Subwoofer integration advice

[boxerfan88]

I just got my Topping DM7 8-ch DAC which resolves my previous clock drift issue while using 2 distinct async DACs.

I am reviewing the subwoofer integration REW charts, and I need some advise here.

The crossover point is set to 80Hz.

The charts below show 3 sweeps from 10Hz to 2kHz with different subwoofer delays, namely -10ms, 0ms, and +10ms.

First up is the frequency response chart: note that the -10ms has a heavier dip in the red circled area.

Next up is the step response chart:

In your opinion, which subwoofer delay is preferred?
-10ms? because the peak is nearer to the start of the step?
+10ms? because the SPL dip is less?

Second question -- should I push it even more to -20ms (which is the max the software can do) ?

Thanks in advance for your feedback.

 

[ernestcarl]

I just got my Topping DM7 8-ch DAC which resolves my previous clock drift issue while using 2 distinct async DACs.

I am reviewing the subwoofer integration REW charts, and I need some advise here.

The crossover point is set to 80Hz.

The charts below show 3 sweeps from 10Hz to 2kHz with different subwoofer delays, namely -10ms, 0ms, and +10ms.

First up is the frequency response chart: note that the -10ms has a heavier dip in the red circled area.

View attachment 333656

Next up is the step response chart:

View attachment 333657

In your opinion, which subwoofer delay is preferred?
-10ms? because the peak is nearer to the start of the step?
+10ms? because the SPL dip is less?

Second question -- should I push it even more to -20ms (which is the max the software can do) ?

Thanks in advance for your feedback.

Keep what you already have which is no additional adjustment.

Since you are using a PC with the Topping DM7, it is technically possible to push the sub's peak energy closer to 0ms with FIR EQ without incurring too much pre-delay creeping in... but that would require additional DSP.

 

[boxerfan88]

Keep what you already have which is no additional adjustment.

May I clarify -- does your recommendation mean to leave it at 0ms delay?

Since you are using a PC with the Topping DM7, it is technically possible to push the sub's peak energy closer to 0ms with FIR EQ without incurring too much pre-delay creeping in... but that would require additional DSP.

I'm a n00b at FIR EQ.

Could you share the rough concept?

Does it mean to use rePhase to tweak the phase at the crossover region such that the peak is closer to 0ms?

 

[ernestcarl]

May I clarify -- does your recommendation mean to leave it at 0ms delay?

Yes.

Does it mean to use rePhase to tweak the phase at the crossover region such that the peak is closer to 0ms?

Mostly around the xo... but can be full-range.

Could you share the rough concept?

Basically it's when you equalize both magnitude and phase response to get a better summed frequency response.

One could apply a more basic/simple generalized "global" all-pass 'excess phase' correction convolution filter in the signal chain (works fine with stereo-only setups where same filter is used for all channels) like what I did for the ff. example using REW exclusively:

Step response


*maximum phase bass energy is shifted from ~30 ms to ~13ms

Erlan_Rt_Speaker_AP_phase_inverse_correction.mdat

drive.google.com

or Individual channel FIR EQ correction (rePhase below is used to create the FIR phase only corrective filters in combination with JRiver's 'DSP Studio' for the rest of the 'min phase' PEQs):


The latter is not as simple as it seems since every system setup is not going to be the same, and it takes a significant time investment to learn how to use the software and/or hardware DSP tools of your choice e.g. Acourate vs rePhase and REW vs FIR Designer.

 

[boxerfan88]

Thank you very much for sharing. I will need some time to digest it.