Power Ratings and their Significance or Insignificance

laatsch55

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#1
RMS--root mean squre, i also believe this rating required a 20 minute warmup and some other not-to-nice to amp things.
 

nakdoc

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#2
Man that was fast

IHF

Institute of HiFi. Predates my coming of age. I have no clue what that rating specified, but it seemed to be the one that the RMS crowd hated.
 

laatsch55

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Rod Elliots site will be inundated for a bit getting this straightened out. Yeah nakdoc, we small but we move fast.
 

nakdoc

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DIN

Deutches I something N something
The universal European standard, probably the primogeniture for the EU. DIN power was kind of neat. It was a music power, but instead of running into 8 ohm test resistors, they had a nominal 4 ohm load with capacitance and inductance, a sort of "average" dynamic speaker simulation. DIN did the preheating trick, and I believed capped the distortion at 1%, so it was an honest attempt to spec power. Here in the states we learned about DIN by listening to thin B&O receivers rated at 22 watts DIN that could play quite loudly with B&O speakers. I do not believe DIN was 20-20K at 1%. We need to add to this thread and do a little research.
 

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Yep, Now if you start with distortion, nom theres another can of worms.
IF, you load test with Caps and a resistor, with your average zoebel network in place and no inductor in the output wont you ring like a BELL ??
 

speakerman1

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Pure Fu(*ing Magic. No one really can explain how it works. They just do theories and such. Yes you can do measurements; but how does it really work?

Larry
 

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#10
laatsch55 said:
With Stu around a guy needs that.
Agreed! Now, about the topic at hand: I realize this may have been discussed in just about every tech magazine: these all in one package 5.1 systems boast power wattages from their receivers that are ridiculously over-rated. My Sony 5.1 receiver is packaged with 140W X5 plus 200W for a total of 900 watts of power. I didn't read the spec sheet in the OM, but there's no way it compares with proper measuring techniques. When I finally open that OM will I find that's peak power at an unacceptable distortion figure with no frequency range parameter?

Nando.
 

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Elite-ist said:
laatsch55 said:
With Stu around a guy needs that.
Agreed! Now, about the topic at hand: I realize this may have been discussed in just about every tech magazine: these all in one package 5.1 systems boast power wattages from their receivers that are ridiculously over-rated. My Sony 5.1 receiver is packaged with 140W X5 plus 200W for a total of 900 watts of power. I didn't read the spec sheet in the OM, but there's no way it compares with proper measuring techniques. When I finally open that OM will I find that's peak power at an unacceptable distortion figure with no frequency range parameter?

Nando.
Not only that, but they typically measure each distinct section at a time (front L/R, surround, center, subwoofer). So individually each section can supposedly put out either x number of continuous watts or y number of peak watts for a certain period.

Thing is... typically all sections will draw current to do their work from the same power supply. So then you get the rob peter to pay paul syndrome... and all those specs that look really good on the back cover go to crap.

Best measurement... ears, I'd gather... At least RMS from 20 to 20 gives you an overall idea, if just for the two front channels.
 

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Elite-ist said:
laatsch55 said:
With Stu around a guy needs that.
Agreed! Now, about the topic at hand: I realize this may have been discussed in just about every tech magazine: these all in one package 5.1 systems boast power wattages from their receivers that are ridiculously over-rated. My Sony 5.1 receiver is packaged with 140W X5 plus 200W for a total of 900 watts of power. I didn't read the spec sheet in the OM, but there's no way it compares with proper measuring techniques. When I finally open that OM will I find that's peak power at an unacceptable distortion figure with no frequency range parameter?

Nando.
The story of the US power rating standard is interesting. Around 1975 some council became concerned about all the (lying) power ratings, so they produced a standard:

RMS power, both chanels driven into 8 ohms, 1/2 hour warm up at 1/3 power, at any frequency between 20-20kHz, at some specified distortion.

Car stereos were exempted. The standard held up well, until the middle 1990s. Sony was the first company I noticed that began to fudge a bit. They would rate their amp power between 40-20KHz. This allowed them to use small power transformers and small heat sinks, and fully lived up to the "ball-less" Sony sound. Many of these 5.1 systems specify 1 or 2% distortion, probably because no one cares. I've seen power ratings list 40-15kHz, and subwoofers...well they make up all kinds of strange conditions. The nice thing is, companies still disclose the test conditions, for anyone that cares.
 

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#14
Nakdoc, I think this generation has been taught to Believe everyone and everything in a position of authority, we were brought up to question it.
 

Elite-ist

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So curiousity prompted me to turn to the last page in my Sony HT-DDW900 OM for specifications.

Power Output And Total Harmonic Distortion:

With 6 ohm loads, both channels driven, from 120-20,000 Hz: rated 90 watts per channel minimum RMS per channel, with no more than 0.7% total harmonic distortion from 250 milliwatts to rated output.

That's for the reciever powering the front, centre, and surround speakers. The sub-woofer has its own amplifier.

Nando.
 

laatsch55

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#16
To me that rating is totally worthless, at .7% some gold ears out there would already be outside screaming down the street.
I think the 6 ohm qualification was a way to state more power without the slippery slope of 4 ohm and less getting in the way.
AND, I still say subwoofers are not necessary with a good speaker. 120 HZ on the low end?? Give me a break.
 

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laatsch55 said:
Did it really say.7% and not .07%??
I've been waiting for this all morning: Yes.

The satellite speakers are full range and rated at 6 ohms each. That's why I wanted to build an old school Pioneer Elite 5.2 system. My Elite SP-99D Sound Processor would be the foundation of that system with multiple amplifiers driving four older Pioneer CS-99A speakers. I hadn't decided what to use for dual subs.

Nando.
 

Elite-ist

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#20
Thanks for rethreading the extra comments, Web. Lee eggs me on all the time. Can't he partially ban himself as punishment?

Nando.
 
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