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SVT Distortion

H

HometownLetdown

Sep 14, 2011
81
0
#1
I have searched and cannot find exactly what my problem is.

I have and SVT Classic with 8x10 and a Pbass.

When I am playing sometimes the sound will start to distort for 10-30 seconds almost like I am running it through a distortion or fuzz pedal and then go back to normal. I changed out the speaker and instrument cables and still have the same issue. I cant replicate by any specific means it just happens out of the blue.

The bias is set to green on both lights after the amp has warmed up and has no signal running through it.

Current EQ Settings:
Gain 5
Bass 6
Mid 8
Freq 3
Treb 7
Master 4

Thanks for any suggestions on what this may be.
 
#2
First thing I'd do is check all the tubes and make sure they're seated in the sockets properly. Doesn't sound like power tubes are the problem. If you have any spare preamp/driver tubes, you might try swapping them out one at a time to see if you have a culprit. Someone else might have some ideas, but beyond that and you're always better off taking it to a qualified tech, especially if you know as little about them as me ;)
 
#3
JimmyM said:
First thing I'd do is check all the tubes and make sure they're seated in the sockets properly. Doesn't sound like power tubes are the problem. If you have any spare preamp/driver tubes, you might try swapping them out one at a time to see if you have a culprit. Someone else might have some ideas, but beyond that and you're always better off taking it to a qualified tech, especially if you know as little about them as me ;)
Click to expand...

+1 for Jimmys suggestion.

Intermittent problems are usually bad/intermittent connections. Any connector is subject. Tube? Tube socket? Potentiometers? Input/Output connectors?

A word to the wize. There are high voltages inside that thing so if you don't know where they are stay out.

Because the problem is intermittent, taking it to a tech may get your amp back with NPF (no problem found). So I say live with it as long as you can. A good Tech does have ways of making intermittent problems surface.

Thats a great amp and well worth fixing.
 
#6
Nope, no biasing required. The hardest part of changing preamp tubes is getting inside the amp. After that, anyone can do it. But if you're unsure, definitely take it to a reputable tech.
 
#15
HometownLetdown said:
When I am playing sometimes the sound will start to distort for 10-30 seconds almost like I am running it through a distortion or fuzz pedal and then go back to normal. I changed out the speaker and instrument cables and still have the same issue. I cant replicate by any specific means it just happens out of the blue.
Click to expand...

The tube suggestion is a good one, but... have you tried connecting a patchcord from PREAMP OUT to POWER AMP IN on the back? That power amp in jack has a switch in it (to disconnect the internal preamp when you plug in an external one). Sometimes the contacts corrode and cause weird stuff like this to happen. Sometimes just inserting and remove a plug in that jack is enough to clear up the problem.

Usually JimmyM suggests this... is he getting old and slow? :hiding:
 
#19
punkrockmike said:
where was your 810 made/what year is it? try it with a different speaker cabinet. i had a somewhat similar problem and it turned out to be my ampeg 810. it was one of the ones made by loud technologies in vietnam. mud city. almost sounded like you're describing. tried it with a different cab and it sounded as smooth as butter.
Click to expand...

I have an old 8x10 before they were made in Viatnam, but I will try another cab as soon as I pickup the other 8x10.

dukeisdog said:
What bass are you using through the rig? Is it an active bass? If so, switch out the battery.
Click to expand...

No it's not an active bass. Before I was using a MM Sterling and I checked the battery still had issues, now I am trying with a Fender Pbass with SD Q-Pounders SDB-3
 
#20
punkrockmike said:
where was your 810 made/what year is it? try it with a different speaker cabinet. i had a somewhat similar problem and it turned out to be my ampeg 810. it was one of the ones made by loud technologies in vietnam. mud city.
Click to expand...
:eyebrow:

Funny how people hear things differently. I hear the newer Ampeg 810e's and they sound not the least bit muddy to me. It's the SLM cabs that sound muddy to me.
 

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