Hi M.

> I've been trying to use my A-114 to double the frequency of a
> waveform (as
> suggested by some articles about modular synthesis), but
> couldn't get it to
> work.
> (After all, a ring modulator gives the sum and the difference
> of its inputs,
> so having the same signal at both inputs would give only the
> sum, the same
> waveform one octave higher, yes )
> It seems that the sound doesn't change much at all if I send
> the same sine
> wave trough both its inputs.

From a quick look-see I did last night I'd say your 114 is probably working fine - I think the reason you are apparently not *hearing* a doubling of frequency is due to the rather approximate sine shape output from the 110. The 110 sine output is actually a kind of logarithmic approx to a sine wave, and it gets less accurate as the frequency is increased. On one of my 110's, if I feed the sine into both 114 inputs, at lower frequencies it clearly is being doubled, and switching between the two is easy to tell the difference by listening. However as the frequency is increased, because the 110 output gets more distorted, the doubled output from the 114 actually looks more like a full-wave rectified version of a sine wave (all the positive humps appear flipped to negative): whilst measuring it on the scope it does have half the period (i.e. double the frequency), listening to it I can hear very little difference between the doubled 114 output and the original from the 110 - this doesn't seem too unreasonable since all the frequencies arising from the sharp changes in direction of this 'rectified' wave are probably beyond hearing range. (In the 110's defence, this is working at about twice the 'as advertised' range of the module.) The output from a 122 or 123 filter in self-oscillation is a pretty good sine wave, and feeding this into the 114 does give a fairly nice sine wave at double the frequency out, and switching between the two, the difference in sound is much more noticeable. (This may not help you if you don't have either of these though - I didn't try the 121 multimode because the sine wave from this can be quite distorted.) I also tried the triangle wave from the 110 into the 114 - even though this also loses it shape at high frequencies, the output from the 114 is actually quite rounded, and to my ears sounded like there is a greater difference between the input and the doubled output, when compared to the sine wave.

Tim

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