MATRIXSYNTH

Beautiful Noise

YouTube via substanceg
"One of the results of the Nicolas Collins Hacking Workshop. Triple Schmitt Trigger Inverter feeding Schmitt Trigger NAND with low pass filter on output."

korg sigma / roland dc 30 analog delay

YouTube via abertronic. On Ebay
"demo of the korg sigma and roland dc 30"

Update: images via this auction

Jordan Rudess presents Ellatron for Mellofest 2009

YouTube via OmenieSoftware
"Jordan Rudess is amazing - not only an incredibly talented musician, but extremely generous of spirit and of his time. Despite having a world tour coming up with Dream Theater in a few weeks, he found the time, along with musical collaborator and videographer Richard Lainhart, to put together this great video, which is both a special message to Mellofest 2009 and an emphatic approval of our Ellatron App for the iPhone. Personally, I am so thrilled to see him play Ellatron, and the way he manages to hold the iPhone and play chord pads and individual notes (and fingered chords) at the same time is an amazing feat of dexterity and balance.

Let me say here - thank you Jordan and Richard for putting this together, it was *VERY* well received by both the organizer of the festival and the crowd."
You can find Ellatron on iTunes here:

YAMAHA DD-11 by S-CAT Pt. I

YouTube via PHONICPOTION S-CAT/PHONICPOTION on Ebay
"CIRCUIT BENT WITH 21 MODIFICATIONS"

YAMAHA DD-11 by S-CAT Pt. II

Circuit Bent Speak and Spell (Hell)

YouTube via legionhwp
"Production model of Speak and Hell now available from DAED. HelpWantedProductions.com/daed .htm"

Dave Smith Instruments Evolver

YouTube via SamAshdotcom.
Wish there was a 8 voice PEK like the Prophet '08. A PEK plus a rack PE is just not the same...
"Designed by Dave Smith, founder of Sequential Circuits and long-time music technology innovator, the 4-voice polyphonic Poly Evolver combines some of his best creations into slick-looking 61-key keyboard. Start with the oscillators: two real analog oscillators featuring Sawtooth, Triangle, Saw-Triangle, and Pulse meet two digital wavetable generators with a choice of 96 waveforms (like the Prophet VS). You can hard sync the analog oscillators (like Prophet 5) and link the digital ones with either FM or Ring Mod for a wide pallette of sounds. And there's no skimping on filters either: real voltage-controlled analog lowpass filters - not digital recreations. 4-pole/2-pole switchable, fully resonant (in 4-pole mode). You also get an audio input that can run through the effects and filter to your heart's content. There's more - a 16-step sequencer with MIDI sync, onboard distortion and delay, syncable LFO's... let your sound Evolve!"

Elka synthex

YouTube via emssynthi100
"this synthex is for sale on ebay. someone asked if all the keys work and a demo of the filter. i dont think you can hear the bottom end well but if you look closely you can see what the filter sweeps are doing to my monitors."

images via this auction
Not sure if it's the same one as in the video. It's the only one I see listed as of this post. Update: I have confirmation it is the same Synthex.

Note this seller has the user manual and schematics on CD along with a ton of other manuals.

CASIO VL-1/DIGI.dly by S-CAT

YouTube via PHONICPOTION S-CAT/PHONICPOTION on Ebay
"CIRCUIT BENT WITH 19 MODS BETWEEN THEM."

Stepped Tone Generator

YouTube via UnearthedCircuits
"A circuit built from the Get LoFi.com Atari Punk Console circuit board combined with dual 555 timer circuits that send CV signal to the APC. Rate of 555 or pitch of APC can also be controlled by light using a photo-resistor. Housed in a custom case."
Unearthed Circuits