One of my many side interests is in chasing this stuff. If you want a
scare, walk around your home with an AM portable tuned to a weak station.
My latest find: "Dimmer" noise that was traced to the Microwave fan-speed
switch...was heard 30 feet from the house.

Clearly this fan-speed is a solid-state control, and just as clearly the
noise is far outside the FCC's limits for this kind of gear. But the FCC
doesn't ride herd on this stuff...except in egregious (or well-publicized)
situations.


Mark Durenberger, CPBE


-----Original Message-----
From: Tom Fine
Sent: Thursday, June 19, 2014 11:49 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Upgrading Audio Systems

If there is dimmer hash in a home system, shouldn't the power transformer
eliminate the problem by
only passing low frequencies (60hz)? If not, I'm sure someone makes a
non-ridicu-priced isolation
transformer with a band-pass. I don't have any dimmers or anything else that
rides on the power
lines in my house. However, the place is full of RF from wifi, cellphones,
radio and TV, etc. Never
had any problems with RF or hash. Regarding dimmers, if you like listening
to music, consider
whether you really need dimmers. I view them as a useless cheezy fashion
trend from the 70s. Just
use the lightbulbs you need to do the job. Granted, it's harder in the age
of non-incandescent
lights, but it's possible.

-- Tom Fine

----- Original Message -----
From: "Paul Stamler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 19, 2014 1:20 PM
Subject: Re: [ARSCLIST] Upgrading Audio Systems


> On 6/19/2014 9:19 AM, Tom Fine wrote:
>> Bottom line, a modern audio system shouldn't need a crazy dedicated
>> power plant unless there are regular fluctuations in power line
>> frequency and regular spikes and dips in voltage. I'm not
>> underestimating the incompetence of power companies, these situations
>> are definitely possible. It's also possible to have insurmountable hash,
>> for instance in a space shared with an industrial welding company. But
>> it's not a common problem.
>
> There's also television; I had to clean up some gear for a club that was
> half a mile from a powerful UHF station. In homes, there's also garbage
> from SCR light dimmers, which have become ubiquitous.
>
> Then there's the internally generated RFI from diodes in the gear's power
> supply; careful choice of diodes, use of snubbers and bypassing can
> mitigate that.
>
> Peace,
> Paul
>
>