Help Needed with Unwanted Harmonics

David Ward · Post by **David Ward** » 15 Feb 2001 3:21 pm

I have a problem that I hope can be solved by the collective knowledge of this group.

First, my set-up: Carter S-10, Fender Twin Reverb, Goodrich 120.

The problem: I am getting discordant harmonics with intervals and chords above
the 10th fret. To me it sounds like the
'difference' frequency and is lower than
the notes being played. This tone changes
with the fret position and sort of sounds like a growl.

It is most noticable when I have my volume
pedal on max and decreases when I back off.

I can turn my volume pedal down and turn up
the amp and it is not nearly as pronounced.

This sound is not present when playing a single note and I have tried three different amps with the same results.

If I am guessing correctly, my volume pedal
is driving the amp too much. If this be the case, can the problem be addressed by lowering the pick-up (George L's E66) and
making it less hot? Barring this because of loss of sustain, is there an impedence matching device that I can put between the
pedal and amp?

Thanks in advance for your input.

David

Donny Hinson · Post by **Donny Hinson** » 15 Feb 2001 4:24 pm

I don't think it's an impedance problem. Sounds more like you're driving your amp near the point of distortion. What is your amp volume set at? If you've got the amp volume at "3", and you're flooring the volume pedal, you could be just getting too much signal. Those "ghost" notes (actually notes caused by beats, or "heterodynes") really get noticeable when the signal gets near the distortion level.

Try turning the amp up (to at least 5 or 6) and then using less volume pedal. See if it makes a difference.

Jack Stoner · Post by **Jack Stoner** » 16 Feb 2001 3:34 am

I used to notice the "sub harmonics" or whatever they are more when I was using a PP Emmons and an AB768 Fender Twin. But, in all fairness it wasn't a problem when I was playing out or it wasn't enough to worry about.

Rick Johnson · Post by **Rick Johnson** » 16 Feb 2001 4:33 am

David,
Has the amp been capped in the past few years?
Could be tune up time. Caps, tubes etc...

Rick

------------------
Rick Johnson

Bob Hoffnar · Post by **Bob Hoffnar** » 16 Feb 2001 10:05 am

The "unwanted" difference tones happen on all steels. They are accented by distortion. I could go into it but who cares.

If you want them to stop try plugging into the 2nd input on your twin. The 2nd input on Fender amps is slightly buffered. Right now you are overdriving the input section by using the first input. Another thing that will clear it right up is a Goodrich Matchbox. The Super sustain matchbox is good because it has a volume knob.

Try this stuff before you get out the power tools !

David Ward · Post by **David Ward** » 16 Feb 2001 12:02 pm

Thanks to all that responded. I took Bob's
advice and plugged into the second input and
that, coupled with a more judicious use of the pedal (thank's Donny), solved 95% of the problem.

The amp is a new '65 Twin Reverb Reissue.
I am a tube fan and it is the Holy Grail
of amps (IMHO). It sures sounds sweet
with my Tele and Strat, as well as the
Carter.

Thanks again,

David

Jerry Roller · Post by **Jerry Roller** » 21 Feb 2001 10:05 pm

I recently had a discussion with Ed Buffington who builds the Evans amps. I ask him why the new HV is better than the LV and he described the overtones I think are being discussed in this post. He said the new HV eliminates these overtones which are mainly on the 4th string "E" about the 13th fret. I have noticed this problem in that area of the fretboard from time to time. He mentioned other improvements but this seems to go along with this post. He gave me some technical reasons behind it which were way over my head.
Jerry<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Jerry Roller on 22 February 2001 at 10:03 PM.]</p></FONT>