Captain’s Analog


Posted on October 1st, by Mark Verbos in 18, Analog, Gear, Mark Verbos. No Comments

Captain's Analog with Mark VerbosKORG MS-50
Awhile back I told the tale of the Korg MS-10, the pint sized wonder box I picked up for $75.  It is no secret that the MS-10 is the baby in a family of powerful semi-modular synths; however, in the father position is a machine entirely modular with no pre-patched connections.  Bear in mind people that this is not modular in the way of an ARP 2500 or a Moog 55, it is all on one circuit board, but all the features are brought to the front panel and you need to patch at least a few cables just to get a sound.  The module compliment is strange and suggests more of a utility module, but along side another small modular, like an MS-20, this system becomes very powerful.  I realized the tremendous power of this system way back in 1993, and began the search. Recently, I finally acquired the holy grail, and I would love to tell you about it.

The MS-50 is a slanted front black box about 22” wide and 7” tall.  The front panel is nicely organized with all the knobs on the top part of the modules and the 1/4” jacks on the bottom.  Below the modules there is a group of 5 mults.  Mults are convenient when patching, as they act as front panel Y cables that allow you to send a signal to more than one destination.  The modules, from left to right, are an oscillator, a voltage controlled lowpass filter, a VCA with a variable high pass filter, an ADSR envelope, a unique hold – delay – attack – release envelope, a modulation generator, an adding amplifier, a voltage supply, an integrator, an inverter, a linear VCA, a ring modulator, an analog volt meter, a sample and hold, a noise generator, a divider, a manual trigger, an audio amp and a headphone amp.

The oscillator responds to both 1 volt/oct. and Hz/Volt control voltages.  This is great because it allows the system to be interfaced with both the Korg MS synths as well as other manufacturers’ synths.  There are individual outputs for each the triangle, sawtooth and variable width pulse waveforms.  In addition to the before mentioned control inputs, there are two variable strength inputs. There is also an input for controlling the pulse width from voltage.

The lowpass filter is everything you would expect from an MS synth and then some.  I have been told that the design of this filter uses higher quality parts and is of a greater quality than that of the MS-20.  I don’t know if I believe that, but it is a great sounding and very unique filter.  The key to the distorted hi-hat sound that you hear all over techno records these days is distorting the Korg MS filter.

The VCA is just what you would expect too, except for one small detail, one that I would consider a breakthrough- there is a variable highpass filter.  Although this cannot be controlled from voltage, it allows the sound to be varied quite severely.  I use it to make percussion sounds and to make my thin bleeps even thinner.  This is in no way even comparable to the resonant voltage controlled highpass in the MS-20, but it is a welcome feature.  The VCA is quite regular in every way, offering control of how much the control voltage affects the amplifier.

The envelopes have a few features that separate them from garden variety types. The first is a standard Attack – Decay – Sustain – Release variety but with three varieties of outputs. The first output starts at zero volts and goes up, the  second output starts in negative voltage and sustains at zero, the third output is an inverted version of the envelope.  The second envelope is of the hold – delay – attack – release variety.  The hold stage acts as it does on the other MS synths, converting a trigger into a gate of the length you have dialed up.  The delay sets the length of time that will pass between the receiving of the trigger and the beginning of the attack.  The attack sets the time between start and the peak and of course release sets the time it takes the voltage to die to zero again.  The same positive outputs are available on this envelope, instead of the negative out there is a delay trigger output that sends a trigger as the envelope begins the attack stage.  This envelope is useful for making echoes and other delayed effects when used in combination with the ADSR envelope. It is always welcome to have strange envelope possibilities.

The voltage controlled LFO, or Modulation Generator- as Korg calls it, is useful for all sorts of uses.  It has outputs for triangle, positive saw, negative saw, and variable width pulse waves.  There are external ins for controlling both the frequency and the pulse width from voltage.  This is basically another oscillator set for a lower frequency range.  Why don’t all monosynths have a voltage controlled LFO?  I wish I knew.

The adding amplifier, or Adding Amplifier, is useful in an indefinite number of ways. This is a key ingredient that is missing from the other MS synths.  Using this module, you can modulate any parameter from multiple sources with control over the mix of the controllers. This is important as soon as you want to use both the LFO and the envelope to control the filter.  It also should be noted that the mixer can mix either audio or control signals, and because Korg decided to make all voltages sweep from -5 to +5, audio and control signals are actually interchangeable. This is a concept that is important to note if you want to get the most out of this or any modular.
The voltage supply is only there just in case you need it, as a fixed voltage.  I suppose this could be used to power anything looking for 5 volts.

The integrator is actually a variable slew limiter or glide processor.  This allows any changing voltage to be slowed down under the control of the knob.  This includes portamento type sounds as well as release envelopes.  Send anything through here and you have control over how fast it can change.  Nice.

The inverter is used to make positive voltages negative and vice versa.  This is most useful with control signals, but whatever signal will be accepted.

The second VCA is intended for control signals.  This allows you to automate how much modulation is occurring.  For instance, you could control from voltage how much the LFO is modulating the filter.  VCAs, the more the merrier.
The ring modulator is another thing that separates the -50 from the -20.  The ring modulator on the MS-20 is not an actual ring modulator and thus it can only be used between the two oscillators. This is a true ring modulator and can be used quite effectively on any signals including those from other modules in the system as well as those from outside sources.  Ring modulators are great for robot voices and metallic drum beats.

There is a sample and hold with an internal clock.  The sample and hold is great fro making those computer sounds from old movies.  They are great for adding random modulation to sequences and creating stairsteps in LFO signals.

The noise generator is nothing too special, but necessary for drum sounds and anything random.

The divider works at both audio rate and on clock triggers.  This has outputs of /2 and /4.  On audio this means an octave down and two octaves down, on clocks this means half and quarter speed.  It is worth noting that anything coming out of this will be a square wave.
The audio amplifier is actually an envelope follower and trigger extractor.  This is kinda like the external signal processor on the MS-20. Unfortunately, there is no pitch follower included.

The headphone amp allow you to use the machine with headphones.  Alright.

On the Up Side
This is a very powerful instrument.  It is not too common for this type of versatility to appear in such a small package.  It is well layed out with all the jacks on the bottom to keep the cables out of your way.  It is clean and crisp.  It has a good mix of both normal and abstract utility type modules.  The voltages are all -5 to +5 peak to peak.  I find this to be a comfortable configuration and easy to use for all types of patches.

On the Down Side
The biggest downer here is that there are very few of these out there.  MS-20s pop up all the time, but I have seen very few of these.  The second thing is that I had to pay a pretty penny for this, about a thousand dollars.  I wish it had two oscillators.  I wish there was a pitch follower along with the envelope follower, and a full featured high pass filter would be nice.

On the Outs
All in all I love this thing.  I think it is worth the money, especially when you consider that it was $1200 new.  Just remember that a 303 only cost $300 new and they get over a thousand dollars now.  I looked for one of these for all this time, so I really couldn’t tell you to go out looking for one of these.  Keep your eyes open and if one falls in your lap, be aware that it is something useful.  Again, paired up with an MS-20 this thing is a powerhouse. So, watch out for my records, make good music, and read this space next time for some info about how to make some gear yourself.