Korg m-500 emulation – help, please!

[teevee]

I finally got my Nord Modular G1 – so I decided to start building a Korg M-500, I will start giving a little introduction to the instrument and background

info:

Korg M-500 was a preset synthesizer, made in 1977 it’s like a pre-version of Korg ms-10. But good in a way that you don’t have to use so much time on setting the knobs, when you play live – I had this synthesizer in the past and I really loved it.

There are more info here: http://www.vintagesynth.com/korg/micropreset.php

It has the remarkable sound we hear in many of the early tracks by "Orchestral Manoeuvres in the Dark" (OMD) example:
http://www.youtube.com/watch?v=GTyyr59z4hg

This is the data I have collect:
Front panel:
Link

Block diagram: (Source Link)


I have started working on making this emulation – but there are some missing function, which I’m not sure how to integrate.
1. Portamento – I have added the module without wires, but I’m not sure how it should be integrated.
2. Modulation (with rate and depth)
3. Repeat (with on, off and random) (3 steps)
4. Traveler <I’m not 100 % sure, would the traveler fader be the potentiometer on the vibrato module in this case?

This how the progress looks now:

---

Korg m-500.jpg
Description:
Filesize:	180.24 KB
Viewed:	253 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

---

Korg m-500 v1.pch
Description:	Korg M-500 emulation - in progress	Download (listen)
Filename:	Korg m-500 v1.pch
Filesize:	1.26 KB
Downloaded:	297 Time(s)

---

[egw]

If I recall correctly the traveler actually controlled something like filter cutoff.

[ian-s]

[teevee]

Hello egw and ian-s – Thanks for your answers. I will start saying that this is my first trying to make a emulation from “zero square” so this is something new but hopefully also very learn full for me.

I have build it up only by looking at the circuit (Block diagram) and the front panel, then trying as good as I can – but it’s not possible to avoid that Nord Modular would offer some extra options with its modules and yes Korg M-500 was a cheaper synth by Korg in the late 70s compared to Korg ms-10, Korg ms-20 and other.

Looking at the block diagram is “traveler” placed over the preset selection and beside the “fixed tone” – how can I make my idea more realistic to the real deal from what I have made until now?

All ideas and suggestions would be gold for me – You’re also very welcome to open this patch in your editor and show some corrections

TeeVee

[egw]

My interpretation of the block diagram is that the traveler applies to synth1, synth2, and brass. Similarly, the envelope controls apply only to the synth settings, not the other sounds. But you don't necessarily need to keep these restrictions in the emulation.

[teevee]

Okay this traveler function doesn’t seems important at the moment and I can always make a implementation later.
What about:
1. Modulation (with rate and depth)?
2. Repeat/random repeat – should be with 2 functions:
- One that repeats the note, you hold down
- One that makes a random note trigger when you hold a key.
Note: The modulation rate should also set the tempo of repeating the note.
3. How did I use the portamento module in this`?

[egw]

You really need to find someone who has one to give you sound samples. An emulation that captures the routing architecture but not the sound characteristics wouldn't be very interesting. It's been a long time, but I don't think the random repeat plays random notes (like a sample & hold). Rather, it played notes with a rhythm that had some variation to it (but not truly random). Also, the traveler was really the one function that made this feel like a "synthesizer" rather than a keyboard with fixed presets. I wouldn't have bothered with it without that feature.
Modulation rate and depth controls the speed and amount of the two types of vibrato - pitch and traveler (filter).
Portamento is applied to the pitch e.g. a "glide" from the previous note to a new note when it is played. There are different types of portamento (fixed rate or fixed time, linear or exponential). I don't recall which the micro-preset used.

[teevee]

Korg SB-100 had also this "traveler" function.