On Sunday, November 13, 2011 11:11:06 PM Florian Paul Schmidt did opine:
> On 11/14/2011 05:01 AM, gene heskett wrote:
I almost didn't send that, but the sound reminded me of the sound I
inherited when I became the CE at WDTV-5, back in '84, here in West
Virginia. That put me off so much I told the GM I hadn't heard so much
heavy breathing since shortly after lights out last night, when I asked for
permission to replace a brand new piece of gear with something I knew would
do the job and be essentially transparent to the listeners, an old CBS Labs
AudiMax, followed by, on the other end of the studio-transmitter microwave
path, an equally ancient CBS Labs FM Volumax. They worked, but it was
extremely rare and took a trained ear, to detect that they were working.
As a C.E.T., I had fun keeping them running, first replacing all the small
electrolytics used for coupling capacitors with paper/mylar, which put a
stop to the twice annual rebuild by shotgunning all the caps, then
eventually the gain controlling tetrode nuvistor vacuum tube faded away
(they are made of pure unobtainium now) and I had to adapt a dual gate
Mosfet transistor to handle that. But those 2 processors made it to about
50 years old by the time we switched to all digital in mid 2008.
Now I'm going to wander off topic, sort of.
Frankly, broadcasters sorely need such a characteristic device in the
digital path right now, and if some enterprising coder were to write that
code to interface with the usual EIA digital audio format, and build it
into a black box with the usual connectors on it, he/she would find
themselves busier than that famous cat on the equally famous tin roof until
they had filled up the market, which is, here in the states, 1500 to 2000
tv stations. Multiply that by the number of channels the digital
broadcaster is using today, which for us is 4, and you'll have to hire help
building them for 2 or 3 years.
I don't know if there is all that much info out on the net on how the
Audimax worked, but surely any patents have long since expired. In the
maintenance manual there was a rather complex test method to determine if
it was working correctly, but its only controls were input and output gain
T-pads so one could establish the correct internal levels for optimum
The Volumax is much easier to explain as it was designed to prevent HF over
modulation only, caused by the 17db of pre-emphasis the 75 microsecond
boost caused, allowing full mid-range levels, but rolling off the high end
to prevent the HF stuff from exceeding the allowed occupied bandwidth,
+-75khz for FM's and +-25khz for tv. Its gain control response was sub
millisecond, both ways. But in digital, no such control is needed, but we
surely, sorely need the equ of the Audimax.
In fact, that is one of the reasons I have remained subscribed to this
list. If somebody does this, I will be in the GM's office asking for a
P.O. for 4 of them tomorrow morning. So please somebody do it before I
fall over. Now 77 YO & diabetic, retired (insert laugh track here, they
never really let you) for 9 years, I still appear to have that sort of
clout on the 2nd floor.
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page:
Everyone has a purpose in life. Perhaps yours is watching television.
- David Letterman
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