Super Reverb Tone Degenerated

[FiveG]

Let me see if I can describe this in a way that doesn't sound like a blonde in car repair shop.

I have a 73 SFSR which has been blackfaced. Have had it about two years or so and was worked over by tech and sounded great. Recently, when I was finishing playing, I powered off my pedal board before turning off the amp. When I did, there was sort of a loud hiss/hum that faded out. Didn't know if that was from board, pedals or amp. Turned off amp, turned back on, and haven't had that happen again since.

What I have noticed, recently, is that the tone has seemed to degenerate. It's almost like the depth of tone has disappeared. I'm getting flubby bass pretty quickly on the volume, but I can't get the full, rounded tone I'd been used to. It's starting to distort around 4 with humbuckers (which it did before), but it sounds more like an old transistor radio than it did before.

No idea of the pedalboard incident was involved or not.

Does anyone have any suggestions of whether maybe I've lost my mind, whether some tube(s) or other components have gone, or whether I need to just keep tinkering with tone controls (which I've been doing, believe me)?

FiveG

[Pedro58]

It sounds like you need new power tubes. Try that first and hope that your transformer hasn't gone bad.

[GearHeadFred]

Some basic things first:

Have you bypassed the pedal board to make sure the problem isn't there?
Good cables?

If you're reasonably sure the amp is sounding different, it could be many things.. Has it had a cap job? If not, it is past due for one.

[FiveG]

Thanks, guys. I did bypass the board so that isn't the issue. On cables, one is very good, one not so good, but they haven't changed between good and bad, so I doubt that's the issue. (Probably one to address later, tho'.) Did have cap job done right after I got it, so wouldn't think that's it.

Sounds like my tech needs a visit.

Thanks.

FiveG

[thirstypirate]

You should really try some new power tubes before you pay for a tech to look at it. Not to state the obvious, but tubes will lose there punch when they are old and close to failure.

[FiveG]

You should really try some new power tubes before you pay for a tech to look at it. Not to state the obvious, but tubes will lose there punch when they are old and close to failure.

Never biased a SFSR, but have a meter. How tough are they? (Have biased Carr Merc).

[Mike9]

Unless the bias circuit has been modded yours has a fixed bias and a bias balance pot. Might have a hum balance as well.

[Lil Stevie B]

Unless the bias circuit has been modded yours has a fixed bias and a bias balance pot. Might have a hum balance as well.
If it has truely been blackfaced - the balance pot has been turned into an adjustable bias pot.
I also have a 73 SFSR. And the description you gave happenned to me many years ago. It just sounded kinda crappy and distorted at lower volumes. I swapped out the power tubes and it was better.
But you might want to try some different preamp tubes as well.
It's worth a shot. It won't be wasted money - you always NEED some extra (types of) tubes.

Oh, BTW, I replaced my rectifier tube a couple of years ago. It had the original one in there. I could not tell the difference at all.

[donnyjaguar]

Are you sure that one of the power tubes hasn't conked out - as in blown filament?