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PostPosted: Thu Mar 06, 2008 4:46 pm 
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I just got a Genz-Benz Shenendoah 60...Works better than I had hoped, except that I'm having some trouble with a tricky harmonic when playing a "C" note on the A string. The sweepable mid is nice and all, but it's buggering me to find the sweet spot and take that resonating harmonic out of the mix. I came just short of buying an LR Baggs feedback killer yesterday, I want to see if I can get some input here first.

Being the "helper people" that many of you are, can someone give me the harmonic freq's of C? I know I could look it up on G**gle, but then my post count here is mighty dismal, and I know some of you guys KNOW the answer...

The guitar sounds great through the Shen, but whenever I play a chord involving the C (third fret, A string), the note BOOMS and attains an orbital trajectory. The B and C# above and below do so to a much lesser degree...On a 30 band graphic (an Alesis 230) I can eliminate 160Hz and the resonance is minimized, but the Shen's sweepable mid only goes down to 240Hz...

I'm hoping that finding a harmonic frequency and pulling it will acomplish the same result...Thoughts?

Thanks

Eric the Ignernt


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PostPosted: Thu Mar 06, 2008 4:55 pm 
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this is interesting.
the more i read on this forum the more i realize that this is such a science but the end results are sounds of the gods if the proper measures, attitude and time are taken to achieve it

i have no idea, sorry.
anyone?

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PostPosted: Thu Mar 06, 2008 6:31 pm 
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Assuming A=440, the next higher C should be about 523.3. An octave or two down would be 261.6 or 130.8. Not sure where your 160 is coming from. That would be somewhere between D# and E.


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PostPosted: Thu Mar 06, 2008 7:47 pm 
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Yes, but every note has harmonics that aren't the same note, ie. a higher C or lower...That's what I'm asking about...


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PostPosted: Thu Mar 06, 2008 8:44 pm 
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I stand to be corrected, but I do believe that harmonics are always doublings of the fundamental frequency. So If you know the fundamental, it is straightforward to calculate the harmonics, as in the example given by pfaut in the previous post.

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PostPosted: Thu Mar 06, 2008 9:43 pm 
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Doublings, triplings, quadruplings etc.

So, The A = 440 Hz, the C is 440 x 2^(1/4) = 523.2511 (as previously stated).

The first harmonic is 523 x 2 = 1046.5
The second harmonic is 523 x 3 = 1596.8
The third harmonic is 523 x 4 = 2093

Etc. So the list is:

Code:
0   523,2511306
1   1046,502261
2   1569,753392
3   2093,004522
4   2616,255653
5   3139,506784
6   3662,757914
7   4186,009045
8   4709,260175
9   5232,511306
10   5755,762437
11   6279,013567
12   6802,264698
13   7325,515828
14   7848,766959
15   8372,01809
16   8895,26922
17   9418,520351
18   9941,771481
19   10465,02261
20   10988,27374
21   11511,52487
22   12034,776
23   12558,02713
24   13081,27827
25   13604,5294
26   14127,78053
27   14651,03166
28   15174,28279
29   15697,53392
30   16220,78505


Obviously, it's not important to have so many decimals. Excel gives them, so I just copy and paste.

Another small word of advice. If it is realistic, solve the problem. Do not workaround.

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PostPosted: Thu Mar 06, 2008 10:55 pm 
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I'm going to go with the 1st subharmonic, the 261Hz...That may have actually been the notch I pulled, simply remembered it as 160...It is a BOOOMing resonance, so it really doesn't seem logical that a higher harmonic is the cause...

The Shen's sweeping mid goes down to 240, so it should be in there...

Thanks for making me feel even stoopider, guys, and hey, look at my post count now!!! =D>

Eric


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PostPosted: Thu Mar 06, 2008 11:18 pm 
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Why not sweep using the G's parametric EQ ? You outta be able to diminish those pesky freqs.with a high Q cut.

msg

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PostPosted: Thu Mar 06, 2008 11:33 pm 
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http://www.harmony-central.com/Guitar/harmonics.html

This link provides a quick overview of harmonics.

Some instruments have "rogue" notes - the whole instrument will vibrate excessively, sympathetically to a frequency the strings are producing, therby creating excessive volume of the rogue note. The Violin family and arch-top guitars both have a "post" that physically connects the top to the back of the instrument, and so are particularly prone to having a rogue note. The instrument's pieces are "tuned" (during construction) to a seldom played note, by shaving and shaping the pieces, lessening the chances that a rogue note will be prominent as the intrument is played.

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Last edited by Byron on Thu Mar 06, 2008 11:41 pm, edited 1 time in total.

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PostPosted: Thu Mar 06, 2008 11:41 pm 
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My piano's F#3 resonance shows up in many recordings but I reduce it with a narrow EQ cut there. My Martin D-18 resonates in A.

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PostPosted: Fri Mar 07, 2008 12:05 am 
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Geno, I'm not using the G for this, rather setting up the basic sound for live play. The guitar almost never gives me trouble when recording, though it's very fat in the low end, requiring a low-cut.

Byron, thanks for that link. The sympathetic harmonics are what I'm trying to address. The C note on this guitar is so strong even unplugged that it will dominate when played...It's a Seagull S6...And I play a lot of C... :shock:

Eric


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PostPosted: Sat Mar 08, 2008 4:29 pm 
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Huh, it was in there--Right around 260Hz (the knob doesn't list but the lowest and highest feq's)...Position is important as well, the amp should be set up more as a P.A. than a stage amp. One thing that has amazed me is the lack of mic feedback. I've tried both a Sennheiser 421 and an old SM58, and neither has given me the slightest squeal yet, and I've had the rig cranked a couple of times...cool...

I'm still thinking of acquiring a notch filter. It'll give me more contour control on the Shen...

Thanks for the input guys...

Eric


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PostPosted: Thu Apr 03, 2008 2:39 am 
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This sounds like a resonance in the speaker itself. I have an old Champ amp that had the original speaker when I got it, a real POS. I first changed it for a Jensen RI speaker; it was a great improvement but it would just howl when I played the G string on the 12th fret. So I sold that speaker on eBay and got a Weber Alnico speaker. The difference was day and night. Oh the tone, with no issues on any note. When dialed to 10, it can sound like anything from a clean mini-Twin to Layla just by changes in pick attack and small changes in the volume knob on my Tele.

It sounds like you have the resonance under control, but if you want to get rid of it, it might be worthwhile testing with different speakers.

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