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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