Vintage Synth Repair

hey everybody. i've been recently drooling over getting a memorymoog
or prophet 5, but i don't think that's gonna happen. i have a juno 106
and i'm curious if anyone has ever though of trying to replicate the
"tune" function from one of those older keyboards.

i'm curious if anyone thinks i could "disconnect" the analog
oscillators from the digital tuning controls. i'm already considering
making a warmer filter for it, but i think moding the oscillators
would really help.

thanks,
johnny

It's not possible really.  The Juno 106 (as well as the JX series, etc.) uses programmable divider chips to generate a reset pulse that drives analog wave shapers (voltage-controlled integrators for the sawtooth, followed by comparators for square/PWM and flip-flops for the sub octave)- thus it falls into the vague "DCO" category.  Some similar synthesizers use a voltage-controlled master clock for genuine analog vibrato (though the oscillators will still always have the same relative tuning), but here the clock is derived from an 8 MHz crystal oscillator, so all vibrato, detuning, etc. is software-controlled.

Since there are 2 counter chips (82C53), the closest thing you could do is to make separate (voltage-controlled?) clock sources for each chip.  This would mean that you could independently detune each set of 3 voices (though straying too far will distort the waveforms since the sawtooth integrators are voltage-controlled).  I don't know how musically useful this could be (depending on voice assignment schemes, etc.), but it might be interesting to use separate vibrato for each set of voices (it would considerably thicken up the unison mode, at least).

________________________________
To: vintagesynthrepair@yahoogroups.com

From: cockandswan@hotmail.com
Date: Sat, 4 Oct 2008 18:39:58 +0000
Subject: [vintagesynthrepair] "turning off" digital control on the juno 106 oscillators

hey everybody. i've been recently drooling over getting a memorymoog

or prophet 5, but i don't think that's gonna happen. i have a juno 106

and i'm curious if anyone has ever though of trying to replicate the

"tune" function from one of those older keyboards.



i'm curious if anyone thinks i could "disconnect" the analog

oscillators from the digital tuning controls. i'm already considering

making a warmer filter for it, but i think moding the oscillators

would really help.



thanks,

johnny
























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