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Re: extension cables

Subject: Re: extension cables
From: "Dan Dugan" dandugan_1999
Date: Fri Jan 22, 2010 5:29 pm ((PST))
>> I have a hundred-foot 3.5 mm stereo extension that's .0075 uF from 
>> one channel to shield. Assuming a 2 Kohm source, it would be a 
>> gentle low-pass filter at about 10 KHz, if my slide rule technique 
>> is right.
>> -Dan Dugan
> Hi Dan--
> Its a pleasure to use a rule isn't it?

Actually, it's the 1957 cardboard Shure Reactance Slide Rule. I'm not an 
engineer, I just play one at work.

> Next time I install a long cable run, I'm going to record the test I 
> did where I connected two Rode NT2000's (7dB[A] self noise)-- one to 
> a 20' mic and the other to a 1000' role of cable and placed the mics 
> side by side. Prior to this, I looked at all the charts and did the 
> HF loss computations and then Richard Lee (miclist) suggested the 
> obvious perception test. Result: to my aging ears (significant loss 
> above 9-10Khz), I could not detect any loss of signal or HF.  I use 
> Symetrix SX202 Mic preamps.

An NT2000's output impedance is rated at 200 ohms, 1/10 or less than the 
impedance of a PIP electret. So it could handle ten times the cable length for 
the same amount of rolloff.


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