companders - NE/SA/571/2/3

[samhay]

The NE570, NE571 and NE572 companders don't seem to be mentioned very often around here, but have come up in the Maplin noisegate thread and they are threatening to become the star of one of Rob's epic threads. It seems that they should be quite useful in compressors and swell effects (expanders) and seem to have better noise specs than the OTAs that get used for a lot for these applications.
Unfortunately, I don't seem to be able to find a lot of info available beyond the datasheets, so thought this thread might be a good place to dump any useful info on these chips - particularly applications and anecdotes.

As a note, these chips are still in production by ON Semi as the SA570/1/2 in SOIC and TSSOP formats - PDIP chips seems to be discontinued, but both NE and SA-branded chips in PDIP format are still fairly easy to come by for a few dollars/piece.

datasheets: http://www.onsemi.com/PowerSolutions/parametrics.do?id=969
compandor cookbook: https://www.onsemi.com/pub/Collateral/AND8160-D.PDF

I found mention of the 'Penultimate' dual band compressor published in the Aug 1983 edition of Polyphony (here: https://www.paia.com/talk/viewtopic.php?f=32&t=605). However, it looks a little over-engineered for guitar use - do we really need to buffer the attack and release capacitors? - and the compressor section is very similar to the datasheet example.

[wavley]

Cool audio also makes a 571 and a 575.

I keep meaning to order a replacement 570 for a Digitech RDS-900 that I love. 

Compandors are something I've been meaning to mess around with, there are a few circuits I've played with that could maybe benefit from companding.  It works really well (almost too well) in the RE-501 Space Echo to the point that my RE-101 is way better for fun hissy self oscillation.

[electrosonic]

The Stompbox cookbook uses them extensively.

There is a book by Thomas Henry - Making music with the NE570 Compander. Covers the basics - I couldn't find a copy elsewhere so I bought it via iTunes.

https://itunes.apple.com/ca/book/making-music-ne570-compander/id444134608?mt=11

The link is for the Canadian iTunes store - not sure how that works internationally.


Andrew.

[GGBB]

I have two NE572 but I have no idea what to do with them. Noise gate or compressor projects would be cool. Was also thinking about trying to get more headroom out of a small clone in an effects loop. I'll have to look through the stompbox cookbook.

[armdnrdy]

I have two NE572 but I have no idea what to do with them.

If you need something challenging....the ADA STD-1 uses a 572. 

[Mark Hammer]

The 571 and 570 are interchangeable, both with each other and across prefixes.

The 572 is a somewhat different beast.  It is NOT pin-for-pin replaceable.  The additional buffering of time-constant cap is useful in some applicatiojns, but for most of what we use it for here, such features are superfluous.  Quite honestly, the Figuerdo Penultimate Compressor, referred to, is the only musical application I've ever seen.  Not that it couldn't be; but it just isn't.  That particular design uses the independently adjustable attack and release characteristics to provide for multi-band (well, dual-band) compression in a convenient form.

(Gah!  I spoke too soon.  I hadn't realized the STD-1 uses the 572.  Between that and the MN3011, that two pretty good reasons why we won't see anyone here clone that mythical beast.)

Incidentally, I would imagine that any of us actually owning a 572 would have gotten it at Radio Shack?

Finally, the AMS-100 envelope/trigger extractor circuit makes ample use of a 570/571: http://hammer.ampage.org/files/Device1-1.PDF

[GGBB]

Incidentally, I would imagine that any of us actually owning a 572 would have gotten it at Radio Shack?

They were given to me by a colleague who has a strong electronics background (he's now in IT) and knows about my pedal tinkering. And yes, they were in the original RS packaging (Archer?).

He's now moving from house to condo and getting rid of as much stuff as he can. I got word last week that he's found some BBDs for me - not sure which ones but probably MN3004 (he said they were 512 stage MN series). I've asked him to keep an eye out for anything germanium as well. Maybe if an MN3011 turns up I'll think about cloning the ADA. Anyone happen to have a layout? 

[armdnrdy]

I hadn't realized the STD-1 uses the 572.  Between that and the MN3011, that two pretty good reasons why we won't see anyone here clone that mythical beast.)

Mark, you seem to have no faith in your fellow man. 

I've sourced both the MN3011 & a lot of 572s. I also "acquired" (from a very kind ebay seller) very detailed images of the STD-1 board.

The above items along with the factory docs for good measure....this should allow me to work up a cut down, more guitar friendly version of the original rack unit. This one's definitely on my list!

[Calambres]

The PT-80 delay, the Ibanez AD-80, BOSS DM-2 and the Joyo Analog Delay all use the 570/571...

[deadastronaut]

threatening to become the star of one of Rob's epic threads.

indeed it might.....

[PRR]

> 'Penultimate' dual band compressor... the compressor section is very similar to the datasheet example.

The chip is a fairly complete fairly complex level controller. Unlike a naked optoresistor or even an OTA, there are not many different ways to connect it. If you are not happy with what the chip was meant to do (compand telephone lines!), use something else.

> it looks a little over-engineered for guitar use

First you think it is too plain (datasheet-copy), and then you think it is too fancy?

> do we really need to buffer the attack and release capacitors?

That's a bizarre thing.

I am pleased that I have forgotten most of what I once knew about the '57x chips. They had a lot of funny quirks which were fine for (even intended for) telephone companding, which we had to work-around to change the action.

The op-amps without the diodes form a near-perfect bootstrap. My snap one-coffee impression is that this makes the time-constant infinite? No, that is wrong. It will quickly charge to 1.1V and then act like a grounded capacitor? Seems to me there were internal offsets and we had to gimmick them with tricks like this. I spent way too much time thinking about such problems, before realizing I was wasting my time twisting a dedicated telco compander into anything else.

> do we really need to buffer the attack and release capacitors?

What does it "cost" you? Eight op-amps is a stunning quantity but costs less than one soda-pop drink. The Rs and Ds are even cheaper. Board-space costs money when you build acres of boards but in DIY-land a couple square inches comes out of your stash-pile.

It is also bizarre to see a comp/limiter with NO knobs. No input, output, or threshold, no attack, release, or ratio. It probably hews to the telephone compander's low ratio, selected to make it do the same thing at any input level. A box which *only* does low-ratio with no choice IMHO is bland and limited. A Ross or an RNC will give choices. The Ross is cheaper/simpler and the RNC is a far nicer and more flexible box.

Oh, and the 'Penultimate' will sound a LOT better if the output cap C33 is 2uFd instead of 2pFd. And I suspect he did not actually listen to a build with LM324 in the active filters.

[Mark Hammer]

I hadn't realized the STD-1 uses the 572.  Between that and the MN3011, that two pretty good reasons why we won't see anyone here clone that mythical beast.)

Mark, you seem to have no faith in your fellow man. 

I've sourced both the MN3011 & a lot of 572s. I also "acquired" (from a very kind ebay seller) very detailed images of the STD-1 board.

The above items along with the factory docs for good measure....this should allow me to work up a cut down, more guitar friendly version of the original rack unit. This one's definitely on my list!

"Fellow man" presumes peers.  I made no assumptions about my betters!

Jeorge Tripps graciously bestowed me with a 3011 nearly a decade ago.  I keep meaning to turn it into a scaled-down STD-1....AFTER I finish the Hyperflange...sigh. 

[armdnrdy]

"Fellow man" presumes peers.  I made no assumptions about my betters!

You're killing me Mark! Betters?
Put aside all of the time that you graciously spent helping me off site....
I have learned more from your posts directed at other people than you probably realize! 
And I thank you!

[samhay]

Thanks for the replies.
Have had a quick look at the Stompbox cookbook - looks like the NE570/1 is mostly used for tremolo effects, but nice to see something new.
Somehow missed the Thomas Henry book, but seems like that was exactly what I was looking for.

Paul - you are quite possibly correct that the only way it will work properly as a compressor as per the datasheet.
>It is also bizarre to see a comp/limiter with NO knobs. No input, output, or threshold, no attack, release, or ratio. It probably hews to the telephone compander's low ratio, selected to make it do the same thing at any input level. A box which *only* does low-ratio with no choice IMHO is bland and limited.
That's where I was going with the "Penultimate" design. Some aspects are over-designed for guitar work, yet with all those op-amps, all you get is a box with an on/off switch.

I also came across a 1-chip NE570/1 compressor designed by mictester on the other forum. Haven't lined it up against the datasheet example, but he seems to like it at least.

[Mark Hammer]

A lot of folks will tell you that compressors for bass need to be different than those for guitar, simply because the range of fundamentals necessitates different time constants for different parts of that range.

[wavley]

The 571 and 570 are interchangeable, both with each other and across prefixes.

When used under 18 volts the 570 and 571 are interchangeable, as I found when replacing a 570 with a 571 in my RDS-900, it lasted a while.