http://www.semiconductors.philips.com/acrobat/datasheets/SA571.pdf
Check it out, in the applications bit one of them says "Low level expandorâ€"noise gate". Noise gate! :D that sounds good! But how? :? Can one of the allmighty gurus figure out what to do with this chip to make it a noise gate, and explain the pinout? 'Cause I'm confuzzled. I know what a regular fuzzbox does but this is way above my head. :lol:
There's an expandor noise gate with the 571 in an article from Electronics and Music Maker somewhere in my archives. Yeah, low level mistracking on an expandor makes an OK noise gate.
Cool :D to Geofex!
edit: Am I a dumbass or can I just not find the archives anywhere. I searched Geo for 'compander' and 'SA571' with no results :(
I have one of these laying arround from when i was working on my ADA MP-1. I've been meaning to play arround with it. Seems like you could build a really compact compressor, and i seem to remeber it can be used for envelope controled stuff as well
I wonder how long it will be 'till someone figures out how to make a compressor with it! :D The thought of a cheap easy to make compressor makes my mouth water!
H.
I'll take a look at it... now that i think about it i have a 572, which i s a little differnt, but same concept. It is used as a compressor in the ADA mp-1, at least one side of it is.
Just to muddy the waters, here are some links to the NE570 and NE572 thanks to Midwest Analog Products.
http://www.midwest-analog.com/diychips.html
(by the way, SE and NE chips are interchangable).
The NE570/571 and SA570/571's are very very popular in analog delays. They have a TON of applications, you could use them as a compressor, a noise gate, a "slow gear", etc etc etc.
-Colin
i went ahead and did a basic compressor based off of the application notes. i will try to post it later.
The appnotes Paul posted are a good start for these devices. The main differences between the 572 and the 570/571 is the 572 has independent attack/release times but does not have an internal opamp. The opamp on the 570/571 is actuall quite crappy, it's not exactly quiet either (but quieter than delay lines).
So, compressor, noise gate, slow gear... sounds like I need more than one of these chips :)
I'm kinda crappy in reading appnotes & turning them into a guitar ckt so :lol: Anyone help make a noise gate out of this?
One of circuits that I have lost is one nice stereo compressor article in some european or american electronic mag. The chip was 570 or 571, the project was named "CD compressor" or "Australian..." or something thereabouts and the author had designed the project for reducing cd ´s dynamic range suitable for recordin to casette tape with less dynamic range. There was very good looking pcb, no exotic components and specs were good. I thought that would be nice compressor for home studio for multi synth or tape or computer track mixdown. The designer was from Australia. I have lost that magazine :(
More than likely the June 2000 Silicon Chip unit by Leo Simpson.
http://www.altronics.com.au/cat.asp?cat=11&grp=426&id=K5580
I'm familiar with that unit but I've never seen the circuit.
Quote from: BoofheadMore than likely the June 2000 Silicon Chip unit by Leo Simpson..
No, that uses the SSM2018 VCA.
Thanks Paul, it's not that one then. Now at least I know it's using a SSM chip - the Silicon Chip limiter used an SSM chip.
Yes but howabout the SA571 ? :lol:
For all practical purposes:
SA570 = NE570 = SA571 = NE571
all the same.
SA572/NE572 is very similar but not same -as indicated previously
Boofhead-the NE570 is supposed to have the "best specs". I wouldn't know, a pretty knowledgeable guy on the HCFX forums told me.
I'm surprised no one has mentioned this:
(http://www.midwest-analog.com/graphics/bk570.jpg)
Sounds like it would be a perfect fit for you, smoguz.
http://www.midwest-analog.com/catbooks.html
-Colin
Quotethe NE570 is supposed to have the "best specs"
I know, but out of all the 570's and 571's I've measured I've found *little to no difference between the two* -especially re. noise. They are the same device after all. The 570 is just selected from a sort and is usually quite a bit more expensive, it appear the majority of the devices (and hence the 571) are still "good". The 570 is quoted to adhere to certain telecomunications specs - I believe that was the main reason for it's existance otherwise you couldn't just plug it into the telecoms applications.
Hey thanks for the link Colin :D
Automatic gain control... Would that be a noise gate?
edit: does anyone know the ISBN number for that book so I can check the library?
QuoteAutomatic gain control... Would that be a noise gate?
No an AGC tries to keep a constant output when the input varies - for example if you want to keep a mic to keep a constant output level on the PA regardless of how loud someone speaks, or where they hold the mic.
You might be getting the wrong impression from those app notes about the noise gate function. The noise gate is not just a noise gate it's actually an expander first but with a noise gate function thrown in *with the expander*. This is done by making the expander mistrack at low levels.
If you have a compressor then feed this into an mistracking expander you get a noise gate without the overall expansion function but it requires two stages and it's kind of a crappy implementation.
What you want is a fixed gain at high levels and a lower gain at low levels - that doesn't quite fit in with the circuits in the app notes.
Ah. :lol: damn
Quote from: NasseOne of circuits that I have lost is one nice stereo compressor article in some european or american electronic mag. The chip was 570 or 571, the project was named "CD compressor" or "Australian..." or something thereabouts and the author had designed the project for reducing cd ´s dynamic range suitable for recordin to casette tape with less dynamic range. There was very good looking pcb, no exotic components and specs were good. I thought that would be nice compressor for home studio for multi synth or tape or computer track mixdown. The designer was from Australia. I have lost that magazine :(
Hi Nasse,
That was an article called "Compressor for Compact Disks" that first appeared in "Electronics Australia" in the May 1986 edition, by Colin Dawson. I saw it in a short-lived Canadian magazine called "Hands-On Electronics" - the article appeared in the January 1987 edition. And the chip was an NE572.
I built one channel of the compressor to use for guitar and used the other half of the NE572 as a noise gate. Both operated independently. As far as I can remember the compressor worked quite well and I modified the circuit to make use of the adjustable attack and release times (the original circuit had these optimized and fixed for audio hi-fi signals). Can't remember what happened with the noise gate part....
Given time and a few beers I could scan the article for you. I may even be able to find my original circuit but don't hold yer breath, I have to wade through mountains of my wife's spinning and weaving equipment to get to the boxes where it may be stored.
Cheers,
Peter
:o Wow, thats a nice offer :o
Dont know what I can do for you, but maybe something pops up. I still have not access to good scanner, but maybe it changes soon. Take your time, no hurry, I dont worry but just remembered it was nice article.
Hi Nasse,
Send me your email address.
psnow@magma.ca
Thanks,
Peter
Hi Nasse,
I have scanned the article, if you want it.
Peter
Sure, did you receive my e-mail address. I owe you some beers, cheers, or I should offer you a bottle of Koskenkorva.
Hey peter, mind sending that article to smoguzbenjamin@hotmail.com? :)
And how about sending a copy to me? Email edguidry@lafourche.com. I have an extra chip, and I want to make a compressor for my acoustic.
Thanks.
Hey, what about me?
munkydiy@hotmail.com
Peter:
Please count me in as well:
d<NOSPAM>mcevoyATvoyager.net
You can probably guess what to do with <NOSPAM>. Also what to convert AT to. Sorry, I just don't need any more spam! The 'bots seem to be all over the place!
Don't worry Dave, no bots here as far as I know. :)
Count me in also!!!
Thanks!
Arn C.
arn.conklin@ametek.com
I have a copy of the 570-Noise-Gate article from E&MM that RG sent me years back. I can scan that and post it. Hell, I think I even know where it is!
And yes, 570=571 for the most part, with 570's reputedly being better in the noise department. Like most chips, though, I imagine that evaluating the noise-level differences is a function of the context in which you evaluate it. I expect there will be applications where there is no earthly difference with respect to noise. Note that the NE572 is an entirely different chip. It IS a compander but it is not simply "one better" (as Nigel Tufnel would say).
Although compander chips can function as noise gates, the chief difficulty with them is that the time constants (attack/decay) are set by a single cap. A noise gate that has minimal flutter/stutter and captures the initial attack of the note needs a fast attack and slow decay. The single-cap aspect means you get fast decay with fast attack and slow attack with long decay. I suppose there are compromises that can work, and settings that work terrific for somebody, but ultimately having the rectifier buried deep in the bowels of the chip makes it less tweakable.
Mark, if you could give me that article that would be the best late X-mas present ever! :)
I just checked the spec's of 570/571. Very small differences, noise figures are the same. The only significant diff is 570 max supply voltage = 24V, 571 = 18V.
Kindest regards, Bernt.
:oops:
Quote from: NasseSure, did you receive my e-mail address. I owe you some beers, cheers, or I should offer you a bottle of Koskenkorva.
Nasse,
Sorry, I did not get your email. Can you try again please? Or if you're worried about spam maybe post your email address here with changed characters like AT instead of @, like someone else has done.
Thanks,
Peter
I have emailed the article with the following exceptions:
smoguzbenjamin@hotmail.com All 5 pages was too big, so I re-sent just the page with the schem.
Nasse - no email address yet!
Dave. I get the following error message when I email to your address. Not sure where it's coming from - my ISP or yours or some place in between. I'll keep trying.
550 5.7.1 *** We do not accept spam ***
Hey! I'm no spammer :)
Cheers,
Peter
Dave,
It's gone through now. Wonder why they thought a compressor was spam? :roll:
My e-mail address is <edited by Nasse>, and dunno how big files it can handle, :lol:
BTW, I got some unsuccesful Delivery Message from your e-mail, Peter. There happened be some overhaul at surfeu/tiscali that time so maybe it was because of it, not your e-mail address, or I did a typo
I found 572 is available for about little over 3 euros in Finland, and data sheets and application notes at Philips (just Googled NE572)
Hi Nasse,
Thanks, I'll send it when I get home this evening.
Going back to what Mark said about attack and recovery - on the NE572 both of these can be set by capacitors on pins 2, 4 and 12, 14. But when I built this compressor I used pots in addition to the caps to allow control over these two parameters. I can't remember how I did - I'll have to dig out the circuit and refresh my memory.
Peter
If you want a really sophisticated noise gate you should think about the Drawmer DF320 noise filter. This uses a couple of That (DBX) 2150 VCA chips and a SSM (or is it an?) 2120 and some very sophisticated English circuitry.
Peter,
That's one of the advantages of the 572 over the 570/71 from what I understand. The 570/71 obliges you to assign the two tasks to one cap.
Quote from: Peter Snow
Going back to what Mark said about attack and recovery - on the NE572 both of these can be set by capacitors on pins 2, 4 and 12, 14. But when I built this compressor I used pots in addition to the caps to allow control over these two parameters. I can't remember how I did - I'll have to dig out the circuit and refresh my memory.
Peter:
I'd sure like to see how you did that! For example: would the "recovery" pot translate into a "sustain" pot, or do you have to have a dual-ganged pot controlling both the "attack" and "recovery" parameters in order to produce "sustain".
All I'm interested in is clean sustain. I don't need to worry about any other compressor uses. No "chicken pickin'" for me!
I have a Flatline on the breadboard now. I must confess that this is the first circuit I've encountered that looks like it would be easier to build than breadboard! This 572 thing looks great if I can figure out how to make it sustain -- any ideas? Tom Scholtz didn't write the chip's app notes!
Quote from: Peter Snow
Going back to what Mark said about attack and recovery - on the NE572 both of these can be set by capacitors on pins 2, 4 and 12, 14. But when I built this compressor I used pots in addition to the caps to allow control over these two parameters. I can't remember how I did - I'll have to dig out the circuit and refresh my memory.
Peter:
I'd sure like to see how you did that! For example: would the "recovery" pot translate into a "sustain" pot, or do you have to have a dual-ganged pot controlling both the "attack" and "recovery" parameters in order to produce "sustain".
All I'm interested in is clean sustain. I don't need to worry about any other compressor uses. No "chicken pickin'" for me!
I have a Flatline on the breadboard now. I must confess that this is the first circuit I've encountered that looks like it would be easier to build than breadboard! This 572 thing looks great if I can figure out how to make it sustain -- any ideas? Tom Scholtz didn't write the chip's app notes!
Is it possible to use "steering diodes" for attack & decay on a single cap?
Hi David,
As far as I can remember I put a pot in series with each of the caps. In my ignorance I thought that would allow adjustment of the attack and decay times - and it seemed to work. But at that stage I had never built or used a compressor. Since then I have a greater appreciation of how a compressor works and what it is supposed to sound like. So I will have to dig out the circuit board and take another look - it has been a while....
Cheers,
Peter
Even if you have to use switches to select individual cap values, being able to select one cap for attack time and another for recovery time, would be a boon.
One of the things that has not been discussed much here is multi-band devices. There is a feature article in the current (I guess soon to be recent) issue of Electronic Musician on multi-band compression. The article devotes much of its space to software über-compressors, but the basic principles are still the same.
An old article in POLYPHONY magazine in 1982 or so outlined a two-band compressor built out of the two halves of an NE572. The thing about compression, and to a lesser extent gating, is that the time constants needed for one part of the frequency spectrum are different than those needed for another part of the spectrum. That particular project used a simply active frequency divider (lowpass and highpass filter) to split the spectrum up, with each segment passing through its own compressor path with its own time constant cap values, before being mixed down. This generally makes for a more transparent compression when using gain cells like the 570/571/572, and probably when using OTA-based compressor paths as well, though I have never seen any multi-band devices using a 3080, 3094, or 13600/700.
http://www.promelec.ru/pdf/ne572.pdf
http://www-eu4.semiconductors.com/acrobat/applicationnotes/AN175.pdf
http://www.web-ee.com/primers/files/AN176.pdf
Just Googled those, maybe some info can be found there.
Mark,
We discussed this multi-band comp a while back. Could you scan the compressor article when you get a chance (No hurry, I've got a few things on the burner right now) because I'm really interested in building me one for my acoustic guitar. I think it would be really good for the extended frequencies that an acoustic puts out.
Quote from: Mark HammerEven if you have to use switches to select individual cap values, being able to select one cap for attack time and another for recovery time, would be a boon.
One of the things that has not been discussed much here is multi-band devices. There is a feature article in the current (I guess soon to be recent) issue of Electronic Musician on multi-band compression. The article devotes much of its space to software über-compressors, but the basic principles are still the same.
An old article in POLYPHONY magazine in 1982 or so outlined a two-band compressor built out of the two halves of an NE572. The thing about compression, and to a lesser extent gating, is that the time constants needed for one part of the frequency spectrum are different than those needed for another part of the spectrum. That particular project used a simply active frequency divider (lowpass and highpass filter) to split the spectrum up, with each segment passing through its own compressor path with its own time constant cap values, before being mixed down. This generally makes for a more transparent compression when using gain cells like the 570/571/572, and probably when using OTA-based compressor paths as well, though I have never seen any multi-band devices using a 3080, 3094, or 13600/700.
I loaned all my POLYPHONY issues to Peter Snow, although I may have a photocopy sitting around somewhere. The easy part will be finding it since we have in-laws coming to stay in a week and a half and I have to clean up. The hard part will be getting my scanner back from my son.
Hi Mark,
Must be telepathy - I just got through reading that edition of Polyphony. I could scan the compressor article and send it to Ed, but my scanner is down right now (changing PC's and having trouble). Hopefully it will be back in action tomorrow night.
BTW, thanks for the loan Mark, I have nearly finished reading them all, a great set of resources and a lot of nostalgia. I particularly like an ad in the "user equipment for sale" section at the back of one of the early issues by some guy selling off a whole bunch of Moog analog synth equipment - the seller? Bob Moog!
Cheers,
Peter