>
> MOTM 300 VCO vs. Moog 901B VCO:
> Note: There is a big difference in functionality between these two! The
> Moog 901B has a wide range but isn't terribly linear.
The RA Moog tracking is 10 times ∗worse∗ than a '300.
>Mine have recently
> been calibrated and do well over 5 octaves with the 8' octave range
> setting. This doesn't hold true for the other octave range settings.
That's be cause he had truble finding good capacitors.
> The
> 901B has no PWM, no Sync, and no linear FM. The output of the MOTM 300 is
> very hot, about twice the level of the 901B. I'd love to do these same
> tests with some Moog 921 oscillators if I could find some!
That's probably true: the 921Bs I had were about 6V pk-pk.
>
> - Sawtooth Waves: No major difference. The MOTM might be a tad
> brighter/buzzier but it was really hard to judge. The mid harmonics might
> be coming out more.
That's the OP-275's fast slew rate. The MOTM has more harmonic content.
> When mixed together, the beating between these two
> oscillators is ∗really∗ intense. I had them beating about once every 10
> seconds but the sweep caused by the phase interaction was like a very wild
> PWM with a pronounced almost sawtooth modulation. I could not get this
> kind of beating between like oscillators on the Moog or the MOTM. There
is
> something really wild happening when combining these different oscillators
> running off different power supplies.
What you are hearing is the Moog not tracking with the '300. It's not the
power supplies.
This is just the difference in ∗relative∗ tracking with the Encore as the
"reference".
> - Sine Waves: Very small difference. The 901B sine had a few more
> harmonics in it making it sound slightly more nasal than the MOTM. Both
> seemed to have a few extra harmonics so I might be picking up a tad bit of
> distortion elsewhere in the signal path (VCAs, mixer panels, etc.) but it
> was quite musical.
No argument here.
>
> - Triangle Waves: There was pronounced difference between these waveforms.
> The MOTM had a more "hollow" sound while the Moog seemed to have a
> "rounder" sound. They are both recognizable as triangle when compared
with
> Saw and Pulse but there is a difference. I dare say that I think I prefer
> the Moog triangle wave in this case because it sounds a bit "fatter" than
> the MOTM.
Again, the MOTM waveforms are closer to ideal. But again, this is
subjective.
>
> - Pulse Waves: These are certainly different. The Moog Pulse Width
> control needs to be set fully to the right to get close to a square wave.
> Even at that it doesn't sound as fully "square" as the MOTM VCO in the
> center of the dial. There is a tad bit more buzz in the Moog VCO, leading
> me to believe it isn't quite square. At the narrowest setting (fully left
> on the Moog and fully right on the MOTM), the sounds were very close but
> the Moog had just a bit more nasal quality to it. The MOTM PW that is
> fully to the left is quite different from any of the Moog PW settings.
> Sweeping the PW on both sounds quite good although the Moog PW is
> equivalent to only the right half of the MOTM PW. Both are quite good
> sounding!
I never understood Moog's "offset" with PW on the modular. Very strange.
Keep it coming Eric! (and Ben V. can compare as well).
Paul S.