strange sounding studio .22 part 2 the sequel

[DaveS]

Since trying to find out what’s wrong with this amp it’s been serviced by a top amp tech who changed a valve and an incorrect transistor. The bias hasn’t been changed. Everything checked out fine on the scope and the guy’s a great engineer but he’s not a musician, and it still sounds horrible. I’ve taken into account suggestions from various internet sites, tried different first pre-amp valves, different guitars and still sounds wrong. I would say over a couple of years it’s gradually got worse. A neck humbucker that needed a 2K graphic boost for a bit of clarity through the amp about 5 years ago now reminds me of a telecaster even with the presence off, the treble almost off and no graphic. The same apparent upper mid spike is also evident on the lead channel which now also seems to need to be on 5 to get the same gain that I used to get on 3. Any ideas anyone? A new louder amp is on the horizon anyway but I would still like to be able to use this one. Thanks.

 

[bigbean]

You could try " out of effects loop into another amp" and "out of another preamp or pedal into the effects in" to see if the problem is in the preamp stage or the power amp stage. It might help add some clarity to the issue.

 

[DaveS]

Well, an update. The power amp seems ok. I've just got it back from someone who checked it and found a faulty capacitor between the first two valves. He's replaced it with a slightly higher value, he said, to give a fatter sound. Anyway, the gain has more or less come back, which is good but I'm still stuck with what seems a shrill, harsh sound, which neither the tone controls or graphic can fix. The guy who put me onto the latest engineer agreed with the bad sound. Since changing the capacitor the latest engineer said he liked the sound himself, but recording today the sound to me was painful even at low volumes. It could be my ears, I hope not, but the next thing is a gig and a change of pre-amp valves to see what happens. Having successfully found something genuinely faulty I'm hoping the eq problem can be fixed also. Still open to ideas.

 

[bigbean]

You haven't said how old the other tubes (valves) are.

If they are older than 2 years and you play the amp a fair amount retube every thing (except maybe the reverb tube, v4). V2 is the most critical. V1 is the overdrive - but it feeds V2. V3 is the tone stack tube. The output tubes (EL84s) don't sound to me like they are the culprit but they are pretty cheap tubes so I'd replace those too.

These amps eat tubes. It's allright with me that they do, but it's a fact. Also, tube quality is variable. I just had a JJ 12AX7 in my Fender amp that went tits up after 4 months. Got a bunch of others sprinkled through my amps that are working great after a year. Who knows? Unless they are new, yank 'em!

That's what the car stereo guys used to say, (poor deaf bastards) If you can't crank it / yank it!

Best of luck.

 

[DaveS]

Thanks for the reply.

I just did a gig and it's great to have the gain and sustain back with the new capacitor. As far as the tone is concerned, yes, it's time to check all five of the pre-amp valves even though it doesn't get used more than about once a week.