SSLtech
Well-known member
-So this is a spinoff of the PWM Limiter project that cropped up in the GML opamps thread.
Kev is hosting some pdfs of the schematic, currently there are errors in it, but I've sent revisions off to him. When he updates the hosting I'm sure either he or I will post here to let everyone know.
Kev's home:
http://www.celestial.com.au/~rosswood/data/CompressorSchematic.pdf
some values are unmarked because they haven't been figured out... but that's part of the idea... I would like someone to pick it up and run with it. -The idea here is to try and increase the number of viable projects on the forums, so that there's more to "The Lab" than just cloning and ripping off.
The gain reduction element has been tested to about 40dB gain reduction. The distortion and noise is acceptable on the bench... should be more than acceptable for an interestingly-flavoured instrument limiter... let's see!
The idea is to use reasonably well-available components in an interesting manner, and get away from the old "Well, it's optical so people are going to compare it to an LA2a"... or "It's a FET, so it'll be compared to an 1176"
This is a feedback limiter, with nice accurate gain reduction metering from a simple VU meter, which -in typcal Bill Putnam style- uses a DC voltage modulated in a similar tracked manner to the audio AC signal. That's where the design block layout is tried and tested.
Other than that, it's a PWM "chopper" that's used for gain reduction. The technique is used in Crane Song and Studer compressors, as well as several others that I've probably never seen. It's uncommon, but different solutions usually produce different results...
I'm handing this over to everyone else to play with. My ideal wish is for this to be turned into a working project. Everyone could then have something to do which isn't mired in copyright complexity. Whilst I enjoy recreating classics, and it's undeniable that if you're going to DIY something, then doing something of proven value is naturally more attractive than an unknown and unproven thing, I really, really believe that we should collectively try to be be more original. There's no vanity involved; if this idea turns out to be a piece of unworkable crap, but it prods someone to share something else, or jogs an unrelated idea that they in turn can share with the group, then the group will be the richer and better off as a result...
I'll post a circuit description later this evening, or possibly tomorrow... I'm a little busy today!
Have fun!
Keith
Kev is hosting some pdfs of the schematic, currently there are errors in it, but I've sent revisions off to him. When he updates the hosting I'm sure either he or I will post here to let everyone know.
Kev's home:
http://www.celestial.com.au/~rosswood/data/CompressorSchematic.pdf
some values are unmarked because they haven't been figured out... but that's part of the idea... I would like someone to pick it up and run with it. -The idea here is to try and increase the number of viable projects on the forums, so that there's more to "The Lab" than just cloning and ripping off.
The gain reduction element has been tested to about 40dB gain reduction. The distortion and noise is acceptable on the bench... should be more than acceptable for an interestingly-flavoured instrument limiter... let's see!
The idea is to use reasonably well-available components in an interesting manner, and get away from the old "Well, it's optical so people are going to compare it to an LA2a"... or "It's a FET, so it'll be compared to an 1176"
This is a feedback limiter, with nice accurate gain reduction metering from a simple VU meter, which -in typcal Bill Putnam style- uses a DC voltage modulated in a similar tracked manner to the audio AC signal. That's where the design block layout is tried and tested.
Other than that, it's a PWM "chopper" that's used for gain reduction. The technique is used in Crane Song and Studer compressors, as well as several others that I've probably never seen. It's uncommon, but different solutions usually produce different results...
I'm handing this over to everyone else to play with. My ideal wish is for this to be turned into a working project. Everyone could then have something to do which isn't mired in copyright complexity. Whilst I enjoy recreating classics, and it's undeniable that if you're going to DIY something, then doing something of proven value is naturally more attractive than an unknown and unproven thing, I really, really believe that we should collectively try to be be more original. There's no vanity involved; if this idea turns out to be a piece of unworkable crap, but it prods someone to share something else, or jogs an unrelated idea that they in turn can share with the group, then the group will be the richer and better off as a result...
I'll post a circuit description later this evening, or possibly tomorrow... I'm a little busy today!
Have fun!
Keith