Power amps-> power consumed vs output power.

how can this

channels

consumption is

It's called IHFM rating ;-) The trick wording is "instantaneous bursts"... in other words it's a lie.

'IHFM Music Power Output Rating

"The IHFM Music Power Rating uses a technique that makes power measurements at a frequency of 1,000 cycles per second to indicate the capability of an amplifier to handle instantaneous bursts of music power peaks. Since no distortion levels are defined in this method, the Heath Company has performed its IHFM music power ratings at the same level of distortion as is maintained in its own system of standards for the Hi-Fi use category. That level is 0.7% total harmonic distortion at 1 KC. We believe that this figure is the maximum total harmonic distortion tolerable for high fidelity applications. "In determining the advertised power ratings of Heathkit amplifiers using Heath and IHFM standards, we measure a group of amplifiers selected by statistical techniques to represent normal variations that can be expected in production. These measurements are averaged and the advertised power rating is the nearest whole number of watts. "You will also note that the Heath power Output Rating figure is always lower than that obtained for the IHFM Music Power Rating. This indicates Heath's policy of conservatism in advertised power ratings for its power amplifiers. It is also another assurance to you, our customer, that Heathkit products have quality that you can depend on and trust--with guaranteed performance specifications."

Excerpted from 1962 Heathkit catalog '

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Thanks for the explanation.

I've run a large power amp with a 1khz input signal, measured the voltage at the output and yes, the output power was less than its rated output. When I drove it harder, it tripped the main circuit breaker (at the panel).

I have a Bryston 3B power amp for my home system, it is rated at about

150watts/channel. It has a massive dual power supply, it is an older model (not torrodial transformer type), has quite the DC filtering as well.

This amp is under-rated, for the 150 watts it produces, it will blow away any integrated amp in "fidelity". The low frequencies are well defined, and sounds "thick". It is a Bi-Polar design. Bryston is a Canadian made amplifier, 20 year warranty, just a power switch and gain control via screwdriver (on the late 80's 4B).

how can this

channels

consumption is

The same way that a 120V 15A outlet can power a "5 horsepower" air compressor.

-- Steve

well, really, in Canada, an electrical item must be de-rated for use (unless it is hard wired). Meaning, an 1800 Watt wall outlet (15A/120V) can only supply a 1500 W device.

So, 1500 W only gives you 2 hp at 120V.

They write 5HP peak. ?!?! hehehe, yeah, what ev.....

I had a professional table saw that had a GE 1HP induction motor, when that thing powered up, it would draw much more than 12 A, for one HP!! Cuz its a real motor.

I have a Devilbiss air compressor, it is a 5hp 120V model, ?!?! oh well, its really only 2 hp I guess (1hp=746W)

-- Myron Samila Toronto, ON Canada Samila Racing http://204.101.251.229/myronx19