[Vintage-Audio] Re IHF Power Rating System

[Duane Fischer, W8DBF]

Hello All,

I remember the IHF, (Institute of High Fidelity), power output rating system 
from the late sixties. Can someone tell me why it was created?

I remember the "Peak Power" rating and how cleverly deceptive it was. I 
think the IHF rating was supposed tocorrect this. Right or not?

Then sometime in the middle to late seventies, somebody came out with the 
RMS rating system to replace, or augment, the IHF system. What basis was 
used to determine the accuracy of IHF Vs RMS? Or what was the reason for the 
switch to rating power output by RMS, (Root Mean Square) to begin with?

In fact, perhaps one of you wizards of electronics can explain how the RMS 
equation works.

Thanks!


Duane Fischer, W8DBF/WPE8CXO
dfischer at usol.com
HHI: Halligan's Hallicrafters International
http://www.w9wze.net
HHRP: Historic Halligan Radio Project
hhrp.w9wze.net