String Machine Ensemble (for VM Core)

[utdgrant]

Confession: I've always loved the sound of string machines. I grew up during the 1970s, where they represented pretty much the only affordable polyphonic keyboard with any kind of lush electronic sound. For me, the Holy Grail of ensemble units was that found in the Eminent organs, such as the 310 Unique. ARP later licensed the Eminent design for use in its Solina string machine. So, when the opportunity arose to experiment with voltage-controlled delay lines (Chorus modules) in VM Core, I set out to see if I could recreate that magical Solina sound.

The patch is based on a Sound on Sound article by Gordon Reid, in his Synth Secrets series. You have three parallel delay lines which are each fed with a mixture of two sine LFOs for modulating the delay time. In the original Eminent design, the LFO outputs which feed delay lines 2 and 3 are simply phase-shifted copies of the two LFOs which modulate delay line 1. Six Super LFOs are employed in this patch to achieve the required phase-shifting. I used the Clock Out from LFO 1 to drive the Reset In of LFOs 2 & 3. This keeps them synchronised in phase and frequency. The Phase knob on LFOs 2 and 3 can be turned to +/- 33.3% in order to give you phase shifts of 120 degrees and 240 degrees, respectively. The same principle is used for LFOs 4, 5 & 6.

The LFO outputs are heavily attenuated before feeding into the Time CV sockets of the Chorus modules. After a lot of tweaking, and trial and error, I found that the closest I could get to the classic Eminent sound was:

LFOs 1, 2 & 3: Rate = 1.21 Hz, Attenuation = 22.2% (LFO 1 Depth) x 20% (Fixed attenuverters) x 20% (Time CV knob) = 0.888%
LFOs 4, 5 & 6: Rate = 5.82 Hz, Attenuation = 28.4% (LFO 2 Depth) x 10% (Fixed attenuverters) x 20% (Time CV knob) = 0.568%

These settings are used in the first two variations, "Eminently Mono" and "Eminently Stereo". Check out the YouTube demo I created to hear how similar they sound to the Arturia Solina V2 ensemble sound. Note that I had to boost the top-end by applying a high-shelf EQ of +8.25 dB @ 5.75 kHz to really match them fairly. I don't know if this is due to some asymmetric pre-emphasis - de-emphasis noise reduction circuitry in the ARP design.

I've also had a stab at deriving the classic Polymoog 'Vox Humana' sound from a single-oscillator synth. See Variations 9 & 10.

String Machine Ensemble.png (26.72 KiB) Viewed 2906 times

String Machine Ensemble.voltagepreset

(102.71 KiB) Downloaded 257 times

[ChR_is]

Thanks for sharing! this looks amazing

[utdgrant]

And with the addition of a Poly Octave Oscillator and a Mini LFO, you can turn it into a stand-alone cheesy Italian string machine!

Formaggio String Machine.voltagepreset

(105.66 KiB) Downloaded 365 times