April 27, 2006

Behringer FBQ2496

I purchased a Behringer FBQ2496 to act as a parametric equalizer for my subwoofers. I managed to get it for a great price, and after spending a few hours with my SPL meter, got measurements for input into Room EQ Wizard, a freeware (donations appreciated) audio measurement and correction tool. This software is amazingly good, runs on many platforms, and has just about every feature you'd want. With the FBQ2496 and Room EQ Wizard, I managed to flatten my subwoofer response quite well, although it would be better if the FBQ2496 could go below 20Hz.

This graph shows the measured frequency response of my subwoofers on the top purple line, and the corrected frequency response on the bottom purple line. The target response is the horizontal blue line, assuming a 150Hz cutoff. I performed my measurements with a 160Hz cutoff, to flatten the response as much as possible and allow the processor to handle the different cutoffs. Plus, the LFE channel is not cutoff at all.

The PEQ filters in the lower-right were automatically calculated by Room EQ Wizard, specifically for the FBQ2496. In other words, Room EQ Wizard knows the options available via the FBQ2496, and uses those constraints to determine the correcct filters. No boosts are assigned, as that can be a very dangerous thing to do.

Unfortunately, since my subwoofers are tuned to 12Hz, there's a huge 12Hz bump which the FBQ2496 cannot address. I tried tuning my subwoofers to 16Hz, but that resulted in a fairly gradual decline from 16Hz down, rather than a flat response due to room gain. This is because my subwoofers are ported, and so the frequency response will drop off dramatically once you hit the tuning frequency. You can see this at the 12Hz point in this graph as well.

So for now, I'm keeping that 12Hz bump, until I might be able to purchase a Velodyne SMS-1, which supports filters as low as 5Hz.

Room EQ Graph for FBQ2496

Posted by josuah at April 27, 2006 6:15 AM UTC+00:00

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