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Calculate maximum cable length with given Impedance
Old 1 week ago
  #1
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Calculate maximum cable length with given Impedance

So I am talking only about low impedance mics.

Given that the Audio interface input impedance is 7x -10x the mics output impedance.

So if a mic has a 100Ohms output impedance rating, what is the maximum recommended(without hurting performance) cable length before any issues ?

I dont need answer for a mic with 100ohms, but a formula that will help me calculate the maximum cable length of any mic with its given output impedance.

*Also how it depends on cable resistance*

So that i can find the max cable length difference between two mics which have negligible (output)impedance difference (110ohms, 115ohms).

Please help, thanks in adv.
Old 1 week ago
  #2
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no one?
Old 1 week ago
  #3
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maximum mic cable lengths
This comes right up in a search.
Old 1 week ago
  #4
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i actually want a formula, that thread answers about 200ohm mic, doesnt teach how to calculate cable length mathematically based on microphone impedance.
Old 1 week ago
  #5
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Gotcha.
I'd guess the result -or answers, would be in a range of amounts -at different frequencies perhaps at various lengths?
Old 1 week ago
  #6
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Quote:
Originally Posted by jonny999 View Post
...
So if a mic has a 100Ohms output impedance rating, what is the maximum recommended(without hurting performance) cable length before any issues ?
....
*Also how it depends on cable resistance*
...
First of all, I am very happy when people are seeking quantitative answers to things related to audio. There are two major segments to a proper answer. I'll outline them before I have to go, and come back later as people chime in on the topic.

The two segments are level loss and high-frequency loss. Your question is primarily about level loss, so I'll jump on that factor.

The "issues" related to level loss in cabling has to have some kind of boundary that we care about. Let's use 1dB. For the purposes of signal loss, you can look at the cable as a resistor (R1) in series with the resistance (input impedance, ignoring frequency factors) of the preamp (R2) input.

A 1dB loss is created when the R1 is 12-percent of R2. For a 1000-ohm input impedance that's 120 ohms. If the cable is made of 24-gauge wire, then it'll take about 4700-feet of wire, about 1.4 kilometers to create the necessary 120 ohm resistance.

Ooops...gotta go...will append more later.
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