Korg35 Experts

[Tony Hardie-Bick]

nice write-up!

t.

On 27/07/14 17:26, foRUMS 4 punkdISCO wrote:
> Thanks Tony - from what you say, it is definitely out of my ability..  Some
> of the presets have quite a bit of resonance anyway so its not a biggy..
>
> Btw, I just wrote up what I did and sent to AH:
>
> To AH:
> ======
> The Korg Sigma has 12 Korg35 filters (early MS20) but for some reason the
> joystick and Filter CV Input only controls the 8 filters in the Synth
> section and not the 4 filters in the "Instrument" section
>
> The mod is very simple:
> 1)	Find the Joy Stick CV bus on board KLM-167C and connect this to
> board KLM-168C:
> a.	Electric Bass Korg35 IC pin 2 with 47k inline resistor
> b.	Tuba Korg35 IC pin 2 with 47k inline resistor
> c.	Horn Korg35 IC pin 2 with 44k inline resistor
> d.	Trumpet Korg35 IC pin 2 with 31k inline resistor
>
> The inline resistors are required to give optimum range of control otherwise
> you might not have any audio until the Joy Stick is at, say, 50% etc.  The
> existing front panel "fc" knobs for the above 4 instruments still give you
> extra control so you do get some additional range control.
>
> I wired in 4 way toggle switch so I can go back to factory.  It is pretty
> handy having CV and Joy Stick just controlling the Synth filters, leaving
> the Instrument filters as per their preset setup.  However, Im sure some
> people might decide to just leave out the switch and have the extra control
> permanent.
>
> Pictures:
> https://flic.kr/p/ocCQAk
> https://flic.kr/p/os5vMS
> https://flic.kr/p/ou5M1G
> https://flic.kr/p/otUp3A
>
> I won't have time over the next few weeks to do any audio demo's but it
> sounds frickin ace especially when you hook up some Envelopes or LFOs to the
> Filter CV input giving you a proper 2 oscillator synth that can generate 19
> waveforms all at once, running through 12 Korg35 filters!
>
> I actually now prefer the Instrument section as the Joy Stick only controls
> the LPF.  On the Synth section, the X-Y Joy Stick controls both LPF and HPF
> and I always feel like there is no position that fully and independently
> closes the LPF.  With the Joy Stick at 9oClock, this should be the LPF fully
> closed so nice and bassy however, at 9oClock the HPF is also at 50% so you
> actually just get a BPF at about 50%
>
> With the Instrument voices (with this mod), with the Joy Stick at 9oClock,
> you just get a lovely LPF almost fully closed (nice and bassy)
>
> btw, I got a lot of pointers from this excellent page by Richard Atkinson
> (thanks Richard, if you are read this..)
>
> http://rga24.blogspot.co.uk/2010/04/korg-sigma.html
>
> Schematic:
> http://www.synfo.nl/servicemanuals/Korg/KP-30_SERVICE_MANUAL.pdf
>
> hugs,
>
> Paul
> London
> www.punkdisco.co.uk
>
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