buschfsu

any love for a new THAT comp discussion?
« on: April 07, 2011, 04:38:18 PM »
i know the PICO comp has graduated from the ranks of DIY but id like to start playing with the THAT analog engine designs.  Does anyone have any pearls they want to share about the stock THAT design notes.  i was thinking of building a comp as pictured here.

PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick


gemini86

Re: any love for a new THAT comp discussion?
« Reply #1 on: April 07, 2011, 04:59:35 PM »
What say we save a couple $$ and go with the GSSL in/out combo, nothing that a couple 5332 can't handle, also gives other the option for their preferred opamps.

Other than that, I say we should start prototyping, and see what works, doesn't work. :D
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Biasrocks

Re: any love for a new THAT comp discussion?
« Reply #2 on: April 07, 2011, 06:03:11 PM »
« Last Edit: April 07, 2011, 06:07:58 PM by Biasrocks »
http://SharktankPro.com

"I'd rather use an SPX90 than a UA plugin....." Joe Barresi

ruairioflaherty

Re: any love for a new THAT comp discussion?
« Reply #3 on: April 07, 2011, 06:08:44 PM »
I can't say I agree with Gemini, I think the THAT in/out chips are worth the money especially as this project would not have expensive transformers or rotary switches.  Look at AC coupling the 1646 on the output though, as per Ruckus thread currently on the go.

For the metering I think something LM3914 based would be a lot simpler, lots of example of that around the place.

I bought all of the parts to proto the attack/release section way back but I have no idea where they are now!

The 4301 app notes are deeeep, I gave many nights studying those.

Good luck,
Ruairi


Davo

Re: any love for a new THAT comp discussion?
« Reply #4 on: April 07, 2011, 06:26:25 PM »
I agree... the THAT chips are excellent.  I use the 1200 in as many places as I can

myker

Re: any love for a new THAT comp discussion?
« Reply #5 on: April 07, 2011, 06:33:07 PM »
I had pcb's made for the compressor in your schematic, the meter, a bypass, and that chip balanced in and outs as well as a power supply. Never got around to populating them. I think i have five sets or so. Would you guys be intersted in checking those out? I can take pictures if you want.
-mike

ruairioflaherty

Re: any love for a new THAT comp discussion?
« Reply #6 on: April 07, 2011, 06:39:46 PM »
Myker,

Can you post your schematic?  I might be interested for a sideline project I have cooking.

Cheers,
Ruairi


Curtis

Re: any love for a new THAT comp discussion?
« Reply #7 on: April 07, 2011, 07:12:06 PM »
Wasn't the Pico pretty much just the THAT4301 design notes/datasheet examples?  I've got a schematic for (I think) the Pico on one of my backup discs that looks nothing more than the 4301 datasheet circuit grafted on to design note DN101.
--------------------
http://www.thethirdending.com
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myker

Re: any love for a new THAT comp discussion?
« Reply #8 on: April 07, 2011, 07:20:26 PM »
Hmmmm, not sure I have that. I had the pcb's designed by an engineer and i believe that he kept everything above and beyond the that schematics, which are the same as the ones posted above. Its pretty much the same as the THAT drawing, just throw a 1200 in front and the 16?? on the back end. I'll look when i get home.

gemini86

Re: any love for a new THAT comp discussion?
« Reply #9 on: April 07, 2011, 07:32:39 PM »
Just make sure not to put up any pico schem's here, obviously. That's kindof a no-brainer but just wanted it to be said that this is NOT a pico clone project.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."


EmRR

Re: any love for a new THAT comp discussion?
« Reply #10 on: April 08, 2011, 10:54:23 AM »
Wasn't the Pico pretty much just the THAT4301 design notes/datasheet examples?  I've got a schematic for (I think) the Pico on one of my backup discs that looks nothing more than the 4301 datasheet circuit grafted on to design note DN101.

Looks are deceiving....Lots of fine details are different, many not obvious from schematics.  I have pages and pages of notes concerning the Pico design, parts selection, and adjustment, none of which are obvious. 
« Last Edit: April 08, 2011, 10:59:47 AM by emrr »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

dmp

Re: any love for a new THAT comp discussion?
« Reply #11 on: April 08, 2011, 11:13:54 AM »
Quote
I have pages and pages of notes concerning the Pico design, parts selection, and adjustment, none of which are obvious.
Interesting... I bought a Pico SEII from another member and finished it, but had trouble getting information so it might not be built to spec...
And I have had pretty mixed feelings about it in use. Recently I lent it to a studio that did a comparison to 3 other compressors on a mix and the Pico came in last (sounded 'cheapest'). I wish it hadn't become such a secretive project...
It does certainly appear to be pulled almost completely from the datasheets in my experience.

EmRR

Re: any love for a new THAT comp discussion?
« Reply #12 on: April 08, 2011, 11:36:16 AM »
Sounds not built correctly; a main reason it was withdrawn from DIY.  I own a lot of channels and they outperform other types I have on a regular basis.   A properly built and aligned DIY Pico should sound exactly like the current commercial product, minus the nuances of the later bells and whistles.

Back to subject:

THAT app notes are there as a starting point for new designs, and should be pursued. I wouldn't expect the straight version to be the end-all.  There are a lot of commercial designs using the 4301, and I doubt they are all uniform in sound and operation.  
« Last Edit: April 10, 2011, 04:08:57 PM by emrr »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

geoff004

Re: any love for a new THAT comp discussion?
« Reply #13 on: April 08, 2011, 12:27:21 PM »
The 4301 seems to have so many different things that it can do.  And there are a ton of compressors around here.  And I think there are still Pico-type schematics floating around online.

Sorry to try to steer the thread differently, but why not design some kind of gate or dynamic noise reducer into a nice little package (maybe 500 series, maybe not - I don't think anything like that exists for that format).  I've got an ancient Burwen VCA-based noise reduction unit and would love to have more. 

I'm just saying there are a lot more possibilities.

Re: any love for a new THAT comp discussion?
« Reply #14 on: April 08, 2011, 01:14:15 PM »
I've been interested in this for awhile.  I started a PCB layout based on THAT design notes a couple years ago but got distracted by a million and a half other things.  I'm mostly interested in creating a few low-parts-count projects for my undergrads to assemble with relatively little hassle; a simple, regulated bipolar power supply and a usable, affordable finished product.  I think something along these lines would be fantastic.  I'm going back and forth between using THAT 16xx and 12xx for I/O versus using opamps.  The simplicity of InGenius and OutSmarts chips is brilliant (and they sound alright, too!), but I like the idea of my students "seeing" the diff amp in action, so to speak, and having the ability to swap amps.

JohnRoberts

Re: any love for a new THAT comp discussion?
« Reply #15 on: April 08, 2011, 02:04:54 PM »
The THAT chipsets are a very nice starting point. I have designed a few compressors over the years and never had such neat connect-the-dots solutions.

I guess this depends on how much time and effort you are willing to invest in making something truly different than the other hundred canned solutions out there, based on the same parts and same app notes.

I would suggest a two PCB solution, where one circuit board handles the basic I/O and VCA block. With a second circuit board to handle all the side chain manipulations. This side chain processing is where the rubber meets the road and where you will spend all your time tweaking stuff to make subtle changes. Note: One VCA path could be made into multiple different products by attaching different side chain processing (gates, de-esser, etc).

I see several useful circuit tricks in your cut and paste schematic that I have used before, but the design trade offs in even one small section would require a lot of words and time to describe what it is going on, let alone how to optimize it (as if there is a single optimal solution).

Compression has some general "always good" and "always bad" characteristics, and other less objective fashion elements. In other words there can be more than one good compressor solution.  In an ideal world you can cover several "good" compressors with one and a few controls, but the world is rarely ideal.

I have wasted more time than I should thinking about an ultimate analog dynamics engine, and I have pretty much settled on a digital side chain, and computer interface to handle the too many knobs, switches, and variables I want to control, while still keeping it simple to use. I still like the analog VCA path, for now (while I have some ideas about possible improvement there too that involve trade offs. Everything involves trade-offs).   

Unfortunately I neither have all the tools to design the full computer interface, nor do I think my design time is well spent on making yet another fancy compressor, when there are still green fields to harvest that haven't been this fully explored.

JR
Visit https://circularscience.com to hear what properly "cleared" drums sound like.

living sounds

Re: any love for a new THAT comp discussion?
« Reply #16 on: April 08, 2011, 02:57:15 PM »
Just make sure not to put up any pico schem's here, obviously.

Why not? They originally put it in the public domain, didn't they?

ruairioflaherty

Re: any love for a new THAT comp discussion?
« Reply #17 on: April 08, 2011, 03:23:29 PM »
Interesting... I bought a Pico SEII from another member and finished it, but had trouble getting information so it might not be built to spec...
And I have had pretty mixed feelings about it in use. Recently I lent it to a studio that did a comparison to 3 other compressors on a mix and the Pico came in last (sounded 'cheapest').

I'm with Doug here, I have 8 channels of Pico from the 1st iterations to the 2nd most recent (The P3) and they all sound excellent, nothig cheap about them.  There must be some problem with it.  If you decide to sell let me know, I'm looking for a VCA comp donor project.

Quote from: Geoff004
Sorry to try to steer the thread differently, but why not design some kind of gate or dynamic noise reducer into a nice little package (maybe 500 series, maybe not - I don't think anything like that exists for that format).  I've got an ancient Burwen VCA-based noise reduction unit and would love to have more.

I think you'll find very little demand for a noise reducer, software does these tasks much more efficiently these days where it still struggles with compression that feels right.

Re the question about posting Pico schematics this may help
http://waynekirkwood.net/forum/php/viewtopic.php?f=7&t=300&sid=18ce537c9ddc1d3350c334e7b849971a



JohnRoberts

Re: any love for a new THAT comp discussion?
« Reply #18 on: April 08, 2011, 03:45:50 PM »
Just make sure not to put up any pico schem's here, obviously.

Why not? They originally put it in the public domain, didn't they?

Legality aside, taking something that a person doesn't want to give away is not very gracious.

I guess it comes down to personal philosophy, my participation here is mostly to help people who want to learn, not trying to get something for nothing.

JR
Visit https://circularscience.com to hear what properly "cleared" drums sound like.

ruairioflaherty

Re: any love for a new THAT comp discussion?
« Reply #19 on: April 08, 2011, 03:55:29 PM »
Quote from: JohnRoberts
I guess it comes down to personal philosophy, my participation here is mostly to help people who want to learn, not trying to get something for nothing.

John,

It's hard to explain just how much I've learned from your posts. The effort does not go unappreciated, thank you.


 

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