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Gear / Technical Help => Ask The Tapers => Topic started by: Craig T on August 02, 2004, 11:49:42 AM

Title: mystery problem - channel swap!
Post by: Craig T on August 02, 2004, 11:49:42 AM
Recorded RRE saturday night SP LSD2>v3>PDAudio-CF>iPaq running Live2496 (7/30/04 release) and my channels swap back and forth 4 times during a 2 hr set.  This is a new one for me.  iPaq has been running fine in 16bit, the only change was updating the Live2496 software to the latest release.  I'm assuming it has to be a problem somewhere in the digital path.  I also just got my V3 back from Grace for the dc offset and battery light fixes, but I can't imagine the V3 causing the problem.  I haven't had a chance to try to recreate the swapping, I hope to record a few hours of stereo playback this evening.

I'm open to suggestions.  This one has me mystified.
Title: Re: mystery problem - channel swap!
Post by: bhtoque on August 02, 2004, 02:10:36 PM
The LSD2 is a stereo mic right?

Might it be a problem with it's cable or connections?

JAson
Title: Re: mystery problem - channel swap!
Post by: Craig T on August 02, 2004, 02:13:59 PM
I suppose, but that doesn't explain the dropouts.  I'll open up the cable connectors tonight to see if anything looks odd.
Title: Re: mystery problem - channel swap!
Post by: Brian on August 02, 2004, 02:31:19 PM
hmmmm.  this is the second problem from the LSD2 posted in 2 weeks.  starting think there might be a problem with this microphone .... ie. cheaply made.
Title: Re: mystery problem - channel swap!
Post by: Craig T on August 02, 2004, 02:39:36 PM
I suppose, but that doesn't explain the dropouts.  I'll open up the cable connectors tonight to see if anything looks odd.

I guess I should give a bit more detail why I don't think its the mic.  At the 4 locations where the channels swap, there is obviously some dropped samples.  If the mic were to blame, the recorder would keep recording, maybe some analog noise, but something other than dropping some samples.  Seems far more likely to be in the a/d or something in the iPaq either hardware (PDAudioCF) or software.  I'm thinking it might be in the translation from pcm/spdif to wav.  Maybe a bug in the new version of Live2496?  Some testing is definitely in order to try to isolate the problem.  I'll post what I find.
Title: Re: mystery problem - channel swap!
Post by: Brian on August 02, 2004, 02:44:54 PM
oh well then that makes sense.  thanks for keeping us updated.
Title: Re: mystery problem - channel swap!
Post by: Craig T on August 02, 2004, 02:47:57 PM
Just got this in an email from Gordon Gidluck (Live2496):

Any loss of bytes would result in one or more damaged or missing frames which
would mean channel swapping in 16-bit files. 24-bit files could result in white
noise.


looks like dropped samples in the writing of the wav file.  so it was a software/hardware issue using Live2496 to record to a pcmcia hard drive (somewhat slow, I've definitely had the white noise when I try to attempt 24bit recording on it).

I guess of the possible problems, this one is minor.  It appears the added features of the new version of Live296 has now rendered my iPaq worthless for even 16bit recording.   :(  Good think I saved the older version that was working for me.

Title: Re: mystery problem - channel swap!
Post by: Chris K on August 02, 2004, 02:55:42 PM
ditch the ipaq...get a jb3. no reason to have so much invested in the ipaq if it can only do 16bit.   ::)

return to the ipaq when 24bit is reality  8)