[sdiy] MN3207 and MN3102 Reissues

[Scott Stites]

I listened to the samples of this chorus device at Modzero.  Holy moly, that
*is* a great sounding chorus!  Checking out the switchboard on the
schematic, I don't think I quite understand it yet.

Cheers,
Scott


----- Original Message -----
From: <mirwin at qouest.net>
To: "Gavin Muir" <gmuir at sympatico.ca>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, October 30, 2004 8:56 AM
Subject: Re: [sdiy] MN3207 and MN3102 Reissues


> Gavin,
> The guitar lists are really the most suitable place to discuss the
> cloning of vintage guitar fx units - half the discussion revolves around
>  cloning, subs, copyright issues etc.
>
> Regarding substitutions, most of the original Japanese parts are still
> available, including the different transistors, the MN3207 (and the
> companion MN3102 driver) are about as mainstream as it gets with BBD's,
> relatively easy to find compared with ther BBDs, the NE570/571 compander
> is also a mainstream part. Parts warehouses that cater to the consumer
> electronics repair industry usually have these (check Main Electronic
> Supply in  Vancouver or www.bdent.com). The single supply op amp used in
> the clock circuit (IIRC a BA718) may be hard to find, I tried several
> single-supply op amps with better specs (including TLC272) but achieved
> the best results with a lowly LM358.
>
> The neat thing about the Dimension choruses is that they try to achieve
> a "vibrato-free" chorusing through "static" pitch detuning by means of
> two parallel delay lines modulated by complementary LFO triangles.
> Listened to individually, each delay line output has it's pitch shifted
> alternately up and down (sounds like a VCO being slightly freq-modulated
> by a slow square wave). When the two delay outputs are combined, the
> result sounds like two static pitches, slightly detuned, with a slow
> beating taking place. A wonderful effect. Roland patented this technique
> in the early 80's. The "D" has a better clock circuit than the "C", as
> well as more elaborate cross-mixing and filtering, plus the line drivers
> and bar graph, etc.
> Regards, Mike