Out of phase? Polarity? Something else?

[forumrookie]

Hello, all. I'm hoping that one of you gurus can assist me because I'm lost.

The setup:

Balanced Source (computer interface) TRS to Amp TRS inputs 1 and 2. Amp to speakers Left and Right.

The issue:

I thought that one side was wired out of phase. Sound in one speaker is garbled with no bass definition when panned in the center. If I pan hard left or right, both speakers play together and sound great - stereo image is magnificent... panned hard either way. Makes no sense to me.

When I reverse polarity on one speaker, same result. When I remove one speaker, sound is sometimes garbled sometimes clean making it hard to track the issue. I've swapped out the input/output cables, interfaces (2), the amps (3), and the speakers (3 pair). The only thing that I haven't swapped are speaker wires but the speakers play fine from other sources.

Connecting the speakers directly to the amps - sound is great. Connecting powered speakers directly to the interfaces - sound is great.

Could the TRS cables rather than TS be an issue when it comes to phase/ polarity (left and right)? Anyone have any insight?

 

[everettT]

Hello, all. I'm hoping that one of you gurus can assist me because I'm lost.

The setup:

Balanced Source (computer interface) TRS to Amp TRS inputs 1 and 2. Amp to speakers Left and Right.

The issue:

I thought that one side was wired out of phase. Sound in one speaker is garbled with no bass definition when panned in the center. If I pan hard left or right, both speakers play together and sound great - stereo image is magnificent... panned hard either way. Makes no sense to me.

When I reverse polarity on one speaker, same result. When I remove one speaker, sound is sometimes garbled sometimes clean making it hard to track the issue. I've swapped out the input/output cables, interfaces (2), the amps (3), and the speakers (3 pair). The only thing that I haven't swapped are speaker wires but the speakers play fine from other sources.

Connecting the speakers directly to the amps - sound is great. Connecting powered speakers directly to the interfaces - sound is great.

Could the TRS cables rather than TS be an issue when it comes to phase/ polarity (left and right)? Anyone have any insight?

You should probably list the gear, not just your signal path, which is still a little confusing.

 

[forumrookie]

Sorry about that.

The interfaces are Universal Audio Volt 4 and PreSonus ioStation 24C. (These are not connected at the same time.) They receive input via USB-C from the PC. (Pan and volume controls have been checked.)

The interface's TRS 1/4" outs feed TRS 1/4" ins on one of the three tested amps (Crown XLS1002, Behringer A800, Hafler TA1600). Speakers are all connected to the amps via banana plugs. Speakers if it matters are JBL 4206s, KRK Rokit 8s, and Event 20/20s.

Why and how would panning hard left or hard right play perfectly as if panned to the center position (stereo separation, clarity, depth)? When set to the center position, sound on one of the speakers becomes significantly degraded as if out of phase - the same speakers that just played perfectly 30 seconds prior on the panning test.

On the second series of tests, I used an acoustic/ vocal track. This time I only connected a single speaker at a time switching between left and right outputs. Regardless of side, the lead vocal in the track disappeared with backgrounds and guitar remaining (as if someone connected a vocal eliminator to make an instrumental). How can a single speaker be out of phase? There's nothing to be out of phase with!!

My brain is tired. I haven't been this befuddled dealing with audio in 30 years. I feel like I'm doing something stupid, but I can't figure out what.

 

[ski2xblack]

Hmm. Just spitballing here, but it sounds like you have somehow or other mixed a little summed (or difference?) signal chocolate into your regular L and R channel signal peanut butter. That would account for the wierd and unexpected results with the pan pot. Double check the 1/4" cables to ensure they're the correct tools for the task. Make sure they're fully seated/inserted. Double check the output settings on the mixers, if they have such, to rule out something there.

 

[ski2xblack]

This is some sort of signal mixup. I recall a mixer that had specific output modes, specifically 'stereo', the normal L and R channels, 'mono', which summed the channels, and 'null', which was a difference signal (which was everything panned away from dead center in the mix, which includes all that phasey spatial ambient stuff too). If 'null' was engaged, it did exactly what you describe happening to you when panning. That's why I suggested checking the mixer settings.

 

[m. zillch]

I'm thinking you might have a bad ground(s), somewhere. Could be a poorly seated plug insertion, a loose connection, cold solder joint, bad pin, bad/cracked circuit board, soiled/oxidized contact points, etc.. Ever have a stereo headphone cord that "works" but sounds phasy/staticy and when you spin it or wiggle it it gets cured, at least temporarily? It's like that.

 

[Eppie]

If you pan hard left or right and BOTH speakers play, then something is wrong in the wiring or your source device. You should only get sound in one speaker when panned hard left or right. Seems odd since TRS cable wiring is difficult to mess up.

One other possibility is that the amp is set to bridged mode. That would mess things up if using two speakers on the amp. Make sure any bridge mode switches are off and the speakers are connected for discrete right and left.