How does the SSL Pan-Law work?

[atticmike]

Hello there,

Could someone explain to me the following things concerning the pan-law:

1. What's exactly changing the level? I guess if it is panned to the middle it looses level by a poti changing resistance and dropping the level and to the sides it increasingly gains the original voltage back that was going through the channel?

2. What happens if I send let's say a snare for example to a stereo parallel (via pressing for example 9 and 10 on the output routing matrix), which consists of two mono channels panned each left and right (subgroup engaged on the 2 channels 9 and 10) pan-law-wise? I assume the send is done before the pan law poti which means it lacks the effect of a pan law? Meaning for example that a drum mix on the parallel has louder mono tracks vs the drum mix going directly from the channels to the mixbus? Or is this send done after the pan law poti?

According to the Diagram, it looks like it is before the pan poti regarding question number #2? which means no pan law on the small  fader sends to a bus which returns to subgrouped channels.

[radardoug]

Its after the pan pot. Look at the diagram more carefully.

[amillar]

Hi,

There's nothing clever about the pan pots, they just start attenuating as soon as you come off hard left or right. So theoretically the level sounds the same wherever it's set to, when it's panned centre the measured level will be 4.5dB lower on each of the left and right sides which then acoustically adds up again.

Those who know their dBs will wonder why it's 4.5dB down in the centre, not 3 or 6. It's a bit of a fudge. If you had two channels with an identical inphase signal coming down them then you'd want the pan pot to have a 6dB drop in the signal for the level to sound the same whether both pots were centred or spread left right. If the two channels were fed with non-phase related (i.e. different!) signals then a 3dB drop would make the level about the same however it was panned. So 4.5dB is in the middle.

And, yes, there's nothing clever about the switching either, as radardoug says the feed to the routing matrix is always post pan. So if you only feed to an odd (or even) bus you can use the pan pot as a further level control if you want!

Cheers,

Andy

(P.S. If I haven't said before, thanks for the photos! Looking good  )

[atticmike]

Its after the pan pot. Look at the diagram more carefully.

Okay? On the image it looks like it is pre pan because the pan poti picture comes after the crossing point?

[radardoug]

You read the drawing from left to right! Small fader, then pan pot, then routing! Same for the large fader.

[Showcase]

I think he means the Quad pan, Mainbus pan, sends are not affected by this pan

[atticmike]

You read the drawing from left to right! Small fader, then pan pot, then routing! Same for the large fader.

I've meant whether the pan at the end of the channel after the channel VCA before it goes to the mixbus affects the send?

I mean, let's say a snare on a channel, which is panned mono, drops at the pan poti, which is set to the middle, by 4.5 dB before it goes to the 2bus. Now, the question is, when I send something with the matrix via the small fader which is set to ch out (from let's say ch 24), to a group amp (let's say ch 9 and 10 pressed down on the matrix buttons), which returns on these very channels (9 and 10) via subgroup, whether it gets the 4.5 dB pan law drop from the channel I send it from or not.

[amillar]

I've read this about 5 times now and if I've understood what you're writing correctly then yes, each channel 9 + 10 will see the signal dropped by 4.5dB. If you then panned these both centre to the stereo bus then they'd drop by a further 4.5dB and then sum together to go up by 6dB so you'd end up 3dB lower than you started.

I think.

Cheers, Andy

[Showcase]

I've read this about 5 times now and if I've understood what you're writing correctly then yes, each channel 9 + 10 will see the signal dropped by 4.5dB. If you then panned these both centre to the stereo bus then they'd drop by a further 4.5dB and then sum together to go up by 6dB so you'd end up 3dB lower than you started.

I think.

Cheers, Andy

No, sends doesnt get affected

https://www.dropbox.com/s/v8cvad6y6qeie45/Pan%20law%20for%20busses%20SINE.mp4?dl=0

[atticmike]

The topic is ancient but I have yet to get a proper elaborate response, basically:

When you send via small fader output, let's say from a mono snare track, to two adjacent busses on the matrix (5&6 for parallel compression, returning on CH 5&6) and don't press down the pan button at the matrix, will it drop there by 4.5 dB?

Because to my knowledge, the matrix sends are post VCA large fader but not post pan pot, which would mean that on the drum parallel, compared to the individual tracks going to the main mix bus, the mono tracks would be 4.5 dB louder, on the returning channels 5&6 where the parallel drum happens, right?

What actually happens when I would press the pan button? Would then a drop occur when panned in the middle?

Or are matrix sends actually post channel pan pot (large VCA to Pan sending to matrix)?

My question also applies to cue sends btw. Having let's say a cue send of a drum room going to a reverb and a mono snare going to the same FX cue, that would probably not have a pan law drop right? I'd have to do it manually with the cue send level?

[radardoug2]

Why dont you just do it, measure it, and report back?

[atticmike]

Why dont you just do it, measure it, and report back?

Just thought someone on the SSL forum would have knowledge about this.

[radardoug2]

You have had several replies. If this is a problem for you, why not try it? A lot of us have worked on SSLs but dont have them here in our bedrooms.