magiccarpetride;629022 Wrote: > What exactly does a demagnetization track on the Test & Burn-in CD do?
The theory is that music playing through the system is not always completely symmetrical so the magnetic field generated by current flowing through the circuitry may slightly magnetize certain components which can slightly change their behavior. These test tracks are supposed to play completely symmetrical series of tones that decrease in magnitude which tends to release this acquired magnetic state. This can really only affect devices which contain magnetic material (stuff with iron, nickel etc). Most modern stuff doesn't have transformers, but the leads on a lot of components have steel cores, nickel is used all over the place in connectors and as contacts in components (almost every SMD resistor ever made uses nickel contacts) This effect is significantly more pronounced in tube circuits. Many of the parts in a tube are steel and can be magnetized. This magnetization WILL effect how electrons flow through the tube, changing its behavior slightly. I have heard this effect in tubes, primarily small signal tubes such as in preamps, phono amps etc. In these cases I demagnetized the tubes directly (I built a tube demagnetizer, similar to a tape demagnetizer, but designed for tubes). On certain tubes type this can make a big difference. I haven't experimented with the "demagnetize" tracks though. For a long time I was skeptical of this "source not symmetrical" bit as the source of the magnetization, I couldn't believe that it was really that bad, until I started looking at waveforms of drums. In certain types of drums the initial peak of the waveform is quite a bit louder than the subsequent "negative" peak etc. This is very much a non-symmetrical waveform. But wouldn't the phase of that initial peak be random from track to track, studio to studio etc? Not necessarily. The frequency of certain drums is low enough that common close mic techniques can produce fairly common phase for the drum peaks from track to track and album to album, particularly if the same engineer is doing the recording or they are done in the same studio etc. So if you listen to music with a lot of low frequency drums, done by the same engineer/studio etc, you could easily wind up magnetizing certain parts of your system. How much of impact this is going to have on the sound is whole different ball game, I have not done much study on THAT. I haven't done much experimenting with these test tracks, but I would not rule out that they could have some impact on sound. Any such affect is probably going to vary radically from system to system and user to user. John S. -- JohnSwenson ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=87458 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
