# Question about REW automatic equalization



## gorman (May 25, 2017)

Hi! I've recently bought an UMIK-1 to properly measure audio related stuff.

I have a pair of AudioEngine A2 connected to my PC and they had pretty bad bass resonance.

As such, I've downloaded REW and "Equalizer APO" to try and fix things.

Now, the result is quite nice, compared to before. But I'm not sure I understand the reasoning behind REW filters allocation.

So, this is the measurement I took, I calibrated for 75db as instructed here https://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew

http://i.imgur.com/d1oiUdP.jpg

I then went to EQ and set up stuff as instructed here: https://www.minidsp.com/applications/auto-eq-with-rew

The resulting filters took care of the bass problems but appear to leave all the frequencies above 800Hz untouched. Is this correct? The response seems quite far from being linear:

http://i.imgur.com/BiyqQYZ.jpg

Any help? Be kind, I'm a total newbie concerning all of this. Thank you.


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## gorman (May 25, 2017)

Pictures fixed, now they should load correctly on click.


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## Wayne A. Pflughaupt (Apr 13, 2006)

REW is primarily looking for modal problems, which don’t occur in the upper frequencies.

Don’t even think you’ll be able to get away with applying 20+ dB of equalization to a speaker with tiny woofers and low-powered amplifiers. You can’t get any bass from those speakers – you need a subwoofer for that.

Regards, 
Wayne


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## gorman (May 25, 2017)

Wayne A. Pflughaupt said:


> REW is primarily looking for modal problems, which don’t occur in the upper frequencies.
> 
> Don’t even think you’ll be able to get away with applying 20+ dB of equalization to a speaker with tiny woofers and low-powered amplifiers. You can’t get any bass from those speakers – you need a subwoofer for that.


It never occured to me (to expect extra low frequencies), AudioEngine provides these specs: 65Hz-22kHz ±2.0dB and apparently they slightly exceed them, measuring reasonably flat till 55Hz or so. I'm new to REW not completely new to equalization, hi-fi and so on.

In fact my doubts concern the higher frequencies, not the lower ones. There's plenty of bass (for speakers this size and up to the frequencies it's reasonable to expect it at for the size) and the problems there were with it are indeed mostly fixed by using the EQ filters REW calculates.

What I can't explain is why nothing is done for frequencies above 800Hz, which show plenty of non linearity in their response and which, up to a certain extent should be less limited by the size of the speakers, as far as volume is concerned.


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## gorman (May 25, 2017)

It's like REW, from 40Hz to about 800Hz strives to achieve the target level (set at 74.5). After that it ignores everything. There's probably a reason for this, I'd just like to understand it.


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## Wayne A. Pflughaupt (Apr 13, 2006)

It could well be that I’m missing something, perhaps John will show up and comment. In any event, it’s easy enough to equalize the highs in real time using the RTA feature.

Regards, 
Wayne


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## gorman (May 25, 2017)

Wayne A. Pflughaupt said:


> It could well be that I’m missing something, perhaps John will show up and comment. In any event, it’s easy enough to equalize the highs in real time using the RTA feature.


I'm trying to understand how (from the manual) but I'm afraid this flies over my head.
If I raise the "individual max boost" and "Overall max boost" the curve is smoothed more evenly, with filters acting on higher frequencies... but then everything sounds *wrong* with far too much highs.


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## JohnM (Apr 11, 2006)

REW hasn't attempted any correction above 800 Hz because the response lies too far below the target. If you used the HF fall control in the target settings to have some downward slope as frequency increases parts of the response would fall into a range where REW would apply correction, but generally speaking it is not a good idea to apply EQ above a couple of hundred Hz as the effects become too location dependent. There is more on that topic in general in the help. If you did want to apply EQ higher up best using manually applied, broad filters and modest levels to do some tone shaping to taste.


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## gorman (May 25, 2017)

Thanks!


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