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Subwoofer Time Alignment

QMuse

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When I have time I'll try to take a "very near-field" measurement of the mains and see if the step looks more 'normal' i.e. minus SBIR.
I agree. It would be interesting to see how step and phase response of your mains is looking when there is no XO either in miniDSP and all settings of their internal DSP is set to default. You should examine phase and step response of 20-20kHz and 30-110Hz sweep when they are in the middle of the room vs when they are now. You should check both mains as they shouldn't be major differences between them.

I'm still suspecting their internal DSP.. :D
 

ernestcarl

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This looks very good. It would also be interesting to see the phase response of 40-110Hz sweep and step and phase response of 20-20kHz sweep.



There is something strange happening with step response of your mains but I doubt it has anything to do with SBIR. That shape of step response is simply not "normal". Even when a main speaker itself is not fully phase corrected (such as mine) step response shouldn't be looking like that with 40-110Hz sweep as only speaker's woofer will be playing - it should be looking fairly similar to your sub response.
So usually you don't need 3 "shaping" XO filters as one should do the job just fine.

Anyway, I have created a separate thread to show how this should be done in a "standard" case.

The 'shaping filters' I used to try to help keep the response curves closer to target aren't particularly agressive -- in fact, no additional headroom was required.

After trying out the same impulse alignment method now with my sofa setup, I don't see much of a difference in the resulting summed responses other than the time delay needing to be altered by a few milliseconds more.

One thing I realized from this exercise: the xo 'shaping filters' weren't particularly necessary, either way. But I decided to move the sub's xo to 85Hz since it gave a teeny-tiny 'better' response.

At the MLP with all filters...

PHASE
1597571870034.png


The actual xo point
1597571908109.png


The weird impulse and step response
1597571950473.png


1597571957481.png


and what I got measuring very close to the monitor:

1597572008426.png


1597572022340.png


I don't think any of my filters were aggressive enough to cause the apparent mishapen form of the responses at the MLP. The type of xo used also didn't cause that much of a change. Part of it is already inherent in the 'look' of the monitor's native impulse, and part of it is clearly SBIR related.

1597572223324.png


1597572230948.png


All in all, I don't think there's much to worry about here.
 

ernestcarl

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I missed seeing this alignment tool in REW:

1597573510726.png

duh!

I haven't tried it out yet myself. But in case someone wants to... It's there folks for you to have a go at it and test!


*I've only made use of the old, basic time offset tool:
1597573806994.png
 

ernestcarl

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I missed seeing this alignment tool in REW:

View attachment 78433
duh!

I haven't tried it out yet myself. But in case someone wants to... It's there folks for you to have a go at it and test!


*I've only made use of the old, basic time offset tool:
View attachment 78434
Just an update: successfully used the Alignment Tool mentioned above and here's a link to a simple snapshot of it at work:

https://www.audiosciencereview.com/forum/index.php?threads/two-double-dip-regions.17460/post-582657

It worked best after after applying some simple filters e.g. just a few PEQs, HP cut off, and low pass (to filter out none phase compliant/conflicting frequencies above 130-40Hz) for the sub prior. Speakers were left as is with no correction.

Didn't work as expected for another setup, but for my desk it worked really well.
 
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If you are have a 2 channel setup with ( preamp/amp) no bass management like a AVR, how much do you worry about latencies in a SVS sub from built in dsp? That is, when you can't delay the main speakers in a preamp like you can in a AVR?
 
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dasdoing

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If you are have a 2 channel setup with ( preamp/amp) no bass management like a AVR, how much do you worry about latencies in a SVS sub from built in dsp? That is, when you can't delay the main speakers in a preamp like you can in a AVR?
it will be below 10ms (my sub in my setup is 6,3ms late), which most don't seam to care off. you can check if you can hear 10ms delay here: https://www.audiocheck.net/blindtests_timing_2w.php?time=10
actualy in this case most will delay the sub even further a bit (phase knob) to align phase (meaning, make the delay fit into 360 degree steps) and avoid a dip in the crossover region
 
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it will be below 10ms (my sub in my setup is 6,3ms late), which most don't seam to care off. you can check if you can hear 10ms delay here: https://www.audiocheck.net/blindtests_timing_2w.php?time=10
actualy in this case most will delay the sub even further a bit (phase knob) to align phase (meaning, make the delay fit into 360 degree steps) and avoid a dip in the crossover region
This is the part i am having a hard time with. How could a smooth crossover blend be forgiving of a significant latency to the ear (for the above mentioned)?
 

dasdoing

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This is the part i am having a hard time with. How could a smooth crossover blend be forgiving of a significant latency to the ear (for the above mentioned)?
subs procedures are coming from the movie crowd. it doesn't matter for a movie. personaly I delay my mains, and I align using excess group delay and an eye on the dip.
Do AVRs delay mains? never had one
 
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subs procedures are coming from the movie crowd. it doesn't matter for a movie. personaly I delay my mains, and I align using excess group delay and an eye on the dip.
Do AVRs delay mains? never had one
Oh yeah, even if you have a dsp sub connected wirelessly (with a wireless transmitter that adds significantly more latency), a AVR or PrePro will account for latencies seamlessly.

How did you delay the mains on your 2 channel amp?
 

dasdoing

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Oh yeah, even if you have a dsp sub connected wirelessly (with a wireless transmitter that adds significantly more latency), a AVR or PrePro will account for latencies seamlessly.

How did you delay the mains on your 2 channel amp?
my DSP is all done on my PC, incl. the crossover, where I delay the main signal
 

samysound

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If you are have a 2 channel setup with ( preamp/amp) no bass management like a AVR, how much do you worry about latencies in a SVS sub from built in dsp? That is, when you can't delay the main speakers in a preamp like you can in a AVR?
The latency for a SVS SB2000 (older non-pro version) is 5ms.
 

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