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Anyone have a nice Preamp with envelope or gate extraction??
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numbernone



Joined: Aug 16, 2006
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PostPosted: Thu Feb 08, 2007 3:39 pm    Post subject: Anyone have a nice Preamp with envelope or gate extraction?? Reply with quote  Mark this post and the followings unread

I am looking around like crazy for a good preamp for boosting external audio for modular processing. I have seen so many I dont even know where to begin!! Ideal design would include an envelope follower and or gate extraction with threshold controls. I am working on a panel or 2 to mimic & expand on the functions of my Fenix (which I will never gig, or take anywhere ), and it has a pair of lovely pre's with lots of extras. My MS20 also has its incredible ESP, but i want it all on one surface. Any suggestions would be greatly appreciated.
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6079smith



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PostPosted: Thu Feb 08, 2007 4:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

Have you seen this?
Seems to fit the description.
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Fernando



Joined: Dec 30, 2006
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PostPosted: Thu Feb 08, 2007 6:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

I think the preamp on the Oakley's EFG envelope follower is a nice one (note it uses a dual gain pot)
I bought the pcb time ago but is not populated yet.
I include the preamp section for your study (1) (deleted!)
You could buy the current issue of the Oakley EFG wich should include the pre amp and gate extraction.

As envelope follower, it seems Harry Bissell designed a very efficient one, but maybe he optimized it for guitar, not shure (ask him)
http://www.edn.com/article/CA265499.html

One could also use Harry's "MorphLag" simple and elegant circuit... it is a lag circuit with attack, decay and shape controls using three op amps.
http://www.wiseguysynth.com/larry/schematics/Morph-Lag.htm
but it expects a cv, so you may use a comparator before this to extract a gate and then shape it with the Morph/Lag to approximate the original signal (or whatever)
Very possibly I'm wrong and will work fine with the amplified audio signal at it's input...

I have an envelope follower circuit I like (how it looks, never built it) from the only spanish book on synth circuits (Juan Bermudez's "Nueva Generacion de Instrumentos Musicales Electronicos", not shure if he is the author of this circuit though)
I think it may work very well (2)
Maybe one could switch one or two capacitors to further control the response (see 0,22 policarbonate cap)
I like that it has attack and decay controls.

And there is also the Polyfusion, wich looks interesting too.
The schematic includes a good switch trick (3)

For gate and trigger extraction there are many around.
Maybe you could use a simple comparator to extract a gate (from original signal or from envelope output) and then a gate-to-trigger if you need it
http://www.cgs.synth.net/modules/cgs24_gatetotrigger.html


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Last edited by Fernando on Thu May 08, 2008 6:46 am; edited 3 times in total
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midgetfidget



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PostPosted: Tue Nov 20, 2007 6:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

I want to build something like this. I need to have 4 or so pre-amp channels to run audio from my pc through my modular for processing. The envelope detection is not a necessity.

Can I use vcas for this? I have some designs for some simple vcas, will the gain be high enough?
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loss1234



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PostPosted: Thu May 08, 2008 5:16 am    Post subject: Reply with quote  Mark this post and the followings unread

fernando

can you repost those images please?? i would love to see the envelope followers!

thanks

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fluxmonkey



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PostPosted: Thu May 08, 2008 5:46 am    Post subject: Reply with quote  Mark this post and the followings unread

assuming (as he stated) that fernando originally posted the schematic for the Oakley EFG, from their documentation--this is copywritten work and can not be posted w/out Tony's permission. As per his web page:

Quote:
Schematics for any Oakley project are now available as individual downloadable pdf files for a small fee. The Oakley Modular schematics are available for 2GBP each. The larger and more complex rack projects are available for 4GBP each.


very reasonable. i agree that this a great design.

bbob
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Fernando



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PostPosted: Thu May 08, 2008 6:34 am    Post subject: Reply with quote  Mark this post and the followings unread

I didn't post the envelope follower. I posted a tiny portion of a some-versions-old part of the preamp (2002 I think). I'm sorry if I did something wrong. My sincere apologies!
Note that I promoted to buy the current real thing.

I'm reposting the other images. Please report back if you build Bermudez or Polyfusion followers.

Anyhow, Harry Bissell worked a lot on env foll so his multiple layer one (see EDN article) may be very nice. Please report back here if you build it and tell Harry.
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creatorlars



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PostPosted: Thu May 08, 2008 8:57 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm going to build that Digisound 80-13 module sometime in the next week or two, and I'll let you know how it goes. I'm very interested in modular vocal processing.
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Fernando



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PostPosted: Thu May 08, 2008 10:02 am    Post subject: Reply with quote  Mark this post and the followings unread

creatorlars wrote:
(...) I'm very interested in modular vocal processing.


then it's good to have n env followers, n vcas and a bunch of filters and processors, this way you can patch interesting vocoders of different types and sizes and use the modules for anything (vs having those modules dedicated to that task only)

a great source for filter banks could be Ken Stone fixed bandpass and the Steiner. Of course, any filter would be great.

vcas based on ssm2164 or it's current clone might be easy and cheap too

but again, imho, it's not necessary to have so many vcas, env foll and filters like in a vocoder... you may work with 3 or 4 bands and do very interesting things for shure
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loss1234



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PostPosted: Thu May 08, 2008 12:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

fern-can you explain a little more how you can get 3 or 4 band vocoding with an envelope follower, some filters and some vca's?

sounds really very interesting!

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CJ Miller



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PostPosted: Thu May 08, 2008 12:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

I too have used bits of the Digisound for preamp. My envelope and gate/trigger extractor is from Barry Klein's book, which I think he got from Electronotes. For a given application I might tweak parts for gain or thresholds.

The Oakley modules do seem great. Tony had the schematics on line back in 99 or so but took them down shortly after. They are really nice circuits which I believe he updates from time to time. I'd love to have the money to buy some from him sometime. It's difficult at times because people might post their circuits freely for a while, and then prohibit their posting later. It's cool that he offers just the PDFs for builders again.
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Fernando



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PostPosted: Thu May 08, 2008 3:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

loss: just read the basics of the vocoder anywhere, it's very easy to depict.

the idea is that you shape a sound with an aproximation of the timbre of another sound, but you may introduce whatever variation on this transfer function if your system is of modular nature.

you have sound A, the sound you'll analize (trad. "speech")
and sound B (trad. "carrier") the sound you will shape with the result of that analisys or whatever you like really

traditionally, to analize sound A, you use n filters in parallel, fixed at certain bands and with a certain bandwidth and place an envelope follower at the output of each filter. This way you get the amplitude value of each band.

btoh, you have sound B, trad. a raw timbre to shape, passing through anothre battery of filters (trad. at the same freqs of the analisys) with an vca at each output.

when you control the vcas with the curves from the analisys you sort of transfer the timbre of sound A to your sound B

Just draw a diagram with all the elements and you'll see that you can make anything you like by using different filters and settings and sending the envelopes to a different band, etc endless fun.

Buchla has a timbre processor that works within this concept, iirc

take a look to the Doepfer vocoder to see the different functions

The EMS vocoder 5000 is a nice example too. It uses a matrix for the transfer

But with a modular you can do amazing things

the trad. circuit looks like this:

A --> vcf analisys --> env foll --> control output (to vca)
A --> vcf analisys --> env foll --> control output (to vca)
A --> vcf analisys --> env foll --> control output (to vca)
... (n bands)
A --> vcf analisys --> env foll --> control output (to vca)


B --> vcf processing --> vca --> audio output
B --> vcf processing --> vca --> audio output
B --> vcf processing --> vca --> audio output
... (n bands)
B --> vcf processing --> vca --> audio output

audio outputs = C


There's something else, only found in certain vocoders that I find very interesting. It comes directly from the original use of the vocoder, to synthesize the noise part of speech. It is a pitched/unpitched or voiced/unvoiced detector.
It will send a trigger to switch from the synthesis source, B, to white or pink noise, and more or less sofistication can follow to detect and sinthezise consonants.
To my surprise this is done using two or three band pass filters and statistically decide if a consonant is there.
The EMS have one. I think there's something related on the MS20 and there is a good description within the schematics on the net of some 80's vocoders (Elektor vocoder, ETI vocoder, PAiA vocoder, lots of info)

sorry it's late at night here, tomorrow I'll look for mistakes and typos but it's more or less this...

one more thing, if one would use resonant filters and many for the analisys, and resonants filters for the synthesis it sould be sort of a Fourier transform, you might be familiar with that already.

Oh, and take a look to Ken Stone's Real Modem. He proposes a modulator/demodulator using two ring modulators and introducing processing in between. A similar aproach but using a very simple setup that produce many interesting sounds (as in all Ken Stone's proposed circuits!)


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Last edited by Fernando on Fri Jan 06, 2017 12:58 pm; edited 1 time in total
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fluxmonkey



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PostPosted: Thu May 08, 2008 7:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

the circuit from the spanish book is almost identical to one from Nic Collins originally published in Electronotes #60 and included in the Preferred Circuits collection. He notes that "an actual gate can be applied to the circuit [after the 220 ohm resistor follwing the 2nd amp] to make it serve as an AR type of envelope generator when not in use as an envelope follower".

bbob
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Fernando



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PostPosted: Fri May 09, 2008 12:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

thank you bbob! first clue I have about the origins of the circuits on that book since I bought it ca. 1980...

edit: I'm reading the original article in EN 60, thanks again. It uses the last 1/4 of the 3900 for a trigger output being a more compact circuit than in my book. An envelope follower made out of a 3900 and a few components, super!!!
Thank you so much Nicholas Collins!
(Electronotes is the holly grail, thank you so much Bernie!)

.

Last edited by Fernando on Sun Nov 12, 2017 10:31 am; edited 2 times in total
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loss1234



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PostPosted: Sat Jun 14, 2008 5:24 am    Post subject: Reply with quote  Mark this post and the followings unread

anybody know what the black arrow pointing OUT of the input attached to a 1% 100k resistor is for? is it a pot to an input? is it going to gnd or +v or -v???

thanks

_________________
-------------------------------------------- check out various dan music at: http://www.myspace.com/lossnyc
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blue hell
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PostPosted: Sat Jun 14, 2008 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

loss1234 wrote:
anybody know what the black arrow pointing OUT of the input attached to a 1% 100k resistor is for? is it a pot to an input? is it going to gnd or +v or -v???

thanks


I'd say it behaves like just another input being summed/mixed with the input marked as such. There certainly is no need or reason to tie it to gnd or any supply voltage.

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loss1234



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PostPosted: Sat Jun 14, 2008 7:39 am    Post subject: Reply with quote  Mark this post and the followings unread

so its not a pot?
just a weirdly marked input

thanks

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Fernando



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PostPosted: Sun Jan 15, 2017 10:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Nic Collins article and schematic is available at his own website:

http://www.nicolascollins.com/ (see "make" section)

A great website full of interesting stuff.
A great artist, researcher and maker!

His envelope follower using just one LM3900 looks great, hope to build a couple soon.
Note that a device like a Serge VC slope (DUSG et al) should perform similarly.
Of course, Collins circuit in EN60-7 is an elegant and super compact solution for an Envelope Follower.

This is one of the circuits I first wanted to build... in 1981, when I was 13!



fluxmonkey wrote:
the circuit from the spanish book is almost identical to one from Nic Collins originally published in Electronotes #60 and included in the Preferred Circuits collection. He notes that "an actual gate can be applied to the circuit [after the 220 ohm resistor follwing the 2nd amp] to make it serve as an AR type of envelope generator when not in use as an envelope follower".

bbob

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gabbagabi



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PostPosted: Thu Jan 26, 2017 10:36 am    Post subject: Reply with quote  Mark this post and the followings unread

i guess this could be a necroposting record
props

It's just a jump to the left.
And then a step to the right.
With your hand on your hips.

Let's do the Time Warp again.
Very Happy
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Fernando



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PostPosted: Fri Jan 27, 2017 5:42 am    Post subject: Reply with quote  Mark this post and the followings unread

I don't see the fault in updating or adding info to an old thread.
Do you discard info just by not being posted in the last month or week?
I don't.
We are using circuits from the 70s and 80s to build all this stuff, we didn't discard all that info and wisdom.

Maybe it is much noisier to add that kind of comments, since it is already obvious that it is an old thread.

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gabbagabi



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PostPosted: Fri Jan 27, 2017 5:51 am    Post subject: Reply with quote  Mark this post and the followings unread

i did not meant it bad
was just impressed
Smile
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Fernando



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PostPosted: Fri Jan 27, 2017 6:28 am    Post subject: Reply with quote  Mark this post and the followings unread

g.gabba wrote:
i did not meant it bad
was just impressed
:)


I know, I know, no problem
I even enjoyed the dance :P

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