Dumb Question: What's the "Quad" in SSL Quad

[Clueless]

I've become curious exactly what the Quad refers to when people talk about the Quad compressor. Google hasn't helped me answer the question. If I had a rack full of distressors, could I emulate a Quad compressor, and if so, how?

 

[AudioGaff]

I've become curious exactly what the Quad refers to when people talk about the Quad compressor.

The quad compressor is not a 4-ch compressor, I am almost postive it just the nick name given to it because it is the same compressor that came from the highly successful and still very popular SSL 4000G console which was their first console to offer dymanics on every channel as well as on the master section.

If I had a rack full of distressors, could I emulate a Quad compressor

No. I don't think so. The Distressor is great and flexable unit, but the famous SSL compressor provides a very unique sound. There is the Alan Smart C1 & C2 which are clone type versions of the SSL comp. You can get an updated two channel version of the quad from SSL in their new XLogic G-Series compressor.

 

[Clueless]

Hmmm, perhaps it's called a quad compressor because the master section of the SSL board had both a master stereo summing bus (2-buses) and a master stereo sidechain bus (2 more buses), and that the true sound of the SSL compressor is a function both of the stereo bus (mixed one way) and controlled (artfully) by the sidechain mix? In other words, the quad compressor's sound just wasn't there without suitable driving of the side chains?

M

 

[anonymous]

Just a guess here, but maybe it's called the quad compressor because it uses 2 VCA's per channel (one for the sidechain, and one for the audio path). A stereo implementation results in 4 VCAs in use...thus 'quad compressor'.

Cheers,

Kris

 

[AudioGaff]

2 VCA's per channel (one for the sidechain, and one for the audio path)

There ya go. Now that makes perfect sense. I was thinking quad as is 4 as in the 4K series.

 

[RecorderMan]

The Quad compressor on the mix buses of an SSL is quad...or four channel. LF, RF, LR and RR respectively. Usually only the front is getting used.

 

[anonymous]

The Quad compressor on the mix buses of an SSL is quad...or four channel. LF, RF, LR and RR respectively. Usually only the front is getting used.

Duhhh, or maybe it's called the quad compressor because it's actually set up for quad. Thanks recorderman! I've never used an SSL desk, so I had no idea.

Does this mean that you can split up the quad compressor on a 4000 series board into two stereo compressors? If so, then maybe you could patch one into a drum submix, and leave the other on the mixbus...

Cheers,

Kris

 

[Clueless]

Recorderman,

When all four channels are being used, does it behave the way a stereo compressor does for stereo, ie., a signal over the threshold on one of the four channels will effect gain reduction on all four channels?

 

[anonymous]

This one, I know....yes! The sidechains are set up such that any time the threshold is exceeded, all channels will receive gain reduction. Maybe its possible to unlink them (either through the patchbay, or a switch), but to my knowledge this was the way they worked (from some discussions on techtalk with RO member ssltech). Also, the autofade (and quad fader) was done through the compressor VCAs as well...

Speaking of techtalk, get yourself over there now, and fire up a soldering iron and make yourself a Quad compressor clone...its cheap, easy, and sounds great!

Cheers,

Kris

 

[RecorderMan]

Originally posted by Clueless:
Recorderman,

When all four channels are being used, does it behave the way a stereo compressor does for stereo, ie., a signal over the threshold on one of the four channels will effect gain reduction on all four channels?

yes

 

[AudioGaff]

Originally posted by RecorderMan:
The Quad compressor on the mix buses of an SSL is quad...or four channel. LF, RF, LR and RR respectively. Usually only the front is getting used.

RecorderMan, The built in compressor in the master section is quad, but I was referring to any outboard comp that has been made based on the quad from the 4000G was either in mono or in stereo only. Correct? (not including the newly released multichannel Xlogic unit)

 

[RecorderMan]

Originally posted by AudioGaff:

Originally posted by RecorderMan:
The Quad compressor on the mix buses of an SSL is quad...or four channel. LF, RF, LR and RR respectively. Usually only the front is getting used.

RecorderMan, The built in compressor in the master section is quad, but I was referring to any outboard comp that has been made based on the quad from the 4000G was either in mono or in stereo only. Correct? (not including the newly released multichannel Xlogic unit)

You are correct there. They make it so you can hook up two together. But yes...the outboard ssl ones and/ the Alan Smart ones (a copy of the SSL compressor that I like a lot) come stereo. The "Quad" is generic as a name at that point.

 

[Clueless]

OK, here's where I think my question gets answered:

short form: Quad compressor is a generic term to describe a style of compressor originally created by SSL.

long form: if you have a stereo compressor like a C1 or a C2 that bahaves like an SSL quad compressor, you can get a true quad compressor by doing the following: using the first compressor as "front" and the second as "rear", create four sub-mixes:

L-Front sidechain = Mix1 (L-F, R-F, L-R, R-R)
R-Front sidechain = Mix2 (ditto)
L-Rear sidechain = Mix3 (ditto)
R-Rear sidechain = Mix4 (ditto)

Feed L-F into "front" left input, with Mix1 into the sidechain.
Feed R-F into "front" right input, with Mix2 into the sidechain

and so forth.

"front" left out will be a true quad compressor L-Front output.

Did I get that right?

 

[Hack]

"oh man, I am so hi,... I have no idea whats going on"

-towlie

 

[CMajorMusic]

I think quad was the early version of sorround sound. There was a quad bus on old neves too. The quad compressor was used for 4 channel sorround mixes made. Thats what I have heard from a few engineers

 

[TimPiazza]

Quadraphonic recording was a short-lived surround sound format in the 1971-ish era. It lasted just a few years on the consumer end of things, but long enough for my dad to bring home a "top of the line" quadraphonic component audio system. The only component that didn't survive was the 4 channel 8-track cartridge recorder. I don't think that one was ever released to the market. He worked for Sylvania and they sold this stuff in the employee store.

You could actually buy quadraphonic records, and a few of the stylus manufacturers made special quadraphonic stylii for your turntable--though in truth, they used the same 4 wires so I suspect that was a lot of smoke and mirrors. I seem to recall a quad version of Dark Side of the Moon, and Rick Wakeman's "Journey to the Center of the Earth"--wow--there's a blast from the past!

Sorry for the intrusion, I'll return to lurk mode now.

Tim

 

[TimPiazza]

Hey, I'm back, I got curious and found something interesting. This quote is from the Roncocas Valley Journal of Applied Mathematics...

"Four channel magnetic tapes were first to appear, followed by quadraphonic LP's. Both required an additional outlay for equipment, but whereas the magnetic tapes were genuine, the quadraphonic LP's were a complete fraud. Elaborate technical articles appeared in magazines such as Popular Electronics explaining how they worked, but the mathematics was completely incomprehensible. The editors, fearing to admit ignorance, published them with tacit approval, just as the naked emperor paraded in the Hans Christian Anderson story. Rather than attack the technical articles point by point it is easier to consider that if a phonograph needle has only two degrees of freedom it can handle no more than two independent information channels. The bandwith of the LP record was not great enough to permit the use of subcarriers.

As far as we know, the quadraphonic LP never was publicly denounced as a fraud. Such records still can be found in thrift shops and at yard sales, but they merely are stereophonic recordings with enhanced stero effects."

I guess my suspicions had a reasonable basis.

Tim

 

[maxk]

For the SSL ? I am slightly confused by what you mean with the sidechaining thing, there isn't a sidechain on the bus compressor on a 4000 series desk; but yes, quad bus is referring to 4 buses. Quadraphonics were probably the original intent, but I think practically if someone is using all 4 nowadays its for two stereo mixes in a broadcast setup.

For the quadraphonic record thing: I do believe quad styluses were snake oil.. as far as I understand, the quad mix was encoded then recorded to the vinyl so it could be listened to with 2 channel stereo but could also be sent to a decoder, after the stylus, and be decoded to 4 channels. The 4 channel info was all in the vinyl and needed an outboard decoder to work, any stereo stylus should do. Also, fun fact: Alan Parsons originally intended Dark Side to be quadraphonic... we are used to the stereo version of a quadraphonic mix.

 

[FlyBass]

Off topic, yet still quad

Note to fun fact: A better sounding 5.1 mix of Dark Side the Moon was able to be created because of Parsons' quad recording. I also heard he used one of the few quad microphones made by Neumann for some field recordings used on Dark Side.

 

[Davedog]

Ya had to really dig to find this thread.