Power Amp Inverting Phase

Airplay355

I was reading the manual to my B&W sub because my bass is souding strange. I can tell which main speaker the sub is behind and if I put the sub in the middle, I lose most of my deep bass (obviously). Initially I had the sub with the EQ to compensate for corner loaded position (position A), the low pass filter on 80 hz, phase at 0 degrees and volume at 1/4th. This setup sounded fine with my old Polk system, but it sounds like garbage now.

So, I finally decide to read the manual. For two channel setup they suggest 180 degrees for the phase, but say that I might want it at 0 if I am using line level inputs (which I am) and if the my power amp inverts the phase. Now I really don't know alot about phase but I thought that 0 degrees meant the driver moved out to produce bass, and 180 degrees meant the driver moved in. My Jm labs are moving out to produce bass and so is my sub, does that mean they are in phase? Or could they still be out of phase. I don't really know what out of phase bass sounds like but I'm going to try both and see what happens. Someone help me out here.

heiney9

Typically when a speaker is out of phase you will notice a marked drop off of bass. This is typical of when the polarity of the speakers in relation to amp are reversed. Having said that, I'm not an HT guy so I'm not sure why they want you to run your amp/sub 180 d out of phase. Or why they would ask if your amp inverts phase. This may have something to do with the sub playing in relation to the mains. For 2 ch listening I would make sure all the setting are "in phase" or 0 as your manual suggests. Maybe somone else with more HT knowledge can help. In the end all connections create one big electrical circuit and things need to flow properly to get the desired output.

H9

Airplay355

My sub is in a 2 channel setup and they suggest 180 degrees for 2 channel listening while they suggest 0 degrees for HT. My sub is at 180 degrees now but I still have plenty of bass. Does this mean it isn't out of phase?

heiney9

Wish I could help more. I'm just not up to speed with HT configurations. Hopefully some of the other guys with HT can help ya out

H9

RuSsMaN

Airplay, some amps invert the phase of the signal. It's just a fact and inherent in some designs. It doesn't matter if the speakers move out or in first, as long as they both (l/r) do the same thing - there is no difference in low end response.

That's the main reason that a lot of powered subs have a phase inverting switch on them. One setting should have more pronounced low end (and match the phase of your system), use that setting and you're done.

Cheers,
Russ

disneyjoe7

Dido what Russ as said, use want sound best 0 or 180 degree's.

Airplay355

so theres a possibility that it would sound better out of phase?

disneyjoe7

Yes, what Russ was saying (I agree with him) some amp are out or phase to the input of them. It sounds ok when 2 channel due to both channels being the same and to the speakers also. But another amp that is in your sub can be straight as to the input, so swithing the sub 180 out of phase is in phase due to the above statement that the amp itself out of phase.

Airplay355

does 180 degrees mean the drivers will always move in and 0 degrees means they will always move out?

disneyjoe7

Lets say it another way....

An amp can be straight input to it's output, meaning the signal is in time within the amp. An amp could be designed with an inverting signal within the amp, so the signal doesn't have the same timing input to output.

You have 2 amps of different manufactors and or designers. So it possible that one is out of phase to the other. Nothing is wrong just different so if the sub sounds better when switched out of phase it could be really in phase to the front speakers.

I hope that clears it some
:cool: