avia test disc question

[shamus]

hi all.........attempting to tweak my ht with my new avia setup disk...got a problem....while testing the phase(which i thought i had mastered) all the speakers except the center are in phase with the sub....i checked and double checked my connections, + to +, - to - and everything is hooked up correctly........... my question is just for the hell of it, i reversed one of the wires + to -, - to + and that fixed it............whats up with that???????????? can i leave it that way??? will it harm my center or receiver???? is it a flaw with the receiver???(yamaha mid range price) or center speaker(cambridge mc500)????????????????

 

[MACCA350]

This could be due to positioning, room acoustics, delay settings or something else. Have you tried adjusting the phase settings on the sub to find a good medium? Since changing the wiring, have you checked (with avia) the phase between the center and the left or right speakers to see if they are in phase with the polarity reversed?

Either-way, keep tinkering and you'll find your nirvana

Cheers

 

[Buckle-meister]

...while testing the phase(which i thought i had mastered) all the speakers except the center are in phase with the sub...

It's not so much that the speakers should all be 'in-phase with the sub' as that the speakers should simply be 'in-phase'.

i checked and double checked my connections, + to +, - to - and everything is hooked up correctly........... my question is just for the hell of it, i reversed one of the wires + to -, - to + and that fixed it............whats up with that???????????? can i leave it that way??? will it harm my center or receiver???? is it a flaw with the receiver???(yamaha mid range price) or center speaker(cambridge mc500)????????????????

Connecting + to - and - to + will not do the centre or receiver any damage. All you have done is wire the speaker out of phase with regard to the other speakers, i.e. it's drivers are moving backwards when the other speakers' drivers are moving forward and vice versa. That said, I can't imagine that either the centre or receiver is flawed in their wiring. That explanation for your problem is almost certainly not the correct one

How does the centre sound both in-phase and out of phase? Can you hear a difference? I can only describe an out of phase speaker as sounding more "airy", or less "solid" (apologies to all who abhor subjective terms )

Regards

 

[edwelly]

If you switch the center's phase, wouldn't it be out of phase with the other speakers (fronts and rears)?

 

[Buckle-meister]

If you switch the center's phase, wouldn't it be out of phase with the other speakers (fronts and rears)?

Yes, but for some strange reason, Shamus has found that:

...just for the hell of it, i reversed one of the wires + to -, - to + and that fixed it...

Who knows?

Regards

 

[edwelly]

Yes, but for some strange reason, Shamus has found that:



Who knows?

Regards

Hmm, that doesn't make sense... At least from the ay I read it. I mean I can understand if everything bu the center and sub were in phase, but if you switch it then you have 4 other speakers out of phase...

 

[Buckle-meister]

...if you switch it then you have 4 other speakers out of phase...

..or just one out of phase.

I'm guessing you're a 'glass is half empty' kinda guy!

Regards

 

[shamus]

your right guys..... when i switched it, it put the center in phase with the sub but out of phase with the other speakers........... any way to fix this or just live with it????????? i guess the main thing would be to make the l/r main speakers in phase with the sub??? right? as far as the surrounds go they too may be out of phase(hard to tell) with the sub but not as drastic as the center. i do have a variable phase but it appears from 0 to 179 keeps the mains in phase and only at 180 does it put the center and surrounds in phase..... one more piece of info .... my mains are cambridge t500 with built in subs...however i set my receiver to small anyways(it sounds better that way untill i can get a receiver with a more flexible crossover...this ones stuck at 90) but the subs in the mains still put out some juice.... maybe the subs in the mains are throwing things out of wack?????

 

[Buckle-meister]

...when i switched it, it put the center in phase with the sub but out of phase with the other speakers........... any way to fix this or just live with it?

Your sub is the only speaker that has a variable phase control (clearly variable between 0 and 180), so in the first instance, you should wire all your speakers normally, and then adjust the phase (if necessary) to suit. The way you have described things above, is the reverse way to think.

In order to solve a problem, sometimes a step backwards is required. I would recommend disconnecting/switching off the sub, wiring all your speakers correctly (double check this part) and see how it sounds. Does it now sound ok or not? It should sound fine. If it doesn't, then at least you will have eliminated the sub as being the cause of your problem and can troubleshoot from there.

i do have a variable phase but it appears from 0 to 179 keeps the mains in phase and only at 180 does it put the center and surrounds in phase...

This is incorrect. If the sub is in phase with speakers (both speakers' drivers move in and out in sync) when the phase control is set to 0, it will be fully out of phase (one speaker's driver moves in as the other speaker's driver moves out and vice versa) when it is set to 180. Everything in between will be a smooth transition from the former to the latter. It's just that you may not be hearing this.

... my mains are cambridge t500 with built in subs...however i set my receiver to small anyways(it sounds better that way untill i can get a receiver with a more flexible crossover...this ones stuck at 90) but the subs in the mains still put out some juice.... maybe the subs in the mains are throwing things out of wack?????

You are correct to set the mains (and almost certainly all other speakers too) to small as they are not full-range speakers (i.e. can cleanly deliver 20Hz to 20kHz) and because the sub is purpose built to handle low frequencies whereas the mains are not. A crossover of 90Hz isn't a disaster either, so I wouldn't worry about that. The subs in the mains should not be 'throwing things out of whack' because in principle, the sub and the mains are never playing at the same time.

Let us know how you get on.

Regards

 

[shamus]

now im realy confused..........are u saying all speakers if wired correctly will be in phase with the sub????? ive got all speakers in phase with each other... checked the avia phase pattern(and even thx)....for some reason when integating the sub (actually 2 subs, front and back) it throws either the center off or the l/r mains (surrounds are hard to tell) i even ran the frequency sweeps and it shows a big drop off in the middle range
?????????????? by the way ...am i understanding sub phase correctly??? it has something to do with canceling each others frequency???????
sorry to be a pain but please help!!!!

 

[3db]

Does it matter that the sub is out of phase

I think the crucial thing is the center is in phase with your mains and surrounds as this dictates almost entirely, 99% if not higher, the perceived location of the sound with respect to movies and music. The subwoofer is responsible for bass and bass is supposed to be omni directional. So from that premise, does it matter that the sub is in phase with the rest of your speakers. I have the Sound & Vision test DVD and used the phase control on the sub to achieve max SPL at my seated position and not to achieve phase with the other speakers. Maybe I'm way off on my assumption but i don't think its critical.

 

[shamus]

it is crucial because you may lose a lot of the frequency where the speakers cross over with the sub..

 

[3db]

Don't think so

it is crucial because you may lose a lot of the frequency where the speakers cross over with the sub..

You won't lose any frequencies because they are out of phase. There still there, just out of phase is all

 

[mulester7]

.....you guys are trying to please a meter.....now picture how fast those cones are going back and forth.....do they blur or not?....you move away from 0 concerning sub phase-control, and you're taking authority away from the subs....and let me add again, I only have experience with front firing....WRONG....I had the SVS 16-46 Plus cylinders being kicked by two strapped Carver's 1000 per....I only wish I could have kicked the 16-46 cylinders with strapped K2's....I don't mean louder either, and that part some here will never understand....and that's my view on out-of-phase speakers....please your ears....authority and clean is good....steep rolloff is what you want most, when speakers come together to hand-off......chop-chop....phase issues matter a whole lot less with chop-chop, like, they don't exist....

.....edit....so, did that guy take the "THRUST-FIRE" of a decent 4th of July rocket, on a naked butt, or what?, haha.....

 

[shamus]

all i know is my next receiver will have an automatic room correction setup device so i wont need to go through this again!!!

 

[mulester7]

......well, here we go again....you 6.1 and 7.1 owners, you need to try what we talked about the other night....series 2 speakers on channel 6, you 6.1 owners, and, you 7.1 owners, if possible, wire 2 speakers in series on both rear channels.....4 total....another way to achieve 16 ohms from a single 8 ohm element....cross-wire at either end on your present rear singles, for right at the same effect....the polarity is reversed, you might need to drop the treble a bit on the rear channels, but don't worry, I ran my main's regiment cross-wired one-deep for months....the rears, when you cross-wire one, or wire two in series, brings one circuit of 16 ohms, and the rears will now blend life and clarity to the front soundstage widened by the surrounds....yep, would be a good move.....like I said, set the front three to sub-reference levels with the surrounds widening, and bring in enough rears to bring the soundstage closer, sure, but now, the rears are adding life, via full-range clarity to the soundstage.....and, ALL, this setting is being done with all channels stereo.......

 

[Buckle-meister]

First of all Shamus, sorry for the delayed response; I had guests.

...are u saying all speakers if wired correctly will be in phase with the sub?

Not quite. If all speakers are wired correctly, they will be in phase with each other. The sub is different for two reasons:

1. It is not usually wired like the other speakers, but powered independantly and fed it's signal through a coaxial digital cable.

2. It is the only speaker that will have some form of phase adjustment capability, either through a switch (to select either 0 or 180 degrees), or a rotary (to select anywhere between 0 and 180 degrees inclusive, i.e. greater control than a switch).

...ive got all speakers in phase with each other... checked the avia phase pattern(and even thx)....for some reason when integating the sub (actually 2 subs, front and back) it throws either the center off or the l/r mains (surrounds are hard to tell) i even ran the frequency sweeps and it shows a big drop off in the middle range

It sounds as if you are simply struggling to integrate the subs with the other speakers. If the (correctly wired) speakers all sound fine with the Avia calibration disc with the subs off, then that is probably the most likely explanation.

...am i understanding sub phase correctly??? it has something to do with canceling each others frequency? sorry to be a pain but please help!!!!

Don't worry Shamus. My advice is:

1. Wire up all speakers correctly (leave the subs switched off for the moment).

2. Listen. Do the speakers sound ok? They should.

3. If the answer to 2 is yes, then now switch on the subs. It is only by experimenting with the subs placed in various locations , and possibly with the phase control that they would be found to be in-phase. Just put them in a position and with the phase control set to where music/films sound good. That is all that is required.

The subwoofer is responsible for bass and bass is supposed to be omni directional. So from that premise, does it matter that the sub is in phase with the rest of your speakers.

It is difficult to tell where deep bass (i.e. from about 60Hz and below) is coming from, but it still matters (depending on how one feels about the issue ) that the sub is in phase because there's more than one speaker in the room.

I have the Sound & Vision test DVD and used the phase control on the sub to achieve max SPL at my seated position and not to achieve phase with the other speakers.

Why would you use the phase control to achieve a maximum SPL? Why not just use the volume knob on the sub itself?

it is crucial because you may lose a lot of the frequency where the speakers cross over with the sub.

I wouldn't quite say that. Remember, the front mains will cover from (in your case Shamus) 90Hz to 20kHz. The subs are therefore covering up to 90Hz. In other words, the sub covers less than 1% of the sound of the mains!

You won't lose any frequencies because they are out of phase. There still there, just out of phase is all

In practice, true, but in principle, two speakers facing each other wired 180 degrees out of phase generating the same sound, would cancel each other at the point of collision of sound.

.....you guys are trying to please a meter.....now picture how fast those cones are going back and forth.....do they blur or not?....you move away from 0 concerning sub phase-control, and you're taking authority away from the subs....

You know I don't want to argue with you Mulester7, but I must disagree here. The way I see things, a good methodology for setting up one's system is to set it up 'by the book' and tweak from there if desired. In this way, a datum is first established by which tweaking may then be compared and judged.

Moving the phase control away from 0 degrees may cause a lack of authority to be introduced in your own room, but wont in all rooms.

...my view on out-of-phase speakers....please your ears...

There's always that. At the end of the day, if tweaking is a person's 'thing', then by all means tweak to your heart's content. If nothing else, it can make life much easier.

all i know is my next receiver will have an automatic room correction setup device so i wont need to go through this again!!!

It's not so bad. All it takes is a little experimenting and/or reading. I hope this helps a little.

Regards

 

[shamus]

thanks... im thinking maybe im relying to much on the drop off of volume to decide if its in phase or not... i raised the volume up and i think it sounds pretty good!!! thanks

 

[jaxvon]

In or out of phase is also dependent on distance. With the way your setup is laid out, you wiring your center 180 degrees out of phase may end up creating an in-phase sound at your ears. Remember that sound does not travel instantly, so even two speakers that are in-phase can be made to cancel each other somewhat by varying their position.

 

[shamus]

i was wrong about what i asked before(switching the wires on the center put it out of phase with the regular speakers)...right now all speakers are wired correctly and in phase with each other... the problem right now is the sub... it seems either i can put the mains in phase with the sub by setting the phase knob to 0-179(i notice no difference between these two ranges) but that appears to put the center and surrounds out of phase... or i can put the knob to 180 which puts the sub in phase with center and surrounds but out of phase with the mains... im assuming anyways that they are out of phase by the drop in sound level and the dips in the frequency sweeps around the crossover points... is that correct??????????????????????????