John Curl's Blowtorch preamplifier part II

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#55,407
canyoncruz said:
Um, there is a magnet next to the CD disk! Anyway, Google Scholar the effect.
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I did, paramagnetism is so small that typically only a
SQUID magnetometer can detect it, and as I just said a paramagnetic material can not support a residual magnetism i.e. it can not be de-magnetized. Maybe you can supply a reference that does not just happen to have all the right words.

The stress tensor from mechanical stress is probably orders of magnitude more than the magnetic forces even in several Tesla fields.
 
#55,408
Sy,

But you can measure in the optical domain and hear a difference. All you EE's talk about analog sections. DACs etc. How many of you have actually made the optical portion better? No matter how good the electronics, if the optical signal is not optimum, you will have error correction. . I say, the less error correction the better the sound. I guarantee you, a spatial filter will make a bigger difference than your super electronics, on CD players.
 
#55,409
Scott, how did it affect the optical properties. There are many papers and studies showing it doesn't take much of a field to change optical properties. In fact some where done to come up with a better plastic for optical storage. I am talking optics! Did you measure the polarization. Was it now elliptical? did it rotate? how did this effect the signal to the photo diode which uses polarization to route the light to it? did you measure an increase of scatter within the plastic? etc.
 
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#55,411
The less error correction can only make a difference if absence of the extra "thrashing" of the digital circuitry to do that changes the level of electrical interference that affects the analogue side of things - in cheaply done consumer gear this may be a factor. More likely, I feel, is that the servos being driven more aggressively to try and recover the data makes the barely good enough power supplies spray far more interference noise into areas where it does "bad" things ...
 
#55,412
canyoncruz said:
But you can measure in the optical domain and hear a difference. All you EE's talk about analog sections. DACs etc.
Click to expand...

I'm unaware of any ears-only test demonstrating audibility when there are no uncorrected read errors. If you can point me to one with evidence better than claims of alien abductions and anal probing, I'd appreciate it.

And your assumption is incorrect- I'm not an EE, I'm a polymer scientist with a specialty in electrical and optical (especially IR) characteristics of plastics.
 
#55,413
canyoncruz said:
Scott, how did it affect the optical properties. There are many papers and studies showing it doesn't take much of a field to change optical properties. In fact some where done to come up with a better plastic for optical storage. I am talking optics! Did you measure the polarization. Was it now elliptical? did it rotate? how did this effect the signal to the photo diode which uses polarization to route the light to it? did you measure an increase of scatter within the plastic? etc.
Click to expand...

So cite some, unless you forgot we are talking permanent change when the field is removed. Paramagnetism does not have this property. You are also starting to spew a train of buzzwords. A silicon photo diode by itself is not polarization sensitive BTW.
 
#55,414
canyoncruz said:
I remember an experiment, in the early 90's. I think it was Rotel that did it, But the took a disc recorded it onto a new disc and so one. They was an improvement after the second go around, any more and the signal and sound degraded. Wish I could find it.
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Now you're moving into the territory of different sound from bit perfect copies, not worth the time (and what does this have to do with magnetism).
 
#55,415
canyoncruz said:
I remember an experiment, in the early 90's. I think it was Rotel that did it, But the took a disc recorded it onto a new disc and so one. They was an improvement after the second go around, any more and the signal and sound degraded. Wish I could find it.
Click to expand...
The answer for why a burnt CD often sounds better is pretty straighforward: the centering of the hole is 'perfect' with respect to the tracks alignment, because it was put down dynamically, not stamped out. Hence on playback the servos have a much easier time of keeping the laser precisely focused on the data - and we're back to power supplies generating less noise, and finally better audible quality ...

While people keep insisting that the digital, and power supply, circuitry live in a different universe from that dedicated to the analogue we'll keep having these arguments ...
 
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#55,418
fas42 said:
The answer for why a burnt CD often sounds better is pretty straighforward: the centering of the hole is 'perfect' with respect to the tracks alignment, because it was put down dynamically, not stamped out. Hence on playback the servos have a much easier time of keeping the laser precisely focused on the data - and we're back to power supplies generating less noise, and finally better audible quality ...

While people keep insisting that the digital, and power supply, circuitry live in a different universe from that dedicated to the analogue we'll keep having these arguments ...
Click to expand...

Right Frank.
 
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