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Project Specific Discussions => Dynamic Processors => Topic started by: elskardio on April 19, 2017, 09:12:38 AM

Title: Attack/Release schematic for Pico Compressor?
Post by: elskardio on April 19, 2017, 09:12:38 AM
Hi,
does anyone have a copy of the Attack / Release schematic for the Pico Compressor?
Please PM me if you do.
Thanks
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: bruno2000 on April 19, 2017, 09:16:16 AM
You can find the circuit on the app notes page of THAT's website.
Best,
Bruno2000
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: elskardio on April 19, 2017, 09:27:43 AM
Hi Bruno,

the Pico was using the same circuit found in That  Design Notes 115?
(http://www.thatcorp.com/datashts/dn115.pdf)

I thought it was different... I remember reading about a TL072 in the circuit.

Thanks
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: EmRR on April 19, 2017, 09:59:48 AM
Modified variation, only available to purchasers of the one board run, less than 30 people got it.  Officially unobtainium.  If you have a PCB purchased second hand, the person it was purchased from is the only person who should provide you with that info, just like a pico PCB.  If you purchased a board from FCS, your invoice would get you a replacement schematic.  Put any Pico related schematics up here, or link to one, it'll be taken down as per Pico user agreement.   Working with THAT app note is your best bet.  It is apparently borderline stable, with layout being critical. 

FWIW, I don't ever use the attack/release mode on any of my Pico.  If you are after a similar Pico compression sound with more control, you'll get the control but not the sound.   The stock mode is really where I think the Pico shines.    A/R is based on modified Peak, I never use Peak mode either. 
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: chrispsound on April 19, 2017, 10:53:23 AM
If layout is a concern just copy the 4301 demo board layout.  You don't need AR mode.  There are only so many places you could put a TL072.  The hard part for me is  the metering.  I would like to switch from gain reduction to  output.  Just idiotic rambling.  Probably not the best place to talk top secret stuff.  And for good reason, the  Pico and FCS compressors are the cats meow and deserve the respect they get around here.
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: elskardio on April 19, 2017, 10:56:32 AM
Working with THAT app note is your best bet.  It is apparently borderline stable, with layout being critical.

Thanks for the info emrr!

I've been experimenting a lot with the DN115 schematic and the control circuit is pretty unstable... Even with match transistors and tight pcb layout. Everything is fine for a few months and one day you power up the unit and there's noise and oscillation generated by the control circuit. Auto mode is always fine and I also don't use the variable controls but some friends/customers wants the extra bells and whistle  ::)
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: Script on April 19, 2017, 11:05:25 AM
Extra bells and whistle? Ok, why not put ATT and REL knobs on the front panel then, but without any wiring inside. As this comes pretty close to what they do on the original Pico in soft knee, feed-forward, automatic release mode plus Att/Rel engaged. It's all really so subtle ;)
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: elskardio on April 19, 2017, 01:19:48 PM
Extra bells and whistle? Ok, why not put ATT and REL knobs on the front panel then, but without any wiring inside.

Very tempting  ;D
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: ungifted on April 19, 2017, 05:16:56 PM
TL072 based attack release is here:
http://burnit.co.uk/sdiy/images/boxotrix/schematic_compressor.gif
Pico AR is very similar to DN115 schematics with 2 OP07 instead of LM393 and 2SK170
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: shot on April 19, 2017, 07:24:29 PM
@Ungifted..

Did you try that one with TL072 ?

I built one with TL074 (schemo by mr Foote) and it's not good.
Is this TL072 version supposed to be better than THAT app note DN115?
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: ungifted on April 20, 2017, 04:52:52 PM
I think I'll try to renew my that4301 project (just to note, bugfix to my last PCB: solder RMS 2M resistor to negative pole, not to ground!) new bunch of fixed pcbs is in progress, and I think I'll finally find some time to test TL072 variant too. Currently I've tested pico AR and it seems to work ok: but like Script mentioned "It's all really so subtle".  :)
Title: Re: Attack/Release schematic for Pico Compressor?
Post by: Whoops on September 03, 2020, 08:09:09 PM
Hi,
does anyone have a copy of the Attack / Release schematic for the Pico Compressor?
Please PM me if you do.
Thanks

(https://i.imgur.com/q15GbY2.gif)