Low Frequency spitting

[JammyDodger]

Hey All,

I didn't know where else to post this. I have an Orange Rocker 30 Amp. I has developed a spitting, non-harmonic distortion when I play low notes on the guitar. This occurs on both channels.
I've changed out tubes and tried a different speaker with the same results. The amp is 19 years old

I'm thinking maybe a power supply cap? Any thoughts?

Cheers, Mike

[TUBEDUDE]

Lows demand more power, so it could be a filter cap. Have you cleaned up jacks and checked for any sketchy looking solder joints? Do any of the filter caps look different, dark spots, crusty or misshapen?

[xtian]

Try another guitar also. Combo or head? Is fault vibration related? Can you reproduce the "spitting" by using a sine wave generator at a specific frequency? If you can, then your hands will be free to chopstick around to see if you can find faults.

[Stevem]

Does this take place only once a certain volume level is reached?

[JammyDodger]

This is a combo unit although I've removed the chassis and have the same issue

I will try a sine wave approach and poke around a bit.

It is more apparent at higher volume levels I plugged a bass guitar into it just to see and it was much worse. I am not over driving the amp, just moderate to loud levels,

Thanks for all the responses!

[R.G.]

Random sideways thought: have you tried a different speaker/cab? I once chased a "growl" sound for several days until I found out there was a speaker rub at a resonance.

[R.G.]

Mine was a combo too. I disconnected the internal speaker and wired it to a cab. Issue vanished. Its a quick and easy test to eliminate the speaker and cab.

Of course, it may be something else entirely. Put a scope on it and see if the bass glitches are there in the electrical signal. If they are, that eliminates the speaker and cab possibility. I found mine because there was no glitch in the electrical signal, so it had to be mechanical.