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 Forum index » DIY Hardware and Software
A question about modular signal levels
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midgetfidget



Joined: Aug 22, 2006
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Location: melbourne, aus

PostPosted: Wed Dec 20, 2006 8:26 pm    Post subject: A question about modular signal levels Reply with quote  Mark this post and the followings unread

This is probably really obvious, but anyway here goes:

I plan to make either rene schmitz's MS20 clone or maybe a polivoks clone filter to be used on audio from my synths/drum machines.

Seeing as they are designed for use in a modular do i need to add any circuitry to the signal path to do this? Amps/buffers etc..
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Uncle Krunkus
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PostPosted: Thu Dec 21, 2006 7:21 am    Post subject: Reply with quote  Mark this post and the followings unread

I think you'd need an amp at the front end to bring the line level up to about 5V P-P. There's also a possibility that, being a filter, it would process the line level signal just fine, but the noise level might suffer depending on how noiseless the filter design was. I'd try it without first and see.
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Funky40



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PostPosted: Thu Dec 21, 2006 2:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

i have made an Amp modul with 10x amplification.
They told me that this is the normal amplification needed for Line Level signals.
It works very fine. ( it was my very first strippboard projekt. Very simple )


Polivoks Filter:
You can try to decrease the input Resistor i think (maybe 10k instead of 100k ). this way it should work without an extra OP Amp.
( but i'm also really beginner in electronics, understanding nearly nothing. so maybe i'm wrong )

if Polivoks, i suggest to take the UA 776 chip. Seems to be much better.
and yeah, it's great on Drums
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fonik



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PostPosted: Thu Dec 21, 2006 4:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Funky40 wrote:
if Polivoks, i suggest to take the UA 776 chip. Seems to be much better.

did you try both, lm42450 and UA776? marc b. told me the resonnance control would be better but i never tried a Ua776... (sorry for kidnapping this thread)

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Funky40



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PostPosted: Thu Dec 21, 2006 5:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi fonik,

no, i'm just knowing the UA776

I'm at www.synthesizerforum.de "at home".
there are some People who have tryed both.

Elektrolabel for example like both.
Serenadi recommend the UA776 ( he is one of the most experienced modular Users there in my view).
Then also Sägezahnsmoo recommends the UA776, also a very experienced Person.

With the LM 4250 it seems to sound nice, with the UA776 it seems to get the Balls.


I know somebody here who has some LM 4250 and i will see him next week,
i ask him to bring me one,and i will test it.
If all works i will make some Audio Demos
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fluxmonkey



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PostPosted: Thu Dec 21, 2006 7:12 pm    Post subject: Re: A question about modular signal levels Reply with quote  Mark this post and the followings unread

midgetfidget wrote:
This is probably really obvious, but anyway here goes:

I plan to make either rene schmitz's MS20 clone or maybe a polivoks clone filter to be used on audio from my synths/drum machines.

Seeing as they are designed for use in a modular do i need to add any circuitry to the signal path to do this? Amps/buffers etc..


Ken Stone's stomp box adapter: http://www.cgs.synth.net/modules/cgs46_sba.html

b
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Scott Stites
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PostPosted: Thu Dec 21, 2006 7:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cool thing about Rene's MS-20 filter is the less signal level it sees, the more apt it is to go into self-oscillation at high resonance settings. I imagine it's probably true of the original filter, but I've never tried it on an actual MS-20.

Cheers,
Scott
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midgetfidget



Joined: Aug 22, 2006
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PostPosted: Thu Dec 21, 2006 11:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the tips guys.

I'm making this to replace my beloved frostwave resonator that was stolen in a break in. Sad

i'm pretty sure that pedal had some sort of amp/mixer built in.

Anyone have any schematics for a small 12v+/- power supply? most of the ones i've seen around are probably too big for a pedal
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fonik



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PostPosted: Thu Dec 21, 2006 11:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

midgetfidget wrote:
Anyone have any schematics for a small 12v+/- power supply? most of the ones i've seen around are probably too big for a pedal


if you don't mind to use an wallwart try this:
http://modular.fonik.de/soundlab/sl_psu.pdf

and the schematic:
http://electro-music.com/forum/viewtopic.php?highlight=soundlab+psu&t=12968
(it can easyly be laid out on stripboard too)

you'll need a 9V AC 500mA wallwart...

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softfin



Joined: Oct 11, 2006
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PostPosted: Fri Dec 22, 2006 4:11 am    Post subject: Reply with quote  Mark this post and the followings unread

I've heard a lot of promising comments about the Polivoks and it seems simple. So I have to consider building it too Cool

Does anyone know where one could find ua776s for cheap in Europe?
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softfin



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PostPosted: Fri Dec 22, 2006 6:46 am    Post subject: ua776 vs. MC1776 Reply with quote  Mark this post and the followings unread

I just found out that i could obtain MC1776s for a decent price locally. I read somewhere that they are similar to UA776. I checked the specs and they are close but not exactly the same.
I would be grateful if someone more experienced than me could give the datasheets a quick look and see would the mc1776s work in the polivoks vcf.

Here are datasheets for both.
MC1776
UA776

Thanks.
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