Why does adjusting 100Hz on EQ affect high E string

[clintonb]

I noticed that if I play my high E string on guitar and turn down the 100Hz slider on my EQ pedal, the high E loses a little body and warmth and sounds a little more plinky. Its even more noticeable when playing both the high E string and B string together.

If a high E string is 329.6 Hz how come the 100Hz slider affects its tone?

Do guitar strings produce lower frequency "undertones" as opposed to higher frequency overtones? Does such a thing exist?

Or is this a case of my graphic EQ pedal slider affecting a wide band of frequencies surrounding 100Hz including 329.6Hz? If I use a parametric EQ with a narrow band, would decreasing the volume at 100Hz still have an effect on my high E string?

[guitician]

The waveform of a stringed instument is complex with many resonant overtones. If you are playing the high E string, and, are at the same time, letting the other strings "drone" unplucked, they still effect the "Picked Up" signal adding some small added sounds. The wood the strings are attached to add some resonant tones to the string also.

[cbarrow7625]

Clinton,

It really depends on the type of EQ it is. All filters have a bandwidth, the most common being 1/3 octave. If your eq pedal has a bandwidth wider than 1/3 octave for some reason, it can certainly affect a wide range of frequencies above and below the center frequency. But even beyond that, it could just be a poorly implememented EQ scheme. There may be some other unintended interactions happening in the pedal when the 100Hz slider is moved. It certainly won't happen in all pedals. I think you should try another few pedals and get one that does what you want.

[Enzo]

I'm with guuitician here. Your high E resonates with the low E string and to lesser extents the other strings. While the low E might be resonating at the high E nodes, it still imparts some overall energy to the string, which I'd bet adds some of that bottom end.

And I think cb has some points too. First we have no idea the Q of the EQ bands in your pedal. The bands on an EQ are not straight sides snatches of the audio spectrum, they are smooth - hopefully - curves up to a peak at the center freq. but off band is not zero response, it is merely down some db from the peak.

[bnwitt]

Everone's hitting on it. Your strings when plucked are not producing pure sine waves. There are harmonics being produced by the vibrating string and by the guitar itself with all of its parts. 110hz is A2 A is the the fourth harmonic of E. E is the 5th harmonic of A. I would venture to bet if you used a signal generator to run a pure 329.6hz sine wave into your eq the 100hz control would have much less impact on the output unless of course your eq is way off.

82.4 E - open 6th string
87.3 F
92.5 F#
98.0 G
103.8 G#
110.0 A - open 5th string
116.5 A#
123.5 B
130.8 C
138.6 C#
146.8 D - open 4th string
155.6 D#
164.8 E
174.6 F
185.0 F#
196.0 G - open 3rd string
207.6 G#
220.0 A
233.1 A#
246.9 B - open 2nd string
261.6 C - "middle C"
277.2 C#
293.6 D
311.1 D#
329.6 E - open 1st string
349.2 F
370.0 F#
392.0 G
415.3 G#
440.0 A - 5th fret on 1st string
466.1 A#
493.8 B
523.2 C
554.3 C#
587.3 D
622.2 D#
659.2 E - 12th fret on 1st string

[Robert M. Martinelli]

[QUOTE=bnwitt;96364] 110hz is A2 A is the the fourth harmonic of E. E is the 5th harmonic of A.

Actually A is the "fourth" of E only from a "musical theory of intervals" standpoint ( their frequency ratio being 82.4/110=0.749090909 approximated to 3/4 in theory books ), and E is the "fifth" of an "A" from the same standpoint ( their frequency ratio being 82.4/55=1,49818...approximated to 3/2 in theory books ).

The actual ( physical ) "fourth harmonic" of an "A" note is another "A", but two octaves higher ( or four times the fundamental "A" frequency ).

I pretty much agree with all the other things said so far about the guitar's sound complexity, strings/body interaction, EQ bandwidth, harmonics and so on.

Regards

Bob

[bnwitt]

I'm probably not explaining what I mean correctly. I'm referring to string node harmonics on a vibrating string. The type that effect the tonal output of the magnetic pickup position on an electric guitar. These in turn create sympathetic vibrations in the guitar wood and other parts of varying frequencies. It's the character of your instrument known as timbre:

http://cnx.org/content/m11059/latest/

http://www.cpo.com/ipcres/pdfs/unit4/ch12sec3.pdf

You might be surprised to see what that one plucked note produces when run through a spectrum analzyer.