> -----Original Message-----
> From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, 10 January 2002 12:54 PM
> To: Open Topic Forum
> Subject: Re: [OT] Nothing to do with Protel, but anybody want to improve
> the quality of their Hi-Fi?
>
>
> At 05:41 PM 1/9/2002 +0000, Stephen Casey wrote:
> >Check out
> >
> >www.russandrews.com
> >
> >I have learned a huge amount from Mr. Andrews. Mains voltage variation of
> >10% can have a +/- 1% effect on playback speed of CD's. Amazing, don'tcha
> >think?
>
> It would be amazing, yes. But I don't believe it at all. Perhaps some CD
> player somewhere was not crystal-controlled. But I also doubt that anyone
> who did not have perfect pitch would be able to detect a 1% variation in
> playback speed, and it might be difficult with perfect pitch
> (unless the CD
> output was being compared with some standard).
>
> > Oh yes, and over three thousand UK pounds for speaker cables - they
> >must be very good! He also sells woven earth wire, to rewire
> your home with.
> >Could make a big difference.
>
> In the weight of your wallet!
>
> I looked at one of his publications, The Power and the Glory.
>
> From that PDF:
>
> "The mains voltage has a surprising effect on the performance of a CD
> player. The motor speed is voltage controlled, not frequency controlled
> with a crystal reference as most people would expect."
>
> This person doesn't expect motor speed to be crystal-controlled!
> I'm not an
> audio engineer and I have never seen a CD player design, but a CD
> player is
> simply a device for reading data, I'd then expect that the data is loaded
> into a FIFO memory and from there to a DAC; the rate of data transfer to
> the DAC would be frequency-controlled, so motor speed is irrelevant, as
> long as the drive can read data fast enough to keep the FIFO from running
> out of data. Someone correct me if I'm wrong!
Especially since a CD is constant linear velocity (i.e. the rotation speed
[r.p.m.] slows as the read head traverses from the inside track towards the
rim of the disc)!
Ccertainly the clock rate of the digital components would have a measurable
effect on pitch and tempo of the music (note that I wrote "measurable" and
not "audible" :-).
However, systems like CD players will have a either a crystal oscillator or
a ceramic resonator providing their frequency reference. At the cheap end
of the crystal oscillator scale, a frequency accuracy of 100ppm over the
life of the component would be usual (i.e. 0.01%). Ceramic resonators are
lower spec, but you'd still expect 0.5% or better.
Although oscillators can be "pulled" by supply voltage variation (the amount
of "pull" being a function of circuit design), the logic + clock supply of a
CD player will certainly be regulated, so variations in mains supply will
have a negligible effect on the logic supply, and hence the clock.
I browsed through most of the brochures on Mr Andrews' site and concluded
that there's a much easier way to make money than my current job - just sell
high end audio accessories! Just about any claim can be made, because
apparently there's a willing audience willing to believe!
Still the brochures provide some light entertainment to read on my lunch
break!
John Haddy
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