Alisa filter: anyone?

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Vorg
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Alisa filter: anyone?

Post by Vorg » Thu Feb 27, 2014 7:14 pm

I've recently been blessed enough to give a try to one of those soviet beasts and it instantly became quite my favourite monophonic EVER. Never heard anything that nasty before.

I was wondering: does anyone know what the heck of a filter do these guys have? I read they were roughly based on Moog's ladder but its sound didn't remind me much of it, judge by yourselves! [The ending part of the video reminds me about Björk's "Declare Independence", and I'm quite sure there's no soviet analog synth :D involved in it.]

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Post by vicpop » Thu Feb 27, 2014 10:06 pm

Very nice sound... a diy version of the oscs and/or filter would be interesting

Found some schematics here (cyrillic text): http://www.ruskeys.net/eng/pasp/alisa1377/pasp.php

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equalpyramid
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Post by equalpyramid » Thu Feb 27, 2014 10:35 pm

Sounds amazing!
:animal:

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Vorg
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Post by Vorg » Fri Feb 28, 2014 6:27 am

We definitely need a think tank for that, vicpop! :D I can read cyrillic but unfortunately that doesn't mean I understand it; anyway I've got some friends who can help: would it be a fair starting point if I manage to translate those papers?

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ndkent
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Post by ndkent » Fri Feb 28, 2014 6:40 am

Yes, with the Polivoks being the big exception, a lot of Soviet synths seem to have transistor ladder filters. In other words attempting to build a Moog filter with local parts and possible shortcuts.

I guess one big issue is they use Soviet parts. I guess one could try to obtain them or swap available parts and compare the results.

As fore the video, sounds really overdriven, would probably want to hear something with more & different filter action to get more of the the idea.

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Vorg
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Post by Vorg » Sat Mar 01, 2014 9:27 pm

Good tip, ndkent; "unfortunately" that's more or less exactly how the one I personally tried sounded like. It seemed almost impossible to dial in some "classic" mono-bass sound, it just kinda "distorted" no matter what you did, and did it that nasty way you heard.

Love it. Need it. At least part of it. Somehow. NOW. :D

What about modding an A-108 with soviet ICs? I guess it sounds like a nightmare, by now, but I wonder if it couldn't be an idea.

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Post by horstronic » Sun Mar 02, 2014 7:17 am

Wow, that's a really dirty synth!

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kvitekp
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Post by kvitekp » Sun Mar 02, 2014 10:00 am

From schematics (thanks vicpop) here it Alisa-1377 appears to use a variant of ladder VCF with some quirks. The diodes (A) in the feedback op amp buffer may be responsible for that distinct over driven sound. Not sure what (B) diodes are there for though.


Image

КР159НТ1Б is a matched transistor pair, seems to be still in production.

кд503а diode seems to be similar 1N4748 or 1N5720

К153УД2 op amp seems to be similar to LM101H/LM301A
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aladan
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Post by aladan » Sun Mar 02, 2014 11:05 am

That video example shows a 1387, not a 1377. The schematic is here: http://ruskeys.net/pasp/alisa1387/c/alisxem2.jpg

What a funky way to draw op-amps!

Here's a 1377: https://www.youtube.com/watch?v=6SRYIPlt3z0

http://ruskeys.net is a pretty cool site.

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Vorg
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Post by Vorg » Sun Mar 02, 2014 10:07 pm

This guy gets more and more interesting... I guess it could easily develop in a project! Some time ago I became friend to a russian ebay seller (I kept buying from him some FT363 equivalents to put in some tonebender clones): even if kvitekp immediately found readily available substitutes, I'm gonna send him an email to see if he can help seeking for some components. :nana:

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aladan
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Post by aladan » Sun Mar 02, 2014 10:38 pm

Vorg wrote:This guy gets more and more interesting... I guess it could easily develop in a project! Some time ago I became friend to a russian ebay seller (I kept buying from him some FT363 equivalents to put in some tonebender clones): even if kvitekp immediately found readily available substitutes, I'm gonna send him an email to see if he can help seeking for some components. :nana:
I'm quite enjoying my Polivok original-parts clone from the other thread here at the moment, so I'd be up for some Russian filter action and grabbing a few of the matched transistor chips for prototyping and experimentation.

Cheers,
A.

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Vorg
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Post by Vorg » Thu Mar 06, 2014 6:22 am

Just a quick update: sourcing for кд503а seems a bit harder than I thought, but I still haven't tried ebaying 'em. :bananaguitar:

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Aluaris
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Post by Aluaris » Thu Dec 10, 2015 3:32 pm

I have the rack midi version of Alisa made by the one of Moscow synth repairer for me. :tu:

Image

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oberkorn
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Post by oberkorn » Thu Apr 14, 2016 2:16 pm

bumbety bumb
did anyone try to build this filter?

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Post by jhulk » Thu Apr 14, 2016 5:22 pm

erica synths uses the lm394 and has them made in latvia he also does a pnp version and metal can lm394

he also made a descrete opamp based on the hard to get russian opamp

differential opamp ICs K118UD1A(B) as clones

so certainly a version could be made

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Post by abelovesfun » Thu Apr 14, 2016 6:05 pm

I would give it a shot if the schematic were translated.
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Re: Alisa filter: anyone?

Post by BARD » Mon Jul 27, 2020 1:16 pm

I'm late to the party, but I've just repaired one 1387 and that synth indeed sounds interesting.

The filter is little different beast than Moog. First of all it's 12dB and the resonance feedbacking is positive, so the gain don't drop when the resonance is cranked up. This could be feasible to clone with standard NPN / PNPs and 741s.

1377 and 1387 have slightly different topologies.

Would be interesting to do that filter on germanium transistors though :)

I'll consider making this filter clone for Eurorack in close future.

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