Without going into technical details of when and why increasing the
output gain of a mic might be useful,.. these tips:
1) Older Rode NT-4's may not have the -12dB* attenuation pcb "pad"
built into the 3.5mm cable that Rode supplies. Newer models do. [If
you want, email me, off list, as to whether your NT4 does or doesn't
have the PCB with the serial #. Its in the battery case].
Here's what the small PCB (printed circuit board) looks like with the
jumper wires part of the mod already complete:
http://www.uwm.edu/~type/Mic%20Preamps/NT4_cable_PCB_Mod_CU_07.jpg
The tiny black rectangles are the resistors. There are a two on each channe=
l.
2) You can remove the PCB board completely and re-solder the wires
directly onto the XLR5F connector (keep track of the wires/contacts
of course) -or-
3) You can leave the PCB in place and
(a) heat and remove the two resistors in the corners nearest to the
3.5 mm end of the mic cable (b) solder two jumper wires over the two
10K resistors on the left and right channels. I soldered right onto
the #2 and #4 connectors.
Here's the diagram of the PCB in-place modification:
http://www.uwm.edu/~type/Mic%20Preamps/NT-4ConnectorCircuit&ModSm.jpg
We're doing the modification on 30 units and putting them into the
hands of students if you're wondering how "dangerous" I think it is.
But, its your gear! Those with mics under warranty might want to
wait.
Again, thanks to Allan Haighton and folks on this and the micbulders
list for helping solve the NT-4 riddle. Rob D.
*If plan to do the modification and can measure output carefully,
consider a before and after test and let us know what you get. I
checked it quickly without a sine tone and forged without a careful
control measurement.
=3D =3D =3D =3D =3D
At 11:38 AM -0700 9/3/05, <> wrote:
>From: "Rob Danielson" <>
>Subject: Re: [Nature Recordists] Mic attenuation on purpose (was Min mV/Pa=
4
>MD..
>> 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) that I was trying to account for in the tests a
>> few months back. I was wondering what the circuit is and why it would
>> be there if not to protect the mic pre circuit. Maybe its a music
>> recording assumption? If so, its not very compatible with recording
>> in quiet places or even moderately noisy situations.
>
>As drawn, the circuit would supply only 6 dB of attenuation, but it's safe
>to assume that most consumer devices load down the attenuator further and
>account for the 12 dB that you observed. But of course that will vary fro=
m
>recorder to recorder.
>
>I think that your analysis that it is a "music recording assumption" is sp=
ot
>on. Most portable devices, which are the ones that would use the 3.5 mm
>mini phone input, can only take a few hundred mV at most, even with the ga=
in
>turned all the way down. Folks who record in loud venues would find the
>microphone putting out more than that.
>
>Are you interested in trying to sus out the entire NT-4 circuit? I'll hel=
p.
>I just can't see it!
>
>Eric
>
>
>------
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
[Non-text portions of this message have been removed]
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