Adding an External Sidechain to an Aphex Compellor 320A

[cpsmusic]

Hi All,

I picked up an Aphex Compellor 320A a while back. I've been using it lately as a mix bus compressor and really like it, as it adds "cohesion" in a very transparent way.

The problem I've run into is that I often need to print stems which I can't do as the 320A doesn't have an external sidechain.

Would it be easy/hard/impossible to add an external sidechain to one one of these?

I've attached a schematic of the unit's main board.

Cheers,

Chris

 

[abbey road d enfer]

The problem I've run into is that I often need to print stems which I can't do as the 320A doesn't have an external sidechain.

What do you mean? I don't understand how an external side-chain to a comp/lim would help printing stems.
Are you mixing in harware or from a DAW?

Would it be easy/hard/impossible to add an external sidechain to one one of these?

Do you mean an input for an external signal to feed the side-chain?
This should be easy.
You need to interrupt the connection from H101-3 and use H101-4 as input.
It would help if we had the schemo of the other parts of the unit

 

[cpsmusic]

If you want the sum of the stems to be the same as the original mix, and you have a compressor on the mixbus, then you need to send the full mix to the compressor's sidechain as each stem is processed. Otherwise the each stem only gets the gain reduction of its own signal which is not the same as that of the full mix.

I think I've got the rest of the schematics for the Compellor somewhere - I'll have a look for them and post them.

Cheers!

 

[cpsmusic]

Here's more of the schematic:

 

[abbey road d enfer]

If you want the sum of the stems to be the same as the original mix, and you have a compressor on the mixbus, then you need to send the full mix to the compressor's sidechain as each stem is processed. Otherwise the each stem only gets the gain reduction of its own signal which is not the same as that of the full mix.

Then, what is the point of creating stems? I thought it would give the possibility to process them individually. Applying a predefined compression to something that's gonne be altered seems weird to me...
I am amazed at how new practices make things more complex, now that technology has made the essence of the work easier.
I see the same thing going in live sound reinforcement, when it takes a crew of five to do what used to be done by a single SE.
Call me outmoded.

 

[abbey road d enfer]

Here's more of the schematic:

There's a connection that must be interrupted between H101-3 on the first board and the same H101-3 on the other board. Is tehre a ribbon cable between them or are they both PCB connectors?
That means either cutting in a ribbon cable of cutting a PCB track.

 

[cpsmusic]

Then, what is the point of creating stems? I thought it would give the possibility to process them individually. Applying a predefined compression to something that's gonne be altered seems weird to me...
I am amazed at how new practices make things more complex, now that technology has made the essence of the work easier.
I see the same thing going in live sound reinforcement, when it takes a crew of five to do what used to be done by a single SE.
Call me outmoded.

Stems are mainly used for remixing and for DJs doing club mixes. Some mastering engineers work from stems too.

 

[cpsmusic]

There's a connection that must be interrupted between H101-3 on the first board and the same H101-3 on the other board. Is tehre a ribbon cable between them or are they both PCB connectors?
That means either cutting in a ribbon cable of cutting a PCB track.

I'll have a look - from memory there is a ribbon cable.

 

[abbey road d enfer]

Stems are mainly used for remixing and for DJs doing club mixes. Some mastering engineers work from stems too.

I understand that. What I don't get is what's the point in keeping the same compression, when the mix is different.

 

[nick_t]

If you want the sum of the stems to be the same as the original mix, and you have a compressor on the mixbus, then you need to send the full mix to the compressor's sidechain as each stem is processed.

But it won't be the same even if you do that. Say you have 24 stems to print off. At minimum, the sum of the stems will contain 24x the Compellor’s noise and distortion levels.

 

[cpsmusic]

But it won't be the same even if you do that. Say you have 24 stems to print off. At minimum, the sum of the stems will contain 24x the Compellor’s noise and distortion levels.

That's true, but I'm not sure there's any other method that gets as close?

 

[nick_t]

I guess I agree with abbey road denfer, and not quite seeing the benefits. eg. why would you want the sound of a peak limiter kicking in on every individual track, if the thing that actually caused the peaks in the first place isn't as loud in the mix any more?

 

[cpsmusic]

I'm not actually sure of the benefits of this either, other than it's often something that is requested. Possibly it's because whoever is using the stems wants a mix of, say, nine out of the ten stems, and that these sound basically the same as the full mix. I think I'll ask about this over at one of the production forums.

 

[scott2000]

I think I'll ask about this over at one of the production forums.

Maybe reach out to Kevin Grainger at Wired Masters and tell him exactly what you're trying to do and what the best way to go about it would be. He's very helpful from my memory and has been at the stem thing for quite some time.