Unwanted acoustic guitar harmonics

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Monkey Allen

Monkey Allen

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Can anyone help out?

...I recently recorded an open chord acoustic guitar GCD strumming song and listening back, throughout it sounds like there is some harmonic overtones ringing. The tone changes with the G C and D...so it's kind of nice in a way but I think it's a bit obtrusive. Does anyone know of a way to bring down the levels of those harmonic rings? I tried a quick eq job but it didn't really reduce them. I know there's such things as harmonic exciters (which I just guess accentuate the harmonic tones...though I could be mistaken)...is there anything that will do the opposite....harmonic reducer, for want of a better term?

It's my first recording since swapping out the default tubes for NOS MUllard and Tele in the ART MPA GOLD.

I recorded it last night and didn't notice it at all...but tonight after I recorded a tambourine and a shaker I noticed it. The soloed guitar tracks still ring the harmonic...so I suppose it's not the interplay with the tambourine and shaker that's ringing them out.

The strings are half new, I was strumming closish to the bridge. I had a CADm177 at about the 12th roughly a foot away and the 57 aimed about a foot away from the body of the guitar slightly under the treble strings

Do you think I have used too much tube gain and in doing so produced too much sensitivity in the harmonics picked up?

thanks
 
You're running the mics into ... a pre-amp or amp? Try running them straight into what ever recording device you are using.
 
Your issue is not likely to stem from tubes or the signal path generally.

Nor can I think of an easy way of getting rid of the once they are there.

However, two things you might like to check are:

1: Mike positioning . . . can you find a mike position that reduces the sensitivity to those harmonics? Start with one mike, play and listen. Then try the other.

2: Playing style . . . is there something about the playing style that accentuates the harmonics? Can you try a different strum or pick? Or pick a different chord shape?
 
First I'd try to isolate whether the honkers are coming more from one mic or the other, and adjust accordingly. On the neck mic, I'd try rotating the face of the mic back and forth across the long axis of the guitar to get some fine-tuning in it's sound. I suspect that maybe the body mic may be picking up more of them. You might want to try moving in the mic a bit closer, and emphasizing miking the saddle area and rejecting the sound hole area.

But I suspect that maybe the harmonics are in the guitar sound itself, and that miking adjustments will have only a limited effect. If that's the case, after maximizing you mic positions, run your tracks through some parametric sweeps to eliminate the worst of the honking harmonics. It may take a couple of passes per track. This should take care of the majority of the issues.

There are some EQ plug-ins that include harmonic filters. The one I use the most (and is really an excellent surgical EQ) is the Uniqualizer by Roger Nichols Digital. The difficulty here is that you really need to ID both the fundamental and whether the harmonic series is an odd or even (or both) series, and as to whether the series declines in energy linearly or logarithmically in order to properly target it. This is IMHO best done by a visual inspection of signal with a decent FFT analyzer, one of the best free ones IMHO being the SPAN plug by Voxengo, though it may take some practice to properly read a spectral analysis of ny signal.

G.
 
I know very little about electronic solutions to this problem, so I would probably address it at it's source- the guitar. To that end:

Dampen the top of the guitar with something like a sheet of neoprene, or maybe even a folded up beach towel, softly wedged between the top and back of the guitar;
Put a feed-back eliminator or sound-hole humidifier in the sound hole;
Maybe put some speaker baffling material (the stuff you find in speaker cabs) INSIDE the guitar;
Change strings. Bigger strings would probably produce fewer, or lower-volume, harmonics;
Or, try a different acoustic guitar. I have a 12-string that is just FULL of harmonics- I love to play it for just that reason, but I have heard other, sometimes higher-priced 12's, that did not have the harmonics mine has (FYI, it's an Arbor.) The Ventura it replaced, a bud's Alvarez, and even another bud's Martin, all have fewer or less-noticable harmonics. You don't say, but from your post it sounds like you are having problems with overtones- harmonics that are of a higher frequency than the played note(s). I would think a cheaper guitar, with either a thicker top, or a laminated top, might tame those for you.

All that said, I confess, I have never tried any of them for that kind of a "problem:" I LOVE harmonics and usually do everything I can to get more of them.
 
There's a lot to think about in those suggestions and tips...so thanks a lot. But just quickly, coz I have to go to work...yeah...Glen...it is the body mic causing most of the problems and the frequency of the harmonic is honky...SPAN helped me to find the area...about 600hz or thereabouts. Actually, last night I was trying to find the drone up around 5 or 10k...I just thought it was higher because it was a harmonic sound...I learned.

I've recorded lots of times with a similar setup and have never had such a drone as I describe. So I thought it must have been because of me driving the preamp/ tubes too hard...especially the tube.

Well...so I just went and did a very quick eq job around -6db with a q of about 14 @ around 600hz...and what a great improvement...maybe tonight I can fine tune that a bit.

thanks for the help...
 
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