slew/unslew filter mod.

When high frequency controlled voltages are applied to the unmodified Synthi filter they are low-pass filtered by the C31 capacitor. This means that the filter will not respond to high frequency CVs, and respond slowly to rapid changes in incoming CVs. The switch removes C31 cap. from the CV input circuit, so the filter will respond to high frequency controlled voltages.

All modifications are at your own risk and the synthi assumes no liability for personal injury caused or damage to equipment or loss of use caused directly or indirectly by the use of these plans.


Expand and preserve your beloved Synthi

“Many Synthi users dare not make mods because they’re afraid to depreciate their valuable instrument.

Is understandable, but is a pity because the mods wonderfully expand the Synthi and open doors to fantastic new sonic worlds. Here’s an idea I think is worth to be shared. I’m surprised no one else had it before.I did a few mods on my Synthis A MKI and AKS using push-pull pots instead of switches to avoid drilling holes in the panel. LEDs in the spare anti-rotation holes left by the original pots (push-pull ones are smaller) show that the mod is active when the knob is pulled. This makes the mods fully reversible and preserves the Synthi’s original appearance.”

Modified EMS Synthi A

DC shifter/amplifier with inverse switch and preset switch
to trapezoid voltage. Extra trigger-circuit with threshold pot.
Changed patchboard lines and many more…

Check out Sam’s site here!