tone stack are particularly sensitive. Futz with the volume pot wiper lead and the lead coming off the 250p cap