Matrix Mixer

[timdrage]

just to save for future reference, some more expensive pro monitor mixers to look out for:

Excellent Onkyo MAT-1010 - 10x10

Allen and Heath Mixwizard 3 12m - 16 in x 12 out !

[crochambeau]

My Secret Satan on ILF gifted me a Pladask Elektrisk Matrise which is a 4x4 active matrix mixer with selectable polarity on each output column.

It fucking rules.

[xdugef]

My Secret Satan on ILF gifted me a Pladask Elektrisk Matrise which is a 4x4 active matrix mixer with selectable polarity on each output column.

It fucking rules.

ILF?

[crochambeau]

It's sort of a guitarish place.

[timdrage]

oooh that looks nice!!

[FireAlarmPoet]

My Secret Satan on ILF gifted me a Pladask Elektrisk Matrise which is a 4x4 active matrix mixer with selectable polarity on each output column.

It fucking rules.

So I've been soing some research on phase inversion, as this is the first time I've ever heard of such a feature, let alone as a feature on something I could and would want to build sometime. Phase cancellation, so I've read, could be incredibly useful tool for editing so I'm eager to try it myself, but from what I understand, that's the only benefit of phase inversion.

Tell me: what would a phase inversion switch be useful for on a matrix mixer? Is it something to do with triggering other devices? Like if you needed a square wave to read as 'hi' at a certain point, where it would normally read 'lo' without inversion at that same point... that sort of thing? Is it an audio purist thing? Or is it something else altogether? Frankly, I just don't get it. I'm not dismissing it, I just don't understand it's purpose.

[fire]

switch the polarity on one of your stereo speakers wires and see

can also be used to simulate 4channel sound when additional speakers are cross wired into the system, i believe a matrix mixer should be able to do this

[crochambeau]

Polarity inversion is a utility effect that sort of hides in the realm of decent microphone preamps or high end mixing desks.

For our purposes it can be useful (or not) depending on your approach/needs.

As an example: the LPB-1 power booster effect is a single transistor in common emitter configuration. This can provide ample gain, but with only a single transistor the absolute phase (I prefer the term polarity) is inverted. So, if you take a single LPB-1 and insert it in a feedback loop with a mixer, you'll either get fuck-all or a feedback signal based on the minor differences (distortions) that the circuit provides, plus phase cancelled core.

Should you flip the polarity on that, everything becomes additive and it is a different system entirely. This means: if there is a pedal you have always considered a dud in a feedback loop, inverting polarity MIGHT embellish it with superior results.

Having polarity inversion on hand is a highly useful function... I have already been designing it into some things, and when you have multiple end channels as fire says, swapping polarity on one can have big results on what is heard in the room.

Yet, it remains a non-glamorous utility function, this is because it's a not all the time tool, unless you walk very particular paths.

[crochambeau]

switch the polarity on one of your stereo speakers wires and see

can also be used to simulate 4channel sound when additional speakers are cross wired into the system, i believe a matrix mixer should be able to do this

You mean the wiring a speaker + left to +right?

The resultant "3rd channel" difference is a particular function that no matrix mixer I have yet seen provides. You need to veer into M+S processors to start grafting the signal into these sorts of branches.

[FireAlarmPoet]

Fascinating... so in theory anything could have an inversion switch, correct?
Yet the most impact it could have is on the output stage e.g. speakers, headphones, etc.
So then would it be worth it to add a polarity to switch to pedals like you said, or is that redundant?
It sounds to me like correcting the polarity is imperative for the final result/output stage, useful for the mixing stage, uncertain yet possibly game-changing for fx loops and then negligible for anything else.

Speaking of pedals, how would one go about changing polarity on those? I get the speaker example since there's only two things it can do: push out or pull in. But for a pedal, is it a matter of flipping +/- for power, for the output, input or something else entirely? Seems to me that would just create a short and either the signal wouldn't pass or the pedal would get fried.

[crochambeau]

Fascinating... so in theory anything could have an inversion switch, correct?

Correct.

So then would it be worth it to add a polarity to switch to pedals like you said, or is that redundant?

It becomes redundant (and possibly annoying) as soon as there is more than one polarity switch in a given signal path.

It sounds to me like correcting the polarity is imperative for the final result/output stage, useful for the mixing stage, uncertain yet possibly game-changing for fx loops and then negligible for anything else.

Yeah, a lot of people get by just fine without it.

Speaking of pedals, how would one go about changing polarity on those?

There are numerous ways to go about it, here's a passive example:



That is a signal input (drawn as a jack, but can be "built in"), a 1 to 1 ratio transformer (you can grab anything, but ratios turn up or down voltage, it gets complex - if in doubt, err on the 1 to 1 ratio), a DPDT switch and an output jack. It can also be achieved with a single transistor (dirty), multiple transistors (a bit less dirty) or an operational amplifier (widely considered clean). I can provide drawings of those other instances given enough interest..

But for a pedal, is it a matter of flipping +/- for power

No, this may very likely put your active semiconductors in harms way.

But for a pedal, is it a matter of flipping +/- for the output, input or something else entirely?

When you have a common ground plane, everything is referenced from that plane, so swapping your ground and signal MUST be done from a floating (not common/ground referenced) node, otherwise your signal simply goes away. The simplest method by which to achieve this is in the drawing I just supplied. A transformer and a DPDT switch to put the signal on its head if need be.

Seems to me that would just create a short and either the signal wouldn't pass or the pedal would get fried.

Yes, the former (signal not passing) for swapping leads on the common referenced signal and latter for swapping power leads. You just need an additional stage to pull it off.

[FireAlarmPoet]

Thanks!

[fire]

You mean the wiring a speaker + left to +right?

The resultant "3rd channel" difference is a particular function that no matrix mixer I have yet seen provides. You need to veer into M+S processors to start grafting the signal into these sorts of branches.

yeah, simple phase flim flammery, this guy splains it...



http://kantack.com/surround/surround2.html

[timdrage]

Learning new things for new matrixes





Go home kicad you are drunk

[crochambeau]

I love KiCad, once you get past the library management it's a joy to use.