mid-high timing by LR separate EQ for bass

[skyfly]

If I do EQ (parametric EQ in RME ADI-2 DAC) differently on left and right channels for bass, will I have timing mismatch (phase mismatch) of left and right channels for mid and high frequencies?

 

[puppet]

I don't think it works that way. Your EQ for each channel, left or right, effects the phase of that channel be it left or right. The combined left and right phase, or timing, will have to do with the distance to the listening position. So, each channels' phase is independent of the combined L&R phase, or timing.

 

[alex-z]

No, any phase shift from EQ applied to bass frequencies should not reach into the mid-range and treble.

However, you may not want to EQ the bass of each channel individually. It is rare that music will hard pan bass to a specific channel, it is usually treated as mono at the mixing stage. In my opinion, measure the combined channels at the listening position, and below 200Hz let them share EQ.

 

[dualazmak]

Interesting question and discussions.

I myself set common/same XO/EQ/delay for L-SPs and R-SPs by DSP EKIO all the way for sub-woofers, woofers, mid-range squawkers, tweeters and super-tweeters; I also intensively measured and established 0.1 msec precision time alignment all over the drivers as well as L to R;

In case if you really need to apply different XO/EQ for L and R sub-woofers and/or woofers (I believe that would be very rare case though), I would like to suggest you to "measure and tune" the time alignment of actual "air sound" (not the DSP software's theoretical predictions) carefully in 0.1 msec precision at your listening position using a measurement microphone on independent objective air sound analysis platform.

I did the time alignment measurements and tuning using my rather naive but reliable reproducible fully validated methods shared in my project thread as follows;
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507
- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

And these two posts would be also of your reference;
- Perfect (0.1 msec precision) time alignment of all the SP drivers greatly contributes to amazing disappearance of SPs, tightness and cleanliness of the sound, and superior 3D sound stage: #520
- Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers: #687

If you would be interested in using the test tone signals I prepared and used in these measurements and tuning, please simply PM me writing your wish.

 

[dualazmak]

No, any phase shift from EQ applied to bass frequencies should not reach into the mid-range and treble.

However, you may not want to EQ the bass of each channel individually. It is rare that music will hard pan bass to a specific channel, it is usually treated as mono at the mixing stage. In my opinion, measure the combined channels at the listening position, and below 200Hz let them share EQ.

Yes, in general, I agree with you.

I have a little bit of worry, however, that odd (different between L and R) XO/EQ in bass may affect phase/time-align mismatching between woofer to mid especially in the Fq overlapping zone where woofer and mid sing together. I assume no phase/time-align issue in mid to high (tweeter) zone if the woofer-mid XO is far away from XO for mid-high with slope of - 12 dB/Oct or steeper.

And let me emphasize that actual room sound phase/time-align would also greatly dependent on room acoustic environment including degree of asymmetricity of the room as well as various furniture; also from this perspective, objective precise measurements of room air sound at listening position would be needed for our confirmation and fine tuning if needed.

In any way, as I wrote in my above post #4, we (and the OP) would be better to objectively measure/confirm (and fine tune if needed) actual time alignments of room air sound at listening position hopefully in precision of 0.1 msec.

 

[skyfly]

I wanted to try different LR bass parametric eqs (different cut/boost, different frequency, different Q value) to address sharp suck out at certain bass frequency (51 ~ 52 Hz) (L+R is quieter than L only or R only at the listening position; the narrow suck out is over 20 dB with 1/48 octave smoothed curve, far less in "psychoacoustic smoothing" in REW).

I tried it a little bit long time ago, but failed in eliminating the suck out. I merely moved around the suck out frequency. I am not sure whether I might have been successful if I tried harder

 

[dualazmak]

A little bit out of our discussion, but I sometimes do not like the REW's "psychoacoustic smoothing". Please refer to my posts here and here.