Re: [Phys-l] decibels

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2011, Aug 29, , at 05:25, chuck britton wrote:

> Check out vacuum cleaners and you will find that the advertised 
> wattage (horsepower) will invariably exceed the volts x amps. Same 
> with audio amplifiers. (Consumer specs - the Pro's won't put up with 
> such cr*p)


The V X A is average.  The power amps. w/ which I'm familar have large caps.  This stored powr. enables the amp. to deliver more than the average for short times.    


Suction cleaners?  No idea. So I measured our small one: (Kill a watt)

PF always ~ 0.97
suction only 1035 W (not VxA) inlet blocked 910W
brush and suction on 1070W
do + brush partially blocked 1120W   (folded craft paper pushed against brush) -- much grater load than rug resistance.  (1080W)

Claim:  12 Amps cleaning power -- even w/ brush resistance omly ~ 9.8A

Note: values are estimated average.

> http://en.wikipedia.org/wiki/Line_level
>
> Here's a bit more on dB's in the audio world - specifically the 
> mismatch between 'Professional' and 'Consumer' reference levels.


I don't understand the complaint;  just different stds.

bc