Frequency response calibration

ketju

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This might be a simple question and the reply might be also obvious. Anyway, I wish to get a sort of confirmation for this matter.

If I wished to calibrate/check the frequency response of the sound card, I assume that also the other attached equipment should be included in this signal chain in order to get a reliable result. Let us say that I have a sound card, from which the signal goes to Behringer DEQ2496, thence Yamaha GA analog mixer. So, my question is that in order to get the frequency response checked and get the correction factors determined by REW, shall the signal from Yamaha GA mixer output be connected to the input of the sound card. Is this reasoning correct?

Also, if somebody is familiar with the Behringer DEQ2496, I wish to have your opinion whether it would be better to AutoEQ the entire frequency range or only the bass part (let us say 20-300 Hz, for example). Some hifi oriented persons seem to favour the latter option. However, is this only a matter of taste or is there any scientific/empiric evidence for favouring certain option? The aim is to calibrate our PA system (music band use).

Your opinions will be highly appreciated
 

Wayne A. Pflughaupt

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If I wished to calibrate/check the frequency response of the sound card, I assume that also the other attached equipment should be included in this signal chain in order to get a reliable result. Let us say that I have a sound card, from which the signal goes to Behringer DEQ2496, thence Yamaha GA analog mixer. So, my question is that in order to get the frequency response checked and get the correction factors determined by REW, shall the signal from Yamaha GA mixer output be connected to the input of the sound card. Is this reasoning correct?
You’re kind of combining multiple functions with that signal chain.

Calibrating the sound card is not the same thing as checking the frequency response characteristics of a piece of hardware.

The reason for calibrating the sound card is to create a calibration file that compensates for any deficiencies in frequency response it might have. Thus, upon measurement, REW “sees” it as having perfectly flat response.

The reason for adding hardware to the loop is to see what its frequency response characteristics are (with the calibration file removing the sound card from the equation), both with and without equalization. Adding EQ filters or adjusting tone controls during the calibration (in the case of the DEQ and the mixer) allow you to graph their effect.

However, all this is probably overkill with a PA system, as very few PA speakers would qualify as hi-fi, at least from an audiophile standpoint. Virtually non of them have any extension beyond 12-15 kHz on the top end, and 40 Hz on the low end, if a sub is used. Even a cheap sound card like the ancient Soundblaster has better response than that!

It’s typical to EQ full range in a PA system, and this often includes notching out feedback frequencies. However, I’m not sure I’d trust the DEQ’s auto-EQ capabilities. It’s been on the market for well over 10 years, so it’s a pretty primitive auto EQ system. You’d probably have better luck using REW’s RTA feature with pink noise and adjusting the filters manually. Just be sure you get all that done before the audience shows up. :)

Regards,
Wayne
 
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