FW: [TenTec] Ten-Tec External Speaker

[Bill Ames]

I asked a frien of mine (non ham) who has experience in speaker and
enclosure design what he thought of my opinion and K4TAX's thoughts. I
thought the group might be interested. See below.

Bill Ames
KB1LG
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>From Mark Weiss:

They're both correct, but in different contexts.

K4TAX (he must really be popular around 4/15) is correct from a
communications standpoint. His discussion of filtering noise when listening
to communication radio has merit because such systems deal with non-hi-fi
audio. The point is to represent the range of frequencies containing the
most intelligence (ie., the range in which we best discern phoenems and
consonant sounds); there is no need to amplify hiss and static and hum and
thumps.

OTOH, in a different context, KB1LG makes a point that is valid with hi-fi
speakers built in the 1950s and '60s--that efficiency was mutually exclusive
to quality. In the early days of speaker design, little was known about the
interaction between magnet flux density and frequency response. There is an
optimum match between flux density and moving mass of the diaphragm. Too
much flux results in excessive electrical Q; the result is a peaky midrange.

Newer designs strike a better balance between these parameters to achieve
high efficiencies while retaining smoother response. Innovative magnet/pole
piece gap designs, intended to increase the depth of the magnetic field
across a greater in/out range along the gap have resulted in vast
improvements in quality, while increasing efficiency and reducing
compression losses due to the voice coil moving outside of the optimum
magnetic field.


Take care,

Mark & Mary Ann Weiss
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