Subwoofer Latency

[Ron Texas]

I received this from a manufacturer:

There is no wireless function in the [subwoofer]. If you run it with crossover out, there is no latency. With crossover engaged, and if you have a matching 24 dB/Oct Linkwitz-Riley high pass, the subwoofer signal is delayed a full wavelength at the crossover point compared to the high pass signal.

Why a full wavelength? That seems like a lot of latency. Does anyone understand this? I thought plate amp latency was in the 2 to 6 ms range.

 

[Deleted member 2944]

Assuming there's no DSP at work, group delay is directly associated with the filters used.

Maybe they have "wavelength" confused with "period" in their description? In a normal 24db/octave LR alignment there's a 360 degree difference between HP and LP.

Dave.

 

[House de Kris]

That's correct. A fourth order filter has 360 degree phase shift at the crossover frequency. And, 360 degrees is a full cycle, which is the same time as a wavelength.

 

[Deleted member 2944]

A 4th-order crossover has 360 degree phase shift (between LP/HP outputs) at all frequencies, not just the crossover frequency.

I was thinking more of 'acoustical' wavelength in my initial comment. Sorry if not making that clear.

Dave.

 

[House de Kris]

Interesting, that does not reflect my experiences with simulations or measurements.

 

[Deleted member 2944]

Edited my previous post to make it clearer.

Dave.