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DIY Microphone
01/01/2025 | Views: 4179 | Circuits | by: ELECTRONOOBS      


I made this high quality microphone for 20 dollars. But the commercial one costs 500 dollars? So how come? Well you see, both my homemade version and the 500 dollar microphone are using the same capsule which is like the heart of a microphone. And I was able to buy the same capsule that the 500 dollar microphone is using for only 13 dollars. So all I have to do is to add the rest so I’ve made a PCB for the amplifier, designed the shape of the microphone, passed the audio data to a USB connection and made myself a super high quality microphone for 20 bucks. Actually the quality is so good that is on the same standards as other mics that could cost you 20 times more. You have everything you need below in the description, and that being said, let’s get started.



Part 1 - What we need


Check below the capsule I will use for today, the JLI 2555 and is the same capsule used in this microphone that cost around 500 dollars. This will be later connected to the PCB I’ve ordered for the amplifier, since the audio signals from the capsule are very low, as you can see, just a few mV. Before we even start I have to mention this project was made by DIYperks and he made a super high quality video on this topic, so good that I had to try it myself as well. So please, check DIYperks channel for support.

For this project you will need, obviously, the microphone capsule, the preamplifier transistor and the amplifier PCB, an ADC or analog to digital converter molecule for audio and my 3D design together with some small components such as screws, elastic bands, ball screws, metal mesh, and the passive components for the amplifier. The full part list is below and the total price is around 20 dollars.


homemade high quality capsule microphone


Part 2 - 3D files


Now download and 3D print my design from below. The design has the main case, the outer ring and the small ring. In my case I want to paint them silver but that is up to you. So I use some spray paint and give a few layers to the rings. Now that we have all the parts, we can start assembling everything, starting with the PCB.




Part 3 - Schematic


Another crucial component is the audio amplifier. This has very low noise input and a great amplification and will increase the sound from the capsule to line level. Connect all components and check the final schematic for all the values. In my case the THAT1512 did not work, it might have been a clone. So I've used the INA217 instead and it worked. It might have a bit more noise, but it works...

DIY THAT1512 microphone amplifier


Part 4 - PCB


Let’s start assembling the amplifier PCB first, so we can have it ready later when we assemble everything. Download my GERBERs files from below for free. Then go to PCBWAY.com and click the quote now button. As always add the settings such as the PCB size, amount and color. In my case I want my PCB to be red. Save to cart and on the next page upload my GERBER files. Make the payment and in just a few days, receive the awesome PCBs for the amplifier. They look so nice so we could assemble it. The component list is quite specific and you need to use good quality capacitors. So make sure you get some non polarized audio capacitors like in the part list above. They are a bit more expensive but we really need them. Connect all components and check the final schematic for all the values. Now I have the PCB all assembled.




Part 5.1 - Assemble the capsule


We now need to prepare the capsule. The JLI 2555 is a permanent polarized capsule and that’s great. If you use any other different membrane, the process should be the same. Since the output of such membranes is so low, we need to first pre-amplify the signal. We do that with a simple transistor (JFET). The middle pin of the capsule would be our signal and the other pin would be, let’s say, the ground connection, but the signal is coming out on both pins because this is an analog signal.

The transistor I will be using has 4 legs instead of 3 as we usually have. But we won’t need the fort one so we can simply remove it so it won’t create confusion. Now I solder the gate to the middle pin of the capsule. The closer the transistor is to the capsule the better, to reduce noise. Now we have the capsule with the other two legs, drain and source so step 1 is done.

Step 2 is to add wiring. Now as mentioned by Matt from DIY perks, adding a stiff audio wire to the capsule is the worst scenario since any vibration would be transferred to the capsule through the wire. So we need to use wires as thin as possible and reduce weight. I've used enammeled copper wire from small DC motors. To reduce electrical interface we should cover the wires in a metal shield. So we solder wick, and believe it or not, the copper is waved with a hole in the middle just like a tube. I use a metal wire to open it up. I take two thin wires and glue them to the metal wire and pass it backwards. And now we have our noise cover which has such a low mass that it won't create any vibrations.

We sand the enameled from the tips of the thin wires and solder them to the two pins of the transistor from the capsule. Also, solder the copper insulation to the exterior pin of the capsule which is the ground tap. Check with the multimeter and see if we have a good connection and also mark the negative side with a marker for example and just like that step 2 is complete.

DIY THAT1512 microphone amplifier


Part 5.2 - Add mesh


Now for the step 3 is to enclose the capsule. To avoid interference and nose, all microphones have a metal mesh around them. I’ve bought a few types of mesh and I’ve decided to go with the one of 0.8mm holes because I like better the color than the brass one. To give it shape I measure the diameter of the capsule and make a hole into a wood board. Cut some of the metal mesh and then, using a hammer and a wood cylinder, I give the mesh the shape of the capsule. We need two of them so it will go around the entire capsule. Now download and 3D print my design from below and print it. I've also painted it silver.

Now that the paint is dry, first take the small ring. Take the part and first add one of the metal meshes. Make sure it has a small hole so the copper write from the capsule could pass. Now add the capsule and pass the wire. Carefully add some epoxy all around. Before the epoxy is hard, add the other side of the metal mesh and make sure they are connected. Both sides of the metal mesh and the copper braid of the wire must be in contact to act as a shield. Let the epoxy to dry and we’ve got our microphone capsule ready.

DIY THAT1512 microphone amplifier


Part 6.1 - Assemble everything


Now take the amplifier PCB with the ADC module. Also take the capsule with the mesh and pass the braided wire inside the 3D prined case. Connect the wires from the capsule to the 3 pins for G, plus and minus where G is the ground so connect it to the copper braid insulation. Cut some more metal mesh and add it all around the interior walls of the case. We need to make a faraday case to avoid electrical noise from the exterior. Add a metal mesh to the lid as well and make sure you add an insulator between the metal mesh and the PCB. Make sure the USB type C connector could be reached through the hole in the case and screw the PCB in place. Now that the PCB is in place, use some small screws like this ones and close the case and the microphone is ready, finally.

DIY INA217 microphone amplifier PCB


Part 6.2 - Final touches


You could add the microphone to a microphone arm with yet another vibration holder but since my design already has the capsule suspended in mid air and it is so small that basically creates no vibrations, the sound from the table should not pass to the capsule. So guys, it is time for a test so use a USB type C cable and connect it to your PC and let’s check it out.

circuit INA217 microphone amplifier PCB


Part 7 - Full Video


So guys, that’s how I’ve my version of the DIYPerks high quality microphone. The quality is amazing and I wish I had an expensive microphone to compare it with but my budget is not high enough. But if you do want to support my work, check my PATREON page and also my PayPal for donations. The PCB design, the schematic, the part list and the 3D files for the case are free.

If my videos help you, consider supporting my work on my PATREON or a donation on my PayPal. Thanks again and see you later guys.





13/01/2025 | Views: 4179 | Circuits | by: ELECTRONOOBS      












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