7 comments on “OB-Mx 2-voice board

    • Yes, I did read that a long time ago. I actually got in touch with Lynx Crowe some years later regarding the voice boards and he was very helpful. He mentioned that he would be interested in collaborating on a new synthesizer as long as it wasn’t with Don Buchla!! Don’t know what he’s up to these days though. I also got in touch with Richard Bugg who was in the development team for the original OB-Mx (before Buchla was involved). I have one of their prototypes on the shelf…

  1. Hi, I have an OBMx, one thing that I have always wondered about is that the original prototypes supposedly sounded a lot better i.e. the moog filters actually sounded correct and had real moog punch.
    What did they do to mess up the sound so it has no punch?
    I have always wondered if it was an underpowered section in the signal chain such as a tiny capacitor where there was a big one resulting in a shortage of current? Thoughts? If you could work that mod out there would be a stampede. It has as I understand it good chips, where in the signal chain did it go wrong in your opinion. I wonder if there is a simple mod that can transform the OBMx into what it was meant to sound like http://www.soundonsound.com/sos/1994_articles/sep94/oberheimobmx.html

    • I think there are a couple of things that could contribute to the sound. There are tantalum capacitors at several points in the signal path. Using tantalum caps this way is usually a no-no for audio. Also, a digitally-controlled potentiometer is used for gain trim in the signal path, this could also be an issue. SSM2024 VCA’s are used quite a lot in the signal path. I’ve read that they are not the best sounding VCA’s. However replacing them with another VCA would be a major redesign, and I don’t know how many people with OB-MX’s would be willing to throw out their old voice boards for new ones. However something like swapping out capacitors is more feasible. The original prototype OB-Mx is a completely different design. I have one of these units and one day I may try and ‘finish’ the design as it has some major issues.

  2. Quite an undertaking! I understand this project has been mothballed. If it ever comes back to life let me know. I have an empty OB-Mx that needs filling…

    • I did 20 boards a number of years ago. They work fine, the problem is the cost and complexity of building them and the fact that the CEM’s aren’t available at present.

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