Subwoofer phase question

[Programmer32]

Hello,

I have just set-up a new SVS PB12 NSD to go along with the powered subs in my BP7006. Everything is set-up alongside the viewing wall with the sub facing the listening position a few feet from the right speaker.

DEF Tech recommends that I keep the fronts set to large and they sound good to me either way.

My question is what effect does setting the SVS phase to 180 have? I tried the infamous LOTR Sauron being destroyed intro as a test and didn't notice much of a difference at 0 or 180. I assume the BP7006 side firing subs would be at zero along with the SVS.

Should I need to change the SVS phase to prevent boomy or distorted bass?

Thanks!

 

[Irvrobinson]

Many simple systems do not need a phase adjustment, so it is not a surprise that you don't hear a difference. Also, 180 degrees is a crude adjustment. My Velodyne sub has phase adjustable in 15 degree increments, for example. FWIW, I have a relatively simple 2.1 system, and I couldn't hear any differences even with such a wide and granular range of adjustment.

 

[Programmer32]

Many simple systems do not need a phase adjustment, so it is not a surprise that you don't hear a difference. Also, 180 degrees is a crude adjustment. My Velodyne sub has phase adjustable in 15 degree increments, for example. FWIW, I have a relatively simple 2.1 system, and I couldn't hear any differences even with such a wide and granular range of adjustment.

Thank you Irvrobinson!

The SVS does have incremental phase changes. I had been told to try the 180 and if I didn't hear an appreciative difference, to leave it at 0.

I think the original thought was the side-firing frequencies may hinder the front-firing ones from reaching the seating position. I guess that theory was incorrect, and your post supports what I heard.

Thanks again for your time!

 

[caper26]

What happens is depending on your setup and crossover, your mains AND sub have the potential to play the same frequencies, which (because of the behavior of low freqs) WILL interact with each other before they reach the LP. Somewhat of a (bad) analogy would be subs compared to a very wide spray on a hoze nozzle and tweeters like a very narrow beam spray, both aimed at the LP. This is why tweeters should be ear level, since the sound would actually shoot right over your head of they are too high. Anyway, people have different opinions on this topic of phase, and sub/mains overlapping. My opinion is this: having full range speakers is like having MORE subs in your room, so why would you ever want to NOT use them? (example would be set the to SMALL in receiver settings, and let sub only handle low freqs) My reasoning is that by having them set to large, you get better room response (even out the bass reponse in the room). Now, in my 2.1 setup, if I sit on the couch opposite the speakers (the LP), and change the phase (within the receiver, not the sub, since both mine are 0 or 180 so it doesnt matter), I noticed a considerable different (increase) when it is at 180. Now, this 'increase' may not be for everyone... Hope this helps a bit.

 

[Programmer32]

What happens is depending on your setup and crossover, your mains AND sub have the potential to play the same frequencies, which (because of the behavior of low freqs) WILL interact with each other before they reach the LP. Somewhat of a (bad) analogy would be subs compared to a very wide spray on a hoze nozzle and tweeters like a very narrow beam spray, both aimed at the LP. This is why tweeters should be ear level, since the sound would actually shoot right over your head of they are too high. Anyway, people have different opinions on this topic of phase, and sub/mains overlapping. My opinion is this: having full range speakers is like having MORE subs in your room, so why would you ever want to NOT use them? (example would be set the to SMALL in receiver settings, and let sub only handle low freqs) My reasoning is that by having them set to large, you get better room response (even out the bass reponse in the room). Now, in my 2.1 setup, if I sit on the couch opposite the speakers (the LP), and change the phase (within the receiver, not the sub, since both mine are 0 or 180 so it doesnt matter), I noticed a considerable different (increase) when it is at 180. Now, this 'increase' may not be for everyone... Hope this helps a bit.

Thank you Caper26! I appreciate the explanation and I agree with your Large vs. Small position on the set-up. Especially, with the lowest crossover point on my receiver being 100Hz. That would be a lot of low-mids and upper-bass potentially lost if I went to Small .

The only thing that I have found is that by keeping the fronts at Large, plugging the LFE's into the BP7006's and the PB12-NSD, that I do put the volume on the SVS sub up to between 12 and 1 o'clock to make it come through (at least with music being played in DOLBY ProLogic II Surround).

I hope the sometimes lack of bass I perceive with music is not phase related? I was playing Roni Size Reprazent last night, and even though there were some good low tones, I thought there would be more bass with my Drum'n'Bass?

I do understand there is no .1 channel in a stereo mix, so I would expect this higher SVS setting to be much more intense the next time I play a DTS encoded Blu-ray that has a dedicated LFE signal. I'm just hoping I can dial in everything in the LP so that the BP7006 subs handle the general LFE and small channel (center, surrounds) redirected bass with a little growl while the PB12-NSD comes alive for the deep tones and explosive rumbles.

Hopefully I get a chance to play this weekend! And please enjoy yours!