[TowerTalk] Tower and antenna decisions

[Jim Brown]

On 10/26/2013 10:57 PM, Grant Saviers wrote:
> You're the audio expert, but didn't Bob Carver figure out some clever 
> variable supply voltage tricks with his big Sunfire amps?  I have two 
> and my "Signature" stereo is rated 2 to 16 ohms (1250w/ch 4 ohms) and 
> runs stone cold even when delivering big power.  No other amp I've 
> tried had the headroom needed for my B&W 801Fs to generate max 
> orchestral peaks at concert hall levels.
>
> So isn't what you are suggesting been done before in the audio domain?

For at least four decades, solid state audio power amps have been 
contstant voltage sources with VERY low output Z (typically 0.1 ohms or 
less) , so the voltage is constant with load Z, and power out increases 
as load Z decreases (P=I squared R, or E squared /R))

There are good reasons for this -- the low output Z of the amp damps 
mechanical oscillation in the loudspeaker to clean up the sound (so that 
the bass isn't "floppy." The "damping factor" is the ratio of the 
nominal loudspeaker Z to the amp output Z (plus the resistance of the 
loudspeaker cable) . The loudspeaker Z is a a very complex function, 
with a dip in the midrange of each driver, rises above that point due to 
inductnace of the equivalent circuit, and at low frequencies, encounters 
resonances with the physical structure of the loudspeaker driver and 
addition resonances of the loudspeaker enclosure. In other words, it 
ain't simple. :)   The nominal Z of a loudspeaker is the minimum value 
of Z in the midrange.

I am not familiar with Bob Carver's work, so cannot comment. Bob worked 
primarily in home systems, and I worked in pro systems.

73, Jim K9YC