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 Forum index » DIY Hardware and Software
SH101 VCF QUESTION
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haxster



Joined: Feb 01, 2006
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PostPosted: Tue Jun 23, 2009 2:50 am    Post subject: SH101 VCF QUESTION Reply with quote  Mark this post and the followings unread

Would it be possible to use an LM13700 for the Transc. op-amps and some kind of transistor pair for the Exponential function converter? I am trying to breadboard this filter but I am stuck on the converter.

Does any one know a simple Anti log function generator circuit?
I found this(see pic) but I am not sure if this one is the correct one to use here. I think the one in the picture is a Lin/log converter. I think I need a log/lin converter. I am not sure how to do that.


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beep



Joined: May 05, 2013
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Location: Germany

PostPosted: Mon Oct 28, 2013 4:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

P U S H

This man made a great post and I'll need some advice, cause I'm about
to try this circuit.

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haxster



Joined: Feb 01, 2006
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PostPosted: Mon Oct 28, 2013 5:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Here is an update to help you build a roland sh101 type of filter. These guys did the hard part of figuring out what the resistor values are to replace the BA obsolete chip with Discrete components: http://mutable-instruments.net/shruthi1/build/smr4mkII. There is a schematic at there website.
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jackdamery



Joined: Apr 26, 2010
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PostPosted: Mon Nov 04, 2013 6:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey not sure if you're on the SDIY facebook group. But I have done it and yes, it is totally possible.

I have some real IR3109s and with advice from guys on the SDIY mailing list I figured out the internal resistor values between the gain cells non-inverting inputs and ground as 432 ohms.

I used one LM13700 to make a 12db version of this filter
For the expo converter I used the standard Thomas Henry current source type. The thing I haven't figured out is the buffers between the gain cells. I used a TL072 in my circuit but next im going to try a FET as it's what Roland preffered to use.

Here's a recording.

https://soundcloud.com/dot/ir3109-12db-ota-build
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jackdamery



Joined: Apr 26, 2010
Posts: 75
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PostPosted: Mon Nov 04, 2013 6:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Also check out page 22 of this pdf

http://www.synfo.nl/servicemanuals/Roland/JP-4_SERVICE_NOTES.pdf

it shows the filter of the JP4. It was discrete originally and then in later versions they used the ir3109.
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roglok



Joined: Aug 28, 2010
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PostPosted: Mon Nov 04, 2013 8:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Rick from Frequency Central created a LM13700 version of the System 100m filter - http://www.frequencycentral.co.uk/wp-content/uploads/2012/05/Roland-121-VCF-Build-Doc.pdf

It's extremely similar to the JP-4 VCF... Sounds and performs great.
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Sethkaine



Joined: Sep 26, 2015
Posts: 16
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PostPosted: Mon Sep 28, 2015 3:16 am    Post subject: All for OTA - Operational Transconductance Amplifiers Reply with quote  Mark this post and the followings unread

Hi SH-101 lovers,

Is the expo converter from Roland Service Notes working? it's for +15v, that's right?
in this PDF :
http://www.synfo.nl/servicemanuals/Roland/JP-4_SERVICE_NOTES.pdf

and the image above sh-101_vcf_schematic.jpg has diff voltage +5v

I'm not aware of the calculation here, but has anyone a schematic for -/+12v or an explication note?
I want to know how this thing is acting like the IR3109, I must try to breadboard from discreet and LM31700...


my topic about OTA :
http://www.electro-music.com/forum/topic-65157.html

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wackelpeter



Joined: May 05, 2013
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PostPosted: Tue Oct 20, 2015 12:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

just finished that above mentioned 121 VCF and hmmm... i'm not so glad with my result... i have used 2xLM13700 and 4x 2SK30 instead of the original parts...

the filter does self oscillate but only in the very low spectrum and the Output is rather a square than a sine... even with no Input at Audio in...

tried playing aroud with the resistors in the Feedback path of resonance...
reducing that 6,8k resistor even lowered the frequency so i thougth ok let's increase it... so i soldered a 4,7k with a 10k trimmer in series and well it's slightly higher and the resonance Output is lower in Amplitude but i only get more of a humming frequency and when i only had 68k in self oscillation disappeared...

any idea how it's original behaviour is?
does it cover a wider range of frequencies in self oscillation?
any Information or Input would be welcome as usual... thank you

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roglok



Joined: Aug 28, 2010
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PostPosted: Sun Nov 01, 2015 4:21 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
just finished that above mentioned 121 VCF and hmmm... i'm not so glad with my result... i have used 2xLM13700 and 4x 2SK30 instead of the original parts...

the filter does self oscillate but only in the very low spectrum and the Output is rather a square than a sine... even with no Input at Audio in...

tried playing aroud with the resistors in the Feedback path of resonance...
reducing that 6,8k resistor even lowered the frequency so i thougth ok let's increase it... so i soldered a 4,7k with a 10k trimmer in series and well it's slightly higher and the resonance Output is lower in Amplitude but i only get more of a humming frequency and when i only had 68k in self oscillation disappeared...

any idea how it's original behaviour is?
does it cover a wider range of frequencies in self oscillation?
any Information or Input would be welcome as usual... thank you


something must be wrong with your build. i am getting a very nice sine wave across the whole spectrum:

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roglok



Joined: Aug 28, 2010
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PostPosted: Sun Nov 01, 2015 4:24 am    Post subject: Reply with quote  Mark this post and the followings unread

did you pay attention to the FET pinouts?

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wackelpeter



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PostPosted: Sun Nov 01, 2015 10:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Roglok,
thanks for your reply.
Have soldered the FET according to the SK30 data sheet i found at my suppliers pages.
These are as per front view (where you can read the identifier) from left to right source, gate and drain...

and when i read the original schematic correct, then there is the gate connected to the Output of the OTA the source to +15V and the drain goes to the next stage and -15V via resistor. correct?

Wasn't there something about 2N3819 Fet's where sometimes the Pins where swapped?

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wackelpeter



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PostPosted: Tue Nov 03, 2015 10:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Problem fixed...
Forgot to cut two rails on my stripboard design so that the gates and drains of the FET's between stage 2 and 3 where tied together... luckily nothing blew up and i have now a sine over the whole spectrum with full resonance and the filter sounds like a filter know and not only like an VCA turning tone on and off...

will now tweak and tune it a bit until i'm satisfied...

should consult my doctor and check my eyes as i have checked the layout a few times but always missed that failure... Smile

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isak



Joined: Dec 13, 2009
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PostPosted: Sat Nov 07, 2015 11:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi wackelpeter Smile

Did you made the VCF on stripboad? Dude, your crazy Smile
Must be a big stripboard Shocked
May I be rude and ask for your stripboard design, I will love to build this vcf Smile

Cheers,
Isak E.

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wackelpeter



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PostPosted: Sun Nov 08, 2015 3:10 am    Post subject: Reply with quote  Mark this post and the followings unread

hm... i've always built all my modules on stripboard... so far 4 cases of 48x35 cm filled with 79 modules are filled...
most competing modules where so far the serge vcadsr and serge vcs and the mfos quantizer...

i mostly use the normal 100x160 mm stripboards... just a very few use the 100x200 mm ones...

can you give me a hint and a link to some good Freeware stripboard layouter? otherwise i could draw it on paper and then scan it... but i think that could be hardly to read...

i also have to say that i used lm13700 and 2sk30 so that this layout is limited to them or equivalent pin compatible stuff (LM13600 would work too)

i maybe start when i have finished replacing two older simple AR-Generators with Ian's AD/AR and Delayed Pulser... just have to twaek it a bit for another LED for the Envelope and include two Switches for different Timings as there are already some holes in my case from the previous modules...


ah nearly forgot it... most important and maybe of interest it's not the SH101 VCF that i've built it's the System 100 121 VCF...
but both are using 4 OTA stages... so i think they are somewhat comparable...
Here's a link to most of the Roland VCF schematics:
http://fa.utfs.org/diy/roland_filters/

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isak



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PostPosted: Sun Nov 08, 2015 9:24 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
hm... i've always built all my modules on stripboard... so far 4 cases of 48x35 cm filled with 79 modules are filled...
most competing modules where so far the serge vcadsr and serge vcs and the mfos quantizer...

i mostly use the normal 100x160 mm stripboards... just a very few use the 100x200 mm ones...

can you give me a hint and a link to some good Freeware stripboard layouter? otherwise i could draw it on paper and then scan it... but i think that could be hardly to read...

i also have to say that i used lm13700 and 2sk30 so that this layout is limited to them or equivalent pin compatible stuff (LM13600 would work too)

i maybe start when i have finished replacing two older simple AR-Generators with Ian's AD/AR and Delayed Pulser... just have to twaek it a bit for another LED for the Envelope and include two Switches for different Timings as there are already some holes in my case from the previous modules...


ah nearly forgot it... most important and maybe of interest it's not the SH101 VCF that i've built it's the System 100 121 VCF...
but both are using 4 OTA stages... so i think they are somewhat comparable...
Here's a link to most of the Roland VCF schematics:
http://fa.utfs.org/diy/roland_filters/

thank you very much my friend Smile
i've attached a simple program called DIY layout creator.
its very simple to work with Smile
thank again my friend!


diy_layout.rar
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wackelpeter



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PostPosted: Sun Nov 08, 2015 1:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

The Program doesn't run on my PC... after installing and trying to open it always two failure reports occur...
tried googling for another Version and downloaded... that one runs but i think it's way to complicated to draw that all with this program..

I think i'll be much faster with drawing it on paper (squared paper or wathever it'S called) and scan that together with some photos guess that will be easier and much faster...

will go on tomorrow...

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isak



Joined: Dec 13, 2009
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PostPosted: Sun Nov 08, 2015 2:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

ohh sorry about that...
you need to open it as admin.
meaning, right click on the icon, and go to "Run as Administrator"

this will fix it Smile
sorry again, i forgot about it.

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wackelpeter



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PostPosted: Mon Nov 09, 2015 7:59 am    Post subject: Reply with quote  Mark this post and the followings unread

Just had a few minutes at work left to figure out some things on the Version i downloaded and installed...
seems as most things i could need i'm able to draw them but one Thing i haven't figured out yet... how can i bend a leg of a Transistor...
mean normally you have them in a straight row or triangle


o e
o b
o c

o e
xo b
o c

the o's here are the legs and the x is a cut trace/hole

i wan't to know how i can bend them that it's like below

o emitter
o base
x or other trace
o collector

is this possible? if so how?

anyway this Programm seems better as i first thougth of it... must get rid of my fear about new technoligies... Very Happy

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wackelpeter



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PostPosted: Mon Nov 09, 2015 10:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Okay....

Here's my first i guess a bit lousy attempt...

the White dots mark where the trace has to be cut on the side with copper rails... indeed also cuts are needed underneath the IC's...
the black dots mark the Points for external wiring... not shown frequency pot which needs +15V and GND on it's outer wipers... also not shown Input attentuators for Signal and CV...

All Electrolytic caps except those 2 on the power rails should be non-polarized as per Frequency Central...
btw. in the schemo i see BP which for me would mean Bipolar... hmm... for non-polarized i'd expected a NP

because lacking a sdt-1000 i used a 2,2k NTC and a 8,2k to 10k resistor in series (that's the one mislabeled with 1k)

Before building please take Care of the Veroboard Size... i guess i missed a bit the Ratio... but everything should fit easily on a 2,5mm raster on a 100x160mm board

would be nice if someone could check if i missed something... maybe i'll do that later...

P.S. tried to upload the diy layout creator file as well... but this doesn't seem to work... restricted file extension

Edit says: like in my first own build i forgot to cut a trace... please do cut between both drain of the FETs between stage 2 and 3


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Last edited by wackelpeter on Mon Nov 09, 2015 2:35 pm; edited 1 time in total
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isak



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PostPosted: Mon Nov 09, 2015 11:33 am    Post subject: Reply with quote  Mark this post and the followings unread

this is great, thank you very much!!!
i have a Q if i may...
what scheme did you use for this layout?

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wackelpeter



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PostPosted: Mon Nov 09, 2015 11:47 am    Post subject: Reply with quote  Mark this post and the followings unread

that was the original schematic attached in the 121 VCf clone pdf from frequency central... see above in this thread...

just figured out the Pins of the LM13700 vs Ba662 and then going for it..

i have to tell that ialso tried to mod this with a small passive hpf via Rotary swith and different cap sizes... works not as well as thought first... it's more lowering the volume than filtering higher frequencies out...

edited that in my previous post too... have spotted the first mistake... both drains between FEt 2 and 3 should be separated... the same i've forgotten in my first own build... i knew someone, who can endlessy repeat the same stupid mistake... Wink

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isak



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PostPosted: Mon Nov 09, 2015 10:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thank you very much!
Very informative Smile
Another Q please, how did you match the FETS?

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wackelpeter



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PostPosted: Tue Nov 10, 2015 7:45 am    Post subject: Reply with quote  Mark this post and the followings unread

They're unmatched as are the LM13700 too... Just straight from one Batch...

I also have no idea how to match FETs... If i would like them matched i had to ask Google and friends how to do...

btw. here's a small revisited Version with the forgotten cut in the rail now drilled...


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isak



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PostPosted: Tue Nov 10, 2015 8:20 am    Post subject: Reply with quote  Mark this post and the followings unread

thank you very much!
you've been more then helpful Smile

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