I have in-room response curves of my Infinity Renaissance 90 speakers, made with Room EQ Wizard, a Behringer UCA-202, and a Radio Shack digital SPL meter. The vertical scale major lines are 5 dB apart.
With 1/3 octave smoothing:
The speakers are bi-amped, with an Adcom GFA-555 powering the woofers and a pair of Eico HF-12 mono amps powering the rest. They are only roughly level matched by ear. I probably could have turned down the Eicos a couple dBs by comparison to the Adcom to flatten the crossover, but the 50 Hz peak can be overwhelming then.
When running the woofers and mids/tweeters off of the Adcom alone, the woofers play about 6 dB below the rest of the speaker - dropping off right around the 200 Hz crossover point. I suspect the crossover caps need replacement, and I've been waiting for months for the caps I bought from Erse to be returned after I sent them back for measurement...
Similarly, I have the treble tone control on the Eicos turned down just a tad because of the 7 kHz peak. I have yet to explore the possibilities of midrange to high frequency sound treatment in my room, which may solve the issue. Parametric equalization would solve the peaks at both 50 Hz and 7 kHz, of course, but I have not had a chance to invest in that yet. Given the two very specific peaks, I may be able to just create in-line filters to address them directly. With proper filters and equal gain between the amps (or just a single amp for that matter, once I get the crossover refurbished), I think I will be able to get the 1/3 octave response within +/- 2 or even 1 dB from 200 Hz on up.
I believe the treble response is limited by the SPL meter's microphone, which is definitely unreliable above a few kHz (I have used common compensation curves for the meter, which make it quite accurate in the bass frequencies, but don't go up to the treble frequencies).
The bass unevenness, including the 50 Hz peak and 67 Hz null, is a result of in-room response. The frequency response and waterfall graphs I'll post now are unsmoothened and compare my room with no treatment versus extensive bass trapping along wall-wall and wall-floor corners using blocks of blow-in cellulose insulation.
The cyan is the treated room, and the red is the untreated room.
a
Obviously there's still a long way to go in improving the sound as far as better rooms, better treatment, and equalization go, but reducing the nulls by 15 dB or so is quite a huge improvement. The decay times are considerably better too, as evident in the waterfall plot comparison. Even though the 50 Hz peak is not decreased at all, its resonance is. The same goes for the 80 Hz peak, and the others as well.
The subjective results strongly correlate with the measurements. With the bass trapping, the sound is immensely improved - the bass was boomy and very peaky without it, but tight and more even with it.
I should go as far as to say for the benefit of everyone here that equalization never will solve the issues of nulls in room frequency response - it can only reduce peaks, and it will only reduce decay time so much as you reduce the frequency range you are addressing. As such, I do think that room treatment is even more critical than equalization, although I do agree that peaks are definitely more conspicuously audible than nulls. So I would go so far as to say that equalization is fine and often desired, but all speakers need room treatment.