JimP
I have gotten focused on the issue of optimizing the crossover/intergration between my prepro (B&K Ref 50) and the subwoofer. 

In the past, I've seen plenty of articles about using the phase control on the sub in case your receiver doesn't have a distance setting.  I've also read that in most cases, the phase control can't correct correctly as what you are trying to do is advance the timing of the subwoofer so its sound (after latency) arrives at the same time as your mains. A phase control can't advance the time, it can only delay it....which brings up a side question about how then does it seem to place the sub and other speakers in phase.

I've also seen an article from 2006 where I think Mark had made the comment that most receivers have enough latency that adjusting the subwoofer distance setting in the receiver to add 2.6 (or was that 2.8?) to the actual physical distance is about average.

So my question is to get the best intergration, does it take a combination of the subwoofer distance setting and the subwoofer phase setting and if it does, how do you go about doing it?

Thanks in advance
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Mark_Seaton
JimP wrote:
I have gotten focused on the issue of optimizing the crossover/intergration between my prepro (B&K Ref 50) and the subwoofer. 

In the past, I've seen plenty of articles about using the phase control on the sub in case your receiver doesn't have a distance setting.  I've also read that in most cases, the phase control can't correct correctly as what you are trying to do is advance the timing of the subwoofer so its sound (after latency) arrives at the same time as your mains. A phase control can't advance the time, it can only delay it....which brings up a side question about how then does it seem to place the sub and other speakers in phase.

I've also seen an article from 2006 where I think Mark had made the comment that most receivers have enough latency that adjusting the subwoofer distance setting in the receiver to add 2.6 (or was that 2.8?) to the actual physical distance is about average.

So my question is to get the best intergration, does it take a combination of the subwoofer distance setting and the subwoofer phase setting and if it does, how do you go about doing it?

Thanks in advance


Hi Jim,

The reason a phase control can functionally work is that phase, and sinusoidal summation (sum of 2 sine waves), while related, is not the same as matching arrival or group delay.  Two sine waves played at the same time can sum completely (+6dB acoustically), partially, or fully cancel each other.  When just looking at the sine wave or steady state behavior, full +6dB summation occurs when the sine waves align with the maximum and minimum pressures occurring at the same time.  This means you can delay one of the signals by any full integer wavelength, or the time from one pressure maximum to another maximum, and the summation will not change in the steady state.  This is what we generally are looking at when we measure frequency response.

This is also why the added group delay of a phase control on a subwoofer can vary the summation.  The significance of getting the time arrival closer is a matter up for debate where you will find experienced experts on both sides of the fence.  Personally I believe it can help significantly, so long as it doesn't cause other offenses.  The one aspect you have to be careful of is subwoofer localization, more so when the subwoofer is rather close to the listening position or behind you.  The interaction with the room and the qualities of the subwoofer factor into this as well, and a rear location in one room will work wonderfully, while being a problem in another.

The best means to optimize the time arrival of the subwoofer and main speakers is heavily dependent on what tools you have available, and partially how patient and persistent you are willing to be.
Mark Seaton
Seaton Sound, Inc.
sales@seatonsound.net
773-290-8436
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JimP
I'm setup to run REW.

Is it possible for there to be a phase mismatch between a receiver and a sub that people try to correct with subwoofer distance settings where it needs to be corrected on the sub with its phase adjustment?
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