Questions about Keeley compressor schematic.

[mattis03]

So I was thinking about building this schematic. But there are some things that I'm unsure about.

First of all, clip and attack knobs on compressor, what do they do?

The pots are reffered to with numbers from 1 to 3, are these representing the 3 legs of a pot?

How am i supposed to know which of the capacitors on the schematic that are polarized?

They say on the website that you can use the LM13700 instead of ca3080. If you would do this, what do you do with the other unused pins?

thanx in advance

[antonis]

C3, C4, C7 & C9 can be either polarized (electro) or not (film) as long as board pin spacings are coincided.. 



EDIT: Ignore my  POT lugs numbering..!!!
(inconsistency between schemnatic and layout..)

[Ben N]

Hi, Mattis.

First, as a point of comprehension, what you posted is a layout, not a schematic, but an actual schematic is what you should post to help anyone responding answer your questions. This is a schematic:


Now, to start answering your questions:

First of all, clip and attack knobs on compressor, what do they do?

I'm not sure about clip, but it seems to be a saturation control for the OTA (LM3080) which allows more or less full-range signal in, with the bass saturating the chip.
Attack controls generally control how quickly compression kicks in from the time the note is sounded, and therefore how much of the attack of a note is left unmolested.
But I'll defer to someone who knows more about compressor circuits than me to confirm or deny.

The pots are reffered to with numbers from 1 to 3, are these representing the 3 legs of a pot?

Yes.

How am i supposed to know which of the capacitors on the schematic that are polarized?

On the schematic, the polarized caps are symbolized by a flat and a curved line, or have a + sign to show polarity--in this case both.

This isn't always true, but here all the caps of 1uf or above are polarized electrolytics; everything below 1uf is a non-polarized (probably film or ceramic) cap.
On the layout you posted, the electrolytics, all of which are polarized, are circular.

They say on the website that you can use the LM13700 instead of ca3080. If you would do this, what do you do with the other unused pins?

Concerting a circuit from CA3080 to LM13700 is a bit more complicated than that, AFAIK. I recommend you do a search of the forum, because there have been several discussions on this question in general and in connection with a number of specific circuits since the 3080 went the way of the dodo.

thanx in advance

Don't mention it.

[amz-fx]

First of all, clip and attack knobs on compressor, what do they do?

The Clip knob is to reduce distortion that is coming from the CA3080.

The Attack control is actually a Decay (Release) time control. It sets the amount of time it takes for the compression to return to its normal baseline once the signal drops below the threshold.

The CA3080 is still available from Rochester Electronics: https://www.rocelec.com/part/REICA3080AE

The compressor will not work as drawn in that schematic since Q3 and Q4 are missing a connection. 

regards, Jack

[aion]

The compressor will not work as drawn in that schematic since Q3 and Q4 are missing a connection. 

Yeah, that whole net connecting Q3-Q4, D1-D2, and R19-R20 should be grounded.

[PRR]

....The CA3080 is still available from Rochester Electronics: ....

"minimum quantity of 65 " -- i.e., minimum (about) $250 per item.

Small Bear was selling onesies/twosies but his stock may be in transition to new sellers.

[mattis03]

The compressor will not work as drawn in that schematic since Q3 and Q4 are missing a connection. 

Yeah, that whole net connecting Q3-Q4, D1-D2, and R19-R20 should be grounded.

What should i do instead to make it work then? 

[antonis]

The compressor will not work as drawn in that schematic since Q3 and Q4 are missing a connection. 

Yeah, that whole net connecting Q3-Q4, D1-D2, and R19-R20 should be grounded.

What should i do instead to make it work then? 

Absolutely nothing..
(both Q3 & Q4 Emitters, as wel as Diodes and respective Resistors, are grounded on layout posted..)

[amz-fx]

....The CA3080 is still available from Rochester Electronics: ....

"minimum quantity of 65 " -- i.e., minimum (about) $250 per item.

Small Bear was selling onesies/twosies but his stock may be in transition to new sellers.

While we wait for the Small Bear stock to be available again, there is always this one:

https://synthcube.com/cart/synth-diy/parts/ics-and-semiconductors/alfa-rpar-as3080-op-amp-ic-ca3080-replacement