One String w/ Harsh Overtones

Chris Bauer · Post by **Chris Bauer** » 26 Feb 2014 4:01 pm

Okay amp mavens, here's a problem I've never run into before...

I'm playing an amp that sounds GREAT on nine strings out of ten. Playing the high B string, though, creates shrill, harsh overtones. It sounds like there's some frequency the cabinet doesn't like. However, it happens when playing that string anywhere on the neck so I'm prone to think it's something in the pickup and not the amp.

If so, though, why doesn't it happen with other amps? I know it doesn't take much to puzzle me so maybe there's an easy answer.

Easy answer or not, though, anyone have guesses on this?

Mike Wheeler · Post by **Mike Wheeler** » 26 Feb 2014 4:10 pm

Sounds like you have a rough spot on that string's changer top. It doesn't take much to cause that sound. Loosen the string and closely inspect the top of the changer where the string rides. If you find a groove, or worn spot, that's likely the culprit. If you're very, very, careful, you can polish it out...just be sure you don't change the radius of the finger top or you'll make it a lot worse.

Then again, there could just be some debris there under the string.

Jon Light (deceased) · Post by **Jon Light (deceased)** » 26 Feb 2014 4:14 pm

Let me answer that question with....a question :>).
Tube amp? What pickup?

Also, quick thought----has this been something you've noticed for a while? Because a dying string can be the cause of many an issue from sitaring to bad overtones to....this, maybe? Then when it snaps and you replace it you say "duh! how many times have I learned this lesson!?"

Chris Bauer · Post by **Chris Bauer** » 26 Feb 2014 4:21 pm

Tube amp with a Tonealigner pick-up. Would string goo or changer issues sound different on different amps, though?

Jon Light (deceased) · Post by **Jon Light (deceased)** » 26 Feb 2014 4:29 pm

My only reason for asking was that a microphonic tube can be sensitive to specific frequencies. A physical thing.
Not a diagnosis. Just a thought.

Craig Baker · Post by **Craig Baker** » 26 Feb 2014 5:54 pm

Chris,
By any chance are you using a Roland amp or an Evans amp?

Sincerely,
Craig Baker 706-485-8792

cmbakerelectronics@gmail.com

C.M. Baker Electronics
P.O. Box 3965
Eatonton, GA 31024

Chris Bauer · Post by **Chris Bauer** » 26 Feb 2014 6:05 pm

No, Craig. This is a tube amp.

Craig Baker · Post by **Craig Baker** » 26 Feb 2014 6:46 pm

Chris,
There was a thread recently about this very topic. If I recall correctly, after this guess and that guess, a string change solved the problem. Hopefully it will be that simple for you.

Sincerely,
Craig Baker 706-485-8792

cmbakerelectronics@gmail.com

C.M. Baker Electronics
P.O. Box 3965
Eatonton, GA 31024

Chris Bauer · Post by **Chris Bauer** » 26 Feb 2014 7:09 pm

Here's hoping!

Tim Marcus · Post by **Tim Marcus** » 26 Feb 2014 7:44 pm

If it were one note, I'd suspect a microphonic tube.

But you are saying it's every note on one string - so I'd suspect something mechanical

Chris Bauer · Post by **Chris Bauer** » 26 Feb 2014 8:03 pm

When you say "something mechanical", Tim, are you thinking with the guitar, the amp, or could be either one? (And yes, it's all the way up the neck with that one string.)

I would assume that something mechanical would involve the guitar but then why would this not happen with other amps? I'm still stymied on this...

Tim Marcus · Post by **Tim Marcus** » 26 Feb 2014 8:28 pm

its strange, but not unusual. Some amps may let more harmonic overtones through than others. Perhaps that is where this problem lies - somewhere up in the harmonic series.

I would try and fix the steel first. Or just use the amp that does not emphasize it

Dennis Detweiler · Post by **Dennis Detweiler** » 26 Feb 2014 8:59 pm

I've had this happen a few times over many years. It's always been a bad string or a groove on the pulling finger. Loosen the string and slide slightly off center on the finger and retune it. If it solves the problem, its a groove. If it's still a problem, put a new string on it, but touch up the top curvature of the finger before putting on a new string anyway.
I've also had a string lose intonation when chording up the neck. Another bad string.

Shorty Rogers · Post by **Shorty Rogers** » 27 Feb 2014 9:39 am

Also, be sure that the speaker is not contributing to the problem. I have experienced similar issues that were only noticeable when certain combinations of amp and speaker came together. Main source of the problem turned out to be loose screws in the end plates and changer mountings. More noticeable with a JBL than a BW.

Chris Bauer · Post by **Chris Bauer** » 27 Feb 2014 11:42 am

So...today it was two strings and I'm pretty sure I'm starting to hear it on a third. Where do I start troubleshooting?

Jon Light (deceased) · Post by **Jon Light (deceased)** » 27 Feb 2014 12:00 pm

While this latest does not quite nail down any theory, let's look at the tubes. A way to try to find a bad tube is to lightly tap on each tube with something like a chopstick. Soft tapping while the amp is on. You are listening for one tube that clearly makes more sound thru the speaker than the others when you tap it. It is not an end-all method but if it does find an obvious culprit, then you have...found an obvious culprit.

Chris Bauer · Post by **Chris Bauer** » 27 Feb 2014 12:19 pm

Thanks! Off to find some chopsticks. (And maybe some dim sum along the way...

)

And, just because even I can be slightly clever every once in a long while, I played with both another steel and another cabinet and the same thing is happening each time. So apparently it's something somewhere with the amp.

Bob Hoffnar · Post by **Bob Hoffnar** » 27 Feb 2014 12:35 pm

Try putting the amp on its side to see if that changes anything. Maybe put something heavy on it. That way you can see if it is some sort of rattle. There are all sorts of goofy things that can happen. One time I went to a guys house and fixed his amp by turning off the window fan it was in front of.

Chris Bauer · Post by **Chris Bauer** » 27 Feb 2014 12:39 pm

Thanks, Bob. I'll try it all!

In the meantime, it turns out that:

1. Each of the tubes has a nice acoustic tone when tapped with the amp off. May be the makings of a new musical style in there somewhere.

2. There's a 6SC7 that kinda barks and rattles a bit in the speaker when tapped after the amp is turned on. Sooo - I'm guessing that's a likely culprit.

Thoughts on yet other things to do before swapping out the tube and seeing what happens?

Jon Light (deceased) · Post by **Jon Light (deceased)** » 27 Feb 2014 12:54 pm

All my preamp tube experience is with the 12 A*7's re: swapping tubes. I can't & won't say anything about dealing with octals. Do you have a replacement?
The one thing I can say--I blew a really nice NOS tube by being impatient and hot-swapping (and shorting something as a result). Shut 'er down when pulling tubes.

Chris Bauer · Post by **Chris Bauer** » 27 Feb 2014 12:57 pm

I don't actually have a replacement, Jon. Working on that. Yet another reason to keep trying things in the meantime...

Lane Gray · Post by **Lane Gray** » 27 Feb 2014 3:50 pm

Again, since you haven't answered the point, have you tried new strings? Even if it doesn't happen on your other amps, it might just be dying strings interacting with that amp. A set of strings is cheaper than any replacement tube...

Chris Bauer · Post by **Chris Bauer** » 27 Feb 2014 7:26 pm

Thanks. Lane. String change wasn't the answer, it seems. So, between that and the fact that another guitar has exactly the same issue, I'm pretty much banking on it being an amp issue. (Now which amp issue, of course, remains a bit of a mystery...)

Craig Baker · Post by **Craig Baker** » 27 Feb 2014 9:22 pm

Chris,
For those times when a genuine chopstick is not available, in an emergency, a pencil eraser may be used as a temporary substitute. Did you mention what amp you're using? There aren't a lot of 6SC7s out there these days. Hope you'll let us know the solution.

All the best with the amp Chris.

Sincerely,
Craig Baker 706-485-8792

cmbakerelectronics@gmail.com

C.M. Baker Electronics
P.O. Box 3965
Eatonton, GA 31024

Tim Marcus · Post by **Tim Marcus** » 27 Feb 2014 9:35 pm

Not only are they few and far between, most of the ones that do exist are unsuitable for an amplifier.

I still have a hard time believing that an amp problem would create issue with only one string. I think it's gotta be something mechanical. Dab of turbine oil on the roller but?