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Class D Switching Power Amplifiers and Power D/A conversion

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Old 14th January 2008, 02:24 PM   #11
fredos is offline fredos  Canada
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Still stable with no load? What happen if you drive it, maybe at 30% of full power and remove load? And if you drive it at HF and remove load? Just curiosity...

Fredos
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Old 14th January 2008, 02:44 PM   #12
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Bwaaaaaaa Haaaaaaaa Haaaaaaa Haaaaaaaa.....

8000W 100A

Specmanship to the extreme.

Rule of thumb is 4A/mm^2. Look at the wire on the toroids in the input filter. Look at the transformer.... You get bigger ones in TV's.

Professional Audio........ Why not just dry up and blow away?

DNA
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Old 14th January 2008, 07:42 PM   #13
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Quote:
Originally posted by Genomerics
Bwaaaaaaa Haaaaaaaa Haaaaaaa Haaaaaaaa.....

8000W 100A

Specmanship to the extreme.

Rule of thumb is 4A/mm^2. Look at the wire on the toroids in the input filter.
if you look at the specs more carefully you will notice that the power draw of this amp is 18A which is perfectly consistent with your 4A/mm^2 rule of thumb

Quote:
Originally posted by Genomerics

Look at the transformer.... You get bigger ones in TV's.

this transformer operates at something like 100 KHZ, its part of a switch mode power supply. its as big as it needs to be.

8000W is music power, not sinewave power

everything is legit ... you can relax now
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Old 14th January 2008, 08:07 PM   #14
wg_ski is offline wg_ski  United States
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Quote:
Originally posted by vasyachkin
well the circuit takes time to trip

...
just because the amp may from time to time pull 100A for one or two cycles not mean it would necessarily damage or trip a 20A circuit

That 20A circuit could drop up to 3% at full load. Add an extension cord and drop some more. Every time the kick hits and the clip light comes on for more than 1/120th of a second you're gonna draw that 100 amps. Then the mains drop by 15%. It comes back up in between, but that's not when it's needed. So much for 8000 watts. Now you've got 6500. Full power is gonna take a dedicated circuit, overkill on the wiring, or both.
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Old 14th January 2008, 09:26 PM   #15
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Quote:
Originally posted by vasyachkin


if you look at the specs more carefully you will notice that the power draw of this amp is 18A which is perfectly consistent with your 4A/mm^2 rule of thumb



this transformer operates at something like 100 KHZ, its part of a switch mode power supply. its as big as it needs to be.

8000W is music power, not sinewave power

everything is legit ... you can relax now
Ooooooh Switch Mode Power Supply. 100KHz..... We are not worthy....

The wire on those toroids still looks a bit thin but I suppose it is exposed so we might up the 4A/mm^2. Looks like the transformer might manage to be about ETD59 size so my telly jibe might have been misplaced.

So..... It's an 1800W for $2700 amplifier.

Thank you for your belated honesty.

DNA
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Old 14th January 2008, 10:05 PM   #16
TOINO is offline TOINO  Portugal
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Quote:
Originally posted by vasyachkin

8000W is music power, not sinewave power
Very descriptive and scientific statement !...

Only data missing is the kind of music !
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Old 14th January 2008, 10:07 PM   #17
wg_ski is offline wg_ski  United States
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Default Par for the course

Quote:
Originally posted by Genomerics


So..... It's an 1800W for $2700 amplifier.

Thank you for your belated honesty.

DNA
Don't go blaming it on this amplifier. They're ALL built/measured/spec'ed this way. Nominal operating condition is 1/8 power, pink noise, into nominal (not minimum) impedance. Class AB, H, D, you name it. The old CS800 could put out 800 watts sinewave from now till the power company turned your lights off but those days are gone. An 8000 watt amp built to run that way would add another zero behind the price tag and weigh 100 pounds - even with a SMPS.

Which is why I'm fed up with this stuff and build my own. I've gotten spoiled to the old school and wish they'd build amps with modern circuitry that had the same oomph as the stuff from the 80's. Modern amps are not *bad* - just not what they could be.
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Old 14th January 2008, 10:34 PM   #18
Eva is offline Eva  Spain
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I hate old school amplifier design. It overlooks almost every fact about practical amplifier use.
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Old 15th January 2008, 12:17 AM   #19
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Quote:
Originally posted by Genomerics


Ooooooh Switch Mode Power Supply. 100KHz..... We are not worthy....

The wire on those toroids still looks a bit thin but I suppose it is exposed so we might up the 4A/mm^2. Looks like the transformer might manage to be about ETD59 size so my telly jibe might have been misplaced.

So..... It's an 1800W for $2700 amplifier.

Thank you for your belated honesty.

DNA
ok i finally understand what your problem is. i can only imagine you designing a fighter jet or an attack helicopter or something ... you would overbuild every part by a factor of 10 and the thing would be too heavy to take off.

believe it or not professional amplifiers actually are much more desirable when they are LIGHT AND SMALL which is of course exactly the opposite of what you prefer.

well then go ahead and build a 200 pound class A amplifier and brag that its 50 watt power rating is more "real" than another amp's 8000 watt power rating.

for a sound reinforcement application nobody would take your 200 pound class A amp even for free.

for your information the I-Tech amplifier is regarded as one of the best subwoofer amplifiers by pros in sound reinforcement and it only weighs 15% more than PL380.

i hope you enjoy listening to sinewaves ...
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Old 15th January 2008, 12:32 AM   #20
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Quote:
Originally posted by TOINO


Very descriptive and scientific statement !...

Only data missing is� the kind of music !
it does not matter what kind.

it really does not.

NO MUSIC approaches the energy content of a sinewave. the best ( actually the worst ) any music can do is approach pink noise which is several Db less energy than a sinewave.

its not a sound engineering practice to design a product for an application other than the one it will actually be used for.

NOBODY BUYS AMPLIFIERS TO LISTEN TO SINE WAVES

a formula 1 car is not a farm tractor. and just because the tractor has more torque and longer mean time between failures does not make it a superior racing machine ...

i suppose a race car's engine horsepower is not real because you have to rebuild the engine after every race ... too bad thats exactly what its designed for. but, but ! but what if i want to use it to tow a trailer to florida ? TOO BAD

i see we have a lot of tractor fanatics here ...
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