Hey all. Phase settings have always confused me a bit and it seems like there should be a way to figure out what is ‘correct’ vs ‘just see what sounds best’. So here is the scenario:
My sub is hooked to a Cary pre which is not in phase. (Not sure if this is relevant but…). I have the sub placed behind and to the side of my mains - which are dipoles. It would seem the rear wave is out of phase w the front wave? Is that correct? If so - what do you think the phase setting should be on the sub given its position behind the dipoles?
You just need to switch and listen to the results. If it isn’t obvious, it isn’t a concern.
Phase adjusts where the peaks and nulls of the bass wave appear in the room. Most people choose the setting that yields the most bass at the listening position. That means that the waveform’s peak is hitting the listening position. On the other hand, if there seems to be little to no bass at the listening position, then the null is hitting the listening position.
Many subs only have a switch that allows 0 degrees or 180 degrees. The problem with this adjustment is that neither option may work well for your listening position because neither setting is optimal if, for example, you need a 90-degree phase adjustment to get the peak in the listening position. This is when the subwoofer’s position comes in, and you will need to use the combination of the phase switch and the position of the sub to yield the bass you desire.
I only buy subwoofers with a continuously variable phase setting capable of any value between 0 and 180 degrees. This makes the sub-positioning less critical, as you can adjust the phase to any value that results in the peak of the bass wave in the listening position. I follow that up with at least two subs to achieve the bass effect I am looking for.
I hope this helps, and best of luck getting your sub dialed in. Once you have it set correctly, the results are glorious.
Thanks for your response. I think it does help me a bit as I wasn’t thinking about the room interaction really.
Does anyone know of a possible phone app that might measure these low frequencies? And yes my sub has a 0-270 phase control.
The easiest way to adjust it is to use and trust your ears. Have a friend or family member adjust the phase dial while you are seated in the listening position with bass-heavy music playing. As the phase is adjusted you should be able to hear when the bass is dialed in.
I don’t have any friends that are this geeky about this. but I’ll see who I can dig up.
You need something like the studiosix SW and a mic for around 200$ (e.g. their itestmic). The built in phone mic won’t be helpful at those frequencies.
Then play a sine wave track at the crossover frequency and measure highest output at the listening position while changing phase (I agree it should be adjustable in the whole range from 0 to 180). At the end fine tune by ear if necessary.
Doing it by pure listening and ignoring everything you can’t immediately hear is always easy, but as correct phase is the starting point for all other measures to perfectly adjust a sub (crossover frequency, level, slope and frequency of EQing, sub level, measure frequency response), with the correct phase you’re more sure you will fiddle from a correct basis than trying to get something right with the following settings later, that was wrong from start.
If you do it by ear, it depends on your room’s standing waves at certain frequencies, if you hear the right phase as better or worse (more or less bass…you probably can’t judge correct prat by ear without equalized bumps). If you then choose the wrong phase because this optimizes a bump in your room, the result will be flawed. You should then better have set correct phase and compensated the bump with EQ. Just to explain how adjusting purely by ear can result in inferior overall result.
I agree with you jazznut. Having panels which are fast - I would think phase to be fairly important. Plus my two variables of an out of phase pre plus dipoles … I guess I was hoping for that ‘correct’ setting based on electronics and then move to room interaction. Sort of like how I set my dac to ‘out of phase’ to invert the signal for my out of phase pre…. This was all ‘known’ adjustments - nothing done by ear.
Why is your pre out of phase?
It’s a Cary slp98p. It is designed that way. They tell you to invert at the speaker terminals. I just do it at the ds dac.
Oh I see. Then just do that and set sub phase as described or by ear. As you vary phase thereby anyway, you’ll find the right one for this kind of combination, as the rules (choose loudest phase setting) applies as well. But you won’t be able to hear this difference, it’s mostly just up,to 5dB, which you hardly hear at 30-40 Hz, you may just be able to measure. As soon as you’re free of resonances with you sub setting, you will be able to hear differences in prat by ear when varying phase.
So I currently have it at 180 figuring this technically puts it at 0 because it is getting an out of phase signal. Is that correct thinking?
…roughly just when your sub is physically in phase with your speakers = the front baffle of your sub is on the same level with the speaker’s front baffle and both sub and speaker better have no delay in signal feed speed from each other and woofers react comparably fast. You see, this is hardly the case for any setup. You need to find out an individual phase setting.
If your sub is physically not in phase with the main speakers, 0 degree can be the right setting inspite of your inverted pre phase.
I’m using a Martin Logan descent. The sub has 3 active 10”woofers. 1 on the front and two angled at about 30 degree angles. I used to use it w my Logan’s prior to the Maggie’s.
So if you placed your sub directly besides the main speakers with the front chassis on main speaker baffle level, the 180 setting could be quite right in theory.
I am pretty certain Martin Logan Tech Support could give you useful information on how to proceed.
Not to discount the value of asking here!
I have to do this when I have my Conrad Johnson tube preamp in the system.