Heath Hi-Fi Question

[Harvey A. Kader]

Ed Goss wrote:

> Hello,
>      Although I recently sold some old Heath hi-fi equipment, I
> haven't been much involved in that aspect of Heathkits; most of my
> time is spent on ham gear.  But I did become curious as to the
> great demand for old Heath amps, like the W4-AM Williamson
> amp, for example.  It's only rated at 20 watts.  Many speaker
> systems today appear to need much more power to drive them
> properly.  And there seem to be many high-powered amps available
> today for reasonable prices.
>      So my question is this: What makes the old Heath amps so
> desireable?  I assume people use the amps and don't just buy
> them to sit on a shelf.  Is there something unique to the sound that
> a modern 150 watt/4-way speaker system can't equal?
>      Thanks for the comments.
> --Ed--
>

Ed, vacuum tube Hi-Fi is a speciality of mine. Let me answer your question.
Alot of Heathkit gear was vacuum tube design, like the W4 amplifiers. What
people call "volume" is actually sound pressure level(SPL). Sound waves are
movement of air. Hence air pressure level = sound pressure level. Sound can
be measured in decibels(dB).

The "volume" that a speaker produces is rated by it's sensitivity(dB/watt).
Speaker size has NOTHING to do with volume. Volume is simply determined by
sensitivity, and amplifier rating(watts). Forget about peak amplifier
ratings - they only apply to peak signals which only last a fraction of a
second.

Modern speakers have higher sensitivity than older speakers. So for a one
watt amplifier signal, a modern speaker can produce more SPL than an older
speaker.

What is great about vacuum tube amplifiers is that for a given wattage they
"sound" louder than their solid state counterpart. Most vacuum tube
amplifiers can easily fill a room to ear splitting volume with only 35 watts
per channel. And that is only at half way on the volume control. The same
volume need 70 watts per channel from a solid state amp. That is because of
the way a vacuum tube amplifier clips at peaks compared to solid state. It
does this gradually - not suddenly. Plus, vacuum tube amps have third order
harmonic distortion(soft) compared to the second order harmonics of solid
state(harsh). Room filling volume can be obtained with single-ended(SE)
vavuum tube designs of only 4 watts! But, one needs sensitive speakers(at
least 91 dB/watt). So, vacuum tube amps with modern speakers sound even
louder than that with more ancient speakers.

Forget about solid state audio - go for vacuum tubes! I have interesting
articles to read about vacuum tubes on my web site :

http://www.angelfire.com/on/vacuumtubes

and on TNT-Audio :

http://www.tnt-audio.com

Once you have heard vacuum tube Hi-Fi you will never listen to solid state
again. The BEST buys in vacuum tube audio are Dynaco, Heathkit, Marantz, and
Fisher. Harvey.

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