Crate V50

[goldtop5]

I have a Crate V50 that's playing at full volume, but is distorted on both the clean and dirty channels. Any ideas?

[Leo_Gnardo]

I have a Crate V50 that's playing at full volume, but is distorted on both the clean and dirty channels. Any ideas?

1: speaker's blown, probably voice coil scraping in its gap. 2: insufficient bias current in output tubes. 3: a bad output tube or one that's not working because of an open screen grid resistor. In any of these cases the amp will get plenty loud but never sound clean. Just thought up another. 4: bad tube or other defect in the inverter/drive circuit causing only the upper or lower half of the signal to get to output tube control grids.

Check the easiest thing first, the speaker.

[Jazz P Bass]

At full volume the Clean Channel WILL sound distorted.

The Dirty Channel is a given.

[goldtop5]

Problem solved! Someone else had set the bias voltage too low (26mV across R80 and R81). I bumped it back up to 400mV and it cleaned right up. I was never too big on Crate amps but this one sounds amazing!!! Thanks Leo!

[g1]

They must have thought the cathode resistors were 1 ohm when they are actually 10. So that would have been 2.5mA bias (or roughly 1W). No wonder it sounded bad .