Schizoid Man wrote:
"Jim Lesurf" wrote in message
...

It may be some kind of 'max' rating for the purpose of indicating what
kind
of requirements there are for fusing or leads, or for working out how
much
of the current capacity of the house mains wiring arrangement it
should be
assumed to demand for safety purposes. May also therefore be a 'peak'
value
not rms. Only guessing though as I have no idea how they obtained the
value, or what the current pun :-) USA regulations may be for this.

So would I be okay with a 300W step down converter? It's only a
temporary, low-volume solution.

You can pick up a suitable transformer at any building site.
They're in the large yellow boxes.
Just make sure you can run faster than a navvy, while carrying a 10Kg
weight.

--
Eiron.

On Fri, 15 Jan 2010 08:47:04 +0000 (GMT), Jim Lesurf
wrote:

5.6A seems oddly precise. The power consumption of an A/V amp will vary
quite widly with the number of speakers connected, with their impedance,
with the level at which you drive them etc. So I wonder whether the
"5.6A" is in fact a typo.

Probably an engineer worked it out and wrote down the answer, not
thinking that the implied precision was misleading.

"Schizoid Man" wrote in message


I've run into any small problem. The Denon unit is a US
model so I need a voltage converter to make it work in
the UK. According to the manual, the power consumption
characteristics a Power supply: AC 120 V, 60 Hz (for North America
model)
AC 115/230 V, 50/60 Hz (for Multiple voltage and Taiwan
R.O.C. models) Power consumption: 5.6 A (for North
America model) 320 W (for Multiple voltage and Taiwan
R.O.C. models)

Doesn't the 115/230 voltage rating suggest that the device will work on 230
volts via a switch setting or other means?

Does 5.6 A mean 5.6 amps?

Yes, but it is curious that it is rated at both 5.6 amps (which is about 650
watts) and also 320 watts.

So given the volage is 220
volts, does the power rating become 672 W (based on a
voltage of 120V)? This rating seems very high given that
the consumption for the multi-voltage models is less than
half this amount, 320 W.

The big point is that as others have said, the 320 watt and up ratings are
based on full power or fractional power use as a power amplifier. If you
don't drive the power amps into speaker loads, I would expect the power
usage to be well under 100 watts, except perhaps for a turn-on surge when
the filter caps for the power amps charge up.

The minor point is that the apparent inconsistencies that we see are
probably due to the test conditions for the safety standards organizatins in
various countries. They test the unit at various levels of power output.
Since the power output for use will be zero, they don't apply.

If you do use the unit as a power amplifier, the 5.6 amp/650 watt rating
would proabably be a high estimate, with the 320 watt rating being more
realistic.

In article , Laurence Payne
wrote:
On Fri, 15 Jan 2010 08:47:04 +0000 (GMT), Jim Lesurf
wrote:

5.6A seems oddly precise. The power consumption of an A/V amp will
vary quite widly with the number of speakers connected, with their
impedance, with the level at which you drive them etc. So I wonder
whether the "5.6A" is in fact a typo.

Probably an engineer worked it out and wrote down the answer, not
thinking that the implied precision was misleading.

Since I'm in the middle of marking exams that rings true. I've lost count
of how many 'answers' I've seen in exam scripts that give values to as many
figures are on the calculator - and are many orders of magnitude in error!

One I read yesterday gave the velocity of propagation along a cable as
something like X.XXXXXXX x 10**-10 m/sec. (Note minus sign) So off by 18
orders of magnitude. :-)

.... correct answer was about 2/3rds of 'c'.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Schizoid Man
wrote:
"Jim Lesurf" wrote in message
...

It may be some kind of 'max' rating for the purpose of indicating what
kind of requirements there are for fusing or leads, or for working
out how much of the current capacity of the house mains wiring
arrangement it should be assumed to demand for safety purposes. May
also therefore be a 'peak' value not rms. Only guessing though as I
have no idea how they obtained the value, or what the current pun
:-) USA regulations may be for this.

So would I be okay with a 300W step down converter? It's only a
temporary, low-volume solution.

I suspect the answer is 'yes' and if I had the kit I'd give that a try with
some small fuses before and after the convertor. But I have no idea if it
*will* work as I only know what you've said about the unit! For all I know
it draws high currents even when not producing any output, or draws huge
current spikes during each mains cycle, or draws a massive surge at
switch-on, etc.

So if you want to have an experiment at your own risk with, say, a 1A fuse
on the UK side of the convertor, then that would seem worth a try to me.
But I'm also washing my hands of any problems. You have been warned. 8-]

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html