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FW: RE: 2 questions (Conrad G0RUZ Oct 14 2002)

-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Conrad G0RUZ
Sent: Monday, October 14, 2002 6:48 PM
To: linrad@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [linrad] 2 questions

Yes Leif that is what I mean by "inbuilt bias", it is totally irrational :-)
In audio what happens is exactly what you describe. When a large transient
occurs in the audio waveform which is normally below say 160Hz with "modern"
music the switched mode psu's don't seem able to deliver the dynamics
necessary, this makes the amplifiers sound bass light somehow. This is
subjective of course and should not be an issue. It should be possible to
design an adequate SMPSU but to my ears nobody has done it yet, although
they are getting better all the time. Of course we are talking of some 10's
of amps. Not really the same as the WSE series :-)

You'll have to forgive me I had some wine, this usually makes me anecdotal

Conrad G0RUZ

> -----Original Message-----
> From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
> [mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Leif Åsbrink
> Sent: 14 October 2002 15:48
> To: linrad@xxxxxxxxxxxxxxxxxxxxx
> Subject: RE: [linrad] 2 questions
> Hi All,
> > Re the power supply, I would be tempted to use a very high
> quality linear
> > PSU. I still don't trust those switch mode supplies. Maybe it's
> because in
> > my profession (pro audio) I have yet to hear a high power audio
> amp with a
> > SMPSU that sounds anywhere near as good as a top amplifier with a
> > conventional PSU. So I have this in built bias against them.
> Your experience is not relevant here. In audio, a switch mode supply will
> loose its low output impedance when overloaded. That means that
> short peaks
> of overload will cause serious voltage swings that will distort heavily.
> Nothing can compete with really big capacitors which is a natural part of
> linear supplies. I do not know, but my feeling is that large capacitors
> that store a lot of energy is the reason for audio performance.
> The switchmode supply is elegant in that the capacitor is made
> much smaller.
> The voltage across the capacitor is allowed to have a large ripple and
> the switchmode regulator can take care of the large voltage variation.
> A linear supply does not want to dissipate all the heat so the primary
> voltage stays within a much narrower range.
> It is of course another thing that ill designed audio equipment may
> pick up interference from the switcher - or the switcher may produce a
> lot of RFI on the low HF bands.
> For WSE converters any "normal" power supply is fine.
> 73
> Leif  /  SM5BSZ