On Thu, 04 Nov 2004 07:56:20 GMT, "harrogate2"
wrote:

It has to be said that in the main amplifier PSUs are very simple and
usually a tad underrated - on the basis that few people can and will
run them to the limit. Voltage rail limiting and the attendant
clipping distortion is likely to set in long before that!

A good amp with a good regulated PSU - as designed by the sadly missed
and late John Lindsey-Hood - makes a world of difference. There you
really do notice the difference, as I'm sure Pinky and others will
agree, but in the commercial world they are very few and far between
and horrendously expensive to boot.

Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it appears
to be horribly overpriced for its power rating - much like my '50
watt' Krell! :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering

In article , Stewart Pinkerton
wrote:


Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it appears to
be horribly overpriced for its power rating - much like my '50 watt'
Krell! :-)

Of course, this assumes that regulated supplies are a good idea... :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Jim Lesurf" wrote in message

In article , Stewart
Pinkerton wrote:


Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it appears
to be horribly overpriced for its power rating - much like my '50
watt' Krell! :-)

Of course, this assumes that regulated supplies are a good idea...
:-)

Agreed. Regulated power supplies are uncommon in power amp output stages
because they sacrifice efficiency without offsetting gains in sound quality
or technical performance.

On Fri, 05 Nov 2004 09:52:03 +0000 (GMT), Jim Lesurf
wrote:

In article , Stewart Pinkerton
wrote:


Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it appears to
be horribly overpriced for its power rating - much like my '50 watt'
Krell! :-)

Of course, this assumes that regulated supplies are a good idea... :-)

True, there are certainly other ways to achieve a clean signal at the
output. Must say I always liked plain old PI filters with a series
choke, but they're kinda big in a reasonably powerfull SS amp!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

In article ,
Stewart Pinkerton wrote:
Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies.

Didn't stop it blowing up into reactive loads, though. ;-)

--
*What was the best thing before sliced bread? *

Dave Plowman London SW
To e-mail, change noise into sound.

Stewart Pinkerton wrote:

On Thu, 04 Nov 2004 07:56:20 GMT, "harrogate2"
wrote:

It has to be said that in the main amplifier PSUs are very simple and
usually a tad underrated - on the basis that few people can and will
run them to the limit. Voltage rail limiting and the attendant
clipping distortion is likely to set in long before that!

A good amp with a good regulated PSU - as designed by the sadly missed
and late John Lindsey-Hood - makes a world of difference. There you
really do notice the difference, as I'm sure Pinky and others will
agree, but in the commercial world they are very few and far between
and horrendously expensive to boot.

Indeed they are, mand despite its well-known problems with capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it appears
to be horribly overpriced for its power rating - much like my '50
watt' Krell! :-)

Requiring a regulated power supply for the main power supply rails in an
audio amp is a sign of defective design in the power amp stage IMHO.

It's perfectly easy and practical to design a power amp that rejects power
line ripple and performs superbly.


Graham

"Pooh Bear" wrote in message
...
Stewart Pinkerton wrote:

On Thu, 04 Nov 2004 07:56:20 GMT, "harrogate2"
wrote:

It has to be said that in the main amplifier PSUs are very simple
and
usually a tad underrated - on the basis that few people can and
will
run them to the limit. Voltage rail limiting and the attendant
clipping distortion is likely to set in long before that!

A good amp with a good regulated PSU - as designed by the sadly
missed
and late John Lindsey-Hood - makes a world of difference. There
you
really do notice the difference, as I'm sure Pinky and others
will
agree, but in the commercial world they are very few and far
between
and horrendously expensive to boot.

Indeed they are, mand despite its well-known problems with
capacitive
loads, the real strength of the Naim NAP250 is that it does have
excellent regulated supplies. That is the main reason why it
appears
to be horribly overpriced for its power rating - much like my '50
watt' Krell! :-)

Requiring a regulated power supply for the main power supply rails
in an
audio amp is a sign of defective design in the power amp stage IMHO.

It's perfectly easy and practical to design a power amp that rejects
power
line ripple and performs superbly.


Graham


Have to disagree with that. The main advantage of a regulated supply
is a lower supply impedence, which gives the most noticable effect in
the form of considerably better controlled and cleaner bass. I built
my own power MOSFET dual mono amp with a dual foldback regulated
supply, and you should hear that driving classical organ pedal reeds
into transmission line speakers! Window shifters let alone shakers!


--
Woody

"Pooh Bear" wrote in message


Requiring a regulated power supply for the main power supply rails in
an audio amp is a sign of defective design in the power amp stage
IMHO.

Agreed.

It's perfectly easy and practical to design a power amp that rejects
power line ripple and performs superbly.

Agreed.

"harrogate2" wrote in message


Have to disagree with that. The main advantage of a regulated supply
is a lower supply impedance, which gives the most noticeable effect in
the form of considerably better controlled and cleaner bass.

While intuition might lead one to this conclusion, bench tests and blind
listening tests don't.

I'm not saying that we should go out of our way to give the power supply a
high output impedance, but in fact a well-built traditional power supply
composed of passive filtering components simply gets the job done.

For example, a typical 20,000 uF filter capacitor with minimum ESR has an
impedance of about 0.07 ohms at 120 Hz, 0.13 ohms at 60 Hz and 0.40 ohms
at 20 Hz. The output impedance of a standard power supply is no greater than
this.

harrogate2 wrote:

"Pooh Bear" wrote in message
...

Requiring a regulated power supply for the main power supply rails
in an
audio amp is a sign of defective design in the power amp stage IMHO.

It's perfectly easy and practical to design a power amp that rejects
power
line ripple and performs superbly.


Graham

Have to disagree with that. The main advantage of a regulated supply
is a lower supply impedence, which gives the most noticable effect in
the form of considerably better controlled and cleaner bass. I built
my own power MOSFET dual mono amp with a dual foldback regulated
supply, and you should hear that driving classical organ pedal reeds
into transmission line speakers! Window shifters let alone shakers!

Did you do a comparison with / without ?

You can disagree all you like. I prefer design theory / practice.

The low supply impedance of the regulated supply is *particularly*
pointless with lateral MOSFETS on account of their highish on resistance.

You use negative feedback around the amplifier to determine the output
impedance and damping factor, *not* the power supply type!


Graham