I'm looking for a good mono EQ for my subwoofer. I need to notch out a few resonant frequencies in my apartment (71 Hz in particular).

Any suggestions?

There's the AudioControl C-131, but it's just a standard 31-channel EQ with no particular emphasis on low frequencies. About $500.

There's a DOD SR831QXLR, which is much the same, but cheaper ($200).

There's a Samson E31i, again the same, for about $200.

And there are two DBX models, 2031 and 3031 for $430 and $625 respectively.

And finally there's the AudioControl Rialto ($600), which is actually a 7-channel EQ, but has a 6-band low-frequency EQ for the subwoofer.

But here's my puzzle:

1) I'm not sure which, if any, of these have RCA jacks. If they don't, I'm not sure which kinds of 1/4" I can convert to line-level RCA (balanced? unbalanced?)

2) Is there any EQ out there designed specifically for a sub? I'd like something with lots of bands in the sub-140Hz range.

3) If my goal is to notch out certain frequencies, am I best off looking for a parametric EQ?

Peter,

Does your sub-woofer have a built in elctronic x-over or are you relying on the x-over in the LFE?

Is the slope on the sub-woofer x-over 12, 18, 24db per octave?

At any rate, try crossing over your subwoover at 60hz or lower creating a roll off in the desired region.

Since you know precisely the frequency of the required notch, this could also be accomplished passively with "off the shelf" x-over components installed between the subwoofer amp and the woofer.

If you have a quality sound card in your PC, try this solution for $30. [Link: anwida.com]

If you must equalize, a parametriq EQ would be most ideal.

It has its own x-over, but I have it tuned fairly high (120 Hz, as that's the highest output by the LFE track). I'm not sure what the slope on it is.

Unfortunately, lowering the x-over to below 71 Hz is not really what I'm looking for, since I want the subwoofer to handle frequencies above 71 Hz as well. I just need to drop that one.

(My problem is a resonance curve in the room, not an overlap of speaker ranges.)

How would I notch that frequency as you describe?

The PC solution, while interesting, isn't quite so practical, as I don't have a computer in my living room. (Actually, check out the TCS at www.tactaudio.com -- it uses a PC to calculate the calibration for the system, then it stores the configuration in the little preamp box.)

Do you know of any good low-frequency parametric EQs? The only parametric EQ I found was 3-band, but the 3 bands were restricted to low, medium, and high frequencies respectively. I'd love a 3-band low-frequency parametric EQ. (There's actually another harmonic I'd like to diminish around 45 Hz.)

Peter,

The Audio Control Richter Scale Series III and the Rialto will do what you want. Check them out at audiocontrol.com. If you need help accessing the product just e-mail me.

[Link: smr-home-theatre.org] has reviews on both products.

Happy Equalizing,
Ron

Ron, thank you for the pointers. Do you have any idea who carries AudioControl equipment?

Definitely check out www.tactaudio.com to see some cool toys.

Peter,

I do. List on the Richter Scale is $350us. I can do better. Click on the little envelope by my name.

Ron

Peter, I use an Audio Control Richter Scale to EQ my subwoofer. The RS has a warble tone generator, calibration mic and display, and 1/2 octave EQ. It does the job.