Jim, audio equipment meets its challenge with the immunity requirements
that Europe places on it. Analog circuitry is highly susceptible to
external fields! Design to withstand the EU standards is no simple task.
In addition, even the analog portions of the audio designs of today employ
actives devices that, by themselves, could operate happily into the VHF and
low UHF region (especially your low noise input stages). And consider the
digital portions of the audio designs of today. Audio is no longer 'second
class' to the rest of the electronic 'stuff' my generation helped lay the
ground work for. These days, audio must play the same game as the rest of
our electronic widgets with regard to RFI/EMC.
Dave - WØLEV
EMC Design & Test, LLC
On Mon, Jun 3, 2019 at 9:28 PM Jim Brown <jim@audiosystemsgroup.com> wrote:
> On 6/3/2019 1:58 PM, David Eckhardt wrote:
> > Really glad to see these concepts taking traction, even if they are
> > just limited to our small group, here.
> >
> As an EE working in pro audio, I found that I needed to join the EMC WG
> of the Audio Engineering Society about 20 years ago, in self defense
> from some fools in G-land who didn't understand the needs of audio
> systems to pay attention from near DC to UHF. I learned a LOT from the
> many fine engineers with strong backgrounds in both audio and RF -- from
> companies as diverse as ABC-TV, BBC, multiple microphone companies,
> equipment manufacturers, and designers of everything from recording and
> broadcast studios to sound systems for churches, stadiums, theaters, and
> performing arts centers. My specialty was those sound systems. I also
> learned a lot of very practical EMC practices from Henry Ott in one of
> his 3-day seminars c.a. 2005.
>
> Nearly everything I recently posted I learned in those days, and I've
> been preaching since getting back into ham radio about 15 years ago.
> I've found most RF engineers and practitioners look down on audio
> because of the very low frequencies involved, but pro audio and ham
> radio have at least two VERY important parameter in common: First, the
> extremely wide range of signal levels involved and the need for work
> very close to noise (in audio, it's the very low level outputs of
> microphones picking up quiet sources in quiet spaces), and the very wide
> range of wavelengths that matter.
>
> Audio extends over two decades of frequency, and transducers must
> provide very uniform response over that range over relatively wide
> vertical and horizontal angles. Transducer design, and the use of those
> transducers in practical systems is several orders of magnitude more
> complex than for antenna systems! We're thrilled if a high performance
> antenna covers a few percent frequency range!
>
> A lot of my teaching/preaching can be found at k9yc.com, and some of it
> is in the ARRL Handbook and Antenna Book.
>
> 73, Jim K9YC
>
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--
*Dave - WØLEV*
*Just Let Darwin Work*
*Just Think*
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