Roland Juno-106 + SH-101 + TR-606 by RetroSound

YouTube via retrosound72

"vintage synth demo by RetroSound
analog pads and sweeps: Roland Juno-106
bass-seq: Roland SH-101, triggered by the TR-606
drums: Roland TR-606"

drummachine jam, md 606 and evolver smallstone

YouTube via enapa1apa
"jam with 606 thru smallstone and evolver, md throu evo too.... chaos and smooth elektrojam.... soundcraft 400b mixer..."

Hand Made TB-303 Clone

via wire to the ear where you can find more info.

"It didn’t have the interesting sequencer of a real 303 but the basic sound was extremely close. With careful Midi programming (back then on Atari Cubase) you could fake the slides and accents that made the 303 so wicked."

Divius - Roland TR808 clone

via Sequencer.de

Roland TB-303 The Beast

images via this auction
via Pawn sphinx on the forum.

You can find more info on The Beast mods here.

Nord Lead 2x Demo

YouTube via theveg99. via fischek. Overview comes in about a minute into it.
"House/Trance Producer Marshal Arnold shows off a Clavia Lead 2x."

Oberheim OB-MX

YouTube via rezfilter. "The Oberheim OB-MX. Sonic Fury."
Hopefully we will see more of these. The OB-Mx is a fascinating bit of synth history.
See these posts for more and be sure to see this post. Don Buchla was involved in the design.
Update: Be sure to also check out the samples in the prior posts including these from Brian Kehew of The Moog Cookbook.

Roland TR-606 "Drumatix" Analogue Drum Machine by RetroSound

Youtube via retrosound72

"vintage drum machine demo by RetroSound
Roland TR-606 from 1982

7 analogue Sounds: Bass Drum, Snare Drum, Low Tom, High Tom, Closed/ Open Hi-Hat, Cymbal

The little sister of the legandary Roland TR-808 with the typical LED step programming."

Alesis Andromeda "'I"ll Wait" Van Halen

YouTube via synthartist69. Sent my way via Mr. Array.

Jim Patchell Patchtron

DIY modular built from scratch by Jim Patchell in 1978.

Note the filter in the Mattson Mini Modular bears his name.

You can find previous posts feature Jim Patchell including more of his modular DIY here.

You can find the Jim Patchell DIY Synthesizer Web Page here.