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[Ivan Beaver]

The limiting factor in long distance line level runs is cable capacitance, which will start to create audible LPF. Every cable, and every input/output impedance combo will be different, so YMMV. I have started to hear audible effects at 1000ft before.


Sent from my iPhone using Tapatalk

And to add the question that should be asked about just about any audio question or spec  "At what freq".

What happens at 100Hz is often VERY different than what happens at 10KHz.

Because of the wide bandwidth of audio, people cannot use blanket statements to describe what is actually going on-although they like to and simply "want to believe".

A good example is pattern control of loudspeakers.

Most people believe that the rated pattern is the same at all freq the loudspeaker can reproduce.

This is FAR from reality.

And how the sound moves through the air is also very different.  With air absorption, above 4Khz is MUCH harder to get to a far distance than 200Hz is.

And it depends on humidity and other factors.

Simple numbers DO NOT describe complex events.

[Kevin Graf]

Jim Brown wrote this paper way back in 1988:

The Effects Of Cable On Signal Quality
By Jim Brown
Audio Systems Group, Inc. [email protected]

System designs often require output amplifier stages of microphones and line-level devices to drive long lengths of cable with its associated capacitance. Most equipment works well in this application, but some equipment will allow significant signal degradation. The simple fact that measurable problems exist calls for more consideration of these factors by manufacturers. Until that happens, systems designers must pay more attention to output circuit specifications and performance.

http://www.audiosystemsgroup.com/CableCapacitance.pdf

[Scott Holtzman]

And radio stations used to (still do?) run their signals to their transmitter or to other stations via phone lines.


Steve.

RT circuits were very popular for STL links (studio to transmitter).

These were tariff offerings where the performance characteristics of the circuit were described by Bellcore.

At each end of the circuit was a "pack", and it used what we call prescription equalization to  provide proper level and frequency response. 

That was one of my first engineering jobs, writing out the settings for 1200 to 9.6 data circuits, RT's and land mobile radio circuits. 

The test equipment was primitive Heikimien test sets that could end and receive tone.  You could also "loop up" and send other diagnostics with in band tones.

[ProSoundWeb Community]