would I be able to hear 1.29ms delay in subs?

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I am considering using a class D amp with DSP to just power the subwoofers in a stereo setting (two satellites + two subs in a stereo). The satellites will be powered full range by conventional amps (i.e., no delay), but I just found out that the DSP in the class D amp has a 1.29ms delay. I plan to have the DSP implement a low pass of 100hz to 130hz.

My research indicates that sound may travel about 1.5 feet in 1.29ms. Would I be able to hear the delay if I align the subwoofers with satellites vertically? How about moving the subwoofers 1.5 feet in front of the satellites? Should I just give up on the idea and use a conventional crossover (perhaps based on op amps) for the subwoofers?

The amp in question is Crown XLS 2002. If I were to use miniDSP instead for the subwoofers (I always want to power the satellites full range), I believe it also has a latency of 1-3ms.

Thanks!
 
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1.29 ms is 46 degrees phase shift at 100 Hz so that is OK.

For comparison: a conventional 4th order Linkwitz-Riley shifts the phase 360 degrees when going across the crossover frequency. Most people accept that phase rotation in the crossover from their mains to their subs.
 
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1.29 ms is 46 degrees phase shift at 100 Hz so that is OK.

For comparison: a conventional 4th order Linkwitz-Riley shifts the phase 360 degrees when going across the crossover frequency. Most people accept that.

Sorry to push this a bit. Is it (i) audible but generally acceptable or (ii) not really audible at all? I am kind of picky on coherence, but I have no superhuman hearing, so if it is not really audible, I would not mind. Thanks again!
 
I suspect that most of us have not tested to see if we can hear the diff. You can certainly move your subs a foot and a half closer to you, and eliminate that delay entirely....


My setup has the subs about 10' closer to my listening position, and sounds great. I have felt no need to mess about with delay for them, though that would be easy to do.
 
I do this kind of sub to main alignment all the time in the 100-120Hz xover range for proaudio.
If your phase alignment is close to right to begin with, you'll have a hard time hearing a 1-2ms misalignment, because like TBTL says, you would be within an acceptable phase shift difference.
But if you are over 90 degrees misaligned at start, the 1.3ms may well be heard, and could go either way, better or worse. Worse if sub is already behind.
 
If a problem, easy to time-warp with DSP.

I've experimented a bit. First of all, generations of audiophiles have lived with corner horns that shift 8 feet or more and never thought about it. When I tried time shifting from maybe a 2-3 foot gap, I thought I could detect a tiny bit tightening of the percussion, just barely.

Crazy to make a system today without DSP.

B.
 
If it uses a DSP, it has delay, no way around it. When you add a lowpass function to the DSP, that will add more delay to the passband (frequency dependent if IIR type DSP, possibly non-frequency-dependent if FIR type). For that matter, an analog lowpass filter also has similar delay. The fixed delay can be adjusted out like you said, move the sub 1.5ft closer to you (if the room behavior work well with that placement!). Though 1.29msec is hardly anything at 100Hz and lower.

A thought experiment I like to use, not mathematically precise by any means, but maybe gives some intuitive understanding: Suppose you were going to do a lowpass filtering function yourself on a line that carries only single tones (for simplicity). You'd be monitoring the signal line with an oscilloscope and putting in attenuation when you see any tone that is below 100Hz. How could you know the tone was 100Hz or lower until you've seen at least a full cycle of 100Hz (which takes 10 milliseconds)? You would have that much delay just doing your intelligent lowpass filter function
 
If it uses a DSP, it has delay, no way around it. When you add a lowpass function to the DSP, that will add more delay to the passband (frequency dependent if IIR type DSP, possibly non-frequency-dependent if FIR type). For that matter, an analog lowpass filter also has similar delay. The fixed delay can be adjusted out like you said, move the sub 1.5ft closer to you (if the room behavior work well with that placement!). Though 1.29msec is hardly anything at 100Hz and lower.

A thought experiment I like to use, not mathematically precise by any means, but maybe gives some intuitive understanding: Suppose you were going to do a lowpass filtering function yourself on a line that carries only single tones (for simplicity). You'd be monitoring the signal line with an oscilloscope and putting in attenuation when you see any tone that is below 100Hz. How could you know the tone was 100Hz or lower until you've seen at least a full cycle of 100Hz (which takes 10 milliseconds)? You would have that much delay just doing your intelligent lowpass filter function

Very interesting perspective!
 
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