KORG monotron mod. experiment / VCOもう一個つけてみました

I've got this nice analog synth newly released by Korg. The synth itself is fun to play, but I want to add another oscillator to enrich the sound. This is my first experiment to add a VCO to Monotron. The 2nd oscillator output is sent to VCF as well as the first oscillator (i.e. the original). This can do soft sync also.

The mod. info including schematics is uploaded at http://gaje.jp/projects/synth_effect/monotron/

Also check http://www.youtube.com/watch?v=rcxOsyN7Klw
The embeded version is introduced there from 4:33.

KORG の新製品のアナログシンセ monotron そのままでも十分楽しいですが、VCO がもう一個あるともっと楽しそうだと思いました。
と、いうことで、まずはブレッドボードでテスト回路を組んで実験してみました。

Category:

Music

Tags:

• KORG
• monotron
• mod
• modification
• synth
• diy
• vco
• sync
• モノトロン
• 改造
• circuit
• bend

[MickeyBoyeeee]

Hey man, nice work - sounds amazing.

Trying to do the same, but have 1 question:

Did you put a switch for sync effect? Does the switch go between VCO2 and Sync, or just switch off sync beforeR17 on your schematic?

Thanks for your time/help, Mick

[gajeanalog]

@MickeyBoyeeee Good luck for your mod. Yes I put a switch for sync effect. I used a 3-position 2-circuit slide switch and wired it to make "off - VCO2 - VCO2+sync". You can do it by wiring "off - VCO2 - VCO2" for one circuit and "off - off - sync" for the other. Hope this helps.

[MickeyBoyeeee]

@gajeanalog Thanks again. If you were going to do the dual VCO by using a second monotron, where would the sync point be? I've cross-checked your schematic with korgs schematic and matched up the op-amp terminals, and see some of the structure is quite similar. I'm unsure but would you tap off of pin 9 of IC2(C) on monotron to get same syncing effect as your circuit?

Thanks again for your help, Mick.

[gajeanalog]

@MickeyBoyeeee I'm not sure if it works. IC2(C) just turns on/off oscillation so it might behave somewhat differently from sync if you put pulses in to pin 9. I could not find suitable place to safely put the sync in the monotorol schematic. It might work if you put negative pulses into base of Q5 (2SA1774) through some capacitor and resistor but I've not tested it anyway. Good luck again and be careful not to burn the circuit :-)

[AlphA202303]

have the second oscillator posted anywhere? BTW: nice jam at the end of the video! :)

[gajeanalog]

@AlphA202303 Thank you. About mod. details such as schematics, I've updated the description. I could not paste URLs here.

[MickeyBoyeeee]

@gajeanalog Thanks alot! This definately helps. Have you done another video of the finished piece?

Cheers, Mick

[MrStarbit]

omg ide love a second vco. that is some awsome sound

[gajeanalog]

@zyguli Thanks for the comment. The second oscillator is built on the breadboard. The output is mixed to the 1st osc. and is put into the VCF.