how to set sub phase control?

[The DirtMerchant]

I've done several tests for the best settings using various methods. What works best for me is to do the settings in my receiver AND adjust the sub phase. I have an SVS PB12-NSD with a continuous phase control currently set at 45 degrees as a result.

One of the issues with low frequency settings, via the processor, and especially when using an auto setup program, it never gets it right. I set the sub at actual measured distance, then use the variable phase control.

Low frequencies sound as if they're coming from my center channel speaker when the phase is set correctly.

Ripped the above from another thread. I noticed my low frequency wasn't quite as AMAZING as it used to be and apparently one of my children messed with...well everything on the back of my sub. I was looking around on setting phase control and came across the above comments. So, Orbson/Rope or anyone...

1) You set the sub to actual measured distance from..what? front/center channel to sub? listener position to sub?
2) adjust the phase control and set based on...? SPL meter and low frequency test tone hitting the highest SPL at listener position?

I guess I'm looking for a step by step on how to set the phase control.

Thanks in advance...

 

[Zing]

1) You set the sub to actual measured distance from..what? front/center channel to sub? listener position to sub?

1. From listening position to sub.

2) adjust the phase control and set based on...? SPL meter and low frequency test tone hitting the highest SPL at listener position?

2. Ideally, you'll want to use a test tone (particularly the same frequency your crossover is set to) and then, yes, have your SPL meter at listening position (set at 80 dB/Slow response/C-weighting), play tone, adjust main volume until the meter gets as close to "0" as possible and then adjust phase knob until you achieve the highest SPL reading on the meter. Make sure to use the main speaker closest to the sub (disconnect the other).

 

[CMonster]

^If seen several suggestions to reverse the polarity of the speaker that's being used and instead look for the lowest SPL value since it's usually easier to read; just make sure to swap your speakers lead back to the normal position afterwards.

 

[jomari]

^If seen several suggestions to reverse the polarity of the speaker that's being used and instead look for the lowest SPL value since it's usually easier to read; just make sure to swap your speakers lead back to the normal position afterwards.

will you still use the same reading instructions as zing posted with the reverse polarity of the speaker, or does that change?

man im old. i cant remember this either.

thanks for the input everyone. i have to remember doing this as well when we move out.

 

[The DirtMerchant]

...Make sure to use the main speaker closest to the sub (disconnect the other).

Bit of confusion, won't I be setting the baseline-0 using the Sub test tone? Or are you saying using the SPL meter
at listening position, use all the locational (Front L/R, Rear L/R, Sub) test tones so they are as close to zero as possible from all spots.
Then, disconnect all speakers except the one closest to Sub (in my case Rear R), and then starting with the phase adjustment knob at 0, move it along until the SPL reads highest from Sub test tone?

Am I making this unnecessarily complex?

 

[CMonster]

Let's start over.
Get some pink noise. If you can hook a computer up to your receiver then just play some from a site like this one: http://www.audiocheck.net/testtones_pinknoise.php

If you can't hook up your computer, you can download an .mp3 file from that site or one of several others by doing a google search. Whatever. You need pink noise from an external source, not your AVR test tones. You want to play it like a normal stereo track so that it goes through your AVR's bass management. Before turning on your system, disconnect the left or right speaker, whichever is further from your sub, and reverse the polarity on the speaker closest to the sub by swapping the leads (either at the speaker or at the AVR, whichever is most convenient. If neither is convenient then just leave as-is.) Fire up the system, set your meter to 70 or 80 db range, C-weighting, and Slow. Set your subwoofer's phase control to zero. Fire up the pink noise and adjust the volume so your SPL meter is reading around 0. If you've already configured your receiver's settings like bass management, distance, and channel levels, there's no need to screw with that stuff.

Now you're ready to start changing the phase and noting the results. If you reversed the leads, you're looking for the phase position that gives the lowest SPL reading. If you didn't reverse the leads then you're looking for the highest SPL reading. Adjust the phase at about 5 degrees at a time and if you have a helper, make sure the meter has enough time to settle-in at each phase position before taking note of the SPL (in other words, don't have a helper continuously turning the control; there needs to be a pause). If it turns out that the SPL is pretty much the same over several phase positions (not uncommon) then you may want to focus on that range in smaller increments.

 

[Zing]

Fire up the system, set your meter to 70 or 80 db range, C-weighting, and Slow.

I would suggest 80 dB as a minimum. 70 is awfully quiet for low frequencies. Otherwise, that was the most amazingly awesome, easy to follow, dead-on-ball's accurate explanation I've ever read.

 

[CMonster]

Fixed.

Fire up the system, set your meter to 70 or 80 db range, C-weighting, and Slow.

I would suggest 80 dB as a minimum. 70 is awfully quiet for low frequencies. Otherwise, that was the most amazingly awesome, easy to follow, dead-on-ball's accurate explanation I've ever read.

:teasing-neener:

 

[Zing]

:bow-blue:

 

[The DirtMerchant]

Thanks, I'll run through this soon.

 

[Yesfan70]

I need to do that same since I finally got my basement cleaned up, the system moved, and all the speakers tweaked. Only the sub's phase control remains. Thanks gang!


And great post Cmonster!

 

[jomari]

likewise folks, appreciate the help on this. ive never really got further with the phase aspect, so this is definitely a great learning curve for me.

thank you for the precise and informative posting!

:text-goodpost:

 

[Rope]

AVIA Guide to Home Theater has a section in audio dedicated to subwoofer setup. Within that section is a sub-section dedicated to variable phase control settings. It's well documented if one takes the time to read while playing the test tones and making the necessary adjustments. It also helps if you have a second party to turn the variable phase knob while you listen.

Rope

 

[malsackj]

Another option is to also use tools to measure.

http://www.prosoundweb.com/article/prop ... in_sync/av

True RTA and an alignment mic? or

Download the RTA application to a smart phone / IPad.