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From: osc!jgk@ames.arc.nasa.gov (Joe Keane)
Newsgroups: rec.audio.high-end
Subject: Re: Tice Power Conditioner
Message-ID: <10311@uwm.edu>
Date: 18 Mar 91 13:47:37 GMT
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In article <10126@uwm.edu> Mike.Reaper@f421.n109.z1.Fidonet.Org writes:
>[] Doesn't it seem like a magnetic coil, storing energy in a magnetic
>   field, and refusing to change voltage quickly, preferring instead
>   to keep a constant current, would shave off or otherwise distort the
>   uppermost frequencies?
 
You mean ``refuse to change current quickly'', right?

It is important to ensure that the amplifier can get high-frequency power.
The power supply output should have a very low impedence at all frequencies.
Or in other words, it should be a good voltage source.

But you don't get this high-frequency power from the mains.  In fact, you
can't; what if the instantaneous mains voltage is zero when you want your
power?  The amount of power drawn from the mains should only change slowly.

So how does the power supply respond to quick changes in the amount of power
drawn by the amplifier?  The answer is capacitors, and lots of them.  The last
thing in a power supply should be a capacitor, or actually a number of
different capacitors in parallel, since each kind is better at supplying
different frequencies.  These are what keep the constant voltage you want.

Now if you had a series inductor after those capacitors, then that'd be a
mistake.  But i hope no one does this.

>   Could it be that this large, energy storing inductor is doing
>nothing more than wiping out the high frequencies (by delaying them),
>by not allowing the equipment power as it needs it?

I won't go into why it's a good idea to have chokes in various places; i'm
sure this is covered in books.  Basically, i'd say that if you see a power
supply which doesn't have any coils, it's cheap and you shouldn't buy it.

>   Isn't a fundamental rule of common sense NOT to put a series 
>inductor in an audio power supply?

No.
--
Joe Keane, amateur mathematician