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Contributor - Level 2

Room Analysis with RTA and Pink Noise

Hi folks,

I am new to this forum, and relatively new to the X32, which I have the rack version of.

What I would like is for anybody to throw me some advice on how they EQ a room using the RTA, pink noise, and a reference Mic.

I usually have limited time for set up and sound check, so any and all ideas would be welcome.

Cheers,

Andy
AndyShrimpton Contributor - Level 2 2016-02-02

2016-02-02

Room Analysis with RTA and Pink Noise

Hi folks,

I am new to this forum, and relatively new to the X32, which I have the rack version of.

What I would like is for anybody to throw me some advice on how they EQ a room using the RTA, pink noise, and a reference Mic.

I usually have limited time for set up and sound check, so any and all ideas would be welcome.

Cheers,

Andy

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Contributor - Level 3

Re: Room Analysis with RTA and Pink Noise

Reference mic into a channel, don't have any processing on that channel (no hpf, flat eq, no compression,) un-route it from LR.

Oscillator routed to LR, generating pink noise, turn it up til it's comfortably loud.

Turn the input up on the reference mic's channel until the input meter is showing a sensible level (eg -18dBFS.)

Go to the meters page, the RTA tab, make the RTA source the channel into which you've plugged the reference mic.

Select the LR bus (or mtx, whatever you're feeding FOH from.) Make sure you're staying on the meters screen.

Adjust the peq to flatten out what the reference mic's hearing.

PS, of course if you move the reference mic around the room you'll need to make different adjustments to the peq. Generally you'll need to take multiple measurements to even out the response in different parts of the room.

PPS, this should probably be done as part of your speaker processing rather than in the mixer.

PPPS, your ears should be making the final decision. If a certain eq curve sounds better to your ears than a perfectly flat line on the RTA, go with what your ears think sounds best.
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Contributor - Level 2

Thanks!

Hi Craig,

Thank you so much for that reply.

It was along the lines I was thinking, up to about half way through, then took a different tack.

I will have a crack using your methods as soon as I can.

Much appreciated.

Andy
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Contributor - Level 2

Speaker Processing

Craig,

Your PPS regarding Speaker Processing. Would you be able to expand on that please?

Cheers,

Andy
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Super Contributor - Level 2

Re: Room Analysis with RTA and Pink Noise

Andy Shrimpton;68833 wrote:
Craig,

Your PPS regarding Speaker Processing. Would you be able to expand on that please?

Cheers,

Andy


The pink noise is not flat I would strongly recommend that you don't use this method. Hardly any pink noise is flat. And even if it were that is not a good idea, that method is time blind.
Contributor - Level 2

Re: Room Analysis with RTA and Pink Noise

I`ll just use an SM58 for that ... usually a beaten to death one.. Smiley Very Happy
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Contributor - Level 2

Re: Room Analysis with RTA and Pink Noise

Pink noise is the usual source for setting up a sound system because it is not flat but represents how we hear sound (white noise is 'flat' in that it has the same energy across the frequency spectrum, pink noise has equal energy in each octave).

TBH, you'll be better off using Dave Rat's method of a CD of familiar, well recorded music of the same genre as the band you are mixing and a good (also familiar) set of headphones. Compare the sound coming out of the FOH to the sound in the headphones (at gig volume and match the headphone volume as closely as possible to the FOH). You can use this method to check the mix during the show to make sure hearing fatigue doesn't lead you to colour the live mix as your ears lose certain frequencies after long exposure to loud music.

https://www.youtube.com/watch?v=cU9BmupC62c
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Contributor - Level 3

Re: Room Analysis with RTA and Pink Noise

Just my $.02 always make sure your PA is flat before you ever leave the shop / house.

I set up my PA outside on a calm day making multiple measurements in free air.

That is my gold / reference standard for the PA, if your PA is properly tuned up and balanced when you get to the venue your changes should not be significant and that's why people say take multiple measurements because if you find a significant hot spot in the room you're likely dealing with mode or reflection within the room, be careful about making significant chance to fix one small part of the room.

Obviously bringing your board into a venue with a foreign PA all bets are off....
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Contributor - Level 2

Re: Room Analysis with RTA and Pink Noise

My pal did that in his back garden a couple of years ago, 3 days later he received a letter from the council complaining of him running a "sheet metal workshop" in his garage
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Contributor - Level 3

Re: Room Analysis with RTA and Pink Noise

Andy Shrimpton;68833 wrote:
Your PPS regarding Speaker Processing. Would you be able to expand on that please?


Pretty much most of the same reasons it's better to use an external XO rather than trying to fudge it with the peq\geq on the mixer:

A speaker processor generally has more bands and tighter Qs to play with: you can get a more accurate result.

A botched scene recall without the appropriate safes or a board reset/restart could nix the settings, and you'll have to dial them in again. The potential for this increases dramatically as you introduce more remote controls to the system (people controlling the x32 via ipads,) or you have over-helpful volunteers who know just enough to be dangerous (ie they know how to recall scenes, but they don't understand how the safes work.)

If your x32 breaks and you need to send it away to get repaired, unless your scene is backed up to USB and your interim replacement console is from the x32 ecosystem, you'll need to dial in a FOH eq somewhere else anyway.

To sum up, you generally get better results and it's much safer if you use a dedicated speaker processor. In the case of an XO, stuffing it up could mean sending a full-range signal to unprotected tweeters, which would be damaging. Whilst nixing settings on your FOH peq probably won't mean you'll destroy any drivers or ears (unless you have really bad luck with feedback or resonance and can't fix it quickly, if for example you're controlling things with an ipad and the wifi has just dropped out,) it's still a bad thing to happen in the middle of a set. Having it separate to the mixer is a lot safer, and usually a lot more accurate.

Whilst a FOH eq to compensate for room acoustics *can* be done using the x32, that doesn't necessarily mean it *should* be done using the x32. If you've got the speaker processing available then I'd recommend using it for your room eq, and saving the onboard eq to "styalize" the mix.