phase control for nearfield placement - AVS Forum
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post #1 of 16 Old 07-21-2013, 06:44 AM - Thread Starter
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I Have a bic pl200 and decided with the way my room is setup to put it nearfield (plus now i should be able to fell the bass better with this small sub). My question is now that its so much father from the main speakers should I set the phase control to 180 instead of zero? I've looked at some sites and it says it will help make bass smoother being that the mains are now 11ft away from the sub. Any help will be great!



Thank you in advance... Oh also if I switch the phase control do I have to rerun Audyessey too???
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post #2 of 16 Old 07-21-2013, 08:33 AM
 
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My recommendation, please, bite the bullet, buy two more PL-200's and be done with trying to make your room come alive with only one subwoofer.

Just saying. In the simple, what you want, your room coming alive, isn't going happen with a single nearfield subwoofer.

Multiple subs aside, two points, one will "NEVER" get the best out of their subwoofer system if they've not taken the time to acquire room measuring capability and obtained a flat response within the capability of their system and two, without a continuous phase control, one is basically working with on and off or left and right but the individual is not going be able to fully phase align a system based on a 0 or 180 degree phase switch.

Again, just saying.

What type of AVR provided or ancillary EQ system do you have and have you run the EQ program you do have?

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post #3 of 16 Old 07-21-2013, 08:48 AM
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Quote:
Originally Posted by glantern30 View Post

My question is now that its so much father from the main speakers should I set the phase control to 180 instead of zero?
No one can say but you, when you try it both ways to see which works better.

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post #4 of 16 Old 07-21-2013, 02:45 PM - Thread Starter
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Originally Posted by BeeMan458 View Post

My recommendation, please, bite the bullet, buy two more PL-200's and be done with trying to make your room come alive with only one subwoofer.

Just saying. In the simple, what you want, your room coming alive, isn't going happen with a single nearfield subwoofer.

Multiple subs aside, two points, one will "NEVER" get the best out of their subwoofer system if they've not taken the time to acquire room measuring capability and obtained a flat response within the capability of their system and two, without a continuous phase control, one is basically working with on and off or left and right but the individual is not going be able to fully phase align a system based on a 0 or 180 degree phase switch.

Again, just saying.

What type of AVR provided or ancillary EQ system do you have and have you run the EQ program you do have?

-[/quote. ]

I currently have a denon 1713 and I did run audyessey. It goes with an energy Rc Lcr, energy rc50 for LR. And Rc 10 for rears.

I was curious to get an opinion, I guess I can run it at 180 for a couple movies and see. At some point I do plan on getting a second one when I do should I run one at 0 and the other 180? Also can I put the second one nearfield as well on the other side of my couch or is it better to Yves one in front and one in back?
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post #5 of 16 Old 07-21-2013, 07:22 PM - Thread Starter
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post #6 of 16 Old 07-21-2013, 09:38 PM
 
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Placement is going be based on how a subwoofer reacts to a room's acoustics. The only way one can tell is to acquire a sound meter and room measuring software. One can download a freeware copy. One only needs a USB measuring microphone and a sound meter to measure their room and find the best placement of their subwoofer system within the confines of their room.

REW

USB microphone.

Go to Amazon and check out sound meters or pick-up the forum standard, a digital sound meter from Radio Shack.

The above basics should get you going in the right direction regarding subwoofer placement. First things first, acquiring the ability to measure and set the gain on your subwoofer and to be able to measure and graph your room's acoustics.
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post #7 of 16 Old 07-22-2013, 10:36 AM
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Quote:
I Have a bic pl200 and decided with the way my room is setup to put it nearfield (plus now i should be able to fell the bass better with this small sub). My question is now that its so much father from the main speakers should I set the phase control to 180 instead of zero? I've looked at some sites and it says it will help make bass smoother being that the mains are now 11ft away from the sub. Any help will be great!
Thank you in advance... Oh also if I switch the phase control do I have to rerun Audyessey too???

Phase switch IMO is a useless feature. You only have the option of toggling between 0 and 180 and that too for the very frequency in question i.e. crossover. Continuously variable phase knob is far superior to just a 0/180 toggle switch. I won't make it to the bones of this subject coz it will easily de-track the problem at hand.

Anyway, leave the phase switch at 0 position. You can easily blend the sub near-field with your mains by adjusting the sub distance. In your specific case, you have to delay the sub wrt mains such that the sound from your mains and the sub reach the MLP at the same time. You need an SPL meter to adjust the phase, though. However, you can do it by ear also. It won't be that accurate; but it will land you in the ball park.

First set all speakers to small and set XO frequency that you want (usually it's 80hz). Put your avr in 2.1 stereo mode. Run an 80Hz test tone. Both your mains and sub will play it simultaneously. Now adjust the distance of sub in AVR. As you increase/decrease distance; at some point you will hear the test tone dropping in SPL, which means your mains are going out of phase wrt sub. At another point your test tone SPL will increase. Leave the distance of the sub where the test tone is heard at its loudest. That is where your mains will be in perfect phase with sub wrt to your MLP.

I have tried sub location both near-field and far-field i.e. close to the mains. While near-field provided tremendous LFE response; but I figured it did not offer as great re-directed bass. LFE sounded extremely great but after some listening I found it to be unreal. Far-field yielded better results with realistic LFE effects and far superior blending with the mains.

But having said that, it's all up to you whichever placement sounds good to your ears.

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post #8 of 16 Old 07-22-2013, 12:29 PM
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Quote:
Originally Posted by braveheart123 View Post

Phase switch IMO is a useless feature..
It's not a true phase/time align control, but hardly useless. The main concern is the combined response of the mains and sub within the crossover region. If the phase of the sub at the listening position is close to 180 degrees out of phase relative to the mains in that region a cancellation notch can result. If that occurs reversal of a polarity switch will remedy it.

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post #9 of 16 Old 07-22-2013, 01:19 PM
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True, but that's why we alter sub distance relative to mains wrt MLP to deliberately induce delay to cater for phase shift by any number of degrees.

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post #10 of 16 Old 07-22-2013, 04:59 PM
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Originally Posted by braveheart123 View Post

True, but that's why we alter sub distance relative to mains wrt MLP to deliberately induce delay to cater for phase shift by any number of degrees.
And if your system does not have that capability? Not all do by any means. If you only have a polarity switch at your disposal it will address the main issue, subs being 180 degrees out of phase with the mains at the LP.

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post #11 of 16 Old 07-22-2013, 05:34 PM - Thread Starter
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Originally Posted by braveheart123 View Post

Phase switch IMO is a useless feature. You only have the option of toggling between 0 and 180 and that too for the very frequency in question i.e. crossover. Continuously variable phase knob is far superior to just a 0/180 toggle switch. I won't make it to the bones of this subject coz it will easily de-track the problem at hand.

Anyway, leave the phase switch at 0 position. You can easily blend the sub near-field with your mains by adjusting the sub distance. In your specific case, you have to delay the sub wrt mains such that the sound from your mains and the sub reach the MLP at the same time. You need an SPL meter to adjust the phase, though. However, you can do it by ear also. It won't be that accurate; but it will land you in the ball park.

First set all speakers to small and set XO frequency that you want (usually it's 80hz). Put your avr in 2.1 stereo mode. Run an 80Hz test tone. Both your mains and sub will play it simultaneously. Now adjust the distance of sub in AVR. As you increase/decrease distance; at some point you will hear the test tone dropping in SPL, which means your mains are going out of phase wrt sub. At another point your test tone SPL will increase. Leave the distance of the sub where the test tone is heard at its loudest. That is where your mains will be in perfect phase with sub wrt to your MLP.

I have tried sub location both near-field and far-field i.e. close to the mains. While near-field provided tremendous LFE response; but I figured it did not offer as great re-directed bass. LFE sounded extremely great but after some listening I found it to be unreal. Far-field yielded better results with realistic LFE effects and far superior blending with the mains.

But having said that, it's all up to you whichever placement sounds good to your ears.

audyessey has already set the distance at 6 ft when in reality its about 2-3 ft away from the mlp. you don't think that's accurate?
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post #12 of 16 Old 07-23-2013, 01:27 AM
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Not very accurate IMO if that distance set by audyssey is based on a crossover frequency other than what you want to set. Sub distance in electrical domain is dependent on specific crossover frequencies coz of differing wavelengths. Wavelength for a 60Hz xo is different from the same for an 80Hz xo; hence the need to change the sub distance.

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post #13 of 16 Old 07-23-2013, 04:07 PM
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Originally Posted by braveheart123 View Post

Not very accurate IMO if that distance set by audyssey is based on a crossover frequency other than what you want to set. Sub distance in electrical domain is dependent on specific crossover frequencies coz of differing wavelengths. Wavelength for a 60Hz xo is different from the same for an 80Hz xo; hence the need to change the sub distance.

Audyssey doesn't consider phase in setting distance. It emits the tone and waits for the sound to hit the mic at the first position, establishing the appropriate delay, which is converted to / stated in feet on the receiver's display. Wavelength doesn't directly affect when the leading edge of the wave arrives, either for treble or bass sounds. Probably two or three hundred reiterations in the Audyssey thread that longer-than-physical distances for a sub are almost always the result of delays that occur in the sub's own electronics . . .
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post #14 of 16 Old 07-23-2013, 05:28 PM
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Audyssey doesn't consider phase in setting distance. . .
And there's the rub. Worst case, a sub may have 90 degrees phase lag at the XO frequency, a main 90 degrees phase lead, so even if in perfect time align you could have a 180 degree difference, resulting in a 24dB or so response notch. Audyssey is a fine tool, but it's not perfect. To get it absolutely right requires measuring software capable of displaying phase response. But in most cases getting it absolutely right isn't necessary, close enough is usually good enough.

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post #15 of 16 Old 07-23-2013, 05:50 PM - Thread Starter
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And there's the rub. Worst case, a sub may have 90 degrees phase lag at the XO frequency, a main 90 degrees phase lead, so even if in perfect time align you could have a 180 degree difference, resulting in a 24dB or so response notch. Audyssey is a fine tool, but it's not perfect. To get it absolutely right requires measuring software capable of displaying phase response. But in most cases getting it absolutely right isn't necessary, close enough is usually good enough.


SO I'm back to square one lol... and audyessey maybe slightly off but close enough. I'll leave the phase at 90 for now and see how it goes. I just did not have enough room to put the sub up front where I wanted to be. I only had two options, on either side of my couch so I put it in the corner opposite of where I sit. It's not bad by all means just not use to felling base like that and on a rare occasion I can localize it. I've never notice a concern that for an example the timing of an explosion was not in sync with the other speakers so I guess that's not too bad. I've learned a lot thou and I want to thank you guys for helping me at least understand what's going on. I really want to get an outlaw lfm plus but now I'm not so sure since it has to be nearfield to me?
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post #16 of 16 Old 07-23-2013, 07:18 PM
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With only a single subwoofer and Audyssey there is really no reason to adjust the sub's phase to anything other than 0°. Audyssey, through a combination of the distance setting it determines and the very specific type of phase-based EQ filtering that it utilizes, should adjust the sub's phasing with your speakers appropriately.

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