GSE 101-VCO vs SH-101 + 101-VCO Tuning Mod [Demo 4]

Today, I am comparing my 101-VCO to the original Roland SH-101 synthesizer.
How close to the original is my 101-VCO?
Saw, Pulse, Pulse Width Modulation, Sub, and Noise waveforms.
The SH-101 did not have the Triangle waveform.
At the end of the video I'll play both of them together, just for fun.

I'll also show you an easy mod for the 101-VCO so that it's pitch CV can
match the tuning of the original SH-101.
It involves adding a 1206 470K resistor to R19 previously denoted "DNP".
All 101-VCOs I make and sell henceforth will have the resistor already installed.
And tuned to match the SH-101 as it should be.

Left Channel = 101-VCO
Right Channel = SH-101

0:00 Introduction
0:26 A Simple Mod to match the 101-VCO pitch CV with the SH-101
1:45 Audio Comparisons
4:25 Both at the same time, just for fun

CRUMAR PERFORMER: Noise Reduction Mod and Sustain Mod

Today I am looking at a friend's Crumar Performer.
We noticed a considerable hiss noise when activating the String sections.
The hiss goes away when using only Brass.
I investigate where the noise is coming from, and what's to be done about it.
I discover a simple way to boost the strings signal without affecting the noise floor.

Another strange deal, by design, the brass button defeats the strings sustain.
I explore the sustain mod to restore the strings decay while using brass.

UNIVOX MINIKORG SYNTHESIZER REDUX

Today a follow-up demo of my Uniox Minikorg w/ a Pitch CV + Gate mod controlled by the Arturia Beatstep, this time sans the annoying percussion. This synth is one big continuous sweet spot! Some delay by Timefactor, a touch of Big Sky reverb, recorded directly via Mackie mixer to a Tascam DR-05. Press play, kick back and let it ride.

Testing Univox Minikorg CV+Gate Analog Synthesizer Mod

Testing out a Pitch CV + Gate mod for the Univox Minikorg, AKA Korg 700/700S. The arpeggio gets faster and ends up sounding inspired by Pink Floyd On The Run. The circuit one the breadboard is from E-Labs, Japan as shared by Cykong.com. I added a buffer on the gate since the Beatstep Pro trigger did not push enough current to make it happen. Strangely, the gate does work w/ the original MS-20. Beatstep Pro can do Hz/Volt, this setting can be made in the Arturia Midi Control Center software. Recorded direct to Tascam DR-05, no additional processing. Here's the lowdown:
Synth - Minikorg
Percussion - Basilimus Iteritas Alter
Percussion Trigger - Varigate4
Delay - Timefactor
Reverb - Big Sky, Hall setting

Korg MS-20 Teardown: Pulse Width Modulation Install

The vintage Korg MS-20 monophonic synthesizer comes with a pulse width knob, but no way to patch a modulation to it. In this video I teardown the MS-20, and install a Pulse Width Modulation routing.

My PWM will come from the MG/T.Ext circuit that is already present on the synth. 90% of the time I want to use the MG, AKA the LFO, to modulate the Pulse Width. So all I will do is add a small pot and current limiting resistor for routing the MG/Total circuit to the Pulse Width.

What about the other 10% of the time I don't want MG going to PWM? Well the MG is only normalled to the Total/External jack. If something is patched into the Total jack, it will override the MG and be routed to the new PWM pot. It behaves exactly the same way as the MG/Total pots for Pitch/HPF/LPF. Pretty sweet.

At the end of the video I patch various things to modulate the Pulse Width. Stay safe, don't electrocute yourself, and be sure to unplug the synth at all times while doing work inside the unit.