jbell wrote:
> I wouldn't think the recorder would introduce noise.
The output circuit of any device is generally one of the main inputs for radio-frequency interference, if special measures aren't taken to prevent it. This is true for power amplifiers in hi-fi and public address systems, for example, as well as microphones.
The whole field of electronic design has had been forced to change fundamentally in response to the greatly increased levels of RF in recent years--also the increasing use of higher and higher frequency bands, and aggressive signaling methods that produce high annoyance factors when they leak in to an audio signal. There is no longer any such thing as a competent audio design engineer who only understands audio-frequency electronics; an understanding of radio-frequency electronic design is now absolutely necessary, just so that you can keep your device from accidentally being an RF detector / amplifier*. And a lot of equipment that was perfectly OK for many years is no longer OK in a growing set of operating environments.
* footnote added later: This reminds me of a recording session that I did about 20 years ago in a suburb of NYC. There was a "heterodyne"--a steady, single high-frequency tone--in the background of the signals from my microphones. I started rearranging my mike cables to find the arrangement with the lowest noise pickup, and then it occurred to me that as a ham radio operator, I knew a little about the design and construction of antennas, and that my goal now should be to apply that knowledge in reverse, to make the worst possible HF antenna with my cable configuration. So I systematically sabotaged everything about the arrangement that would make for a good antenna, and that did the trick.
And a P.S.: Neumann made two generations of extension accessories (cables, goosenecks, thin rigid tubes) for the KM 100 series, specifically because they were confronted with this issue. The first generation was "more modular" in that the cables terminated in Lemo plugs that allowed for extension cables; you would buy a single KA 100 adapter for each mike body, and plug the Lemo of the device (or the extension cable attached to the device) into it. The second generation was more RF-resistant because it did away with the Lemo connectors and the KA 100, so the shielding was continuous from end to end. The costs generally balanced out if you only wanted one type of extension for a given microphone, since that included the hard-wired amplifier adapter part while omitting the Lemo. But people who wanted more than one type of extension device available per microphone, or extendable extension devices, had to stick with the old series and take the higher risk of interference.
Topic: What is KCY? (Read 10500 times)