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Subharmonics using distortion

Discussion in 'Effects [BG]' started by Captain Awesome, Jul 25, 2002.


  1. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    PDX
    I tried playing my 6-string geetar through my Carvin R600 bass amp with the tube channel cranked and the bass turned way up post-distortion and I found that I could create wild subharmonics by playing double stops on the guitar. If I played various intervals on the high notes of the guitar I could make clear, deep bass lines come up out of nowhere, and I could even go lower than a bass. For example, playing a major 3rd through distortion produces a note 2 octaves below the root. Bigger intervals produce higher subharmonics and smaller intervals produce lower subharmonics. If I cranked up a minor 2nd, I'd probably have to have some speakers reconed.

    I tried it on my bass too, but the lower harmonics seemed to low to be safe or usable. I imagine it would sound bad ass with some subwoofers. Does anyone else do this or have a use for it?
     
  2. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    I used to do something like that back in my 4 string days. I would play the root and the 5th together to make it sound an octave lower. For instance, play a C at the 3rd fret of the A string and at the same time hit the G at the 5th fret of the D string. Cool, hah? I still do it sometimes. I know several guys who do it. Its a great effect.
     
  3. geshel

    geshel

    Oct 2, 2001
    Seattle
    You're hearing "beat frequencies", which show up as the difference in frequency between two tones.

    So if you play one note at 100Hz and another at 150Hz, there'll be a phantom 50Hz tone in there too. (it's really a 50Hz modulation of the other two tones! :) )

    When you have two notes at almost the same pitch, you can hear the difference in them as a warble - like when you tune via 5th/7th-fret harmonics. As they get closer in pitch the warble slows down.

    Since a major third is roughly 5/4 the pitch of the root note, the difference in pitch is 1/4 the root frequency, in other words, two octaves down! :D

    Normally these tones would be pretty weak, but distortion does some odd things to a signal. Most notably, it increases the volume of any modulating frequencies relative to the base frequencies, in this case, amplifying the beat frequency more than the others. (this is very similar to how an AM radio receiver works).

    I just love science. . .
     
  4. Wow, that is really interesting
     
  5. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Thanks gesh, that's cool.

    Don't we all.
     
  6. Yeah