 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> Actually, what the heck...
>
> http://blog.orphi.me.uk/about/power
>
> (Table of my work so far.)
I checked our washing-machine and it takes 10W when turned off - as off
as it could be without unplugging it. So now, theres is an extra switch
in the powercable...
This is 1.68 kWh per week - for nothing. The machine has a display which
is switched off in off-mode, and you turn a switch (physically) , which
selects the different programs, to off - so you think it should be
really off. But there seems to be a powerhungry powersupply generating
low Voltage for the microprocessor all the time or something...
In your table you may need a thin line between the different devices, I
first thought the dishwasher takes up to 280W while booting ?!? Or is
this wordpress again?
cukk
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Orchid XP v3" <voi### [at] dev null> wrote in message
news:46dda38a@news.povray.org...
>>>> Huh? You are saying that they deliberately make speakers less
>>>> efficient so that a higher voltage can be used to drive them? I've
>>>> never heard that before.
>>>
>>> Yes.
>>
>> Interesting, how do they do that?
>
> You think *I* know?
It used to be that more efficient speakers in general had more unwanted
resonances and lumps in their frequency responses: IOW poorer fidelity. I
don't particularly know why but that's how it was. Obviously the designers
would have overcome that if they could have, but some chose low efficiency
in return for better sound quality. I don't know how well they are doing
now with that trade-off, it's been some years since I last read any reviews.
>> Hard to see how you could deliberately make the system less efficient
>> without just plonking a huge 50W resistor in series (which would totally
>> screw up the quality of the sound).
>
> And why would that be?
The answers lie in the way passive networks of electronic components work
and in speaker mechanics.
Firstly, the crossover network divides the signal from the amplifier to the
woofer and the tweeter drivers. It must be tuned to the right frequency and
shape the frequency falloff curves and phase so that the sound levels from
both drivers are balanced without dips or humps or comb-filtering at the
crossover band where both drivers transmit part of the signal. It is also
supposed to keep the signal phase true between the two drivers over the
frequency range so they operate in a unison making the sound wavefront from
both drivers combine and arrive at your ear together. That is fekking
difficult to design, because...
Crossovers are passive networks of resistors, capacitors and inductors.
Networks behave much more complicatedly than isolated components because
everything interacts with everything else, not just its immediate
neighbours. Speaker drivers are *also* R-L-C networks, so crossovers must
be designed with that driver's electrical properties being integral to it.
In short, the whole thing is interbalanced, so if one resistor, capacitor or
inductor changes, everything goes out of whack -- crossover frequency,
frequency response, phase response, impedance response, resonances and
ringing -- and the speaker sounds like crap.
For predictability, a speaker and its crossover also rely on the amplifier's
output stage being very low impedance. Signal-wise, the amplifier is near to
a short-circuit, regardless of the voltage swings it generates. A speaker
is a motor and when moving, it generates back-EMF through its crossover. It
has mechanical inertia and wants to overshoot. It also has natural
resonances from driver suspension springiness, cabinet air volume, acoustic
transmission line length, tuned acoustic port, etc. That colouration is NOT
part of the original signal. If the amplifier doesn't soak up that energy
(absorb the current), to damp the unwanted motion (overshoot and ringing) it
will reflect back into the network and colour the sound you hear.
So if you plonk a great big resistor in series with all that, the amp can't
damp unwanted speaker motion, the crossover detunes, the frequency response
goes lumpy, the sound goes muddy, and you think "bleccch!" :-)
>>> Hmm, I think my amplifier (nothing special) is rated at 60 W per
>>> channel. (IIRC, into 8 ohms at 1 kHz.)
For listening at home, the real reason for high-powered amps is not to make
louder noise, but for fidelity. They have higher voltage headroom to
faithfully reproduce the high, short sound transients (eg, snare drum
attack, piano key strike) that would be clipped off by a low-powered amp set
to play at the same average listening level.
>> And what happens when you actually output 60 W in your room?
>
> Well obviously I'm unlikely ever to try this. (It's like all toasters have
> a special setting that transforms bread into charcole. We don't know why,
> but they all have it.)
<Ahem> Just because you didn't figure it out, doesn't automatically make
the manufacturers into idiots. The high setting on toasters is needed to
get even a _little_ colour into *crumpets*. But, as you apparently haven't
toasted a crumpet before, they obviously don't exist and every manufacturer
out there is stupid for gratuitously making toasters with a nuclear setting.
:-P
> (I once tried connecting a line-level output to the phono input. Big
> mistake...)
Ow. :-(
>> I guess also your ears work on a logarithmic scale, so 60 W is probably
>> not as much "louder" than 20 W as you would think just by looking at the
>> numbers.
>
> Yeah, most human senses actually seem to work in a logarithmic way... I
> suppose that means they work well under "all conditions" or something.
A general rule-of-thumb I got from an electronics / audio tech mag once, is
that 10x power sounds roughly twice as loud.
>>> Wait... the *voltage* changes depending on how much you use it? That's
>>> odd. I thought that potential difference was always constant, and it's
>>> only *current* that changes...
>>
>> That's only true if all the cables in the whole system have precisely
>> zero resistance, which they don't.
>
> Really? How interesting...
LOL
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Jim Henderson wrote:
>
> I don't know anyone who gets that kind of standby time. My phone (which
Almost 4 years old Nokia 6310i (with original battery) has 'bout 1,5week
standby time (yes, I can take it with me and talk my average calls for a
week without a loader). A bit over 1 year old Nokia 6021 has over 2
weeks (pure standby, I don't use it as a phone as much as a gprs -modem
and alarm clock). But then again, these are telephones - not
multimediacomputers.
>
> Jim
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Orchid XP v3 wrote:
>
> Pretty tiny compared to the 20 W or so my laptop uses when idling.
Idling? Heck, if ACPI is trustable enough, I've managed to use ~35W max
on full load with my laptop (and somewhere around 15W while running just
SSH-over-bluetooth oslt). These babies are getting more and more
energy-efficient - and that's a good thing.
> (But then... no 3D graphics, only 1 HD, lower clock speed, etc.)
Well yeah, poor 3D, 1HD, 2x1,8GHz C2D, 15" TFT etc (the screen backlight
is one big consumer for me, to be noted).
> We discovered that if you boot into Linux while the fans are off, they
> stay off. And if they're running when Linux starts, they stay running -
> no matter how cold the machine gets. Weird, eh?
I'd guess you were having broken APM/ACPI -support to get some effect
like that. Not good, though, while it might burn your lap AND defect
your laptop.
> Once the laptop was cold, Linux installed just fine...
>
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott wrote:
> wire. Hard to see how you could deliberately make the system less
> efficient without just plonking a huge 50W resistor in series (which
> would totally screw up the quality of the sound).
Mostly by desinging the speaker cabinet. It's easier to make a speaker
that actually sound good and flat if you don't need to obtain 90+dB/W/m
efficienty.
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>> wire. Hard to see how you could deliberately make the system less
>> efficient without just plonking a huge 50W resistor in series (which
>> would totally screw up the quality of the sound).
>
> Mostly by desinging the speaker cabinet. It's easier to make a speaker
> that actually sound good and flat if you don't need to obtain 90+dB/W/m
> efficienty.
Well yeh that's kinda my point, the speaker system is designed to sound
good. Trying to minimise the efficiency (so that input voltage is higher)
is not really on the list of things to do when designing a speaker system.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> (given they know the speed of the car, and that
>> all F1 cars weigh the same).
> But not the same Cx
Easily worked out by measuring the acceleration of the car at two points...
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
KalleK wrote:
> I checked our washing-machine and it takes 10W when turned off - as off
> as it could be without unplugging it. So now, theres is an extra switch
> in the powercable...
> This is 1.68 kWh per week - for nothing. The machine has a display which
> is switched off in off-mode, and you turn a switch (physically) , which
> selects the different programs, to off - so you think it should be
> really off. But there seems to be a powerhungry powersupply generating
> low Voltage for the microprocessor all the time or something...
Oh, that's cute.
Well, the washing machine registers a flat 0 with the dial turned to
off. (It's a dial, not just a push button or something. So presumably it
physically disconnects something somewhere.)
OTOH, my PC still drinks 4W even when "off", so...
> In your table you may need a thin line between the different devices, I
> first thought the dishwasher takes up to 280W while booting ?!? Or is
> this wordpress again?
Check the source code. It says <table border="1">. However, the CSS
seems to think it would be funny to remove the grid lines and vertically
center all cell contents... (Again, unfortunately there is no way I can
alter the CSS, much as I long to do so.)
--
http://blog.orphi.me.uk/
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>> Pretty tiny compared to the 20 W or so my laptop uses when idling.
>
> Idling? Heck, if ACPI is trustable enough, I've managed to use ~35W max
> on full load with my laptop (and somewhere around 15W while running just
> SSH-over-bluetooth oslt). These babies are getting more and more
> energy-efficient - and that's a good thing.
The maximum load I saw was 40W (during the boot sequence - when
everything turns on at once). In normal running it hovers somewhere
below that.
>> (But then... no 3D graphics, only 1 HD, lower clock speed, etc.)
>
> Well yeah, poor 3D, 1HD, 2x1,8GHz C2D, 15" TFT etc (the screen backlight
> is one big consumer for me, to be noted).
I didn't check specifically. My laptop has a very dim LCD with poor
saturation and a horribly narrow viewing angle. No matter how you
position your head, 50% of the display is always inverted...
>> We discovered that if you boot into Linux while the fans are off, they
>> stay off. And if they're running when Linux starts, they stay running -
>> no matter how cold the machine gets. Weird, eh?
>
> I'd guess you were having broken APM/ACPI -support to get some effect
> like that. Not good, though, while it might burn your lap AND defect
> your laptop.
Should be noted: It's an *ancient* laptop!
(Now *my* laptop seems to do all this in hardware, not software. Doesn't
matter what software is running, the fan turns on and off now and then...)
--
http://blog.orphi.me.uk/
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>> Of course if you are in a call average power use will be much higher,
>> which is why "talk-time" is something like 8 hours and "standby time" is
>> usually a week or so.
>
> I don't know anyone who gets that kind of standby time.
That would be *me* then. My phone typically needs charging once every 9
days or so. (Bearing in mind that I never make or receive any calls or
text messages. The phone does however tell me the correct time, which is
more than my watch does. It also doubles as a very high power torch...)
--
http://blog.orphi.me.uk/
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
