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> Mine has a nifty engine that breaks down all sorts of bio matter into
> simple carbohydrates and then burns them. It's flexible enough to work on
> matter as diverse as fruits, grains, and meats, although certain spices
> have been known to give it trouble. Also, you need a fair amount of fiber
> mixed in, otherwise the whole thing can get clogged.
Rent-A-Ruminant?
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> Why do you think that those frequencies are far above 50 Hz?
50 Hz = 3000 rpm, but some of the parts like the valves only
move during a portion of a revolution, and have higher frequencies.
Camshafts are 2:1, I think, so if a lobe is about 30 degrees then
the upper frequency might be around (50*2*24)=2400 Hz sound
at 3000 rpm, or 160 Hz at a 200 rpm idle.
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Tim Attwood wrote:
>> Mine has a nifty engine that breaks down all sorts of bio matter into
>> simple carbohydrates and then burns them. It's flexible enough to work on
>> matter as diverse as fruits, grains, and meats, although certain spices
>> have been known to give it trouble. Also, you need a fair amount of fiber
>> mixed in, otherwise the whole thing can get clogged.
>
> Rent-A-Ruminant?
Nah, one of these :)
http://www.peoplepoweredmachines.com/reel_mower_landing.htm?gclid=CJjJm8adqY4CFQsEIwod4SvTSw
--
...Ben Chambers
www.pacificwebguy.com
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Gail Shaw wrote:
> "Orchid XP v3" <voi### [at] dev null> wrote in message
> news:46dc4c7a$1@news.povray.org...
>> John VanSickle wrote:
>>
>>>> Damn... pitty we can't use heat to do *useful* stuff!
>>> Heat already does useful things. For instance, it causes cute girls to
>>> wear skimpy clothing.
>> Hey, neat!
>>
>> (Pitty it's too damn hot to do anything about it...)
>>
>
> Two words...
>
> Swimming pool
One word: beach :)
--
...Ben Chambers
www.pacificwebguy.com
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>> I was just illustrating that a normal mobile phone can do all that stuff
>> (both transmitting and receiving to the base station) for around 10 mW.
>
> I *think* the xmit power of a cell phone is a bit more than that...But
> I'd have to check.
Sorry yes, that was average power for the whole phone, a phone can transmit
at higher powers (if you are in a very weak signal area) but only for a very
short time period (I guess just 1 packet every minute or so to let the base
stations in range know you are still there incase of an incoming call). 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.
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> Without *anything* happening, it uses 110 W.
Ah good to know, it's roughly what I suspected...
> With my stonking-great video card with a fan the size of a plannet, it
> uses 190 W. (Roughly. It waivers a lot.) During the boot sequence it tops
> 280 W. (Presumably when all those electric motors all start up at once...)
It seems to me that before Windows gets going (or more specifically all the
device drivers) everything just runs in max power mode. Once Windows is in
charge of the PC it can then back things off like the GFX card and putting
the CPU in sleep mode when it's not needed.
OOC what power does it use when you're doing nothing in the BIOS settings
screen?
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>> 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? Most speakers (electrically speaking)
seem very simple to me, just a cross-over network and then a coil of 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).
> Hmm, I think my amplifier (nothing special) is rated at 60 W per channel.
> (IIRC, into 8 ohms at 1 kHz.)
And what happens when you actually output 60 W in your room? BTW on most
amplifiers you need to get the input signal at the right level (not too high
or too low) to get the quoted maximum output power. 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.
> 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.
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Gail Shaw wrote:
>>> Heat already does useful things. For instance, it causes cute girls to
>>> wear skimpy clothing.
>> Hey, neat!
>>
>> (Pitty it's too damn hot to do anything about it...)
>>
>
> Two words...
>
> Swimming pool
Heh... I didn't know she was like that... ;-)
--
http://blog.orphi.me.uk/
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>>> 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?
> 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?
>> Hmm, I think my amplifier (nothing special) is rated at 60 W per
>> channel. (IIRC, into 8 ohms at 1 kHz.)
>
> 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.)
By the way... I notice with interest that the sound level drops
*dramatically* as you walk through the doorway. I mean, it's really
drastically quieter just slightly outside the door. I am be half-deaf
inside my room, and yet from outside it doesn't seem all that loud.
Really. You'd think the sound would travel more.
(Perhaps this is related to the mysterious "waves can't pass through
holes smaller than a certain size" phenominon?)
> BTW on
> most amplifiers you need to get the input signal at the right level (not
> too high or too low) to get the quoted maximum output power.
Yeah, probably.
(I once tried connecting a line-level output to the phono input. Big
mistake...)
> 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.
>> 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...
--
http://blog.orphi.me.uk/
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>> And when I start up the engine of my car, the various parts move far
>> too fast for the eye to follow. But you *can* see the blur of moving
>> objects, and there is little doubt that they're moving. ;-)
> Why do you think that those frequencies are far above 50 Hz?
My engine *idles* at several thousand RPM...
> What sound does your motor make? Can you find the base frequency on your
> keyboard?
Surely that's just the resonant modes of the exhaust system and the chasis?
--
http://blog.orphi.me.uk/
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scott wrote:
>> Without *anything* happening, it uses 110 W.
>
> Ah good to know, it's roughly what I suspected...
Pretty tiny compared to the 20 W or so my laptop uses when idling.
(But then... no 3D graphics, only 1 HD, lower clock speed, etc.)
>> With my stonking-great video card with a fan the size of a plannet, it
>> uses 190 W. (Roughly. It waivers a lot.) During the boot sequence it
>> tops 280 W. (Presumably when all those electric motors all start up at
>> once...)
>
> It seems to me that before Windows gets going (or more specifically all
> the device drivers) everything just runs in max power mode. Once
> Windows is in charge of the PC it can then back things off like the GFX
> card and putting the CPU in sleep mode when it's not needed.
>
> OOC what power does it use when you're doing nothing in the BIOS
> settings screen?
Hmm, I'll go check it out sometime...
BTW, when I installed Linux on my dad's laptop, we discovered something
interesting. We tried to install the software, but the machine began to
behave more and more strangely. Eventually I noticed that the laptop was
utterly *scalding* hot to the touch. We rebooted it, and the various
fans immediately kicked in at full power.
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?
Once the laptop was cold, Linux installed just fine...
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
>>> And when I start up the engine of my car, the various parts move far
>>> too fast for the eye to follow. But you *can* see the blur of moving
>>> objects, and there is little doubt that they're moving. ;-)
>
>> Why do you think that those frequencies are far above 50 Hz?
>
> My engine *idles* at several thousand RPM...
The significant character here is 'M'
>
>> What sound does your motor make? Can you find the base frequency on
>> your keyboard?
>
> Surely that's just the resonant modes of the exhaust system and the chasis?
>
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. ;)
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>>> Why do you think that those frequencies are far above 50 Hz?
>>
>> My engine *idles* at several thousand RPM...
> The significant character here is 'M'
Hmm. What is 2,000 RPM in Hz? 33 Hz? That's interesting...
>>> What sound does your motor make? Can you find the base frequency on
>>> your keyboard?
>>
>> Surely that's just the resonant modes of the exhaust system and the
>> chasis?
>>
> 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.
AFAIK, the retina sees the "integral" of incident light over time,
roughly. So I'm not sure why an object moving fast enough would appear
to stop moving. Become invisible, perhaps, if it's small enough...
> 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. ;)
How about my tuning fork? That says "440 Hz" on it, and I can see that
vibrating plainly enough... ;-)
(Oddly though, it doesn't seem to make much audible sound, despite the
ends of the fork traversing really quite some distance. I can only
surmise that it doesn't move the air around very much or something...)
--
http://blog.orphi.me.uk/
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Orchid XP v3 wrote:
>>>> Why do you think that those frequencies are far above 50 Hz?
>>>
>>> My engine *idles* at several thousand RPM...
>> The significant character here is 'M'
>
> Hmm. What is 2,000 RPM in Hz? 33 Hz? That's interesting...
>
>>>> What sound does your motor make? Can you find the base frequency on
>>>> your keyboard?
>>>
>>> Surely that's just the resonant modes of the exhaust system and the
>>> chasis?
>>>
>> 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.
>
> AFAIK, the retina sees the "integral" of incident light over time,
> roughly.
Not really
> So I'm not sure why an object moving fast enough would appear
> to stop moving. Become invisible, perhaps, if it's small enough...
>
>> 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. ;)
>
> How about my tuning fork? That says "440 Hz" on it, and I can see that
> vibrating plainly enough... ;-)
Again the question is if you see the 440 Hz or a much lower frequency
wobble. The ends of the fork should be a little wider and a little
transparent. Anyway I think what you see is that it is moving, not the
movement itself.
>
> (Oddly though, it doesn't seem to make much audible sound, despite the
> ends of the fork traversing really quite some distance. I can only
> surmise that it doesn't move the air around very much or something...)
>
Perhaps otherwise it would loose energy too fast and the tone would die
out quickly.
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"andrel" <a_l### [at] hotmailcom> a écrit dans le message de news:
46D### [at] hotmailcom...
>>
>> (Oddly though, it doesn't seem to make much audible sound, despite the
>> ends of the fork traversing really quite some distance. I can only
>> surmise that it doesn't move the air around very much or something...)
>>
> Perhaps otherwise it would loose energy too fast and the tone would die
> out quickly.
Think of a big impedance mismatch between the fork and air.
You get a better match when you put the round end on a thin hard surface as
a guitar top or a box.
Then the vibrating surface is much bigger and can transmit energy to the
air.
Note that the sound dies faster then.
Marc
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On Tue, 04 Sep 2007 10:13:37 +0200, scott wrote:
> 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. My phone (which
is fairly new) only gets about a day, maybe two of standby time. Course
I use it for other things (like navigation) which cut down on the
available battery, natch.
Jim
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On Mon, 03 Sep 2007 16:40:09 -0700, Darren New wrote:
> Depends on the phone system. CDMA was originally designed to be an
> undetectable transmitter for military use. IIRC, its power ranges
> between 2.5mW and 5mw.
That sounds like the range I was thinking of. 1 mW isn't very much.
Jim
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"Orchid XP v3" <voi### [at] devnull> wrote in message
news:46dda414$1@news.povray.org...
>>> And when I start up the engine of my car, the various parts move far too
>>> fast for the eye to follow. But you *can* see the blur of moving
>>> objects, and there is little doubt that they're moving. ;-)
>
>> Why do you think that those frequencies are far above 50 Hz?
>
> My engine *idles* at several thousand RPM...
No it doesn't!
What kind of engine do you run in your car??? a nitro engine???
Any car engine is capable of idling far below 1000rpm. Most idle aroun
600-800rpm depending on auto or manual gearbox...
HTH
Cheers Dre
>> What sound does your motor make? Can you find the base frequency on your
>> keyboard?
>
> Surely that's just the resonant modes of the exhaust system and the
> chasis?
>
> --
> http://blog.orphi.me.uk/
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> Nah, one of these :)
>
>
http://www.peoplepoweredmachines.com/reel_mower_landing.htm?gclid=CJjJm8adqY4CFQsEIwod4SvTSw
Ah, I thought they ran on beer =)
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Gail Shaw wrote:
> "Orchid XP v3" <voi### [at] devnull> wrote in message
> news:46dc4c7a$1@news.povray.org...
>
>>John VanSickle wrote:
>>
>>
>>>>Damn... pitty we can't use heat to do *useful* stuff!
>>>
>>>Heat already does useful things. For instance, it causes cute girls to
>>>wear skimpy clothing.
>>
>>Hey, neat!
>>
>>(Pitty it's too damn hot to do anything about it...)
>>
>
>
> Two words...
>
> Swimming pool
Which results in--even skimpier clothing! Win-win!
Regards,
John
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Dre wrote:
> No it doesn't!
>
> What kind of engine do you run in your car??? a nitro engine???
>
> Any car engine is capable of idling far below 1000rpm. Most idle aroun
> 600-800rpm depending on auto or manual gearbox...
I've seen several engines that idle at more than 1000rpm. I even saw
one go as high as 1 800 (though I'm pretty sure there was something
wrong with it).
--
...Ben Chambers
www.pacificwebguy.com
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Orchid XP v3 wrote:
> AFAIK, the retina sees the "integral" of incident light over time,
Errr, not even close. Indeed, if something is completely still, you
can't see it at all. That's why your eyes are always moving (saccades).
--
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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Chambers wrote:
> Dre wrote:
>> No it doesn't!
>>
>> What kind of engine do you run in your car??? a nitro engine???
>>
>> Any car engine is capable of idling far below 1000rpm. Most idle
>> aroun 600-800rpm depending on auto or manual gearbox...
>
> I've seen several engines that idle at more than 1000rpm. I even saw
> one go as high as 1 800 (though I'm pretty sure there was something
> wrong with it).
>
My 4 stroke, 49.9 cc moped engine idles at 1800 to 2200. That is, if the
manual is to be trusted, since in all three places it lists an ideal
idle speed it has a different number. But, there is a difference between
cars, and chainsaw motors with wheels.
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"Chambers" <ben### [at] pacificwebguycom> wrote in message
news:46de0bbd@news.povray.org...
> Dre wrote:
>> No it doesn't!
>>
>> What kind of engine do you run in your car??? a nitro engine???
>>
>> Any car engine is capable of idling far below 1000rpm. Most idle aroun
>> 600-800rpm depending on auto or manual gearbox...
>
> I've seen several engines that idle at more than 1000rpm. I even saw one
> go as high as 1 800 (though I'm pretty sure there was something wrong with
> it).
>
> --
> ...Ben Chambers
> www.pacificwebguy.com
Well car engines tend to idle higher when they are cold as the ecu tells
them to (engines dont like being cold). An engine at operating temp
shouldn't need to idle above 1000rpm, thats just a waste of fuel.
1800rpm is way too high for idle and as you say, there was something wrong
with it.
I was just pointing out to Orchid that his engine *doesn't* idle at
*several* thousand rpm, thats a gross exaggeration.
Cheers Dre
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"Sabrina Kilian" <"ykgp at vtSPAM.edu"> wrote in message
news:46de1a62$1@news.povray.org...
> Chambers wrote:
>> Dre wrote:
>>> No it doesn't!
>>>
>>> What kind of engine do you run in your car??? a nitro engine???
>>>
>>> Any car engine is capable of idling far below 1000rpm. Most idle
>>> aroun 600-800rpm depending on auto or manual gearbox...
>>
>> I've seen several engines that idle at more than 1000rpm. I even saw
>> one go as high as 1 800 (though I'm pretty sure there was something
>> wrong with it).
>>
>
> My 4 stroke, 49.9 cc moped engine idles at 1800 to 2200. That is, if the
> manual is to be trusted, since in all three places it lists an ideal
> idle speed it has a different number. But, there is a difference between
> cars, and chainsaw motors with wheels.
Exactly, my model nitro engines need idle (2.5cc) idle around 2000-3000rpm
otherwise they stall, but they are a little different to a car engine, size
and rotating mass tend to have a lot to do with that :)
Cheers Dre
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On Tue, 04 Sep 2007 19:22:04 -0700, Darren New wrote:
> Orchid XP v3 wrote:
>> AFAIK, the retina sees the "integral" of incident light over time,
>
> Errr, not even close. Indeed, if something is completely still, you
> can't see it at all. That's why your eyes are always moving (saccades).
*That's* how an SEP field works. I always wondered. ;-)
Jim
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> I don't know anyone who gets that kind of standby time. My phone (which
> is fairly new) only gets about a day, maybe two of standby time.
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?
I know my mum had to charge her old phone every 24 hours or it would die,
but she got a new battery for it and it went back to lasting for ages again
.. but yours is new.. hmmm, what make/model is it?
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>> 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?
Because if you put a resistance in there large enough to causes a
significant change in efficiency it would create a low pass filter with the
capacitance of the cable. Also the resistor would heat up, so if you
listened to loud music, after a while it would start to get quieter, and
your speakers would start to get warmer... Doesn't seem like a good idea if
you are striving for optimum sound quality...
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>> What sound does your motor make? Can you find the base frequency on your
>> keyboard?
>
> Surely that's just the resonant modes of the exhaust system and the
> chasis?
Ermm, rev your engine, notice how the pitch of the sound corresponds to the
rpms? Some part of the sound will be due to resonances in the system, but
there will be a obvious frequency component (and harmonics) that are equal
to the rpm (that obviously change with engine speed).
Actually Formula 1 teams use this exact method to check what RPM their
competitors' cars are achieving. From the RPM trace they can estimate the
power output of the engine (given they know the speed of the car, and that
all F1 cars weigh the same).
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"Dre" <aus### [at] hotmailcom> a écrit dans le message de news:
46de288a@news.povray.org...
>
>but they are a little different to a car engine, size and rotating mass
>tend to have a lot to do with that :)
And number of cylinders as well
Marc
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scott wrote:
>> I don't know anyone who gets that kind of standby time. My phone (which
>> is fairly new) only gets about a day, maybe two of standby time.
>
> 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?
I put my phone into flight mode for over a week when I was in the States
for a conference recently, because I didn't want to use it for anything
other than an alarm clock. It was switched on for the entire time, and
the battery level only went down by about 10-15%.
This seems to indicate that even on standby, a cellphone uses a
considerable amount of power simply staying in contact with the network.
I reckon if I only connected it to the network to make calls, the
battery could last up to a month.
I'm not sure bluetooth makes that much difference, because it's not
nearly as active.
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"scott" <sco### [at] laptopcom> a écrit dans le message de news:
46de46c6@news.povray.org...
>>> 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?
>
> Because if you put a resistance in there large enough to causes a
> significant change in efficiency it would create a low pass filter with
> the capacitance of the cable. Also the resistor would heat up, so if you
> listened to loud music, after a while it would start to get quieter, and
> your speakers would start to get warmer... Doesn't seem like a good idea
> if you are striving for optimum sound quality...
>
Some power enclosures come with a built-in kind of protection : a light-bulb
in serie with the speakers. When input power increases, the bulb wire gets
hot then its resistance increases and the voltage at the ends of the coil
is limited.
Marc
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"scott" <sco### [at] laptopcom> a écrit dans le message de news:
46de58a3@news.povray.org...
(given they know the speed of the car, and that
> all F1 cars weigh the same).
But not the same Cx
Marc
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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] devnull> 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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