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Phase checking my monitoring

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Phase checking my monitoring

Postby mat6066 » Thu Nov 15, 2012 1:32 pm

Hi,

I've been using Alan Parson's 'Sound Check 2' CD to check my monitoring. On the CD there are some pink noise tests for checking the phase between one's monitors; there is a 'phase check' signal, and then subsequent signals both in and out of phase broken into different frequency bands.

Whilst my monitors phase cancel perfectly when running the 'phase check ' signal and also the signal between 0-200 hz band, I can still hear a (much reduced) sound when running the pink noise tests in the bands ranging from 200 hz up to 15 khz.

Is this something that should concern me?

If it is, what are the solutions please?

Cheers,
Mat
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Re: Phase checking my monitoring

Postby Richie Royale » Thu Nov 15, 2012 2:42 pm

At a guess this is comb filtering from reflective sufraces in your room, such as the desk or walls. Do you have any acoustic treatment in the room?
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Re: Phase checking my monitoring

Postby Hugh Robjohns » Thu Nov 15, 2012 3:04 pm

mat6066 wrote:Whilst my monitors phase cancel perfectly when running the 'phase check ' signal and also the signal between 0-200 hz band, I can still hear a (much reduced) sound when running the pink noise tests in the bands ranging from 200 hz up to 15 khz.

The wavelength of sound below 200Hz is very long and slight movements of the head or measurement mic won't make much difference to the relative ephasing of the signals, and so won't affect the depth of cancellation significantly.

At higher frequencies the wavelengths are much smaller and small differences in distance can have a big effect.

Clearly, there is still a substantial amount of cancellation going on since what you hear is much reduced.

your results may also be influenced by local HF reflections diluting the effect.

hugh
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Re: Phase checking my monitoring

Postby mat6066 » Sat Nov 17, 2012 10:24 pm

Thanks Hugh for the information and to both of you for the tip on HF reflections. I have a got sound treatment in the room but perhaps I could increase the amount of HF absorption - much of my budget has gone on bass trapping.

Cheers,
Mat
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Re: Phase checking my monitoring

Postby DC-Choppah » Sun Nov 18, 2012 4:28 am

This test also stresses your monitors phase matching.

You need identical speakers to phase match over a wide band. Nothing does that perfectly, but you can really tell the difference between the high end monitors vs el-cheapos with the phase match test.
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