Korg MS-20 Retro Expansion by Yew Tree Magic's Martin Walker

This one in via Martin Walker of Sound on Sound, who brought us the Yew Tree Magic's Steampunk Shruthi Sound Designer Edition.

"With additional top-mounted panel controls and handsome cherry hardwood side panels, the Retro Expansion is a heavily modded version of the Korg MS-20 Mini by Martin Walker that includes the following additional features:

1. MULTI-OUTPUTS: separate TRI, SAW and PULSE output sockets, all available simultaneously, plus a separate output for OSC2.

2. PWM: an additional input for OSC1 variable pulse width modulation, using the existing pulse width knob to control PWM level.

3. SYNC: An OSC2 Sync toggle switch, to lock it with OSC1 for those screaming lead sync FX.

4. FM: An FM input added to OSC2 with its own rotary level control, so it could be modulated at audio rates by OSC1 among other options.

5. VCO MIXER: expansion for the existing mixer section, adding two extra input sockets, each with its own level control knob.

6. DIODE RING MOD: a more traditional transformer/schottky diode ring modulator circuit to achieve far more mellow ring mod options than the integral (XOR) option.

7. Final casework mods include a new top-mounting panel for all the new controls, a 1/4-inch jack output, and cherry hardwood side panels from Dolmage Designs.

If you're interested in adding any or all of these Retro Expansion mods to your own MS-20 Mini, all details of the circuit changes and more photos are available at www.yewtreemagic.co.uk. They should also work on the original MS-20 and more recent kit versions."

Yew Tree Magic's Steampunk Shruthi Sound Designer Edition

This one in via Martin Walker of Sound on Sound and Yew Tree Magic. In addition to the Steampunk style case, there are a number of mods available. If you already own a Shruthi SMR4-mkII, step-by-step guides for the mods are also available on site.

"Housed in a polished wood and brass steampunk-styled casing, the SDE (Sound Designer Edition) is an extensive mod by Martin Walker, giving a host of extra features to the Shruthi-1 with the SMR-4 MkII analogue filter, including:

SHAPES: six filter shapes (LP2, LP4, BP2, BP4, HP2 and Notch).

FLAVOUR: six resonant types from extra IR3109 acid squelch, soft resonance, germanium limiting, to evil half-wave rectification.

FMOD: allows the audio signal to directly modulate the filter cutoff frequency - cue rubbery, wobbly sounds and FM mayhem!

DRIVE: for adding overdrive and distortion effects.

FEED: variable filter feedback for extra tonal changes and circuit-bent mayhem.

RESCMP: three different resonance compensation treatments mimicking Roland, Moog and Korg filter types.

Extensive audio demos and step-by-step circuit mod guides are provided at www.yewtreemagic.co.uk/soundworlds2.php, so you can add any or all of the mods to your own Shruthi SMR4-mkII synth."

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