Can you diagnose this amp problem??

[willhutch]

Symptom: There is unwanted distortion coming from my amp. It sounds like a square wave. It is significantly quieter than a plucked string. After I hit a note and it begins to decay, the sound becomes very noticeable. The sound is louder if I turn up the amp or the guitar's volume. It disappears when either volume hits zero. The pitch of the distortion is dependent on the pitch of the note(s) played. It is louder when I play low notes.

The Amp is a SF Vibrolux Reverb. The sound happens in both inputs of both channels. It happens regardless of whether or not the reverb or trem is engaged.

Troubleshooting efforts: I swapped each and every preamp tube and the power tubes. The problem persists. I have not changed the rectifier.

Question: What kind of malfunctions lead to this symptom? I understand it could be any of a myriad of problems. But where would you suggest I start looking?

[mark norwine]

my guess.....speaker rub

[Old Tele man]

my guess.....speaker rub..to "verify" this, simply unplug the connector to the cabinet speakers and temporarily plug-in a "known-good" speaker.

...if the noise is gone, it's the cabinet speaker(s).

[willhutch]

Mark Norwine!!! You, sir, are correct!!!!

Hey, why am I so happy?? The original CTS speaker in my vintage Fender is rubbing! Well, at least it ain't the amp itself.

Good call. See? Thisis why I hang out here!

[mark norwine]

You do this "amp fixing stuff" long enough and you begin to see same stuff over & over & over & over......

This was the tip off....

After I hit a note and it begins to decay, the sound becomes very noticeable.

It's a "signal-to-noise ratio" issue. the buzz volume is reasonablly constant, but is hidden behind the note. As the note decays, the buzz seems to get louder.

Get the old one reconed & you'll be fine.

[Jon Silberman]

Mark, do you have any plans to build more amps at any future point?

[mark norwine]

I still build a few amps every year.....some are new / unique designs "just for me", others are proven circuits, built for close friends.

However, I can honestly say that {at this time} I do not aspire to ever again own an amp company, nor do I have any desire to solicit business, have a backlog, etc. And my "free time" is never again going to be saturated with amp work because of commitments that I've made.

But I still enjoy designing amps, and from time to time, these designs wind up being fully built and {usually} given away to local players.

And, truth be told, I've made a couple {2 or 3} 'Pups since closing the business in 2003

So, yes, I still build from time to time, but I can honestly say I don’t have plans to build more. It's more like I build one for the fun of it, and then someone comes around, hears it & takes it.

But the "future" is wide open. I'm 48, and {hopefully} have many good years left. Who's to say that Carlson Amps won't someday exist again? Not me! I never say never. But, no, there are no plans at this time for any such "structured company".

These days I'm far more interested in making music than I am in making amps. I have been studying chord melody jazz with a great teacher, and I'm playing in a twenty-one piece jazz/swing band. I'm busier than ever.......

If your question was a general one, I hope I’ve answered it. If, on the other hand, you had a specific amp thought in mind, PM me and I’d be glad to discuss your needs.

Best,

mn

[Caretaker]

my guess.....speaker rub
What he said.

[willhutch]

Well, Mark...er...Mr Norwine, I hope you continue to hang out here and help us dummies get out of the amp trouble we create for ourselves.