SA571 - Noise gate with 1 simple IC?

[smoguzbenjamin]

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! 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:

[R.G.]

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.

[smoguzbenjamin]

Cool 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

[Brian Marshall]

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

[humbuck]

I  wonder how long it will be 'till someone figures out how to make a compressor with it!  The thought of a cheap easy to make compressor makes my mouth water!

H.

[Brian Marshall]

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.

[Paul Perry (Frostwave)]

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).

[ExpAnonColin]

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

[Ansil]

i went ahead and did a basic compressor based off of the application notes.   i will try to post it later.

[Boofhead]

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).

[smoguzbenjamin]

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?

[Nasse]

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  

[Boofhead]

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.

[Paul Perry (Frostwave)]

More than likely the June 2000 Silicon Chip unit by Leo Simpson..

No, that uses the SSM2018 VCA.

[Boofhead]

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.

[smoguzbenjamin]

Yes but howabout the SA571 ? :lol:

[Boofhead]

For all practical purposes:

SA570 = NE570 = SA571 = NE571

all the same.

SA572/NE572 is very similar but not same -as indicated previously

[ExpAnonColin]

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:


Sounds like it would be a perfect fit for you, smoguz.
http://www.midwest-analog.com/catbooks.html

-Colin

[Boofhead]

the 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.

[smoguzbenjamin]

Hey thanks for the link Colin
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?