News from my weekend

Haible_Juergen#Tel2743 HJ2743 at
Mon Feb 12 20:10:00 CET 1996


For all those who are interested in the progress of my DIY's
and Mods:

I checked the possibility of HP mode on the OB-8 by directly
routing signals out to a mixer from certain points of the
filter. The 2-pole HP sounds phantastic and should work as
intended. Now as I switch to 4-pole mode, the same (!) node in the
filter acts as a 6-dB/8ve filter with resonance, which is very useful
as well, IMO. It does very little filtering (rather flat slope), but it
has the desired resonance peak. (And unlike a BP, it adds the
peak without loosing bass; more like a peak EQ than a BP!)
I will definetly do the Mod this way now, using the same node
for both additions and thus only need a single 2-way electronic
switch added to each voice.

I almost finished the PCB design for a new module of "JH-3"
on the computer. The module will contain a MS-20 filter section
and two mixers. As I am severely running out of panel space,
I decided to use the following panel layout:
Both mixers can be used separately from the filter, but are
normalized to the filter's signal input and CV input each.
Both mixers have three inputs: One has a centered pot with a
+/- 1 gain range, one has a pot with 0 ... 2 Gain, and one
has a second jack instead of a pot, cause it's actually a VCA
input that is mixed to the other ones. The input of the (+/-) channel
is normalized to the VCA channel input. So when I set a gain of
 -1 I can use the VCA channel inversly (i.e. CV=5V => Gain=0,
CV = 0 => Gain=-1) - this is good for OVCE/Panner functions
and doesn't cost me any additional knob.
The filters themselves are arranged in exactly the same way as
in the MS-20. I was thinking about switchable series / parallel modes,
switchable HP/LP for each filter, but I decided to use just the
original configuration (limited space ...). After all, it's just these
original dirty MS-20 sounds that I wanted to import to my Modular
ever since I sold my MS-20 ...

I also finished the PCB layout of the 14-stage ARP phaser.
Not yet built; guess I will etch the two pcb's together, soon.
The Phaser will not be part of JH-3 (limited space, already one
phaser inside, so far), but I hope it will make a useful stand alone
unit, mostly connected to the Korg Lambda, I suppose.

This was my news from the weekend - thanks for listening!

JH. (age 31)

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