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 Forum index » DIY Hardware and Software
Marjan Urekar's BUCHLA 194 Fixed Filter
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funkyfarm



Joined: Jan 21, 2007
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PostPosted: Tue Feb 20, 2007 2:22 pm    Post subject: Marjan Urekar's BUCHLA 194 Fixed Filter
Subject description: Splitting input signal into four bands
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Marjan wrote:
Splits input signal into four bands
under 200/200-900/900-4000/4000 Hz,
using just few transistors.


http://members.tripod.com/urekarm/synth/download.html

Has anyone have a attempt with this marjan urekar's version ?

Schematic with BC550/560

The four 1uF capacitors at each output have to be unpolarized, no ?
for both positive and negative "phases" of the audio signal to pass through ?

Am I wrong ?
I see them as 1000nF polyester caps...
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Scott Stites
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PostPosted: Tue Feb 20, 2007 3:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
The four 1uF capacitors at each output have to be unpolarized, no ?


No, they can be polarized. You just connect the positive end at the point that the signal will always generally be more positive.

Back in our Buchla phase, Jeff Pontius built a couple of these and gave me one - forgot I had it! Thanks for the reminder, I'll have to dig it up.

Cheers,
Scott
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funkyfarm



Joined: Jan 21, 2007
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PostPosted: Wed Feb 21, 2007 6:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yep !

About the caps, I hadn't noticed the circuit was supplied only by +15V and Ground (if there's a link in between...)

I was thinking about adding a mixer, because 4 outputs is a lot ! (each with its filter, VCA, etc...)

There's only one INPUT, and OUTPUTS are :

Low : under 200 Hz
Lo Mid : 200-900 Hz
Hi Mid : 900-4000 Hz
Hi : above 4000 Hz


So,
mixing Low and LoMid (normalized) at Low output
(if nothing connected into LoMid socket)

mixing Hi and HiMid (normalized) at Hi output
(if nothing connected into HiMid socket)

then the signal would be splitted in two Hi/Lo bands...

maybe adding an extra "Medium" socket, fed by a mix of the LoMid and HiMid outputs...

Or maybe it would be clever to customize the circuit to only three outputs...Wink
with the same bandwidth...

What would be the two best cutoff frequencies ?

I guess that we can say, with no shame, that the maths would surely be something like f=1/T=RC....somehow...somewhere, no ? Laughing
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funkyfarm



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PostPosted: Mon Mar 31, 2008 12:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you marjan !

I've perfboarded one.

The schematic is all correct, included all capacitors polarization.

It works great, this design has lot of gain ! (Q boosted ?)

I still think a dual mixer would be great.
Total spectrum would be split on two sockets (under 900Hz, above 900Hz)

This is great for stereo effect...

Otherwise, three bands could be enough I guess.

I wish I kwen how to change cap for customizing bands...


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vtl5c3



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PostPosted: Mon Mar 31, 2008 11:31 am    Post subject: Reply with quote  Mark this post and the followings unread

I built one of those a while ago. The original CBS schematic has an error on it. Not sure about Marjan's though.
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mono-poly



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PostPosted: Mon Mar 31, 2008 12:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yeah i wann build one of these.
Who is coming up with some other 100 series stuff?

Smile
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Scott Stites
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PostPosted: Mon Mar 31, 2008 1:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cool
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funkyfarm



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PostPosted: Tue Apr 01, 2008 12:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

vtl5c3 wrote:
I built one of those a while ago. The original CBS schematic has an error on it. Not sure about Marjan's though.


The original CBS schematic is on-line ?

vtl5c3 wrote:
Not sure about Marjan's though.


now you can be Very Happy

(i'll throw some stereo samples with my oncoming dual vactrol cross fader...)
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funkyfarm



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PostPosted: Tue Apr 01, 2008 12:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

mono-poly wrote:
Who is coming up with some other 100 series stuff?

Smile


Definitely.
Buchla clones have changed my patch.
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CJ Miller



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PostPosted: Fri Apr 04, 2008 8:48 am    Post subject: Reply with quote  Mark this post and the followings unread

mono-poly wrote:
Yeah i wann build one of these.
Who is coming up with some other 100 series stuff?

Smile


Nearly all of the Buchla schematics I have I downloaded from Magnus Danielson's pages, but I can't find a link now. About half of the total series 100 modules, and a few 200. The 100 modules look much simpler, easier for me to understand and build. But the 200 modules look much more interesting, musically. I can hardly understand the functionality of synth circuits at all, and Buchla's genius gives me a headache when I am trying to figure his stuff out, even just to clone! Another factor which has kept me from experimenting with Buchla circuits is that it seems they don't use the same 10v peak-to-peak voltages as other modules. I am scared to even breadboard the stuff now, maybe when I am more experienced.

I heard that years ago, somebody published a book in Japan on cloning the 100 series Buchla modules! It had schematics, PCB layouts, and other info. Mark Verbos confirmed that he has seen this book with his own eyes. This would be the ultimate resource if you want to clone 100 series modules, but it is very scarce.

If anybody knows more about this book, please do let us know!

Part of my problem is that I am attracted to many of Buchla's more sophisticated circuits. Maybe somebody with the skills should try making a run of MARF PCBs?? Razz
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vtl5c3



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PostPosted: Fri Apr 04, 2008 8:56 am    Post subject: Reply with quote  Mark this post and the followings unread

I have a photocopy of the japanese book. About half the circuits are Buchla 100 based, the other Moog modular. The author did make changes to some of the circuits, plus they use Japanese silicon instead of US or european parts. I've scanned some of Buchla 100 stuff in and will be glad to forward to other users via PM. I don't think that the 194 is included.
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Coriolis



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PostPosted: Fri Apr 04, 2008 11:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Here is Magnus' Buchla page - 100 series at the top, and 200 series further down.
http://rubidium.dyndns.org/~magnus/synths/companies/buchla/
Doesn't do me much good tho, as I find the 200 series schems almost unreadable. Does anyone know who drew these? They're original I think?

I agree the 100 series doesn't look so interesting compared to the stuff were building in this forum today. But back then it was a different matter, of course. They seem to be completely made with discretes also. I wouldn't bother building these I think, except perhaps the 194.

C
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mono-poly



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PostPosted: Fri Apr 04, 2008 11:09 am    Post subject: Reply with quote  Mark this post and the followings unread

But the best Morton albums are done with the 100 series Smile
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ericcoleridge



Joined: Jan 16, 2007
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PostPosted: Fri Apr 04, 2008 1:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

CJ Miller wrote:

I heard that years ago, somebody published a book in Japan on cloning the 100 series Buchla modules! It had schematics, PCB layouts, and other info. Mark Verbos confirmed that he has seen this book with his own eyes. This would be the ultimate resource if you want to clone 100 series modules, but it is very scarce.


I was recently asking around, to various DIY people on the web, about building a Buchla style touch-plate interface. One of the people I e-mailed told me he had used this Japanese clone book for it's PCB layouts of the touchplate keyboard and circuitry. He's looking for it for me.

I know there is a good article in Synapse for a similar touch controller, but I thought it would be cool to have the original Buchla touchplate artwork.
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Coriolis



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PostPosted: Sat Apr 05, 2008 2:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Eric, if you get hold of that, I'd be very interested too. I may try to build that synapse circuit at some point, but it would be great to see the Buchla as well..

C
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6079smith



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PostPosted: Sat Apr 05, 2008 6:44 am    Post subject: Reply with quote  Mark this post and the followings unread

That book you guys are talking about sounds really interesting, if just for academic purposes...

Back on topic, I built a dual version of this not so long ago on perfboard - directly from the schematic left to right, so it fills quite a bit of real estate. It does exactly what it says on the box. It's nice how something so simple can have so much sonic usefulness...
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vtl5c3



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PostPosted: Sat Apr 05, 2008 7:21 am    Post subject: Reply with quote  Mark this post and the followings unread

ericcoleridge wrote:


I was recently asking around, to various DIY people on the web, about building a Buchla style touch-plate interface. One of the people I e-mailed told me he had used this Japanese clone book for it's PCB layouts of the touchplate keyboard and circuitry. He's looking for it for me.


One of the Stokes brothers, by any chance?
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