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Which subwoofer phase should I set?

JustAnAudioLover

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Mar 25, 2021
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Hi there!

Due to space constraints, I had to position speakers in a less-than-ideal fashion:

1742147988690.png


(Not exactly to scale)

As you can see, the subwoofer is right next to the couch and, important information, it is facing the L/R speakers.

Basically the L/R speakers are firing sound to the MLP, and the subwoofer is firing sound towards the right speaker.

In this scenario, what phase should I set? 0° or 180°? I tried both settings and it seems pretty similar to me, but I'm not very sensitive to bass, so I'm not sure what I should do...

Thanks in advance for your help!
 
This should be set on a case-by-case basis, so measure both using software like Room EQ Wizard or HouseCurve for iOS and choose the setting with better phase- and frequency response.
 
This should be set on a case-by-case basis, so measure both using software like Room EQ Wizard or HouseCurve for iOS and choose the setting with better phase- and frequency response.
I unfortunately don't have a calibration mic and use an Android phone :/
 
I would spend hours sweating over trying to figure out the correct cable to purchase.
Maybe don't worry about it. ;)

It's only important at the crossover frequency where the sub and main speakers are both operating together. (That's assuming you have a proper crossover.)

80Hz (a common subwoofer crossover frequency) has a wavelength of 14 feet, so if the main speakers are 7-feet further from your ears than the sub, you are at one-half wavelength and 180 degrees out-of-phase (which means the soundwaves will cancel-out at that frequency and that spot). In that case you can use the 180-degree setting to correct it. With a 14-foot difference, you'll be back in-phase, etc. Probably neither setting is "perfect".

...Sometimes you "main stereo amplifier" will flip the polarity/phase.

And... If there is a standing wave peak at the crossover frequency (depending on room dimensions/acoustics) it might be better to have cancelation.
 
I launched a subwoofer test video on youtube and found out that no matter what I do, there seems to be a null in the 60 ~ 70 Hz at 180°, and it gets even worse with phase at 0°.

Seems like even correctly setting up a subwoofer is pretty complicated... I would have thought it would be the most simple thing in the world ^^"
 
But like if you sit down and listen to 'thanks to you' at phase 0 and then listen again at phase 180 - do you hear a difference?
 
But like if you sit down and listen to 'thanks to you' at phase 0 and then listen again at phase 180 - do you hear a difference?
The song from Boz Scaggs? Just tried, I'm not sure there is an audible difference - but note that I have amazingly bad echoic memory so it's hard for me to A/B compare things even a few seconds apart.
 
Same here. The reason I suggested that song is because the bass parts there are memorable beyond hearing - you can feel it emotionally, especially if fronts are time-synced well with the sub. I use it to confirm dsp/room correction setups. It should be played from an uncompressed source like qobuz rather than YouTube or spotify. But if you don't feel much difference - I'd keep the phase at 0.

You can also search youtube for tricks -
 
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