Telamon wrote:

I keep reading these posts about using headphones or speakers that limit
the frequency response. I think that is a poor strategy. Get a high
fidelity speakers and headphones and use the radio tone controls and
filters to limit the response when conditions create noisy signal
reception. When reception is good you get the fullest bandwidth possible
for the best sound. That's what I do to enjoy program listening, which
comprises most of my listening.



For the most part, you're correct: shaping the audio at the receiver
is the more versatile solution. But consider that the audio stages of
most comm receivers tend to have a higher noise floor, and higher
distortion than a hi-fi music listening system for which the wideband
headphones were created. Wideband headphones will exacerbate not only
the distortion components of the audio, but the noise as well. And it's
the noise, more than the distortion, that will just flat wear you out
with long term use. To the degree that, as the mind adapts to the
listening conditions, you'll actually experience subtle, but important,
shifts to your natural hearing sensitivities. Eventually, with
sufficient exposure, you could begin to lose some sensitivity at
specific frequency ranges. This noise is generally not variable with
volume, but, being a component level product of the electronics, is more
or less a constant. Shaped headphone response reduces it's apparent
presence, and reduces tendencies to fatigue.

Consider also, that SW audio, itself, is frequency shaped, but
atmospheric and electronic noises are not. Even entertainment
programming is bandwidth limited. So, at best, wideband headphones or
speakers will accurately reproduce the noise, while but the program
audio will still be bandwidth limited. Often no more than 5khz bandwidth
is transmitted. And comm audio, itself, is of higher distortion than
wideband entertainment audio, and that distortion, with higher end
headphones will be far more irritating than with shaped response. ICOM
R71 audio is legendary for being horrid, despite the fact that the audio
stage amp is actually quite low in distortion. The bulk of the
distortions are generated in the mixer and detector stages, with
distortion components approaching 20%. Believe me when I tell you,
headphones don't make it any easier to listen to. JRC audio isn't much
better. And when listening to SW, also bear in mind that the audio is
distorted at the transmitter.

Frequency shaping at the receiver, in such cases can reduce, but not
eliminate, the offending distortion products, and highly detailed
headphones can permit these products to be heard anyway. And the
offending thermal noise is still there, which can now be easily
distinguished and work it's fatigue over the electronically shaped audio.

It's in cases like these that users often prefer to use a pair of
Trimm's or Brush Clevites for long term listening. As bad as they sound,
they eliminate the offending noises and distortions from the audio
reaching the ear canal. Granted, they do introduce distortions of their
own, but often these distortions are far less offensive than the noises
and distortions accurately reproduced through wideband headphones and
speakers.

Some broadcasters I know still prefer to use Trimms or Clevites when
working on the air. First, they match damn near anything, and you can
listen to phono cartridge output with them, so loading is less of an
issue. But the main idea is that the audio is less detailed, so they
don't hear the artifacts in the air monitor, but rather simply use the
phones as a reference to detect that they are, in fact, on the air, and
rely on their instincts and experience to fill in the details. They can
then concentrate on what they're doing, instead of listening to themselves.

What it comes down to, in the final analysis, is personal
preference. And in that, if what you're doing is working for you, then
there is no need to change. But if you notice ear fatigue after a period
of extended listening, it may be time to consider an alternative strategy.