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Old January 29th, 2009, 06:44 AM   #1
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Unbalanced extention cord - how long?

Dear all, tell me please: in practice/real world - how long unbalanced extention cord may I use with XL1 "on board " mic, without getting to much hum/noise? Making it 2-3m long would add a noticable degradation in sound quality?
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Old January 29th, 2009, 09:49 AM   #2
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Extending an unbalanced audio cable (for realistic lengths) doesn't so much degrade the audio signal (at 1000', you'll get degradation...) as it opens up the signal to RF interference. The "noisier" the RF environment you are working in with an unbalanced cable, the more noise is likely to present itself into your signal.
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Old January 29th, 2009, 05:02 PM   #3
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There are several factors that come into play with unbalanced cables and sytems; these include the cable properties, the impedance of the systems involved, your signal strength, and the environment.

If you are in an environment that is electrically noisy, it can couple into unbalanced cables, and the longer the cable the worse it gets. Noise comes from time varying electrical and magnetic fields; e.g., from power cables, discharge lighting, switches, motors, and near by radio transmitters just to to name a few sources. (Balanced system and cables tend to cancel this noise.)

Cable have capacitance that effectively shunts the signal, and the longer the cable the more capacitance. This tends to reduce high frequency sounds, especially in consumer-type circuits that usually use higher impedance. Balanced or unbalance in and of its self has no effect on this.

Higher impedance circuits will often be more susceptible to noise because because they allow the noise voltage to be higher in the circuit. This is because many sources of noise coupling are essentially weak signals. See the note above on high frequency loses.

And it takes less noise to interfere with a weak signals, such as a microphone output.

The typical recommendation is that unbalanced circuits, which tend to be consumer and higher impedance circuits, should be limited to around 20 feet. But in reality it depends on the combination of the above factors as well as your need, and you may find you can run much longer cables, or you may find you cannot get satisfactory results with shorter cables.

The XL1 microphone is unbalanced, but has a fairly low output impedance, so the primary issue will be electrical/magnetic noise pickup. In typical applications 20 feet is not a problem, but it depends on how electrically noisy the environment is.
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Old January 29th, 2009, 05:27 PM   #4
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Thank you guys! Especially Don, as always - we can count on you. What I am thinking to achieve is to get more flexibility by taking off the board the on-board XL1 mic (or use the tele/wide mic, that comes from broken L1 unit) and put it into parabolic dish. So Im gonna make an extention cord that would allow me tu step aside, just 10 feet woud be fairly enough for me. As I am an avid birder and naturalist and mostly I will be recording nature/birds voices in a wild and rural areas - I do not expect to much RF noise. Anyway, I wanted (and I am glad) to hear your opinions.

All the best
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Old March 4th, 2009, 05:43 PM   #5
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One more question at this thread:

http://www.dvinfo.net/conf/canon-xl1...-question.html
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