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Re: Mic attenuation on purpose (was Min mV/Pa 4 MD..

Subject: Re: Mic attenuation on purpose (was Min mV/Pa 4 MD..
From: Rob Danielson <>
Date: Sat, 3 Sep 2005 13:02:56 -0500
Hi Mike-- Thanks for your thoughts. Methinks this is getting too
technical for the list. Let me know, off list, if its okay for me to
follow-up, off list. Rob D. <>

  =3D =3D =3D

At 12:33 PM -0500 9/3/05, Mike Feldman wrote:
>Rob Danielson wrote:
>
>>... I'm looking into the
>>  nature of small circuit built into the unbalanced, 3.5mm cable that
>>  Rode provides with the NT-4. I've by-passed the circuit in my NT-4
>>  cable and mic output jumped up 12dB-- the same dB drop in output (and
>>  increase in noise)...
>>  I'm waiting to recommend the simple cable modification until I can
>>  figure out if there are bad consequences I've not grasped. Here's
>>  what I think** the circuit is should anyone have ideas:
>>  http://www.uwm.edu/~type/Mic%20Preamps/NT-4ConnectorCircuit&ModSm.jpg
>
>If I'm reading your drawing correctly, you're shorting the series
>resistor of the pad, but not opening the parallel resistor.  So there
>would still be some attenuation dependent on the input impedance of
>the sink.
>
>>  **umashankar mantravadi, who is on this list, has commented on the
>>  micbuilders list that my circuit drawing looks more like line to mic
>>  pad, which, I assume, would have much greater attentuation than
>>  -12dB. Maybe the four tiny components on the pcb are not simple 10K
>>  resistors, as labeled and measured? I dunno. I think I have the basic
>>  circuit structure right though. Rob D.
>
>Sure looks like an L-pad.  You mentioned earlier they're labeled EDI
>on the pcb ... "Electrostatic Discharge" current limiter perhaps?

--


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