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Re: extension cables

Subject: Re: extension cables
From: "Robb Nichols" robb_nichols
Date: Fri Jan 22, 2010 9:12 am ((PST))
Mogomi Cable has a nice little utility on their website for plotting the 
frequency response of a mic cable.  You have to know the output 
impedance of the mic and the input impedance of the recorder, along with 
capacitance and resistance of the cable, but you may be able to 
reference all of these specifications easily.  Look here:

I would add to Phil's comments that noise typically isn't a big problem 
outdoors if you have a well-shielded cable.  But if you're leaving it 
out for a while, be aware that pesky critters like to chew on them.

Best regards, Robb

Philip Tyler wrote:
> Hi Vicki
> The short answer to your question is what ever length you can get away 
> with.
> An unbalanced cable is going to be prone to picking up all sorts of 
> electrical nasties and the longer the run the more nasties it is 
> liable to pick up if they are around. As with all things what you can 
> get away with when there is no other electrical equipment around is 
> going to be a lot longer than if there is nearby electrical equipment. 
> Although just moving a cable a little one way or the other can have an 
> effect on what it is picking up.
> Another thing to bear in mind is any cable acts like a capacitor which 
> for, shall we say 'normal' runs is not going to be a problem. But as 
> the length gets longer it can start to attenuate frequencies acting 
> like a low pass filter. This is dependant on the input impedance of 
> the unit your using but try and go for low capacitance cables if there 
> is a choice.
> So if you use good quality cable and if there is very little 
> electrical equipment causing interference then 100 feet (+) should be 
> OK, you may even be able to go longer.
> The other thing you could do is use something like a FEL 3.5 series 
> mic amp and put that at the far end with the Telinga and then run the 
> cable back to the LS-10. You would then have a +20dB signal now 
> running along the cable which will be less prone to problems.
> Have a look here:
> <>
> Phil
> ________________________________
> From: vickipowys < 
> <>>
> To:  
> <>
> Sent: Fri, 22 January, 2010 10:33:03
> Subject: [Nature Recordists] extension cables
> All,
> I have been happily using a Telinga 'LS-10' stereo mic with PIP (plug
> in power) connected to an Olympus LS-10 recorder, with a shielded
> extension cable measuring 7 metres.
> What I would like to know is what is the potential maximum length of
> cable I could use with such a set up? Fifty metres? Or less than that?
> I am well away from civilization and radio waves although I do have
> mains power connected to my house, and have found that I need to use
> shielded cable to prevent mains hum.
> The sort of cable I mean will have 3.5mm plugs and sockets. I have
> ordered some 2-core shielded cable, but while I await its delivery I
> am hoping someone might comment on cable length.
> Any suggestions?
> Vicki Powys
> Australia

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