Record quality audio at home with a Homebrew USB Condenser Mic! This week, we are hacking a tiny little gadget, the USB soundcard, and turn into a studio quality microphone. It's a microphone that carries the whole package, it has a shock-mount, pop filter, preamp and an internal DAC.

The project was housed on a Retro Altoids container. Its cardioid pickup pattern, smooth frequency response and 16-bit, 44.1/48kHz resolution give you professional audio results no matter what you're recording. The project consists of four main components, the USB soundcard (DAC), the mic preamp, the enclosure and the microphones themselves. Don't worry I made the project as simple as I could so everyone in the DIY community can enjoy making the USB mic project!

Why Make a USB microphone?
USB microphones are made for easy, plug-and-play use. They’re fantastic for podcasters, musicians, voice actors, audio students, tech-reviewers and people who just want something better than the microphone built into their laptop. If you don't have a USB mic, you might want to try a Homebrew version before you buy one! Don't worry, the project fits on a $10 budget! DIY is the most rewarding thing to do!

Perfect For Podcasting:

As podcasting continues to grow in popularity, creators need both audio quality and ease of use. This mic can help you wow your listeners and set yourself apart in a crowded podcasting community.


Video & Sample Audio Coming Soon!

Step 1: Aux Version - Prototype

Sorry guys, I wasn't able to post the 3.5mm aux version of the mic that I've promised. It had flaws and the TL072 chip that I've used was very uncommon. I'll be posting a newer version of the 3.5mm aux mic soon! I usually use the aux mic on my DSLR since all DSLRs support 3.5mm mic jack and not USB ports.

Sample Audio:

If you are curious on how it sounds, I've used it on my "Google Science Fair Entry". The mic was plugged to my Nikon D5300. Please support my GSF project. Thank you! :)

Step 2: Influence

USB microphones are becoming a trend these days. Condenser microphones are a must have for people who loves to records song covers, instrumental covers, video tutorials, product reviews and etc...

Reason Why USB Mics Exist:

A real condenser mic needs a preamp and DAC setup. You are looking at a $500-$2,000 setup. This is the reason why audio companies started to sell consumer "USB Condenser Microphones", they are cheaper, smaller and user friendly. It's the perfect mic for quality-amateur recording.

Advantages Over Traditional Mics:

Companies designed USB mics for them to be able to set a standard. This way, every mic sounds the same no matter how crappy your soundcard is. The mic carries the whole studio recording package! It has an internal preamp and a DAC! Unlike the typical 3.5mm PC mic, USB microphones has a preamp that amplifies the available signal via hardware. It replaced the digital-gain which by the way is the one responsible for that awful grainy noise!

Top USB Condenser Mics (2014):

1st.) Blue Microphones Snowball USB Microphone

2nd.) Blue Microphones Yeti Pro USB Condenser Microphone

3rd.) Audio Technica AT2020USB Studio Condenser Microphone

4th.) CAD U37 USB Studio Condenser Recording Microphone

5th.) Audio-Technica ATR2500-USB Cardioid Condenser USB Microphone

6th.) Samson Meteor Mic USB Studio Microphone (Cardioid)

Why Not Buy A USB Mic From The Shelf ?

Consumer USB mics are extremely overpriced, even if they lye at the $50 price range! You don't believe me? Watch this video! You'll be surprised of what you'll see inside.

Step 3: The Design

The project consists of four main components, the USB soundcard (DAC), the mic preamp, the enclosure and the microphones themselves. All plays a great role in recording quality sound.

The Bad Reputation Of Electret Condenser Mic:

Over the years, hobbyists imprinted the idea that ECMs are the worst sounding mics. Yes they are cheap, it's one of the main reasons why people think ECMs are crappy. The truth is, ECMs are actually good microphones. Not only can it perceive a wide frequency response of 10Hz-50kHz but they are also affordable for the general public. Have you tried these mics? I bet they sound bad! Yes they sometimes do. The reason behind this inconsistent performance of ECMs is not because of the mics themselves, rather it's the unstandardized design of soundcards. Some soundcards are less sensitive to the ECM's sound, that's why we try to increase the mics sensitivity via software by going to the control panel. Gaining volume by software results to the increase of noise, the hissing sound that you hear.

The Solution:

After watching teardown videos on the leading brand-models of USB condenser mics, I was able to find a solution to the problem. A $10 homebrew version of the $100+ consumer USB mic. A USB soundcard was added to make sure that everyone has a uniform soundcard. The USB soundcard also did a great job in isolating the mic from the hostile internals of the laptop, this reduced the hissing sound. An adjustable hardware preamp was added to prevent the user from using the digital mic gain, this reduced the hissing 10x-50x. A two types of foams were added inside the altoids container to act as a pop-filter and shock mount.

Why Not Use Low Noise Op-Amps?

I wanted to make this project doable for everyone. Honestly, I prefer the TL072 low noise Op-Amp, but it is really hard to come by. I chose the single stage design because the parts are widely available. I'm 100% sure that you can find them in your local RadioShack store. For those people who prefers to buy online, Digikey and Newmark (a.k.a Element14) is a great source of discrete components.

Electret Condenser Mic Preamp Design:

This is the initial design of my single stage ECM preamp. The build is pretty simple, low noise and efficient. The potentiometer can be replaced with a 100k version of the pot, this would let you increase the mics sensitivity even more. You will also notice that I have two electret mics wired in parallel, this is done to increase the available signal without using a higher preamp gain, it helps a lot in reducing noise.

Step 4: Parts & Materials

Discrete Electronic Components:

- 2N3904 General Purpose NPN Transistor

- Electret Condenser Microphone (2x)

- 10uF Electrolytic Capacitor (2x)

- 4.7K Ohm ¼ Resistor (optional)

- 10K Ohm ¼ Resistor (2x)

- 10K Ohm Potentiometer


- USB Soundcard/ DAC (with microphone input)

- Altoids Tin Container (Instructable Version)

- ¼ inch bolt-thread

- Gorilla Glue
- Super Glue

Tools & Equipment:

- Portable/ Cordless Drill

- Rotary Tool (Dremel)

- 30W Soldering Iron

- Rotary Tool Bits

- Hot Gluegun

Step 5: Marking the Altoids Tin Container

Use a coin and ruler to mark the guidelines for the cut-out. Be sure to leave a margin, the mesh needs a surface to be glued on.

Step 6: Grinding the Altoids Container

Snips are bad for cutting small pieces of metal so go get your trusty rotary tool (dremel) then grind off the marked surface of your altoids container.

Tip: The sanding drum works great for grinding the round edges!

Step 7: Clean the Container

Be sure to give your Altoids container a rinse. Metallic dusts, acquired from grinding, can short and ruin your circuitry.

Step 8: Finding & Prepping the Mesh

Finding A Mesh:

I can bet the most common question that people are going to ask is "Where can I find or buy a mesh?". You can find/ buy metal mesh from broken speakers. Junkshops have tons of them!

Preparing The Mesh:

Use your scissors to cut the mesh. My mesh isn't wide enough to cover the whole panel so I had to cut them in half in order for it to cover the holes. The round edges can be made by cutting the mesh having a coin as a guide.

Step 9: Gluing the Mesh

Drop some hot glue then swiftly mount the mesh in place.

For some reason I prefer contact adhesive although they cure for more than an hour so I started all over again and used hot glue instead.

Step 10: Installing the Tripod Mount

At first I thought I needed a special thread for the tripod's screw. After doing some trial and error on my workspace, I found out that a 1/4" bolt-thread screws-in perfectly on the tripod's screw!

How Do I Glue It?

I tried to mount the thread with a few drops of superglue, it turns out that the superglue wasn't strong enough. I finally decided to use "Gorilla Glue", it works great, it literally does the toughest jobs in planet Earth!

Step 11: Dismantle and Desolder the USB Soundcard

Carefully open the USB soundcard's enclosure. Any knife would do in opening the enclosure. Just make sure that you don't hit the components inside. Now desolder the two audio jacks, the LED and the Male USB plug.

Step 12: Replacing the USB Plug

Like all USB microphones in the market, your homebrew USB mic needs a female printer cable USB port. The type of USB port that you would find on your Arduino Uno. Having trouble in the USB port conversion? Kindly refer to the USB pin-map above.

Why not use the original male USB plug?

Simple, you don't want to have that bulging male USB plug on your Altoids mic.

Step 13: File a Hole for the USB Port

The best way to make a square hole for the USB port is by drilling a 6.5mm hole on the Altoids container.

It's not square yet! Okay, now get the narrowest file you have then file your way until you achieve a square hole.

Step 14: Hot Glue the USB Soundcard

Now hot glue the USB soundcard in place. Make sure that the PCB doesn't touch the Altoids container's conductive surface.

Step 15: Install the Electret Condenser Mic

1st.) Peel off the cotton of the electret mic, this makes it more sensitive from sound.

2nd.) Solder both mics in parallel. Observe proper polarity!

3rd.) Cut two square pieces of packaging foam then hot glue both mics on each foam.

Step 16: Install the Trimmer Pot

Drill a hole then superglue the trimmer resistor in place.

What's the 4.7k resistor for? It lets the trimmer pot have a minimum resistance of 4.7k and a max of 14.7k You can omit this.

Step 17: Build the Circuit

1st.) Carefully read the schematic diagram in step #2.

2nd.) Solder the preamp's components on a perfboard.

3rd.) Connect the trimmer pot to the assembled preamp.

4th.) Connect the USB soundcard to your preamp circuit.


Still having a hard time? Go back to step#2, the diagram explains it all :)

Step 18: Hot Glue the Circuit

Apply a thick blob of hot glue. Hold the circuit until the hot glue cools down. Don't push it to much, you don't want the circuit to short because the conductive container.

Step 19: Cut Foams - for Built-In Pop Filter

Cut the foam in half then cover both mics with it. This works as a pop-filter and prevents the Altoids container from echos.

Step 20: Plug the USB Cable

The moment of truth! Plug the USB mic to your PC!

Step 21: Plug-And-Play Quick Setup

Wait for the computer to recognize the USB mic.

Set To Zero Digital Gain:

To reduce noise, you will have to slide the digital gain to zero. Windows usually sets zero as the default gain. To make sure, go to Control Panel > Hardware & Sound > Manage Audio Devices > Recording Tab > Your Microphone > Levels... You will find a gain slider make sure it's set to zero.

Disable The USB Soundcard's Audio Out:

It's important that you disable the audio-output of the USB soundcard. Otherwise your computer will use your USB soundcard as the default audio output and not your built-in soundcard. To set this, go to Control Panel > Hardware & Sound > Manage Audio Devices > Playback Tab > Right Click On Your Microphone > Properties > Device Usage (dropbox menu) > Disable This Device. This will let you disable the USB soundcard's audio-out while leaving the mic-in functional.


I hope you like the project! If you do, please vote for me in the "Gadget Hacking Contest". I would like to give my dad a GoPro Hero 3 for his upcoming birthday. Thank you! :)

<p>Try to reverse the polarity of the 10uF capacitor :)</p><p>I guess you're aware the electret microphone has a polarity.</p>
So, i rebuilt everything. Windows gain is on zero. tried switching the polarity of the caps. and still a high pitch whine when test it out in skype.<br><br>I didnt use the same Mics as you did, mine where from taydaelectronics, are they just bad? and the USB sound card was the same that you linked. <br><br>I'm pretty sure my mic is wired correctly.<br><br>Thanks for the instructable BTW. it looks really nice and you've done a great job!
<p>Had the same problem, figured out that usb power would be noisy due to smps power supply in our computers..tried it out on a laptop and works fine..To use it on a pc, rig a voltage regulator circuit in this circuits supply..or better yet use 3 aa batteries in series</p>
do not make it too low
<p>Ascas, I need help. Can&acute;t figure out where to connect the negative point of the microphone input.</p><p>This audio out you put in the schematics I assume it&acute;s the positive, so where is the negative connection?</p>
<p>Hi,</p><p>This project is awesome but I have terrible hissing noise on every device I've tried (laptop, stationary PC's) nothing helps. Maybe some instruction on how to build filter for power rail? Or how to connect batteries? </p>
Is it possible to cut out the USB sound card entirely? Can I just hook up the power, ground, and data to a regular female USB connector?
<p>No, you cant. A usb plug is supposed to send digital signals to the computer, an analog signal would not be deciphered by it. If you dont want to use an external soundcard, just connect it to an aux cable (c2 is input and use common ground) and connect to the mic input (available on most computers/laptops)</p>
How does the pot tie into the schematic.
<p>Check the diagram..He just used a trimmer pot in place of a regular pot..you could use either..</p>
<p>Could you possibly stop calling the ADC a DAC? They are the opposite!</p>
<p>So, I designed a PCB for this here is the link should you want to order it <a href="https://oshpark.com/shared_projects/AsjTyFzW">https://oshpark.com/shared_projects/AsjTyFzW</a></p><p><img src="https://644db4de3505c40a0444-327723bce298e3ff5813fb42baeefbaa.ssl.cf1.rackcdn.com/c9b8d12a36f211c270f00f7e8fc47cef.png"></p><p><img src="https://644db4de3505c40a0444-327723bce298e3ff5813fb42baeefbaa.ssl.cf1.rackcdn.com/112831f9834bd3cd282e59e1589f987e.png"></p>
<p>Here is a slightly updated version with header holes to make wiring easier. <a href="https://oshpark.com/shared_projects/XU14C2bt">https://oshpark.com/shared_projects/XU14C2bt</a></p>
<p>I am having issues and want to use Oshpark to make custom PCB so I know the setup is correct. But looking at the PCB design you have I can't really see what is what, and why is it so big..</p>
<p>Hey ASCAS I want to ask the voltage rating of 10uF capacitor. Is it 10uF 35V or 10uF 50V</p>
<p>Alright Gentleman, I had a bad semi wreck in 14 and apparently in the memory loses I suffered in the accident reading the schematics for boards is one of them.... some one please dumb this down, I hurting my self right now trying to decipher it..... I know this sounds really bad but its not a joke.... I really am having issues.... So Im guessing what I am asking for is a foot bone connected to the leg bone aka which Caps attach to which, and what legs of the NPN attach to what. I am only putting those on the board, the mics and Pot are going to be elsewhere. HELP!!!!!</p>
Hello Ascas. Ive been waiting dun sa AUX Version mo na mic. Di ko kase maintidihan itong usb mic kase hindi naman ako Proper na nakapag aral ng electronics. kaya diko tlga magets even if their saying it is to easy to build it. And by the way im a filipino too. and im proud of you men haha (y)
Just made a custom pcb layout and solder everything. It's working, and the sound is good :)
<p>Hi Ascas, I made the circuit but i cant hear much audible volume from the computer. I checked the volume levels they are okay. Are my mics faulty??</p>
either the connections are wrong or the sound card is faulty
<p>Hi ASCAS, nice job. Would it change the circuit schematics if using TL072 Op-Amp that you preferred? If so, couldn you raise the corresponding schematics?</p><p>The TL072 op-amp is cheap and easy to find in my town. Thanks for your posts.</p>
if you want low noise you can use bc109 or bc549 instead of 2n3904
TL072 requires 15v dual power. That isn't suitable for USB
<p>I tried building it but as it seems my computer 5V USB power supply has very poor regulation and my amplified signal had a very annoying high-pitched noise. So I switched to battery power and P2 output. I also added a high-pass filter on the amplified signal (~60Hz cutoff) so I could get rid of some power line hum. Turned out to sound pretty good!</p>
<p>I found the same thing, but I was able to get rid of the whine. I put a <br>low pass filter (470ohm resistor, 100uf cap, 0.1uf cap) between the <br>power and the preamp circuit, and finished everything off by grounding <br>the circuit to the case.</p>
<p>I glued a piece of paper between the USB soundcard and the container and would recommend it to everyone building this.</p>
Are these parts available in the philippines
<p>Yes I bought all of the parts here, in the Philippines.</p>
<p>Hi ASCAS, particularly where in the Philippines do these Altoid Tin Cans be purchased? I can't find then in any stores I went-into. Thanks in advance for the reply......</p>
<p>you can by a really cheap tobacco tin from any decent shop and us that instead</p>
<p>I have some electret microphones, but I dont understand the polarity, there are 2 leads, but there are no plus or minus markings. Can somebody help me?</p>
<p>TIP: One of microphone pins are connected to aluminum case of microphone. You can use continuity tester(diode sign on multimeter) to check that. </p>
<p>Could you maybe send a picture of the mics? Depending on the version you have, there could be an easy way to determent it. If one of the leads or the trace on the pcb seems to be connected to the metal casing, that would be the negative terminal. </p>
<p>Will this also work with a ksp44 npn transistor? because I still have those lying around.</p>
I think any small signal transistor will work.
<p>This is genius. I need to build one sometime soon.</p>
<p>You could add in a headphone port on the mic, and wire it in where the headphone jack was. A small pot to trim the volume, and that would be a great little set up for streamers or anyone who uses headphones. :)<br>I wonder if you would be able to disable the audio out on the device it's self, so Windows don't even see it? </p>
<p>Yup, you can disable the USB soundcard's audio output and use your PC's built in audio-out soundcard instecad.</p>
<p>Isn't the USB 5V power rail very noisy? Won't the noisy Vcc affect the amplifier? I personally have noisy USB, because they are not designed for analog stuff.</p>
<p>You could add something like this: </p>
where did you get the instructables tin and tripod??
<p>Hello, I tried to make this yesterday and I've got a problem. It works but there is a lot of noise, like someone is using a vacuum cleaner inside my room. What's wrong? I can't figure it out.</p><p>I also haven't fitted it in an enclosure if that could be the case. Maybe its noise from the computer and I should move it further away? or noise in the 5v rail of the usb and it needs another cap? Please help me :).</p>
<p>Hey friend. You should enclosed the circuit with capsule in any metal case and then you can just join your circuit's ground wire with the metal. You'll observe the noise is gone. Noise is always 99% away when the circuit board and your microphone capsules are covered by mesh or metal that is attached to the GND. I hope you understand.</p>
<p>I think You should add a pop filter if you didn't, that's all the advice I can give you.</p>
<p>Really cool stuff man, I really like a bunch of your projects. Most of them are interesting and i can use them in my middle school stem class.</p>
<p>Where do the wires go to from the potentiometer i can not see where they go?</p>
<p>Where do I connect the wires from the trimmer pot to the board? I can not see where they go.</p><p>Thanks</p>
<p>it try to use 2 capsule in prallel and yes it cause phasing problem.. i haven't yet try with 1 capsule </p>
<p>This is a great project and very well documented. I'm not much of an electronics person but I've been looking for a better microphone, since I've been recording the voice-overs for my YouTube videos using the built-in one on my laptop. I might give this one a shot. Thanks for sharing!</p>
hello I have finally just finished soldering everything together but it still only is faintly audible when I do the listen to mic thing and I get nothing when I record it and listen to the recording. I have tried switching the polarity of the cap as I saw was recomended in previous comments mine just didnt get louder like theirs did. I should also mention that I am testing the mic out of the tin so that I am sure it will be working before I finalize and glue everything could this be the issue? thanks for your help this is an amazing project that you have here.

About This Instructable




Bio: Hi I'm Angelo! I am a 18 y/o college sophomore taking my majors in BS-ECE at the DLSU. I use my course as ... More »
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