Nick Roast has forwarded a note from Rode regarding the role of the
12dB pad in the 1/8" miniplug cable:
>
>The resistors are in circuit to decrease the output level. This was done a=
s
>the output level was too high for some mini disc recorders. You have the
>reverse problem, therefore making a straight through cable will fix your l=
ow
>level.
>
>Kind regards
>Darren Rose
>Rode
I discovered a very quick way to do the mod yesterday when doing 18
cables. ( Again, the cable that came with older Rode NT-4's may not
have the attenuation pcb in the XLR-5 connector).
1) Heat and lift up the #2 (red) and #4 (clear*) wires that come from
the cable connected to 1/8" stereo plug.
2) Heat and pry-up one edge of all four tiny 10K ohm resistors. Once
hot, they'll pop off. Make sure all the resistors are cleanly
removed from the board.
3) There's enough slack in the red and clear leads from the cable to
reach to pin #2 (red) and pn #4 (clear) on the XLR-5 connector. This
eliminates the need for the jumper in the diagram I posted earlier:
http://www.uwm.edu/~type/Mic%20Preamps/NT-4ConnectorCircuit&ModSm.jpg
I'd suggest popping out all four resistors as it reduces chance of
shorting when the shield wires pulled up a little tighter.
*The clear lead is colored blue in this diagram.
Here's a shot of the first "jumper only mod" for reference. You can
see the rectangle resistors on the close side that need removing
http://www.uwm.edu/~type/Mic%20Preamps/NT4_cable_PCB_Mod_CU_07.jpg
So, it seems to be a safe mod and great for people who can use the
12dB gain. Thanks Nick!
Rob D.
=3D =3D =3D =3D
At 5:04 PM -0500 9/4/05, Rob Danielson wrote:
>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 chann=
el.
>
>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/P=
a 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 woul=
d
>>> 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 saf=
e
>>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 fr=
om
>>recorder to recorder.
>>
>>I think that your analysis that it is a "music recording assumption" is s=
pot
>>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 g=
ain
>>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 he=
lp.
>>I just can't see it!
>>
>>Eric
>>
>>
>>------
>
>
>--
>Rob Danielson
>Film Department
>University of Wisconsin-Milwaukee
>
>[Non-text portions of this message have been removed]
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
[Non-text portions of this message have been removed]
________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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