Topic: Do I have bad Caps? Strange wave from last nights show

[darktrain]

I am having a hard time trying to figure out this wave, if and what it means if anything. I have attached a couple different pics from various programs. Let me know what you think, Besides one channel being a db or 2 off i can't really hear anything out of the ordinary. And when you split the tracks everything looks ok and also in the magic audio cleaning lab it looks ok, i didn't post a pic but in audacity it shows the lopsided wave also. Used hlsc's>bb>ihp120.

[phanophish]

It looks to me like a slight DC bias.  Were you using an analog signal anywhere with unbalanced connectors?  Such as a line level signal out of your phantom/pre?  Most audio tools will allow you to correct for the offset.  Make sure anything you try and fix is done on a copy of the original file.

Sorry, just read your source info.   That almost has to be what the problem was.  Something in you chain is introducing a slight current to the signal path which causes the resulting wav to have the skew you see in your wavform.  I'm doing a really bad explaining this and cant find a good reference with Google.

[darktrain]

So there is nothing wrong with the file itself that can't be corrected because when i listen to it back it sounds good like there is nothing wrong and that is sort of what the split track shows also, i have wave pad or audacity, how would i correct that?

heres the waveform db view which looks normal and sounds fine, the regular waveform has the scew at the top, i am wondering if i really need to worry about it at all?

[phanophish]

I think Audacity has a check box when normalizing to remove DC Offset (Bias).  If you do that it should clean it up for you.  Ideally you want to find the source of the problem as you effectively loose some of your bit depth to the DC bias skewing the wav.  It is a small loss of quality that most people probably won;t notice when it is not severe but it is there. 

I think you can see the offset in the view at the top of the first image where you can see the whole WAV file.  the top peaks are relatively flat while at the bottom the peaks look much more normal.  Once you run the Normalize with the offset correction your waveform should look much more normal although you may not notice a huge change in the sound. 

[darktrain]

thanks, i was freeked out when i first saw the wave, but upon playback came out pretty clean , you think its from a lose wire, etc...

[darktrain]

The problem may occur when you touch your unbalanced cables with your hands, etc.. I'd definitely check that.

hmmm...never had it happen before but i was holdng the unit for a few songs and then put it in my pants pocket, i may have to run this bb throuygh some tests today , got another show tomorrow

[darktrain]

Narrowed it down to the mic plug(after testing both irivers with the same results and then just mic in), i actually now remember the case being lose and tightening it, maybe a wire twisted and caused just i little difference so i think i will just rewire it

[darktrain]

Ok stripped the plug rewired with same results, could this be a bad plug? tried each cap individual and they produce the same reslut so i tend to think the plug my be bad?

[darktrain]

Not the plug, so could be the cap(s) i get the same result in each channel with the sag in the wave, find it hard to believe both caps have the same issue all at once, anyone with any ideas?

[it-goes-to-eleven]

Have you checked whether this happend in older recordings with those mics? Maybe it has always been there?

[darktrain]

Just went back and looked and indeed there is a little sag, not as obvious though, well these will be off for warranty service