Roland SH101 VCF DIY

[isak]

Hi guys, long time

i just got 18 X IR3109 that i pooled from 3 X broken Juno 106 voices.
i wanna make the SH101 VCF's.
i look at the scheme of the 101 VCF and its not that clear to me.
ive edited the scheme as i see it but there are few connectors that i really dont know where they should be connected.
can you guys please look over the attached scheme and tell me if i did it right and didnt cut out any important component or link?
in addition where pin 1 and pin 13 is connected?
as i understand pin 9 is the CV input?

i thank you in advance.
Isak

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[Grumble]

my guess is that the circuit is powered by a split power, and the points the arrows are pointing to (as well as other points looking like a dot with a line ) is half the voltage, while the ground acts as a negative voltage and the arrow in the top and center of the diagram is the positive voltage.

[isak]

thanks for replying

i'll check in the 101 it self.

cheers

[alanwilder81]

hi Isak,

i am a Roland sound fan too, and i am trying to collect infos regarding the SH 101 vcf variation done by the Frequency Central guys.
I replied in a thread you opened some time ago about it. i am seeking some help and advices, and i am really curious to hear how the modifications on the filter came together

Edited by Blue Hell - assuming http://electro-music.com/forum/post-429544.html#429544 was meant, please correct me when that was wrong.

[alanwilder81]

here's the link to the LM13700 version of the wonderful SH 101 filter,,
schematics and components list

http://www.frequencycentral.co.uk/wp-content/uploads/2012/05/Roland-121-VCF-Build-Doc.pdf

[jbeuckm]

Was there really a 13700 schematic? This link was 3080.

[alanwilder81]

hello
yes, the original schematics shows the CA 3080 OTA
Frequency Central guys reproduced it faithfully.

However, i was pointed to this work by a user in another thread, where it's discussed how to replace obsolete components with modern equivalents , in order to clone the Roland 100 M filter.
Some guys show the results ! here's the link

http://electro-music.com/forum/topic-35191.html

and the stripboard layout

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[wackelpeter]

i would, if already using an LM13700 or 13600 already tend to use their internal buffers instead of the FET's... There is a VCF schematic of one Roland VCF around that does it this way... It can be found at the Roland VCF filter list, linked somewhere in this forums or easy to be found via Google.

The 2SK30 i've used worked somehow, but possibly aren't the best choice... i used them only why i had easy access to them and they were not obsolete and reasonable priced.

To speak clearly it's not among the favourite VCF's i've assembled so far. Compared to other VCF builds i would rate this an average build, which obviously has something to do with my limited competence in adapting this thing for the components i had at hand.

[alanwilder81]

to wackelpeter

why replace the FET buffers? this way the original sound would be completely gone. I aim to stay as close as possible to the orginal design

[alanwilder81]

2N 3819 and BF 245 are ok substitutes fot the original FET s from what i 've heard.
There is a interesting thread on Muffwiggler about the Jupiter 8 VCO cloning, where they discuss and document its original FET s, op amps and OTA replacements with modern components.
here is the link.
I believe it helps a big deal

https://www.muffwiggler.com/forum/topic-92595.html

[wackelpeter]

Because most Roland filters used the same method: OTA stages (BA6...,CA3080,LM13600 or IR3xx) and then different types of buffers after each stage, FET, Op amps.

In the 101VCF it's included in that IR3109 chip.
I have no idea of the internals of that IC but i guess it's something Close to the LM13700... When it works and sounds good, why not do it that way... Maybe sounds a bit different then, but who cares if it sounds better then.

Take a look at the different schematics.

http://www.florian-anwander.de/roland_filters/

[alanwilder81]

thanks Bastian

that makes sense

[wackelpeter]

@Isak

In this schematic from the Jupiter 6 VCF there are the Internals of the IR3109 shown, maybe this helps...

http://www.florian-anwander.de/roland_filters/JP6.jpg

Also see my post before, on this site a few other schematics with the IR3109 are shown and sometimes some more of the designators.