Weirdness with my 5:50 today....any ideas?

[vbf]

Greetings. We played an outdoor festival today and experienced weirdness every time I switched to the burn channel or any pedals with gain. The best way to describe the noise the amp was making is very, very hissy.....extremely noisy. I've never heard it before. The clean channel was fine. But when I got home the amp sounds perfect across the board.....no problems. It is 100 degrees + here today and the amp was in direct sunlight. Also, our power supply was a large, diesel generator with undersized extension chords. I thought maybe a power tube got damaged or possibly the preamp tube in the gain stage. But alas it sounds perfect here at home. Weird!!

Bad tubes don't manifest intermittently, do they? If so, would you guess it's the power tubes or the preamp tubes? Could the (dirty) power from the generator have caused it? Any suggestions, clues, ideas, or postulations?

Oh, and I was using a wireless...pretty good quality unit. But if the cause was the wireless wouldn't I have heard weirdness on the clean channel?

Thanks!!!

 

[Newysurfer]

Greetings. We played an outdoor festival today and experienced weirdness every time I switched to the burn channel or any pedals with gain. The best way to describe the noise the amp was making is very, very hissy.....extremely noisy. I've never heard it before. The clean channel was fine. But when I got home the amp sounds perfect across the board.....no problems. It is 100 degrees + here today and the amp was in direct sunlight. Also, our power supply was a large, diesel generator with undersized extension chords. I thought maybe a power tube got damaged or possibly the preamp tube in the gain stage. But alas it sounds perfect here at home. Weird!!

Bad tubes don't manifest intermittently, do they? If so, would you guess it's the power tubes or the preamp tubes? Could the (dirty) power from the generator have caused it? Any suggestions, clues, ideas, or postulations?

Oh, and I was using a wireless...pretty good quality unit. But if the cause was the wireless wouldn't I have heard weirdness on the clean channel?

Thanks!!!

Likely to be a combination of the heat & the crappy power connections imo.
Probably created power sag thru the gain stages :mrgreen:

 

[Don]

I'll bet it was the generator.

 

[RectoStudioGuy]

Sounds sorce issue. Did you have alot of things connected to each circuit as well?

 

[vbf]

Sounds sorce issue. Did you have alot of things connected to each circuit as well?

Yes, it appeared ad though the generator fed a distribution block (spider box) from which all our power chords were run. There was an acoustic amp, my tube amp, and my pedal board plugged into the same extension chord. The extension chord looked like something you'd use for outdoor use...don't know the gauge though but not heavy duty. Oh, and the sound guy told me that he didn't think the generator was grounded. He also said all the electric guitars in all the bands sounded crappy. It was really weird...every time I selected the burn channel or anything with gain it produced the mid to high frequency noise. The noise increased in strength as gain was applied. I couldn't use the burn channel at all. I ended up turning the gain way down on my OCD pedal to just get through the gig. We got through it but I was definitely limited in what I could do gain wise....very frustrating!!!

 

[THE TUBENATOR]

It sounds like you were getting "dirty power". In addition to having the generator overloaded and undersized extension cords (voltage drop) the RPM's of the generator engine could have been off as well. The RPM's that the armature is turned will determine the output frequency. So you may have been getting for example 98 Volts due to the power delivery issues and perhaps 45 Hz or 75 Hz. If your amp sounded "off" I would say that is was more directly related to the frequency than the temperature or even the voltage. You American Boogie likes 60 Hz. Give it 70 Hz (generator running too fast) or 50 Hz (running too slow) and the rectifier circuit will have trouble digesting it! Most electrical devices are designed to easily accommodate a 10% voltage fluctuation up or down. That is not the case with the frequency. The voltage rectification circuit and the transformers do not respond well at all to frequency changes.

 

[vbf]

wow, that's some awesome info....thanks, everyone.