Re: Pristine: RVW's 1958 Symphony 9 première + Mitropoulos' "A London Symphony", NBC SO, 1945

"Always" is a very long time.

Actually, FM audio was not limited in upper frequencies until the
introduction of the Zenith/GE FM Stereo system in 1961. I have many
recordings made from FM in the 1950s, with frequency response
extending beyond 20 kHz.

Even when FM Stereo was introduced, the typical low pass filter in the
stereo generator was an analog filter with a hinge point at about 17
kHz, with sharp rolloff above that. Brick-wall filters were not cheap
to make in the analog days.

The Optimod is a popular audio processor used in many radio stations
around the world, designed by Bob Orban, who is based here in San
Francisco. I use dozens in my group of 50 radio stations. However,
Orban didn't invent the compressor/limiter. Such devices were in use
in the 1930s, even by the BBC, who designed their own.

There is a series of articles discussing the history of audio
processing (alas somewhat America-centric) beginning with:

http://www.thebdr.net/articles/audio/proc/proc-hist.pdf

Kevin Mostyn
(still in a career of more than 40 years in broadcast engineering)
___________

My real e-mail address is my first name at my last name dot com

On Mon, 5 Jul 2010 00:54:12 -0700 (PDT), frankwm
<frankwmartin@xxxxxxxxxxx> wrote:

<snip>

FM has always been 'bandwith limited' to max 15kHz; the later
Broadcasting House digital transmission chain didn't alter that
parameter...as you can't have the FM frequency-range reaching the
Pilot Tone (19kHz) itself - with it's associated sidebands (clearly
seen on my graph).

<snip>
.

Relevant Pages

  • Re: Amplitude response of a Biquad Filter
    ... Wrong implementation of filter coefficients???? ... But, when I use an ordinary audio file, I see the ... Sampling frequencies ranging from 8 kHz to 48 kHz (audio related ...
    (comp.dsp)
  • Re: Audio Sampling Question
    ... By which you mean ultrasonic frequencies (close to the Nyquist limit imposed by the ... If used strictly for audio frequencies, a front end filter truly isn't required. ... I didn't have that luxury. ...
    (sci.electronics.design)
  • Re: Michael Reichmann reasoning for AA filters?
    ... It causes ringing in the fourier domain (time in audio, space in imaging) not in the frequency domain. ... There is NO power at higher frequencies - that is the point of the stop filter. ... If you look at the fourier terms required to create a brick wall type filter, the even terms are positive, but the odd terms are negative. ...
    (rec.photo.digital)
  • Re: Festool power tools.
    ... "An audio CD can represent frequencies up to 22.05 kHz, ... for a filter), and indeed the reason for "oversampling". ...
    (rec.woodworking)
  • Re: Audio Sampling for Visualization
    ... I have developed a DShow filter that can do this. ... I have the Audio Samples, but I don't know ho to ... > prepare the structure for the Visualization DLLs. ... >> Provides a stereo snapshot of the frequency spectrum of the audio data at ...
    (microsoft.public.win32.programmer.directx.audio)