On 2/27/2013 10:10 AM, Richards wrote:
There is no need to get crude or angry over this.
Who's crude or angry? The late Paul Klipsch, a very bright guy and
Fellow of the Audio Engineering Society, was known for standing up near
the back of the hall at certain technical presentations where he felt it
appropriate, and opening his outer shirt to reveal a Tee shirt
emblazoned with the word :BULLSHIT in large letters. He was much
appreciated for his comments.
What is needed for good speech quality is nothing more or
less than a loudspeaker with flat response AND uniform coverage in the
speech range.
Funny... that is just what the author was
saying. And he suggested a center channel
speaker as exactly that sort of thing.
So is ANY GOOD loudspeaker.
Otherwise, you have been outvoted by an entire
industry - which sells center channel speakers
expressly on the premise they enhance speech
and dialog intelligibility. And outvoted by legions
of movie fans who buy them for that very reason.
Not at all. When film sound is mixed, ALL dialogue is placed in the
center, while music and effects are mixed to left, right, surrounds, and
the sub-woofer. Cinema sound has been done this way for much of the last
half of the 20th century, and the various forms of distribution and
encoding for home playback are based on this.
The function of a center channel loudspeaker is to provide a hard center
channel image, AND to maximize speech intelligibility. The center
channel maximizes intelligibility NOT because of the type of loudspeaker
used, but because it is a SINGLE loudspeaker. Indeed, all three front
channel loudspeakers should have flat response with good dispersion
(that is, uniform coverage over the listening area)...
Exactly what WE are saying ! Apparently you
agree with us, after all. You have just described
what we mean by a "speaker tailored for speech."
I've done far more than that. I've observed that the requirements of
good speech intelligibility are the same as for good music reproduction.
Now, it so happens that Optimus is the "house brand" that Rat Shack used
in the 70s and 80s. They didn't make anything themselves,
Nobody does.... it all comes from some
outfit in China. Besides that is hardly
relevant or probative of any point under
discussion here.
While that is probably true for most vendors TODAY, it has not always
been thus.
You have missed the point entirely.
We are only saying that a small, flat sounding
speaker that does not have a lot of bass or treble
is one that is "tailored for speech" --
A good loudspeaker reproduces what is fed to it. This may come as a
shock to you, but the frequency response numbers typically quoted in
catalogs for ham and consumer products are meaningless because they
include no anplitude tolerances on the response, nor do they provide any
description of angular coverage, nor distortion, nor efficiency.
Modern loudspeakers designed for home use rarely have much useful output
below 100 Hz, but most have response to 10 kHz or more. 100 Hz is more
than enough for speech, and good response to 10 kHz benefits speech
intelligibility if the content is there. When a loudspeaker is used
with a ham rig, the response is limited by (and for the most part,
DICTATED by) the response of the transmitter, including the mic, the
transmit filter, the receive filter, and the output stage. Unless
something is broken in that system, there's rarely much content outside
the range of 100 Hz to 3 kHz.
.
FACT -- not all speakers are well "suited for
speech" intelligibility -- which is why you
specified "small" as a design criterion.
I added "small" to the description only because it needs to fit in a ham
shack without burning a lot of space.
FACT -- there are loads of flat response speakers
that are not well suited for speech applications.
Older, JBL studio monitor speakers with 15 inch
woofers just do not sound as clear as, for example,
the 5 inch Avantone MixCube speaker - or similar
size center channel speakers.
That's because some of those older JBL studio monitors have design
problems!
By specifying "decent small, accurate loudspeaker
that sounds the same over a fairly wide angle"
YOU HAVE IDENTIFIED EXACTLY WHAT IS
RIGHT ABOUT THE CENTER CHANNEL SPEAKER
AND WHAT MAKES IT WELL SUITED FOR VOICE
APPLICATIONS.
No, I've described a perfectly ordinary ideal loudspeaker. What you're
missing is that the same characteristics that make a loudspeaker good
for music also make it good for speech.
FACT -- not everybody agrees what sounds
good. Not all speakers with a flat
response will suffice or please everyone.
More technical parameters are needed (and used) to describe loudspeakers
than you (and most of the high futility community) are aware of. A study
of the work of the late Richard Heyser is highly instructive.
How "flat" response is measured matters a lot. Is it measured ONLY
on-axis, or is it measured at multiple points over a wide angle, or is
it integrated over a full 360 degree sphere? What is the TIME response?
If there are multiple drivers, what is the alignment between them? What
is the crossover, and what are its characteristics? These are some
common problems with loudspeakers, including some JBL studio monitors.
Perhaps the ones you didn't like (and that I probably don't like
either). BTW -- I'm a member of two AES Standards Committee Working
Groups on Loudspeakers. These working groups include most of engineers
who design professional loudspeakers, and many other leading engineers
who APPLY those loudspeakers.
FWIW -- I suspect you would consider me a presumptuous fool if I argued
with an attorney about the law.
73, Jim K9YC
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