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UX2 output volume bias problem?
by Eidolonia on 2009-07-07 14:54:42

NB: This is a re-post of an earlier thread, after a community member pointed out that only threads marked as questions alert the Line 6 folks. Apologies for the clutter.

Here's my original problem description:

I bought my UX2 last November and have been using it happily ever since, but today I came to do some work on a song I'm mixing and suddenly the right speaker sounds way louder than the left. I checked the speakers but they seemed fine; I then swapped the cables in the left and right outputs (so the left speaker was now connected to the right output, and vice versa), and sure enough the left speaker was now way louder.


It's as if there's a balance control somewhere that's been thrown over to the right accidentally, but I can't find it, either on the UX2 itself or anywhere in software. It's connected to my MacBook, and I've checked the balance in System Preferences for the UX2 -- that's set to dead centre, exactly where it should be.


Is there a secret balance control that I've somehow knocked? If so, where is it? If not, how do I fix this?

A couple of people then asked some questions, which I replied to in as much detail as I could:

I spoke to my local guitar shop (where I bought the UX2), and they're happy to send it back provided I tested it as much as possible to be sure that the unit really was at fault, so I connected it up to my other computer, a Vista PC. The UX2 had never been connected to this computer before. Prior to installing the UX2, the computer produced normal stereo sound. I then did a default installation of all the UX2 software and tried to play back some MP3s. As on the Mac, the right speaker was much louder than the left, and swapping the cables (so that the left speaker was connected to the right output and vice versa) resulted in a reversal of the problem, suggesting that the UX2 output is at fault rather than the cable or the speaker. (In other words, whichever speaker is connected to the UX2's left output is the quieter one.) I then tried updating the POD software to the latest release, just in case that somehow fixed it, but no joy.


At this point I'm convinced that the UX2 itself is at fault, rather than the software, the cables or the speakers, but I'll address the questions in this thread anyway, just in case someone has some advice which they haven't offered up yet.


Replying to your points one at a time (please excuse the formatting; I haven't used this forum software before and don't know how to do things gracefully):


"Have you checked balance, panning, or stereo effect with such controls."


Yes. On my MacBook I can only find one system-wide pan control, and that's set to dead centre. The same setting with earphones or built-in speakers produces a correct stereo image. Through the UX2 the right speaker is louder. I've also checked the pan settings in Logic and iTunes, although those settings should only apply to those applications and not to everything. Still, they're all set correctly, and I get the correct output from every application except when using the UX2.


As I said in the original post, I've struggled to find a pan setting anywhere in the UX2's hardware and software. I'm aware of the pan setting on the guitar amp sim outputs, and that's set to dead centre, but I can't find a pan, balance or stereo setting that affects anything else. Is there one?


"Sound control panel (playback) has a balance setting 0-100 for both left and right channels.  Set both to 100."


Are you describing a Windows system? My MacBook doesn't have a 'sound control panel (playback)'. Nonetheless, the balance settings in Vista were set correctly, and I still get correct stereo sound from within Vista with everything except the UX2.


"Also if you play say a mono audio source in stereo mode from a media player do you have the same problem? For example mix a song down to mono and then play it back in stereo in windows media player."


To test this, I created a mono AIFF file from Soundtrack Pro and then played it back from Finder, which should reproduce the test you're requesting, although I'm not sure what you mean by 'play it back in stereo' -- media players don't convert mono signals to stereo signals on the fly rather than just playing the mono signal, do they? Either way, the right speaker was still louder.


"What other application might you have installed that take control or utilize the audio card?"


Nothing. I worked on a project on the 23rd of June without any problems, saved it and went to bed. The next day, when I turned the computer on again, the right speaker was louder. I had changed nothing. I haven't installed new audio software on my Mac for at least a month.


On my PC, I installed nothing apart from the Line 6 software from the CD and the latest release from the website.


"Did you notice this problem after installing a new version of line 6 software?  What configuration of line 6 software were you using when this wasn't a problem. Can you go back to that config to verify?"


I believe I've covered this, but for clarity: no, I installed nothing. The configuration on my MacBook is identical to the configuration two weeks ago which worked perfectly.


"Can you look at the waveform in a DAW software and eyeball the amplitude differences of the left and right channels?"


Sure, but I'm not playing a file which is louder in one speaker than the other. This is happening for everything; mono signals, MP3s on MySpace, AACs from within iTunes, my own Logic projects, you name it.


"How much louder is the bias  ? Use a microphone (live monitoring disabled and play back a source and record it at a fixed distance from the loudspeaker. Then swap channels. Repeat the test but this time swap the channel feed to the loudspeakers/amplifier."


I don't have the gear set up right now, but I can certainly perform this test later. I'm curious, though: what is this test intended to prove?


"If you use headphones do you have the same biasing issue?"


No. Connecting headphones to the 'PHONES' connector on the UX2 gives me correct, balanced stereo output.


"It is 4th July holiday weekend in the US. I'm British fortunately so I'm online. Doubt Line6 guys will be online until tomorrow.

May want to wait to see if help is forthcoming then...."


I started this thread on June 24th -- almost two weeks ago. How long does it usually take for someone from Line 6 to reply to a thread? (Excuse my ignorance; I've never needed to use these forums before, but then my Line 6 gear has always worked correctly until now.)


"Have your recently updated anything on your computer?  Especially the line 6 drivers?"


On the Mac, no. On Vista, I tried the drivers on the CD, still had the problem, tried the latest drivers from the website and still had the problem. Nothing else has changed.


"Interesting... I had the same problem with a brand new UX8...  Here's how I fixed it.  My speakers are powered.  I brought their level down to about 1/4 power, then brought the output of the UX8 up more than a quarter.  After that, the sound seemed to be level on the left and right.  It really seems noticeable with the output of the UX 8 was down low.  Bringing the output volume on the UX 8 up leveled it out."


Was it doing that right from the start? I've been using my UX2 successfully for seven months, and then overnight the stereo balance went wrong. While I could fix the balance by adjusting the levels on my monitor speakers, your solution sounds more like it's hiding the problem than resolving it. If my UX2 is faulty, I'd rather have a replacement that works rather than working around it -- otherwise the rest of the unit may fail a week after the warranty runs out, and then I'm stuck.


Thanks for the replies,

-Eido



Re: UX2 output volume bias problem?
by ChaChing on 2009-07-07 15:26:15

Hi,

Based on the exhaustive testing you have done, its pretty safe to say its the specific output. Going through the signal chain, we couldn't find anything else you would need to adjust. If your dealer is willing to replace the unit for you, go for it.

Thanks

Line6Sach



Re: UX2 output volume bias problem?
by Eidolonia on 2009-07-08 00:28:26

Many thanks for the swift response. I'll return it right away.

Regards,

-Eido




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