Re: [Harp-L] Difference Tones

["Dave Murray" <dmurray777@xxxxxxx>]

> I found a very interesting discussion of difference tones at this website:

I don't understand why the web page claims "Most of the time, you don't want 
to emphasize the difference tones, because they sound harsh and dissonant 
They won't ordinarily fit in with the chord that you're trying to play."

When you mix two frequencies you get the two originals, the sum, and the 
difference. I'm using numbers for ET so there will be some dissonance.

If you are playing on a C harp and play octave 1 and 4 blow you get:
1 blow C4 = 261.63 Hz
4 blow C5 = 523.25 Hz
sum 523.25 + 261.63 = 784.88 G5 (dominant)
dif 523.25 - 261.63 =  261.62 (original note)
So playing octaves spawns a dominant 5 note.

Playing the 4 and 6 blow you get:
4 blow C5 = 523.25 Hz
6 blow G5 = 784.88 Hz
sum 784.88 + 523.25 = 1308.13 slightly flat E6 (makes a triad)
dif 784.88 = 523.25 = 261.63 C4 (low octave)
So playing root-5 splits spawns the triad itself.

Playing the chord 2 3 4 draw you get
2 draw G4 = 392.00 HZ
3 draw B4 = 493.88 HZ
4 draw D5 = 587.33 HZ
sum 493.88 + 392.00 = 885.88 Hz slightly sharp A5 (natural 7)
sum 587.33 + 493.88 = 1081.21 Hz between C6 and C#6 (4)
sum 587.33 + 392.00 = 979.33 Hz B5
dif 493.88 - 392.00 = 101.88 Hz between G2 and G#2 (very low octave)
dif 587.33 - 493.88 = 93.45 Hz F#2 (major 7)
dif 587.33 - 392.00 = 195.33 Hz G3 (low octave)
So playing triads spawns more complex chords.

I could go on, but you get the point; there is nothing inherently harsh and 
dissonant about difference notes if the original two notes have a good 
harmonic relationship. That's how chords work when playing through an amp 
which gives you strong sum and difference frequencies; they still sound 
good.

How would one "not emphasize the difference tones", stop playing chords, 
intervals, and octaves? With your typical Chicago blues mike and amplifier 
setup there's no stopping sum and difference frequencies from coming out of 
the speaker, it's the nature of the beast.

I know that the Siegel-Schwall band "Hush Hush" was the point of interest 
(bend one note of two and the difference note goes down or up while the sum 
note goes up or down (bend high or lower note?)) but the avoid difference 
note thing kind of jumped out at me.

Peace and music,
Dave