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Re: [sdiy] Subtle Chorus (including Dimension D emulation)

2008-07-26 by JH.

>The BBD board needs 2 x MN3007 and 2 x MN3101. These are quite easy to get,
>compared to other vintage BBDs.

Forgot to mention:
BBD board also needs 2 x NE570 (or NE571, or SA571) companders.

JH.

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----- Original Message ----- 
From: "JH." <jhaible@...>
To: <synth-diy@...>; "analog heaven" <analogue@...>; 
"MOTM List" <motm@yahoogroups.com>
Sent: Saturday, July 26, 2008 10:45 AM
Subject: [sdiy] Subtle Chorus (including Dimension D emulation)

Hi,

just wanted to give you a quick update of my upcoming (fall 2008) "Subtle
Chorus" PCB project, which, among other things, will be able to emulate a
Dimension D, (using original ICs and all), plus "Dim T" (Same topology but
with two 20-stage phasers instead of BBDs), plus generic true-stereo,
dual-BBD chorus.
Depending on what configuration you want, this will use one, or up to four
PCBs. (Dim D emulation needs two PCBs.)

 The "Subtle Chorus" is a variable project consisting of 3 different PCBs
that can be combined for various functions.

  a.. You can build a rather simple, true-stereo, dual-BBD Chorus with
voltage controlled Chorus Rate and voltage controlled Chorus Depth, using a
single PCB.
  b.. You can emulate the famous "Dimension D" (Trademark of Roland / Boss)
sound with it's unique filtering and presets, using two PCBs, the "Dim D"
(You even have the choice between vintage HA1457W opamps, or more common
TL071 / TL072 opamps.)
  c.. You can build a similar effect that uses 20-pole all pass filters
instead of BBDs, using three PCBs, the "Dim T".
  d.. And you can build an overkill effect device that allows to choose
between the Dim D and Dim T effect, using 4 PCBs, the "Dim TD" version.
So far, the BBD board design is finished; main board will be the next.
Documentation is here:
http://www.jhaible.heim.at/subtle_chorus/jh_subtle_chorus.html

The BBD board needs 2 x MN3007 and 2 x MN3101. These are quite easy to get,
compared to other vintage BBDs.
The Dim T version doesn't need any BBDs, of course.

JH.

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Re: [sdiy] Subtle Chorus (including Dimension D emulation)

2008-07-26 by JH.

>>   c.. You can build a similar effect that uses 20-pole all pass filters
>> instead of BBDs, using three PCBs, the "Dim T".
>
>How similar is this to your 20pole phaser board from a few months back?


It's the same PCB.
You need the Main Board and two Tau boards for the Dim T effect.
You don't need to solder in all components on the Tau boards, though.
I've also been thinking about a making dedicated board with the two all pass 
filters on one PCB, but I'll probably offer a bundle of two Tau boards 
(together with the main board) at a somehow reduced price instead.

A sound sample can be found here:
http://electro-music.com/forum/viewtopic.php?t=24529
(Short wav file. First, CS-80 dry. Then, CS-80 thru Dim T.)
Longer demo (18MB):
http://www.lulu.com/content/2136864

The effect is less "subtle" than a Dimension D, but IMO very pleasant on its 
own.
(With the BBD board, you'll get the exact Dim D sound, of course.)

JH.