Besides optimizing each single speaker, does MultEQ also optimize the crossover region between satellite speakers and subwoofer?
... is the optimization approach the same for all versions of MultEQ?
... does MultEQ optimize the crossover region between subwoofer and a single satellite speaker or does it optimize the sum of subwoofer and multiple satellites?
To get the crossover region to be as smooth as possible, there are three things that need to happen:
The highpass and lowpass filters applied in the bass management system have to properly add in amplitude and phase so as to not introduce a dip or a bump.
The EQ filters applied to the sub and speaker must not introduce any additional phase that would alter the complex summation of the crossover.
The subwoofer and speaker must be time aligned for #1 to work as designed.
Audyssey takes care of #2 and #3. The AVR takes care of #1.
Sometimes, the roll off slopes of the speakers don't match the fixed slopes of the bass management filters. With MultEQ Pro, the software tries several frequencies to find the best crossover frequency that minimizes summation problems that can occur due to slope mismatch. This is done for each speaker individually.
Will that kind of optimization also produce the smoothest possible result when a lower frequency sound isn't just present in a single channel but in more than one channel?
The optimization of the blend between sub and speaker doesn't care about the content. If each speaker is properly blended to the sub then the content will automatically be properly distributed.
Will the complex addition of satellite A plus plus satellite B plus subwoofer also result in the smoothest response when satellite A plus sub and satellite B plus sub were optimized separately?
Yes, if conditions 1-3 mentioned above are met.
You wrote, "With MultEQ Pro, the software tries several frequencies to find the best crossover frequency that minimizes summation problems that can occur due to slope mismatch."
Is this feature only available in MultEQ Pro?
Yes, only in MultEQ Pro. The memory requirements to store and search over multiple frequencies and slopes are too high for the DSP chips in AVRs. They can only be done on the PC at this time.
I have a question about how changing crossover frequency after the
calibration may affect task 2 in your initial comment (The EQ filters
applied to the sub and speaker must not introduce any additional phase
that would alter the complex summation of the crossover.)?
You mentioned elsewhere that it is acceptable to set crossover
frequency to values other than what Audyssey suggests.
Does it follow then that Audyssey's EQ does not introduce any phase anomalies at crossover no matter what the crossover frequency is?
Your understanding is correct.
is the filter calculation affected by the selection of the crossover frequency?
No, it is not. The filter is always calculated down to the roll off frequency of the speaker that was found in the room measurement.
Just to clarify, when I run an Audyssey Pro calibration, after I select one of the recommended crossovers from the drop-down, The Pro software displayes a progress bar indicating that it is finalizing the crossovers. Are you saying that the final filters are independent of the crossover values that are selected?
Because the filters are being calculated after the crossover selection, many of us have been under the impression that that there is an interdependence.
All that is happening at that point is that the proper highpass filter is being applied to the filter (at the frequency you selected) so that it matches the slope that will be applied by the bass management filters in the AVR.
So Pro does change the filter ("highpass filter is being applied") before it is loaded into the AVR? Does it also set a low pass for the sub channel?
Why is there an additional high pass applied at all? If the (acoustical) response of the MultEQ filter is (more or less) flat then the slope of the high pass in the AVR would be perfectly fine, or are you correcting for non-matching slopes of high and low pass filters that are used in most AVRs, or something else?
Does the consumer version of MultEQ also apply an additional high pass to the filter?
^ Lonely questions waiting for an answer :)
Sorry.. some slip through.
Yes, Pro applies the HP filter before loading on the AVR. That's why you need to go back to that page and make the change if you decide to use a different frequency for the crossover.
This HP filter is also applied in the consumer version. Keep in mind that it's a highpass filter applied to the filter and not to the signal. It's applied to "prepare" the response for the crossover filters that will be applied outside of Audyssey.
So it does correct the slope mismatch of the commonly used 24db LP/12dB HP filters in AVRs? Doesn't that create a mismatch when the crossover frequency is changed later on by the user in the AVR?
Yes, it can create a mismatch. Not usually a big deal, but this is another advantage of Pro because it recalculates the high pass every time you make a change to the xover frequency.