Solid State Amp Question

PDC

PDC

Well-known member
I have an OLD ‘Spectra’ 30 watt practice amp that I have had since the late 80s. It is one of the nicest, warmest sounding little SS practice amps I have ever owned or played through. It is a particularly good platform for ‘Amp In a Box’ pedals and I love practicing with this thing when I don’t want to fire up the glass.

Lately it has started this weird thing where after playing for about an hour, the volume will drift down to about half and drift back up. It will cycle gradually in and out like that till you give up and turn it off. Come back tomorrow and it sounds just fine on initial fire up for another hour or 2 til the volume starts drifting up and down again.

If this was a tube amp, I’d start cycling known good glass through this thing. But as an SS amp, I’m really not sure what to check. The main fuse is good, speaker connections are tight, and I recently cleaned the volume and tone pots with Deoxit.

It’s not super valuable, other than I have owned it forever and it really makes a great practice amp. Any chance of saving this thing, or is it likely just on its way out???

Thank you!
 
Last edited:
glpg80 said:
It’s likely a bad cap causing the issue, it needs recapped in the supply area.

The more you play it stressing the opamps and solid state devices in its current condition, the higher the risk of doing more severe damage.
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Thank you. Sounds like I need to find a shop to dig into this thing for me.
 
PDC said:
I have an OLD ‘Spectra’ 30 watt practice amp that I have had since the late 80s. It is one of the nicest, warmest sounding little SS practice amps I have ever owned or played through. It is a particularly good platform for ‘Amp In a Box’ pedals and I love practicing with this thing when I don’t want to fire up the glass.

Lately it has started this weird thing where after playing for about an hour, the volume will drift down to about half and drift back up. It will cycle gradually in and out like that till you give up and turn it off. Come back tomorrow and it sounds just fine on initial fire up for another hour or 2 til the volume starts drifting up and down again.

If this was a tube amp, I’d start cycling known good glass through this thing. But as an SS amp, I’m really not sure what to check. The main fuse is good, speaker connections are tight, and I recently cleaned the volume and tone pots with Deoxit.

It’s not super valuable, other than I have owned it forever and it really makes a great practice amp. Any chance of saving this thing, or is it likely just on its way out???

Thank you!
Click to expand...
A friend of mine brought over an old late 1980's/ early 1990's Crate amp, he put a better quality speaker and that amp has great tone now.
 
This old Spectra actually has a loop. I did clean all the pots with channel-master and gently tightened the input tab and this symptom ‘seems’ to have resolved. I had the amp on for a couple of hours the other day with zero issues. I did swap AIB pedals and now wonder if the issue isn’t in my pinnacle pedal - that I was using when the symptoms first cropped up…
 
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