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Author Topic: Help with phase and delays vs mains  (Read 1838 times)

Mark Wilkinson

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Re: Help with phase and delays vs mains
« Reply #30 on: April 14, 2021, 10:02:20 am »

The other thing that you can do with delays, that might not be acceptable with the mains is linear phase multiband limiting for speakers with passive crossovers.   You could do it with conventional crossovers to separate out the bands, limit them individually, and sum them back together, but you would re-add all that phase shift. However, with plenty of time on your side, you can use FIRs to achieve per driver limit thresholds (to a point) with no phase deviation at all.

That's pretty neat limiting solution for passives !
And I can see how it can even target very narrow frequency ranges that need limiting.

It kinda reminds me of something Linea Research / DSL have in their processors albeit with much less flexibility than you showed.
Their VX Limiters, that require extra latency to operate.

I keep finding it amazing what can be done when there is processing time to work with.

Below is an example of a 3-way main, where each driver Mid, HF, and VHF has it's own fader.

Green traces are simple on-axis mag and phase, that were tuned to on-ax only for purpose of this experiment, and is why they are so flat.
Purple is where I raised the Mid driver +10dB, cut the HF -10dB, and then raised the VHF +10dB.

I wanted to test how much phase is affected by level changes between sections, when using the steep linear phase xovers i had in place.

Reason being:  Faders on each driver is a setup I routinely use for testing. Helps to isolate things quickly.
I've always been struck by the amount of tonal change that's been available using this technique, without sounding whacky.
There's been waay more room to move spectral balance around than with regular EQ's...
So i speculated it might be due to less phase change, and wanted to see how much fader levels could be altered before phase started messing up like with IIR EQs...
Found out faders can be moved a lot !

Anyway, as you can see, the purple phase with its absurd mag trace, barely peeks out from under the green phase trace.
Still amazes me. Realtime major mag phase change.

I hope this wasn't too much of a sidetrek, but it seems to show an example of the power of being able to adjust mag and phase independently .....with delays, or fills, or anytime when distance provides some natural room for processing latency.

Miguel Dahl

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Re: Help with phase and delays vs mains
« Reply #31 on: April 18, 2021, 05:29:29 pm »

I followed an earlier tip and just highpassed the delays higher. Couldn't hear the weirdness any more, perfect. But still some work to do. The tips in this thread are of great value.

I'll have to leave it as it is for now as another production is moving in to that stage in a few days, and I don't want to tamper with the system when there's another tech using it on a daily basis. That could lead to confusion for him.

ProSoundWeb Community

Re: Help with phase and delays vs mains
« Reply #31 on: April 18, 2021, 05:29:29 pm »

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