[sdiy] GRP Genesi

[Michael E Caloroso]

The ProSoloist/DGX architecture is unique and none of ARP's other synths
had that architecture.  And the routing of filters and EGs changed between
presets.  So no, the Explorer is nothing like the PS.  Several of the
presets - not just the Fuzz Guitar - are inimitable on any other
non-modular synth.

You were not alone sneering at "preset synths"...  I was also arrogant
owning synths with a panel full of knobs and switches.  A friend offered to
sell his PS to me for a good price, and I thought "gee this sounds pretty
darn good".  The aftertouch is stellar.  When I assign AT to volume and
pitch, I can get a natural sounding vibrato.  None of my other gear with
aftertouch could duplicate that effect.  The new GRP module misses out on
the aftertouch.

I wasn't keen on the early Genesis/Tony Banks' connection when I bought my
PS, so my exploration of the PS was not biased by Genesis.  While the Fuzz
Guitar presets are good, many of the other presets sound organic.  The
flute preset is uncanny - I can hear a tone an octave above the
fundamental, but there's nothing in the circuit that generates the octave
tone!

A lot of inspiration came from the 2500 modular when laying out the
architecture in the design phase - voltage controlled filters, fixed
highpass/bandpass filters, PWM.  I've never seen any schematic for the
early Soloist to compare its architecture to the ProSoloist.  I know that
the Soloist had the 4027 (or 4017?) VCO module, probably the 4020 EG
modules, the fixed filters were encapsulated in modules, and a resistor
matrix to configure the presets.  Due to premature degradation, the
aftertouch element did not have a long life in the Soloist.  When it was
first shown at NAMM, Jeremy Hill was busy fixing Soloists that were
breaking.  I've seen one YT video of a restoration of a Soloist and they
were NOT service friendly!

After the poor reliability became known in the field, the decision was made
to design the ProSoloist.

Many owners dreamed about hacking a panel full of controls into a PS... not
worth the effort as you would be limited to VERY discrete settings of EG,
filter cutoff/resonance, etc.  Other than VCF cutoff, those sections are
not CV controlled - IE the ADSR elements were limited to 3-4 discrete
values per stage set by resistors that were shorted to ground via the OC
outputs of the ROMs.  There's no way to get continuous control of those
sections.

MC



On Fri, Jul 10, 2026 at 3:23 PM Paul McLean <keysndrums at gmail.com> wrote:

> In my youth I would sneer at any preset synth (though I did enjoy fooling
> around with the ProSoloist in the music store). Not for anyone serious
> about synthesis and only for people who couldn't be bothered, or didn't
> have the wearwithal to learn. (Funny how arrogant we can be in our youth).
>
> The thing is, you can't discount how GREAT the ProSoloist/ProDGX sounds!
> And you can't sneer at folks like Steve Walsh, Tony Banks, Denish DeYoung,
> Michael Bodicker, Suzanne Cianni and the tons of other artists that used
> the thing. Just can't replicate that "Fuzz Guitar 1" preset.
>
> I found myself buying a ProDGX a few years ago and love it.
>
> I've been amazed at just how much synthesis capability the ProSoloist/DGX
> has; VCO (w/PWM), voltage-controlled low-pass filter,  4 high-pass filters,
> 10 band-pass filters, AR and ADSR envelopes, plus all the aftertouch
> options. I asked SynthChaser about the possibility of patching one out, but
> that guy is way too busy!
>
> Pity ARP didn't develop it further.
>
> Btw, I always read about how the ARP Explorer was a more patchable sort-of
> ProSoloist. I played an Explorer for a while and I can assure they have
> little in common beyond the shape of the case. Just sayin'...
>
> - Paul McLean
> Denver, CO
>
> On Mon, Jul 6, 2026 at 9:42 PM Donald Tillman <don at till.com> wrote:
>
>> On Jul 6, 2026, at 5:25 PM, Michael E Caloroso via Synth-diy <
>> synth-diy at synth-diy.org> wrote:
>> >
>> >
>> >
>> > Other competitors - Moog, Roland, Yamaha, etc - had their preset synths
>> but none lasted as long as the PS [...]
>>
>> Nobody else had the Tony Banks solo from Genesis' "Cinema Show".
>>
>>   -- Don
>> --
>> Donald Tillman, Palo Alto, California
>> https://till.com
>>
>>
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