Home Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

RE: rolled off at 3800Hz

My apologies-- I should be more clear.

The problem with highs in a room is how
to get the H.F. energy to propagate well--
that is-- involve the whole room with enough
energy to drive that room....

I understand what you're talking about when
you refer to tones. In that we can and do hear
the different tones.

The problem arises when one tries to involve
a whole room. Small-surface transducers can
get the tone and bandwidth right, and at near
field, one can hear the tonal differences, but
these small-area transducers do not have the
power and dynamics to drive the whole room with
those tones.

One of the amps that I had that rolled-off so
severely was the Western Electric Model 91A.
With the right transducers, you could not want
any more high-end energy. A cymbal clash, for
instance, was complete despite the amp's limitations.

This only happens right when the correct Western
Electric transducers are used with their amp. It can
be stunningly good, and very accurate across a wide
bandwidth-- most all of human hearing.

Without those transducers, you'll not get the energy
that W.E. intended to put into a theatre audience.

With the recent S.E. amp revolution (started by Japanese
Western Electric Theatre component collectors), Japanese
collectors began resurrecting what Americans had forgotten
existed: movie-theatre sound. The Japanese wanted this
even in their tiny apartments!

Today, we're mostly trying to get the whole human hearing
range measured accurately inside components without any regard
for the room or the listener. Theatre people had to involve
the audience or sell fewer tickets. Japanese collectors,
tired of their own "perfect" measured equipment, snapped
up old American and German transducers, amplifiers and tubes.

Some even went so far as to use old Sprague electrolytic
capacitors, and Allen-Bradley Carbon-composition resistors--
things that add distortion to music. If the Americans did
it, then collect it and use it to sell equipment using it
back to them-- and be able to pay for collecting the "good
stuff", old theatre gear.

When a frequency rolloff involves hearing only tone, it is
immediately obvious. When H.F. CONTENT (should I say CUBIC
FEET of air affected by "highs"), is discussed, perhaps it
could be better understood that mild frequency rolloff is
not a factor, or it is ridiculously easy to correct if it is--
in the listening room..

Many people think that there's too much "highs" in a room
when the air volume affected by higher frequencies reaches
a certain upper limit. This is also true at the low end,
but it displays differently.

Amplifiers and transducers are at their best when they,
together, can drive a room completely acoustically. Good
equipment can deliver the entire human hearing range as
long as it has the speed and dynamics to get it done.

This can be done with amps that measure linear across
20HZ to 20KHZ. It can also be delivered accurately by
amps that are down at 80HZ, and put out almost nothing at
12 KHZ. What happens depends on the room and the trans-
ducers that are used in that room.

I realize that all this talk doesn't relate very much
to what we are told and sold today. Bandwidth and linearity
are cheap, accurate room coverage is costly, and involves
very few audiophiles.

It is possible, however, to experience the delights of
a good movie theatre system in the home. If you do use
large-area transducers, you will require that either the
amplifiers or the source components are going to have to
be rolled-off. Otherwise, people will tell you that
horn-loaded transducers are "yelling" at them.

What is more true-to-life? A tiny H.F. transducer being
driven beyond 22KHZ desperately stressing, straining, and
being driven way too loud in order to get some "highs"
into a room--

OR-- would you maybe prefer a nice theatre transducer
being driven to only 11.5KHZ-- or less than that--
smoothly and effortlessly, with terrific dynamics
delivering all the "highs" that one could possibly hope
for, stand or ever want?

Doing music reproduction effortlessly, dynamically,
and in a non-fatiguing way demands theatre-style gear.

It's the province of amplifier rolloffs, mini-watts
and large-area transducers.

Human hearing bandwidth is easily accommodated with energy
to spare. You don't need super wide bandwidth, or
extra claims to linearity.

What you DO need is to engage the
listening room fully.

Most source material and amplifiers are long on bandwidth
and tone. What they're short on is true-to-life dynamics,
perfect event-timing, and a sense of presence-- total room
coverage that converts the listening room as much as possible
into the recorded venue.

Large panels, theatre speakers, etc., are
designed to get this job done. What audiophiles
call "near-field" listening calls attention to
tone over much more important dynamic contrasts
in music.

There always will be different personal tastes
on how to reproduce music. Fortunately, most
people can recognize a good thing when they hear it.


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  Kimber Kable  

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