NE5534 Microphone Preamplifier and Vibration Reducer
by rkovac12 in Circuits > Audio
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NE5534 Microphone Preamplifier and Vibration Reducer
I bought a Neewer CM14 microphone for my Nikon Z6 but encountered two problems:
1) The preamplifier of the Z6 is horrible and this microphone's output level is pretty low (Its just a cardioid electret capsule, basically)
2) The (big quotes) "anti vibration" mount of the CM14 is a joke
So there are two problems to solve: the microphone needs a preamplifier with an (ideally) adjustable gain and an antivibration mount. Technically, you dont need this exact microphone as its really just an electret capsule connected to a 3.5mm audio jack. You could make a similar-shaped holder for a ~10mm electret capsule ...
Supplies
A 3D Printer
Means and skills to (make) and assemble a PCB
The Printed Files
For the STL files visit this link:
You will need to print 4 parts:
1) bottom of the box
2) top of the box - you can choose from variants with a hole for a potentiometer or without it
3) the "holder"
4) the middle ring which holds the microphone
The Electronics
For schematics and PCB design visit this link:
For the electronics part you will need:
1) To make and assemble the circuit board in the project linked - its a fairly easy one, no special components or skills required. You can order the PCB pre-made, use the toner transfer method or, like me, go full freestyle with a sharpie. Dont forget to read the instructions in the EasyEda project and most importantly - use your brain when making it ! This way you will avoid simple and illogical mistakes.
2) Buy additional parts: A boost (step-up) converter like the MT3608 from here, a LiPo charging board with a USB C connector like the TP4056 from here, a 220k potentiometer and a flat rocker switch (the opening on the box is 19x5.5mm)
3) A LiPo/LiIon cell with approx. dimensions of 30x45x5mm
3) Two right angle 3.5mm jack plugs or just gut an audio cable with appropriate plugs
I added a handy schematic to aid you in connecting everything. I highly recommend using the potentiometer and an LDO regulator - being able to fine tune gain is usefull and the LDO aids cleaning up any noise produced by the boost converter. Remember, any noise on the power line will be heard in the recordings.
Step 3: the Final Assembly
First put together the holder and microphone ring. For the microphone to fit you might need to sand the internals of the microphone tube or to scale it up in your slicer before printing. Use thick rubber bands - you want to keep the microphone centered. We will be reusing the hotshoe adapter from the original CM14 mount.
The box should should slide into the holder (with force), no need for glue.
Now you should have a microphone without handling vibrations and with a low-noise, adjustable preamplifier. Turns out the cartridge of the CM14 is actually pretty good !
If enough people will be interested, i will make a 3D model of the hotshoe adapter and microphone body - for those who dont have the CM-14.