FIR Auto Mag Question

[EA Support]

EA Support

2 February 2023 at 6:26 am #618

>> Hey there quick question for you, is there a reason the FIR Auto Mag
>> (using minimum phase) creates so much more error in the export than the
>> manual FIR magnitude (also min phase) adjustment when using on midrange
>> response 70-500hz.

It really depends what you’re trying to do on each of the tabs. Send us the project or system files, or screenshots and we’ll take a look.

BR,
EA Support

>> One thing that seems a bit cumbersome to me is that the FIR Magnitude adjust is
>> before the FIR Auto Mag. In this case the Auto Mag tries to offset any crossovers
>> you put on the system. In my experience the process has always been to EQ flat
>> and then apply crossovers to have a good interface. Is there any way to rearrange
>> the signal chain?
>> Anyway here is the attached file where I am having a tough time with the LF auto mag

We’ve taken a look at your system files. A few things:

Check “Hide Phase” and set the LF to > 900 Hz and the HF < 300. This makes the plots easier to read.

>> One thing that seems a bit cumbersome to me is that the FIR Magnitude
>> adjust is before the FIR Auto Mag. In this case the Auto Mag tries to
>> offset any crossovers you put on the system. In my experience the process
>> has always been to EQ flat and then apply crossovers to have a good interface.
>> Is there any way to rearrange the signal chain?

No, there is no way to rearrange the signal chain. Take a look at the FIR Designer overview and the 2-way tutorial on our website. This should make the workflow a lot clearer. The issue you’re facing can be solved by using channel targets that include crossover filters. Then the Auto Mag and Auto Phase can push each channel toward the crossover targets by having the Auto frequency regions overlap down to about -40 dB. Again, take a look at all the tutorials and this will become clearer.

To your original question ..

>> is there a reason the FIR Auto Mag (using minimum phase) creates
>> so much more error in the export than the manual FIR magnitude
>> (also min phase) adjustment when using on midrange response 70-500hz.”

.. higher Q changes (both in mag and phase) and at lower frequencies both require longer FIR filters. In your case, on the LF, the Auto Mag is has a lot more detail, and higher mag and phase slope. This requires a much longer FIR filter; maybe > 4096 taps at 96 kHz.

The smoothing on the Auto Mag is maybe too fine, at 1/12th octave. Unless your measurements Import tab measurements are averaged within the coverage area, and/or you are very confident in the stability of the measurements, using smoothing this fine could cause the loudspeaker to sound worse at locations other than exactly where the measurements were taken.

Best regards,
EA Support