Comment 17 for bug 849464

More information from DJ Ed, another user who noticed the problem:
When trying to use Vinyl Control, the pitch controller is constantly varying by +/-0.1% ... +/-0.3%.
Thus the playing track's speed is constantly varying by that amount, meaning that tight mixes are not really possible.
The music sounds "instable" (high wow/flutter like cassette tapes in the old days) this being caused by the varying pitch.
(With vinyl control switched off, the playback is rock solid, I never hear any hickups or other sound issues, even on lowest latency).

The timecode signal quality "scope" shows a circle with a constantly (slightly) varying circumference (becoming wider and narrower all the time even while the control cd is playing at normal speed.)

A similar problem is described here:
http://www.mixxx.org/forums/viewtopic.php?f=1&t=4304

The same problem occurs on two completely different systems, and two different Audio interfaces (in all combinations).

System 1: Dell Vostro
                   Windows 7 32bit Enterprise, sp1
                   Intel Core I5 1,70GHz 4GB RAM
                  video: builtin Intel HD Graphics 4000 , resolution 1366x768
System 2: Dell Lattitude E6500
                   Windows 7 32bit Ultimate, sp1
                   Intel Core Duo P8400 2,26GHz, 4GB RAM
                  video: builtin Intel Mobile $ series Express Chipset Family, resolution 1280x800

Mixxx version: 1.11.0

Audio interface: ESI Maya USB44+ , driver v3.5
                               Tascam US-366 , driver v1.02

Pioneer CDJ1000Mk2's with Serato Control CD (image burned from Serato support site), line-out connected to a stereo Line-In pair of the audio interface.

I've tried everything in the manual and troubleshooting guide, Mastertempo on CDJ is off, Correct input volume / gain settings, latency, different inputs, etc.
When recording the timecode signal from the CD player to e.g. Audacity on the computers, makes a perfect rendition of the timecode audio signal.
I haven't tried other timecode sources, as the Serato control CD is the only one that works with Mixxx and I don't own any Timecode Vinyl.

Additional info: When using a virtual audio cable / VBcable as timecode input and then playing the timecode wav file in a media player on the same pc where Mixxx is running, the same continuous variation in the pitchcontrol and timecode "scope" is seen.