[Wayne A. Pflughaupt]

A different perspective from someone who uses full-range equalization:

1. Judging from your response graph, I’d say you’d see a noticeable improvement. Your 40 Hz peak is pretty wide, and a full 16 dB in severity. There’s no way eliminating that thing wouldn’t make a big difference. I’ll bet that 8-dB peak at 20 Hz is muddying things up at least some. And the depression between ~45 – 60 Hz is more than 1/3-octave wide. Typically wide depressions like that are going to be much more audible than ultra-narrow ones. Overall, I think you’d get audible improvements with a sub EQ.


2 / 3. I don’t think I’d say no one is concerned about the mid and high range. It’s just that it’s easier to insert a corrective equalizer into the sub signal chain than it is the mains. Also, with the upper frequencies, much of the raggedness you see in a graph looks a lot worse than it sounds.

The function of room treatments for the upper frequencies (i.e., above the subwoofer) is the same with bass traps – i.e., reducing signal decay times (with the upper frequencies, long decay times are typically manifested as reverberation or echo). Above about 500 – 1000 Hz, the point where the room becomes less of a factor in response (as far as modal issues are concerned), room treatments are not going to eliminate response problems your speakers might have. Now, if you have a really live and reverberant room, treatments can appear to “tame” the high frequencies by stopping them from endless bouncing around the room. But if your room is already reasonably “dead,” as it would be if you had wall-to-wall carpet and regular room furnishings, additional treatments are not going to do anything for say, a broad response peak at 4 kHz your speakers might have.

For instance, my speakers are a bit “soft” above 8 kHz, yet my room is a bit “live,” given the wood floors. If anything, additional treatment would make a problem like that even worse. So in at least some cases, equalization for the mains makes sense.

But the problem with outboard equalization for the main channels is that it’s a pricey endeavor. Not only do you have the cost of the equalizer for each channel you want to EQ, you will probably need outboard amplification for those channels as well, as fewer and fewer receivers these days seem to be offering amp-in jacks in addition to the usual pre-out jacks.

Fortunately, many recent-model receivers have fairly flexible equalization built in that can be very useful. In most cases, that should be all you need. I’d say if a few tweaks from the receiver’s EQ can’t take care of what you perceive to be a problem with your speakers, then you should probably upgrade them.


4. As recommended, the Behringer 1124 is a good bang-for-the-buck parametric EQ. If you’re still on the border, you might pick one up on eBay for typically $50-75, and flip it in the unlikely event that you’re not happy with the results.

Regards,
Wayne