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Diving into the Ring Modulator

Discussion in 'Effects [BG]' started by bassicmelodies, Feb 6, 2013.


  1. bassicmelodies

    bassicmelodies

    Joined:
    Feb 28, 2010
    Location:
    Portland, OR
    Hello Everyone,

    I started studying ring modulation, and was able to come up with some fairly musical observations. Thought I'd share with the bruthas and sistas out there on the TB realm.

    Here's a link to my blog

    Hello again Everyone,
    up late again trying to save the universe! I've got a special treat for you all tonight. Ring Modulation. As a few of you have heard, I now own a Moog MF-102. I've been trying to research how players use this pedal, or others that function in the same schematic. To be honest, it's been rather rough, trenching through the internet looking for settings, tips, tricks, anything and coming up with enough of the picture that I figured out how to fill my gaps.

    So this all starts off with basic addition and subtraction. Whatever frequency (or pitch) you input will be added to and subtracted from the carrier frequency (the one you set with the Freq. knob on the bottom left), which gives you two new frequencies. Now, using the mix knob on the top right you can blend your original signal with the new one, combining to three pitches coming out. If I playA4 @ 440 and set the frequency knob to C6 @ 1040 we hear F#6 @ 1480 and a rather sharp D5 @ 600, which could be interrupted as a D major triad with it's fifth (A) in the bass. Where it gets crazy is when you play notes other than A, the two "new frequencies are going to move because of the moving relationship of your source and the frequency knob.

    Throughout my searches in forums I found it interesting that just about everyone referred to the Ring Modulator as it's own instrument being triggered by yours, and that thinking about it like this yields more musical results. There are a few things to take into account when playing with an instrument like this:

    It is a numbers game. If you tune your frequency knob to close to a perfect unison, it could sound rather hollow, because x-x=0, so some distance between the two is a good idea. Additionally, because of the equations nature, it doesn't take into account that the amount of Hz between pitches increases as you move up through the spectrum. What this can yield is a much more stable set tones, that act more like drones, moving in 2nds instead of 5ths and 6ths. Another common production is that your descending line will have more motion, because of the nature of the spectrum.

    Just for a clear example, moving up 180 Hz from 914 yields what we hear as a Major 2nd (Bb5 to C6), where as moving down 180 Hz from 653 yields what we hear as a Major 3rd (E5 to C5)

    Another thing to keep in mind, you will find negative results in the subtraction side of the algorithm. What happens here is that it will fall further and further into the negative side of the spectrum. What the pedal, and additionally our ears translate this as, is it's inverse. If you cross 0, you will hear two rising pitches. If I understand correctly, it will happen when your source is playing a higher frequency than the frequency knob is set to.

    So I just finished using Excel to create a pitch to Hz spreadsheet and a series of equations displaying the output pitches of two major scales. They are listed below for you to look at, along with the frequency chart. I also posted a video I found helpful on youtube. It's a 3 part series, and it's heady, but I found it helpful.

    This is going to be a rather extensive research, so keep a look out for more.

    Enjoy,
    CJF

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  2. sstbo

    sstbo

    Joined:
    Dec 12, 2012
    Very interesting and a more intelligent approach than I would/could ever take. Kudos!
     
  3. pietrocefa

    pietrocefa

    Joined:
    May 3, 2011
    Tanks a lot...Ring Mod is probably one the most creative and complex musical instrument.
     
  4. bassicmelodies

    bassicmelodies

    Joined:
    Feb 28, 2010
    Location:
    Portland, OR
    Thanks for the reads, glad it was interesting. Found a video of a ring modulator and an oscilloscope. I found this 6 minutes well worth it. Hope you do too!

    http://vimeo.com/38672729
     
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  6. nad

    nad 60 Cycle Humdinger

    Joined:
    Sep 22, 2005
    Location:
    Redlands, CA
    Disclosures:
    Various C-titles: Nordstrand Pickups
    Very cool thread. I <3 ring modulation.
     
  7. bassicmelodies

    bassicmelodies

    Joined:
    Feb 28, 2010
    Location:
    Portland, OR
    Here's my next installment over Ring Modulation. Hope you enjoy it, would love to hear feedback.

     
  8. Vlad5

    Vlad5 Chronic Knob Twiddling Tone Chaser Supporting Member

    Joined:
    Feb 17, 2011
    Location:
    New England
    I have no idea what's going on here, but I subscribed anyway. :)
     
  9. pietrocefa

    pietrocefa

    Joined:
    May 3, 2011
    Keep alive that thread, Tanks a lot for the video.
     
  10. Roscoe East

    Roscoe East

    Joined:
    Aug 22, 2011
    A lot of the phenomena you identify -- as well as the difficulty in generating consistently "musical" results you allude to -- all come back to this one minor error early in you dissertation:

    "Pitch" has no relation in the way a ring modulator works. The Addition & Subtraction of frequencies has no musical equivalent that is homomorphic for all pitches.

    The ring modulator works solely in the province of frequencies; you input a carrier frequency and a modulator freuqncy, and it outputs the sum & difference frequencies.

    The fact that any single given frequency happens to map 1:1 on to a single musical note (and not necessarily an in-tune note) is pure coincidence, both literally/generally, as well as specifically when referring to ring modulators. The relationship between the four frequencies involved in ring modulation almost never maps onto musically meaningful relationships because musical pitch is not based on frequencies but rather on octave subdivisions.
     
  11. bassicmelodies

    bassicmelodies

    Joined:
    Feb 28, 2010
    Location:
    Portland, OR
    Roscoe,

    Thanks so much for this perspective. I've been beating around the bush of the concept, but had a hard time putting it into words as well as you did. The one thing I would reply with is that it's not purely coincidence, if I am intending to place the carrier pitch within the tonality of a song. I could see this going into the Philosophical domain of what is music, and I think a lot of it comes down to if it was intended that way then its closer to music than sound i.e. chaos.

    Again thanks so much.

    Here's an additional video running a condensed version of the sound files ran through Capo. It's pretty cool to see.

    Hope you enjoy,
    CJF

    Video
     
  12. Roscoe East

    Roscoe East

    Joined:
    Aug 22, 2011
    I didn't mean to imply that your results were coincidence; you've clearly put a lot of time and effort into identifying musical (or close-to-musical) equivalents.

    My point was that the reason you've had to work so hard to identify these, and/or the reason so many of those results are out-of-tune, is because it's purely a coincidence that a frequency of (for example) 440Hz produces a fundamental tone that musicians call an "A" note.

    Just because 440Hz sounds like "A" doesn't mean that 440Hz is "A". Calling something an "A" note implies a number of contexts, consequences, behaviors, even baggage, that a frequency of 440Hz is not beholden to. They just happen to sound the same...but they don't do the same things. That's what I mean by coincidence.

    The language that musicians developed over the centuries, and the way that language characterizes the behavior of pitches, is based on a relatively small subset of all possible frequencies, and an even smaller subset of frequencies that are deemed "usable" (sic) as simultaneities. So you're fighting an uphill battle trying to force the output of a ring modulator into a Western tempered chromatic musical context, because notes and frequencies really do live in two separate worlds that only just happen to intersect when we hear them. And only occasionally then.

    Not trying to belittle any of the hard work you've done, just trying to point out why the results might not prove as "musically rewarding" as you perhaps had hoped.
     

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