Subwoofer Phase Switch/Phasing Questions

BrutalPizza

Active Member
Hey

So before I get into my questions and stuff here is what my setup currently consists of:
Amp - Yamaha A-S201
Main Speakers - Cambridge Audio SX80
Sub - Eltax Atomic A-10.2

The Main Speakers are wired to channel A of the amp, and the Sub is hooked up to channel B through it's high level inputs.

The Eltax Atomic A-10.2 like 80% of other Active subs has a phase switch on the back, to allow me to switch it from either 0 or 180 degrees.
I understand what phase means/what phase matching is and how important it is etc, at least I think I do? - The switch essentially adds a delay to the sub driver so you can match it with the phase of the main speakers if it is not already in phase with them correct?

Now what I know I 100% understand is that if the sub was out of phase with the speakers, then I would get less bass/not much bass right?
However, I've tried both 0 and 180 degrees and I get different results lol.

So, with it set to 0 degrees it almost sounds "boxy/boomy" so like, there's more kinda overall range to the bass if that makes any sense? But that loses a lot of low end-thump on kick drums and stuff.
However, with it set to 180 degrees it loses that "boxy/boomy" as I call it, sound. But on 180 degrees it has a really really nice thumpier sound to things like kick drums and toms in metal/rock music, which I actually prefer the sound of.

Shouldn't one of the settings result in no bass/barely any bass at all if it's out of phase on one the settings? Or is it beacuse it only has two fixed settings of 0 and 180 degrees instead of a dial between those two like some subs have, so that it's actually out of phase slightly on both settings in different ways? Which is why there is still bass on both settings, but different sounding bass?

If it helps, the SX80s are 8 ohm speakers, and the driver inside the subwoofer is 4 ohms.
 

hestepare

Member
- The switch essentially adds a delay to the sub driver so you can match it with the phase of the main speakers if it is not already in phase with them correct?

Correct

Now what I know I 100% understand is that if the sub was out of phase with the speakers, then I would get less bass/not much bass right?

Correct, for the frequency range where the sub and mains overlap. If you cross over at 80 Hz, we might be talking about 60-100 Hz or something like that, depending on the slopes. Outside of that, the levels should be the same.

So, with it set to 0 degrees it almost sounds "boxy/boomy" so like, there's more kinda overall range to the bass if that makes any sense? But that loses a lot of low end-thump on kick drums and stuff.
However, with it set to 180 degrees it loses that "boxy/boomy" as I call it, sound. But on 180 degrees it has a really really nice thumpier sound to things like kick drums and toms in metal/rock music, which I actually prefer the sound of.

Difficult to say what causes this without seeing some measurements. My hypothesis is that the 0 degrees is closer to being in phase because if it's louder, it's probably because the phase relationship is better around the crossover area. "Boxy/boomy" sounds like an overemphasis of upper bass. If so, the 180 degree setting would effectively cancel out much of the bass around the crossover, making it sound like deeper bass is more emphasised. Incidentally, 50 Hz (below the crossover frequency) is usually where the big drums on the kit are found.

Chances are your sub is delaying things already if it has any filters whatsoever. Delaying stuff further might bring you into cancelling territory.

You have three options as I see it.

1. Keep it at 0 and turn the sub down a bit so it doesn't sound boxy
2. Set it to 180 and call it a day
3. Buy a measuring mic and a MiniDSP and do it the harder and more expensive way, with possible auditory rewards.
 
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