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> 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
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"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
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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
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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
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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
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>> 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.
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> (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...
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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/
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>> 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/
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>> 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/
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Orchid XP v3 wrote:
> 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.)
Actually, come to think of it... usually the meter shows "full charge"
constantly, until you actually attempt to *use* the phone. Then the
meter instantly drops right down to empty. ;-)
As I understand it, it's just very hard to measure how much charge is in
a battery. If you're not drawing any current, the potential will stay up
at maximum until the battery is *really* low. The battery's maximum
current diminishes long before its maximum unloaded potential does...
--
http://blog.orphi.me.uk/
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>>> 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.
That sounds about right.
>>> 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!" :-)
I'm sure that would be the case.
Now, what if that resistance was part of the design right from the
beginning?
By the way... The documentation for my mum's amplifier claims that it
contains special circuitry to cancel out the electric signals generated
by the speakers themselves. (I have no idea whether this is special or
whether it's something all modern amps do and they just wrote about it
to make themselves sound cleaver...)
>>>> 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.
Hmm, isn't that what *I* said several posts ago? ;-)
>> (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
Wait... Surely to toast a crumpet you want a *lower* heat? (Since it's
thicker and hence nearer to the heat source - and also you want to cook
it slower so it cooks through completely.)
>> (I once tried connecting a line-level output to the phono input. Big
>> mistake...)
>
> Ow. :-(
Sounded a bit like a metal guitar. Also made the sound come out on *all*
input selections. o_O
--
http://blog.orphi.me.uk/
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Brian Elliott wrote:
> 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.
I read about this kind of thing in a DSP book. Damn, IIR filters sound
so complicated! Fascinating, but... I wouldn't want to design them for a
living.
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
> 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.
Ah. Right now rendering two scenes (in a mind of testing) with max
brightness on the screen, ie. burning the CPU. I'm not consuming extreme
memory nor using wireless interfaces
groath ~ # cat /proc/acpi/battery/C1B5/state
present: yes
capacity state: ok
charging state: discharging
present rate: 2749 mA
remaining capacity: 3797 mAh
present voltage: 11671 mV
2749mA*11671mV=~32W.
> 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...
For me the display was the most important part of the machine, I got
nearly what I wanted (I got 15" 1400x1050 matt display, I'd wanted 14").
> Should be noted: It's an *ancient* laptop!
Heh. I though more of an ancient (and broken) Linux distro.
> (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...)
Which is wise choice.
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
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scott wrote:
> 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.
>
>
Yep, but practically creating a good sound leads to less efficient
speakers - afaik real Hi-Fi -speakers with over 90dB/W/m are rare stuff.
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
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On Wed, 05 Sep 2007 07:57:09 +0200, scott wrote:
> Oh wow, that would annoy the hell out of me if I had to charge my phone
> every 24-48 hours... Mine usually lasts about 5 days with a few texts
> and short calls per day. I do make sure that bluetooth is turned off
> when I'm not actively using it though, maybe that makes a difference?
Probably, yes - I leave bluetooth turned on because I have a wireless
headset for it - but I also can charge it off a USB port, so I frequently
plug it in when I'm not using it.
But I also do a fair number of long phone calls for work on the days I
work from home.
Jim
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> Well yeah, poor 3D, 1HD, 2x1,8GHz C2D, 15" TFT etc (the screen backlight
> is one big consumer for me, to be noted).
Yep, and expect the power consumed by the backlight to drop significantly in
future as finally everyone switches from CCFL to LED backlights, LED
efficiency continues to rise, and LCD technology improves (to let more light
through).
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> Whatever it is, that is what you see. If it moves faster than 50 Hz you
> either see it not moving at all or, viewed in the right direction, as a
> semitransparent surface. If you can prove that you can see something
> moving at, say 200 Hz, I have a couple of friends working on the retina
> that would be most interested in such a physiological anomality. ;)
It's easy to see things moving above 200 Hz.
One method is to light the thing with a special light source (eg a pulse at
190 Hz or something). On high speed machinery they use this technique so
that operators don't accidentally put their fingers into something moving at
200 Hz....
Second is to quickly move your eye from side to side to try and "follow" the
movement. You eye can move at an incredible angular speed to follow
objects, and in doing so will make the object you are tracking look less
blurred while the surroundings get blurred. Try flicking your eyes from
left to right as you watch a wheel that is spinning too fast to see, as you
do it some parts become clear. If you do this while looking at the beam of
a cheap projector (one that uses a rotating colour wheel) you will see the
RGB primaries separated because they are hitting different parts of your
retina (I assume this changes at 60 * 3 = 180 Hz).
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"scott" <sco### [at] laptopcom> a écrit dans le message de news:
46dfae45@news.povray.org...
>> Well yeah, poor 3D, 1HD, 2x1,8GHz C2D, 15" TFT etc (the screen backlight
>> is one big consumer for me, to be noted).
>
> Yep, and expect the power consumed by the backlight to drop significantly
> in future as finally everyone switches from CCFL to LED backlights, LED
> efficiency continues to rise, and LCD technology improves (to let more
> light through).
>
And what about e-paper?
http://en.wikipedia.org/wiki/Electronic_paper
No backlight, no need of light most of the time, viewable in plain sunlight.
Marc
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> And what about e-paper?
> http://en.wikipedia.org/wiki/Electronic_paper
> No backlight, no need of light most of the time, viewable in plain
> sunlight.
Yep, already used in some supermarkets (eg the Edeka at Munich airport uses
it) for price tags that consume little or zero power and are fully readable
under normal lighting.
The main problems that need to be overcome though are switching time,
resolution and contrast ratio. At cold temperatures the switching time for
black to white is counted in MINUTES not milliseconds, even at room
temperature they take a couple of seconds to switch...
Totally reflective displays are already used (eg in Game Boy Advance I
think) but for colour ones you only get ~33% of the reflectivity of a
black/white display due to the colour filters. Also in order to see it in
dull conditions you need to add a frontlight (as opposed to a backlight)
which further reduces the reflectivity, leading to lower contrast.
Rest assured there is huge research in this area, expect something like
ePaper to one day become mainstream. There are a lot of hurdles to get over
first though...
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"Orchid XP v3" <voi### [at] devnull> wrote in message
news:46dee812$1@news.povray.org...
>>>> 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.
>
> That sounds about right.
Actually now I think of it, I remember a very common example of two
different speaker designs that speaker manufacturers often choose tradeoffs
with: Infinite Baffle, vs. Tuned Port.
Theoretically, an Infinite Baffle speaker is simply a driver mounted in a
wall (or baffle) that extends to infinity in all directions of its plane.
No sound energy that radiates backwards from the driver (and is inverted)
can get around the baffle where it would interfere with the
forward-travelling sound wave. In practice however, an IB speaker is a
driver in a sealed box with a limited internal volume.
Good points of IB are smooth frequency curve, linear or slow-changing phase
over frequency, good damping, low colouration -- in general high-quality
sound with good 3-D imaging on the virtual sound stage. Bad points are bass
response starts to tail off slowly at a relatively high frequency due to the
limited cabinet volume and can really lack guts on low notes like the bottom
E1 of a bass guitar (~41 Hz).
Tuned Port speakers, on the other hand, have a vent in the cabinet (often in
the front). Its entire purpose is to extend the bass response of the
speaker below the frequency limit usually imposed by the cabinet's internal
air volume. The port connects to the internal cavity by a tube of a length
calculated to tune to a chosen bass frequency half-waavelength. At that
frequency, the wave at the port entrance (ultimately coming from the back of
the driver) is in reinforcement phase with the wave from the front of the
driver, extending the speaker's freq. range.
Good points of TP are deeper extension of bass response for a cabinet size
and relatively flat(tish) bass response below 100Hz down to the tuned freq.
Bad points are the low-frequency response can actually have a peak at the
tuned frequency, then it will plummet off a cliff just below it, the phase
of the bass tends to change dramatically with frequency, the speaker has a
lumpy impedance graph - presenting a very low impedance* to the amp at the
tuned frequency and high-impedance at nearby frequencies (more difficult
load for an amplifier to drive). If not carefully designed, TP can
over-emphasise sound near the tuned freq., causing the effect known as
"one-note bass" or "boom box". The port's resonance has inertia and stores
energy which the driver takes time to overcome, it can continue transmitting
for several cycles after the amplifier has stopped the signal, which means a
TP speaker's extended bass response comes at the cost of "mushing up" the
sound (time-smearing).
Just an example, y'know. :-)
* [impedance could be the opposite way to my memory, but point is, it's
still lumpy]
>>>> 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.
>> [...]
>> 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!" :-)
>
> I'm sure that would be the case.
>
> Now, what if that resistance was part of the design right from the
> beginning?
Possibly... But I think it would prevent the amplifier from sinking the
back-EMF current from the speaker. The amplifier's output stage should have
an apparent impedance (Z) as close to zero as possible, but instead its Z
would be the resistor's value, allowing a back-voltage and thus impacting
sound quality. I don't think there'd be a way to design around that problem
in the speaker alone.
> By the way... The documentation for my mum's amplifier claims that it
> contains special circuitry to cancel out the electric signals generated by
> the speakers themselves. (I have no idea whether this is special or
> whether it's something all modern amps do and they just wrote about it to
> make themselves sound cleaver...)
"We have carefully designed into our mower, a special feature to cut grass!"
Every power amp does it, with negative feedback taken from the output stage.
Any voltage that is not equal to the amp's instantaneous output drive is fed
back, differenced, inverted, amplified and output again, cancelling the
error. That's also how amplifiers get to look like zero impedance or short
circuit to error signals appearing at the output transistor stage.
>>>>> 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.
>
> Hmm, isn't that what *I* said several posts ago? ;-)
Sorry, I probably either missed or forgot that you did. :-) Anyhow it was
more that I thought the others were pulling the discussion of amp power
specs off-course.
>>> (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
>
> Wait... Surely to toast a crumpet you want a *lower* heat? (Since it's
> thicker and hence nearer to the heat source - and also you want to cook it
> slower so it cooks through completely.)
I see what you mean, but a lower heat would dry it out before beginning to
brown it, and then you'd have a circular paver for your driveway. :-)
There's a fair bit of moisture in crumpets, and despite the honeycombing,
they have a dense and rubbery texture. It needs to be high heat to brown
the outside while leaving the inside soft and mmmmm. :-) You don't want
them "cooked through".
>>> (I once tried connecting a line-level output to the phono input. Big
>>> mistake...)
>>
>> Ow. :-(
>
> Sounded a bit like a metal guitar. Also made the sound come out on *all*
> input selections. o_O
That's because it's the same effect as metal guitar: massive overdrive /
extreme clipping.
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"Orchid XP v3" <voi### [at] devnull> wrote in message
news:46deec35$1@news.povray.org...
> Brian Elliott wrote:
>
>> 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.
>
> I read about this kind of thing in a DSP book. Damn, IIR filters sound so
> complicated! Fascinating, but... I wouldn't want to design them for a
> living.
I'm with you on that! Fascinating, wish I could do it, but AIUI, there's
hardly a hope of designing it manually. It's computerised design with an
element of alchemy, dead cats, satanic verse and other ancient rituals
thrown in. Probably a reading of Pam Ayres poetry too! Might as well find
the diff. eqns. for a six-body gravitational orbit.
:-)
> --
> http://blog.orphi.me.uk/
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>> Should be noted: It's an *ancient* laptop!
>
> Heh. I though more of an ancient (and broken) Linux distro.
SuSE 10.2...
>> (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...)
>
> Which is wise choice.
Indeed. I had assumed that *all* laptops work this way. (Surely to be
any other way is at the very least a fire hazard?)
--
http://blog.orphi.me.uk/
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M_a_r_c wrote:
> And what about e-paper?
Hey, I read something about that in Chemistry In Britan...
...12 years ago.
Now, I suppose in product development terms, 12 years isn't very long.
But I don't expect this technology to entire the mainstream in my own
lifetime...
--
http://blog.orphi.me.uk/
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>> I read about this kind of thing in a DSP book. Damn, IIR filters sound
>> so complicated! Fascinating, but... I wouldn't want to design them for
>> a living.
>
> I'm with you on that! Fascinating, wish I could do it, but AIUI,
> there's hardly a hope of designing it manually.
I always wondered why the hell you would put a coin of wire inside a
circuit. I mean, sure, if you put power through it, you can use it to
pick up metal objects. But why would you have such a thing inside a machine?
Ah, but wait. When you turn the power off, the magnetic field collapses.
And what do we know about coils of wire inside a changing magnetic field?
I *so* didn't see that one comming... People are way smarted then me. :-/
Still, the stuff about the Laplace transform was cool. Very hard to
comprehend, but cool...
> It's computerised
> design with an element of alchemy, dead cats, satanic verse and other
> ancient rituals thrown in. Probably a reading of Pam Ayres poetry too!
> Might as well find the diff. eqns. for a six-body gravitational orbit.
Oh, the *equations* are easy enough. Now try *solving* them... ;-)
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
>
> SuSE 10.2...
Ah, the latest out there.
> Indeed. I had assumed that *all* laptops work this way. (Surely to be
> any other way is at the very least a fire hazard?)
>
Not everything in this world work with sense... Unfortunately.
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
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> Now, I suppose in product development terms, 12 years isn't very long.
> But I don't expect this technology to entire the mainstream in my own
> lifetime...
I wonder what people were saying about LCD 20 years ago...
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Orchid XP v3 wrote:
> Indeed. I had assumed that *all* laptops work this way.
But you can override it in software. So if you override it incorrectly,
you have a problem.
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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scott wrote:
>> Now, I suppose in product development terms, 12 years isn't very long.
>> But I don't expect this technology to entire the mainstream in my own
>> lifetime...
>
> I wonder what people were saying about LCD 20 years ago...
But LCD hasn't changed how a screen is used, it's just made it a bit
more efficient and a bit smaller (and, arguably, a bit crapper,
certainly in the low end of the TV market). E-paper requires a whole new
product and a whole new set of habits from the consumer. This will take
a little longer. I don't expect to see e-paper widely used anytime soon,
and only maybe within my lifetime.
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>> I wonder what people were saying about LCD 20 years ago...
>
> But LCD hasn't changed how a screen is used, it's just made it a bit more
> efficient and a bit smaller (and, arguably, a bit crapper, certainly in
> the low end of the TV market). E-paper requires a whole new product
You mean like how LCD has popped up in cars, phones, portable navigation
devices and games consoles etc - none of which had any sort of graphic
display before LCD.
> and a whole new set of habits from the consumer. This will take a little
> longer. I don't expect to see e-paper widely used anytime soon, and only
> maybe within my lifetime.
As I already said, ePaper is already used in supermarkets, it will only be a
matter of years (not decades) before it becomes more cost-efficient than a
lot of existing paper-and-ink based things.
Sure, it's not going to replace a real book or a newspaper for a long time
(perhaps never), but there are plenty of other markets that ePaper will take
over relatively soon.
Another example is the odometer in cars - the OEMs are already asking for a
zero-power display for this so that it is always visible. Expect to see
ePaper based odometers within 10 years in cars, and cars have one of the
longest product development cycles.
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scott wrote:
>>> I wonder what people were saying about LCD 20 years ago...
>>
>> But LCD hasn't changed how a screen is used, it's just made it a bit
>> more efficient and a bit smaller (and, arguably, a bit crapper,
>> certainly in the low end of the TV market). E-paper requires a whole
>> new product
>
> You mean like how LCD has popped up in cars, phones, portable navigation
> devices and games consoles etc - none of which had any sort of graphic
> display before LCD.
Yersss... true, although I still don't think there has been a
fundamental shift in the way pre-existing devices are used. With phones,
the screen technology (as well as the computing and battery technology)
has just enabled several common portable devices to be integrated into
one small one, without changing how the different functions are used.
Navigation devices would also still be small and indispensable without a
screen. Most people don't use the screen with them anyway, the voices
tell them when to turn up wrong-way streets or drive 60 ton lorries down
unmade country roads perfectly efficiently ;-)
>> and a whole new set of habits from the consumer. This will take a
>> little longer. I don't expect to see e-paper widely used anytime soon,
>> and only maybe within my lifetime.
>
> As I already said, ePaper is already used in supermarkets, it will only
> be a matter of years (not decades) before it becomes more cost-efficient
> than a lot of existing paper-and-ink based things.
We might have to curb society's urge to throw everything in the skip
first, but that's another matter of course.
> Sure, it's not going to replace a real book or a newspaper for a long
> time (perhaps never), but there are plenty of other markets that ePaper
> will take over relatively soon.
Yes, I guess I was only really considering the issue of it replacing
actual paper.
> Another example is the odometer in cars - the OEMs are already asking
> for a zero-power display for this so that it is always visible. Expect
> to see ePaper based odometers within 10 years in cars, and cars have one
> of the longest product development cycles.
Fine, but that's really just a gimmick, isn't it? Would it really be
cheaper, more reliable and the rest than a small mechanical dial? Maybe
it would, I'm only being a luddite cynic here... :)
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>> Another example is the odometer in cars - the OEMs are already asking for
>> a zero-power display for this so that it is always visible. Expect to
>> see ePaper based odometers within 10 years in cars, and cars have one of
>> the longest product development cycles.
>
> Fine, but that's really just a gimmick, isn't it? Would it really be
> cheaper, more reliable and the rest than a small mechanical dial? Maybe it
> would, I'm only being a luddite cynic here... :)
In general electronic components are orders of magnitude more reliable than
mechanical ones, which is why car OEMs always try to replace mechanical
parts with electronic ones if they can. It happened decades ago for the
distributor in the engine, and more recently for the odometer. However for
the odometer the ability to see the mileage of the car without turning on
the ignition was lost. ePaper can fix this, because the disadvantages it
has (low switching time, poor quality colour displays) do not matter for an
odometer.
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> Ah. Right now rendering two scenes (in a mind of testing) with max
> brightness on the screen, ie. burning the CPU. I'm not consuming extreme
> memory nor using wireless interfaces
>
> groath ~ # cat /proc/acpi/battery/C1B5/state
> present: yes
> capacity state: ok
> charging state: discharging
> present rate: 2749 mA
> remaining capacity: 3797 mAh
> present voltage: 11671 mV
>
> 2749mA*11671mV=~32W.
Mine goes up to about 45W while using POV with both CPUs, drops to 22W when
idle. There is about 5W difference between min and max screen brightness.
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scott wrote:
> Mine goes up to about 45W while using POV with both CPUs, drops to 22W
> when idle. There is about 5W difference between min and max screen
> brightness.
Wait... a dual-core laptop?
31337!!
--
http://blog.orphi.me.uk/
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scott wrote:
> I wonder what people were saying about LCD 20 years ago...
Um... maybe I'm just stupid, but I'm pretty sure when I was 7 years old
I was *using* LEDs...
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
> scott wrote:
>
>> I wonder what people were saying about LCD 20 years ago...
>
> Um... maybe I'm just stupid, but I'm pretty sure when I was 7 years old
> I was *using* LEDs...
Hahahaha!
Oh dear...
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
>
> Wait... a dual-core laptop?
Yep. I wasn't after CPU power, but the cheapest one to fullfill my specs
(including hardware rs-232 and parallel ports) was equipped with one.
But I won't complain, since C2D ain't a heater.
> 31337!!
Yeah :).
--
Eero "Aero" Ahonen
http://www.zbxt.net
aer### [at] removethiszbxtnetinvalid
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>> Mine goes up to about 45W while using POV with both CPUs, drops to 22W
>> when idle. There is about 5W difference between min and max screen
>> brightness.
>
> Wait... a dual-core laptop?
>
> 31337!!
Intel Core2Duo T7200 @ 2 GHz
2.0 GB of RAM
1920x1200 display
Quadro FX 3D card
It's sweet, and it lasts for like 4 or 5 hours so long as you don't run POV.
And the thing you'll like best? £999 from DELL back at the beginning of the
year :-) I really wanted a high-res screen for CAD work, and Dell was the
only place that offered it at a reasonable price.
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>>> I wonder what people were saying about LCD 20 years ago...
>>
>> Um... maybe I'm just stupid, but I'm pretty sure when I was 7 years old I
>> was *using* LEDs...
>
> Hahahaha!
>
> Oh dear...
:-)
You were probably using LCD too (calculator...watch?), but not in a form
anywhere near suitable for PC displays. I remember when I was about 10 my
dad brought home a laptop from work. It had a black and white screen and
the refresh rate was like 2 seconds. IIRC it ran DOS and we had some Lotus
equivalent of "power point" running - it was hideous to use, if you moved
the mouse too fast it disappeared into a sea of grey blurriness!
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scott wrote:
> Intel Core2Duo T7200 @ 2 GHz
> 2.0 GB of RAM
> 1920x1200 display
> Quadro FX 3D card
>
> It's sweet, and it lasts for like 4 or 5 hours so long as you don't run
> POV.
>
> And the thing you'll like best? £999 from DELL back at the beginning of
> the year :-) I really wanted a high-res screen for CAD work, and Dell
> was the only place that offered it at a reasonable price.
£999 for tha-oh, wait. Quadro FX 3D card...
--
http://blog.orphi.me.uk/
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scott wrote:
>> Hahahaha!
>>
>> Oh dear...
>
> :-)
>
> You were probably using LCD too (calculator...watch?), but not in a form
> anywhere near suitable for PC displays. I remember when I was about 10
> my dad brought home a laptop from work. It had a black and white screen
> and the refresh rate was like 2 seconds. IIRC it ran DOS and we had
> some Lotus equivalent of "power point" running - it was hideous to use,
> if you moved the mouse too fast it disappeared into a sea of grey
> blurriness!
Well, I remember using a "cutting edge" laptop that we weren't supposed
to have from BT.
It was white, and extremely heavy. The display wasn't black and white;
it was blue, purple and pale blue. It was impossible to complete level 9
on Tetris because the blocks were *actually invisible*. As in, there was
no visible evidence of their falling at all. Level 8 was only
completable by fluke, which happened exactly once.
OTOH, it was the first time I got to play with Borland Turbo Pascal 5.5
for DOS (which we also weren't supposed to have, and is one of the few
illegal software products I still possess). Until then, I'd only ever
programmed in machine code and BASIC. (Back when BASIC was BASIC... You
know, with GOTO and line numbers and stuff!)
Also, the display "rippled" when you touched it...
And it had a chess game where if you did this certain move, the game
somehow managed to make a *screaming* sound from the beep-speaker...! o_O
--
http://blog.orphi.me.uk/
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>> Intel Core2Duo T7200 @ 2 GHz
>> 2.0 GB of RAM
>> 1920x1200 display
>> Quadro FX 3D card
>>
>> It's sweet, and it lasts for like 4 or 5 hours so long as you don't run
>> POV.
>>
>> And the thing you'll like best? £999 from DELL back at the beginning of
>> the year :-) I really wanted a high-res screen for CAD work, and Dell
>> was the only place that offered it at a reasonable price.
>
> £999 for tha-oh, wait. Quadro FX 3D card...
Actually the Quadro card wasn't that expensive/hard to find - it was the
1920x1200 display that really sky-rocketed the price (or wasn't even
available) from other suppliers in a laptop that you didn't need wheels to
move about.
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> It was white, and extremely heavy. The display wasn't black and white; it
> was blue, purple and pale blue.
Ah yes :-)
> Until then, I'd only ever programmed in machine code and BASIC. (Back when
> BASIC was BASIC... You know, with GOTO and line numbers and stuff!)
Hehe, although the BASIC I had (on a BBC B) also had functions and
procedures, so you really could keep clear of the dreaded goto.
> Also, the display "rippled" when you touched it...
They still do today (although probably not as bad), try it. Two years ago I
built a test rig to measure the severeness of this exact phenomena - as you
can imagine it's not exactly desired behaviour when you have a
touch-screen...
> And it had a chess game where if you did this certain move, the game
> somehow managed to make a *screaming* sound from the beep-speaker...! o_O
Ah yes - controlling the internal speaker directly, you can still do that on
most PCs and laptops today, although Windows probably blocks any software in
user mode from accessing it.
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scott wrote:
>> Until then, I'd only ever programmed in machine code and BASIC. (Back
>> when BASIC was BASIC... You know, with GOTO and line numbers and stuff!)
>
> Hehe, although the BASIC I had (on a BBC B) also had functions and
> procedures, so you really could keep clear of the dreaded goto.
That's a wonderful language. I once heard it said that BBC BASIC V (the
version that shipped with the Archimedes and its successors) was 'the
Rolls-Royce version of BASIC'. Up till then I was always puzzled by the
bashing that BASIC got for being unstructured and tedious.
(Sighs... built-in assembler, OS graphics library, direct memory
addressing...)
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>>> Until then, I'd only ever programmed in machine code and BASIC. (Back
>>> when BASIC was BASIC... You know, with GOTO and line numbers and stuff!)
>>
>> Hehe, although the BASIC I had (on a BBC B) also had functions and
>> procedures, so you really could keep clear of the dreaded goto.
>
> That's a wonderful language. I once heard it said that BBC BASIC V (the
> version that shipped with the Archimedes and its successors) was 'the
> Rolls-Royce version of BASIC'. Up till then I was always puzzled by the
> bashing that BASIC got for being unstructured and tedious.
>
>
> (Sighs... built-in assembler, OS graphics library, direct memory
> addressing...)
Hmmm, I spent a long time writing programs with BASIC V and the assembler, a
few of them even made it in to Acorn User magazine :-) Oh those were the
days, the thing that I liked best was that you could be in total control of
the CPU, none of this having to worry about someone pressing Alt-Tab or the
screen-saver coming on etc...
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scott wrote:
>> That's a wonderful language. I once heard it said that BBC BASIC V
>> (the version that shipped with the Archimedes and its successors) was
>> 'the Rolls-Royce version of BASIC'. Up till then I was always puzzled
>> by the bashing that BASIC got for being unstructured and tedious.
>>
>>
>> (Sighs... built-in assembler, OS graphics library, direct memory
>> addressing...)
>
> Hmmm, I spent a long time writing programs with BASIC V and the
> assembler, a few of them even made it in to Acorn User magazine :-)
Hmm, I might actually know your surname if I saw it, in that case. I
still have many issues of that mag kicking around somewhere.
> those were the days, the thing that I liked best was that you could be
> in total control of the CPU, none of this having to worry about someone
> pressing Alt-Tab or the screen-saver coming on etc...
Yup. You could sit down, start typing, and have graphics on the screen
inside of a minute. Impossible these days.
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> Hmm, I might actually know your surname if I saw it, in that case. I still
> have many issues of that mag kicking around somewhere.
The surname is Boham, I think they were published around '96 - '98 but could
be a year or two out, it's been a long time. I still have a lot of AU
issues back at my mum's house, I should get them out one day. And fire up
my old A3010, and figure out a way to get the 120 MB of data off the
internal HD and onto my PC to run in the emulator.
> Yup. You could sit down, start typing, and have graphics on the screen
> inside of a minute. Impossible these days.
Well with things like Visual Studio you can get a windows based application
running in almost zero time, but direct access to the screen is much
trickier. I guess that's the price we have to pay for such a wide variety
of video hardware in the market (and hence much cheaper prices).
Still, Microsoft has done a good job with DirectX recently (since version 6,
and similar applies with OpenGL I assume) to get direct access to hardware
independent of the make/model installed. It's only half a dozen DirectX
calls to setup a full screen application with access to the pixel data
directly. It's not the fastest ways to do things though, there's usually a
faster alternative involving textured rectangles and/or pixel shaders.
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scott wrote:
>> Hmm, I might actually know your surname if I saw it, in that case. I
>> still have many issues of that mag kicking around somewhere.
>
> The surname is Boham, I think they were published around '96 - '98 but
> could be a year or two out, it's been a long time.
Ah, doesn't ring any bells. I bet some of the programs would though, I
used to love that section of the mag.
> fire up my old A3010, and figure out a way to get the 120 MB of data off
> the internal HD and onto my PC to run in the emulator.
Hmm, if you still have a regular-sized parallel port on the PC you could
use something called ZeriLink (I think it's still downloadable). It's
a tiny program, with a DOS app and a RISCOS app. You have to rewire a
parallel lead too but it's pretty trivial. Then you set it copying and
go and make a pot of tea. Or six.
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> Ah, doesn't ring any bells. I bet some of the programs would though, I
> used to love that section of the mag.
Aww, I couldn't hope to compete with the likes of Jan Vibe and the other Jan
whose surname I forget :-)
Oh, I just found this:
http://www.drobe.co.uk/riscos/artifact2022.html
>> fire up my old A3010, and figure out a way to get the 120 MB of data off
>> the internal HD and onto my PC to run in the emulator.
> Hmm, if you still have a regular-sized parallel port on the PC you could
> use something called ZeriLink (I think it's still downloadable). It's a
> tiny program, with a DOS app and a RISCOS app. You have to rewire a
> parallel lead too but it's pretty trivial. Then you set it copying and go
> and make a pot of tea. Or six.
Sounds good, I was thinking of programming something similar myself, but
then figured it would be faster to just copy using 1.44 MB floppies 90 or so
times.
I've bookmarked the page for ZeriLink, will give it a shot some time.
Cheers.
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scott wrote:
> Oh, I just found this:
>
> http://www.drobe.co.uk/riscos/artifact2022.html
Interesting. I certainly remember most of those programs!
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