[sdiy] Quantizer project.. incoming CV's switching point to change to quantized output CV's ...

Nathan Trites nathan at idmclassics.net
Fri Jul 9 04:23:22 CEST 2021


Many 200 series clones and third party Buchla format modules are still
calibrated for 1.2v/oct. and most integrating them with other systems have
various modules to scale to and from 1v. A typical situation would be doing
all your sequencing and quantizing in euro, and then a format converter to
get the higher CV and gates.

Panel real estate is a huge deal though so if you aren't designing it for
standalone use, or it's not complicated enough to cover most of a panel,
you may not want to go out of your way to include 1.2v.

Nathan

On Wed, Jul 7, 2021 at 12:46 AM Brian Willoughby <brianw at audiobanshee.com>
wrote:

> Thanks for the experience, Mark.
>
> I learned about "1.2V/Oct" while attempting to research the most
> exhaustive list of features needed for compatibility with everything out
> there. If you're saying the Buchla never made a 1.2V/8va synth - or at
> least not anything that was cross-compatible with anything else, even other
> another Buchla unit - then I guess it's not worth bothering to support
> this. Of course, the design I'm working on could easily support 1.2V/octave
> without any extra costs because it would just be another setting / option.
>
> I've never owned a Buchla, but I've been to a few shows in San Francisco
> and elsewhere that featured them. Out of my price range. ;-)
>
> So... if you plug two 1V/octave cables in, they get summed to 2V/octave?
> Reminds me of getting big pitch bends out of the Matrix-12 (or Matrix-6) by
> applying the same modulation two or three times.
>
> Brian
>
>
> On Jul 6, 2021, at 05:57, mark verbos via Synth-diy <
> synth-diy at synth-diy.org> wrote:
> > Nice enough idea Brian, but my research shows that 1.2V/Oct is a myth.
> Buchla 100 systems have a switch to select between the front panel control
> and the untrimmed CV input. It is exponential in response, but trimming was
> moot given that there was no keyboard with an output other than tunable
> keys. The early 200 series VCOs only have CV ins with attenuators as there
> was not a piano layout type keyboard until the Music Easel (218). Once
> there was a keyboard that was trimmed, the scale was 2v/octave. This made
> sense in a 0-15v CV world, which Buchla lived in until he decided to change
> that out to 0-10v when he switched to blue knobs. The 259, which came out
> in the late 70s is still 2v/octave at its keyboard input. In 2003 when the
> 200e was announced, the 1.2v/octave standard was declared.The 225e doesn’t
> have any trimming on its CV outputs and the one I have puts out around
> 1.14v/octave. To the 200e, that doesn’t matter anyway, because there is an
> internal digital bus for the pitch, which controls digital oscillators.
> When I have made VCOs to be used in 200e systems, I trimmed them to my
> 225e, but there is no guarantee that they will track on someone else’s.
> There is a guarantee that a MIDI to CV converter or a quantizer that is
> trimmed to 1.2v/octave won’t track with a VCO that is trimmed to a 225e
> though. Paradoxically, a Buchla 225e cannot be used to make a Buchla 258
> play in tune unless you plug the CV into both CV inputs.
> >
> > Mark
>
>
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