# REW for calibrating a full range four way active system



## krassyg (May 10, 2009)

I am trying to calibrate my four way miniDSP OpenDRC-DA8 based speakers. My first step is to balance the four drivers in the miniDSP panel. What speaker response should I be aiming for? Flat response sounds horrible; I balanced the drivers using a 3db roll off per octave using the EQ panel of REW and they sound much better for starters, even though I now have too much bass. Am I on the right track?


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## natehansen66 (Feb 20, 2011)

What's the speaker? You really need to do gated measurements as far away from boundaries as you can to get a quasi-anechoic response. The in-room measurement really isn't sufficient for designing a speaker.


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## krassyg (May 10, 2009)

It is a clone of Focal Utopia EM. The subwoofer is separate from the enclosure, the left and right look exactly like the Utopia Scala. The drivers are the same as the Utopia EM except only one midrange and the subwoofer is from the Utopia II subwoofer. Crossover points are 80Hz, 220Hz and 2200Hz.

Right now I am just trying to get them working quickly; taking them outside for measurements is not an option, they weigh a ton. The crossover is active and I can always change the settings later. I have a calibrated miniDSP UMIK-1 microphone; should I set the crossover according to its calibration curve?


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## krassyg (May 10, 2009)

I set the crossover driver levels according to the calibration microphone curve; it sounds terrible! My -3Db curve sounds much better. What am I missing?


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## giordy60 (Aug 5, 2013)

you can post .mdat?


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## Phillips (Aug 12, 2011)

Best thing to do is put them as far way from boundaries as possible measure about 1 meter from the speaker at the acoustic centre of the speaker itself. Normally this is between the tweeter and the driver below-woofer


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## jtalden (Mar 12, 2009)

krassyg said:


> Crossover points are 80Hz, 220Hz and 2200Hz.


From the look of the freq response it is possible the delay timing between drivers is not correct. If timing of the drivers is indeed more than 90° misaligned then there can be significant and unnecessary dips in the XO range.



> The crossover is active and I can always change the settings later.


Do you have the ability to add delays in the active XO? If so, that is probably the first thing to do after selection the XO filters your intend to use. It should be done before any EQ efforts.

If you intend to eventually EQ the system for a particular room installation, there is no real need to first EQ the speakers for an anechoic condition. After placing the speakers in the room location and measuring at the LP the EQ will change anyway so the anechoic effort is in my opinion is not needed. It is often done by many builders though and it doesn't really hurt anything. 

If the speakers are designed to be sold or moved to other installations without changing the EQ then it is best to EQ them for an anechoic situation. The user will then get the best likelihood of reasonable sound.


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## natehansen66 (Feb 20, 2011)

jtalden said:


> If you intend to eventually EQ the system for a particular room installation, there is no real need to first EQ the speakers for an anechoic condition. After placing the speakers in the room location and measuring at the LP the EQ will change anyway so the anechoic effort is in my opinion is not needed. It is often done by many builders though and it doesn't really hurt anything.


Assuming one wants to eq room effects (which I wouldn't over 300hz or so), or has the ability to determine what is a room effect and what is a speaker effect. To each his own.

I still think the reason the op doesn't like what he's hearing is because he doesn't have the proper data to do eq/xo. With the presence of his room in the data I'm not confident in making any suggestions at all.....other than basic level adjustments. The crossovers likely need MUCH work.


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## krassyg (May 10, 2009)

giordy60 said:


> you can post .mdat?


This is the .mdat for the left and right speaker without any EQ, just rough balance of the drivers according to the calibration file of the mike. I still don't understand how should I balance the drivers with REW; speakers sound terrible the way they are right now; thin and no bass. From what I understand I need to also calibrate my sound card(should I do it if I am sending SPDIF?) and get a house curve. How do I get a house curve?


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## krassyg (May 10, 2009)

After a few hours spent googling it appears I need to add 1Db per octave in the REW EQ to properly calibrate the drivers and get a "house curve". That yields a strait line that drops 10Db at 20Khz. I'll play with it tomorrow but I think this will be the sweet spot between flat and my bass heavy 3Db curve.


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## giordy60 (Aug 5, 2013)

You have an excessive level of reflections.










in the red boxed should be little or nothing


beyond the red line there should be nothing, it is a resonance at low frequency


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