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[Sticky] USB-C Microphone (official topic)

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DIY Perks
(@diyperks)
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Building a USB-C Microphone

-official topic-

 

Microphones are ubiquitous in modern life; they can be found everywhere from your smartphone to your TV remote. However, the audio quality on offer varies wildly depending on their intended use, with studio microphones unsurprisingly being highly tuned to provide pleasant and detailed sound capture... but at a significant cost.

This is fair enough... all that R&D needs rewarding, right? Absolutely, but purchasing a $500 microphone only to find that it uses about $20 of easily-sourced core components is a bit of a painful discovery. This price disparity is one of the key reasons that building a microphone yourself can make a lot of sense. Not only can you customise its design to your specific use requirements, but it can cost significantly less than purchasing one pre-made. It's fun too!

This project covers everything from sourcing a good-sounding microphone capsule to building a frame for it and even including a USB interface so it can be used on any modern device whether that be a laptop or a smartphone.
 
 
 
Posted : 31/03/2022 9:21 am
Ismail, Ronflocos, Hepha1st0s and 3 people reacted
theguy
(@theguy)
New Member
 

Regarding the schematic, is it possible to use true-condenser capsules, rather than a large electret? I would be amazed if so - imagine the noise floor performance! Can we get it to the level of a Rode NT1A???

 
Posted : 01/04/2022 9:45 am
Ingmar
(@ingmar)
New Member
 

What a fantastic video. Fell in love with the design, so started on it, although I am an absolute newbie to electronics. but with a great instruction video, schematics and all I thought I would be able to get this done.

It took forever to find and order all the parts, but on my desk now, so i started putting it all together. end result: no sound 🙁

there were a couple of questions i ran into when building, so hopefully getting that right will fix my issue. 

First, on the stripboard template there is a dot right next to the word gain (see attached file). i can't figure out what should be connected there. Could you point out what should connect there?

Second, the USB Audio interface. The video clearly explains the replacement and connection of the USB side, but the audio connector side is not mentioned at all. Could you explain how to connect these?

And third, the capacitors. I figured the 2200uF have a + and a - side to take into account. the 22uf ones don't have that, correct? 

thanks!

 pin
 
Posted : 07/04/2022 9:48 am
DIY Perks
(@diyperks)
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Hey! Welcome to the forum! Regarding that pin, it represents the positive input for the opamp, and I added it so I knew where I could put some tiny 100nF filter caps. After experimenting I found that they didn't make much difference to audio quality (well, none actually), so I excluded them for simplicity.

 

For the audio input of the audio input wasn't mentioned as it's usually fairly self-explanitory - the GND output on the preamp circuit needs to be connected to the ground input of the interface, along with the signal wire. A headphone or phono pinout might help here: https://www.computersense.co.nz/forums/showthread.php?tid=209&pid=365

 

Also yes, if the 22uF caps are non-polarised as suggested it doesn't matter which way around they are.

This post was modified 4 months ago by DIY Perks
 
Posted : 07/04/2022 2:41 pm
holy_mcmully
(@holy_mcmully)
New Member
 

Hi, I was on here a few weeks ago exploring to see whether someone had asked my own question in the forums about substituting/adding an XLR output and found that someone INDEED HAD asked already, and even better... YOU ANSWERED with a circuit diagram. Unfortunately, now that I've returned to the forums, I can't seem to find that thread anywhere. Would you kindly repost or redirect me to that answer?

 

Thank you so much, I'm a huge fan of your projects/channel all the way from Atlanta in the USA!

 
Posted : 07/04/2022 8:00 pm
DIY Perks
(@diyperks)
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That was on the old forum installation and it broke unfortunately, but it's still accessible: https://diyperks.com/community/

 
Posted : 08/04/2022 9:37 am
DeepSpace and DeepSpace reacted
jesperwdk
(@jesperwdk)
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DIY Perks. mabey you must bloke the chinese typing dude ??

 
Posted : 08/04/2022 5:38 pm
guineaparade
(@guineaparade)
New Member
 

Very excited to get started on this build- my work has me doing webinar-like trainings all of the time so this will get plenty of use! Moving out of an apartment which was seriously hampering my DIY possibilities. This is going to be the first project I'll be creating in the new house! Thanks for sharing this knowledge!!!

 
Posted : 10/04/2022 1:59 am
graydon.t
(@graydon-t)
New Member
 

I'm very close to finishing this project, I just need to make the box but I decided to go ahead and test it first.  At first I didn't get any output, then found out I incorrectly connected the transistor but after correcting that and trying for a while I had a few seconds of it picking up me snapping and my voice but it was so faint I could barely make hear it at max volume.  My smallest resistor on the rotary is 5.6ohm so that shouldn't be it. I connected the output to the red and black wire on the audio capture card...which I think is right... The only part I did differently from the original build is that I used a J111 transistor.  Could someone give me any ideas to fix this?

 
Posted : 10/04/2022 12:40 pm
FishOutOfWater
(@fishoutofwater)
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Soooooooooooo I drafted a PCB version of the amplifier circuit and printed it (with a few parts missing (namely the 8 pin dip socket/THAT1512, the 22uF non-polarized caps, and the NMA0515SC DC/DC converter)) on JLCPCB. I'll keep you guys updated on how it goes when it arrives. If it works well I'll release the PCB design so other people can fiddle around with it. Would be cool if we could eventually integrate the USB audio capture part into this so it'll just be one board. 

 
Posted : 17/04/2022 5:24 pm
Coti
 Coti
(@coti)
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Hello,

What type of audio cable are you using? Is it TRS?

Also, how thick is the copper wire?

Another thing, what material can I use for the insulator (inside the housing)

And again, where can I find the rotary switch you used for the project?

And finally, if I want to keep the USB type A interface, how can I connect the USB audio cable to GND out?

 

Many thanks

 
Posted : 17/04/2022 6:57 pm
FishOutOfWater
(@fishoutofwater)
New Member
 

@coti 

I got the rotary switch here: https://www.aliexpress.com/item/32907959214.html.  

I also got a 1k Ohm version of this: https://www.aliexpress.com/item/1005001946117435.html to test as maybe another type of volume control... not sure how that's going to go though. We'll see. 

 
Posted : 21/04/2022 4:05 am
Mike
 Mike
(@mike)
Active Member
 

Hi!

I am a complete beginner in electronics. I was wondering how should I ground the shielding in order for it to work properly. Do I just connect it to the microphone ground pin or is there another way I don't know about?

I could really use some help.

This post was modified 4 months ago by Mike
 
Posted : 22/04/2022 5:42 pm
DIY Perks
(@diyperks)
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Hi Mike, yes, that's correct - just connect it to the mic ground pin and you're good to go!

 
Posted : 22/04/2022 8:28 pm
Mike
 Mike
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@diyperks 

Thanks a lot! That definately helps.

I'm still missing a few crucial components but it's going rather smoothly.

You've made a great tutorial to say the least.

 
Posted : 22/04/2022 8:46 pm
holy_mcmully
(@holy_mcmully)
New Member
 

Could you provide some more detail on the shielding you use for your enameled wire? I've purchased several different sizes of desoldering wick and can't seem to open any of them up the way you did wherein I can run the wires through them.

 
Posted : 28/04/2022 3:16 am
FishOutOfWater
(@fishoutofwater)
New Member
 

@holy_mcmully i read some comments on the original youtube video, and it seems that some people suggest that desoldering wick has its own problems, so i went and bought this: https://www.aliexpress.com/item/32888966537.html in the 2mm size... i hope that won't be too small for this, but we'll see. 

 
Posted : 29/04/2022 6:56 am
Chouxmimouli reacted
Ridian
(@ridian)
New Member
 

Hi there,

So I've been making this project and I've encountered a problem while checking to see if it works. The mic works but it only picks up when I tap it, and not light taps either. Then I found out that it could actually pick up my voice but I have to wrap my finger around it like a ring and talk really loudly and closely, like directly touching it. I haven't gotten into putting the capsule into a brass circle and adding the brass mesh yet as they have yet to arrive, so could that be why it's acting this way? 

 
Posted : 04/05/2022 4:12 pm
Mike
 Mike
(@mike)
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Hi,

I managed to put everything together.

However, two of the 2200uF 16V capacitors went bad (the ones connected to the NMA0515SC). I checked for short circuits and there are none.

I was able to hear the microphone "working" but not properly, as there were loads of really loud humming and buzzing noises in the background (probably from the blown capacitors).

My components are basically the same as the ones used in the video except for the 22uF bipolar capacitors (mine are rated for 100V, in the video 35V). As their specification didn't include voltage ratings, I assumed it wasn't important.

Any ideas what may be causing the problem?

This post was modified 4 months ago by Mike
 
Posted : 05/05/2022 6:10 pm
Phil
 Phil
(@phil)
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I am no audio expert but one thing I am sure of is that the mic looks damn good! It also sounds good to me in my headphones, and I could only nitpick the differences when directly comparing the two solutions (the expensive mic did seem a tad smoother on the transients). I only wish there had been a comparison test of the DIY mic with the off-the-shelf preamp to more clearly see whether improvements could come from the DIY preamp or from the mic itself. I understand the intention was to make a comparison of the high-end vs cheap DIY and an extended range of testing might have resulted in an unnecessarily long vid, but perhaps an idea for the alternate youtube channel?

 
Posted : 06/05/2022 3:53 am
Skrish
(@skrish)
New Member
 

Hi. I wanted to build my own version(using alt components) of the mic from the "Building a USB-C Microphone" YT video. I am very new to anything related to Mics & Speakers. I wanted to ask why do we need a pre-amp if we already have an N-channel JFET(2n4416 from the YT video) which can be an amplifier?

Also, Whats the voltage being fed to the drain of the JFET? And is it possible to use a 3.5mm jack as the mic interface to the Recording device(Laptop/Mobile) instead of having an Audio to USB interface?

Please correct me if I'm speaking erroneously anywhere.

 
Posted : 09/05/2022 3:41 am
Sandy
(@sandy)
Eminent Member
 

@skrish You need the pre-amp to get the signal to what the audio industry calls "line-level". You also need it to get the singal to line level without a tonne of unwanted noise. If you just shoved an amplifier straight in the line after a mic then you'd have a horrible mess of audio as it would amplify absolutely everything that's fed into it.

 
Posted : 10/05/2022 8:02 am
Sham
 Sham
(@sham)
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@graydon-t 

I would try switching the 2.2K resistors in the drain and source to 1K if you don't want to alter the design to much.

If that doesn't work I would switch to a J112, or a J113. It is most likely the JFET you are using though.

Finally you could try adding a high slew rate opamp stage to the output of the differential op amp. If you want to do this I will calculate the transfer function for you if you want such that you can keep a 10uF cap so you have filtering at 20Hz at the output.

I am using a J112 and on my oscilloscope I am seeing 1.1V for a 10 ohm resistor, I am using a similar type of differential amplifier but not the same one.

 
Posted : 14/05/2022 1:19 am
Sham
 Sham
(@sham)
New Member
 

@mike Could it be electromagnetic interference? When I was testing the microphone on an oscilloscope I could see a strong 60Hz signal on my oscilloscope. When I turned the lights off at my work desk the signal went away. Does the humming and buzzing sound like this?

Could also be bad capcitors, here is an alternative: https://www.digikey.ca/en/products/detail/nichicon/UFW1C222MHD1TO/4317500

Also if you can try to make sure you are using metal film resistors, they tend to be the best cost vs performance choice since they work really well at the lower frequencies.

 
Posted : 14/05/2022 1:26 am
Mike
 Mike
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@sham Thanks for replying.

I actually managed to solve most of my issues. I turned out that I soldered the capacitors (the ones I wrote about) to the wrong polarities. Today I fixed the issue.

However, after installing all the shielding, the microphone still picks up some interference. It is not really unbearable but if you focus you can definately hear it.

The background noise is more high-pitch and it is not constant. I can provide you with a sample of the bizzare sound.

Other than that, it works great.

Cheers!

This post was modified 3 months ago by Mike
 
Posted : 16/05/2022 4:42 pm
Sham
 Sham
(@sham)
New Member
 

@mike

If you have an AC-DC converter, (laptop power supply) or really any power brick. Hold the microphone up to it with the gain as high as it can go and see if it changes the pitch of the buzzing. If your mic is picking up EMI then you will most likely hear that 60Hz tone I sent in the previous post. Was it the cap on the negative rail that you placed backwards by accident, if not you may have placed that one backwards to since the ground is at a higher potential then rail, can be abit confusing.

 
Posted : 18/05/2022 12:24 am
Mike and Mike reacted
thijnmens
(@thijnmens)
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I'm currently assembling the microphone with the same components as in the video, except for the rotary switch, as i can edit the audio levels in software. How do i modify the board to accommodate for the missing rotary switch? Do i just put 2 wires in there? (Mic+ -> Gnd and Mic- -> Gnd)

 
Posted : 18/05/2022 1:00 pm
Mike
 Mike
(@mike)
Active Member
 

@sham I've tried bringing my laptop power supply close to the microphone's capsule itself as well as to it's circutry. The pitch didn't change a bit.

The main circuit seems to be fine now. I asked my experienced teacher for help to find my mistakes and possible improvements. He confirmed the cirsuit fits the schematic. He also suggested soldering some 0,1uF capcacitors to the 5V power input so it's more stable, I guess.

 
Posted : 18/05/2022 2:06 pm
Colenave
(@colenave)
New Member
 

I tried following the video but got lost once it got to the 2 and 3 pin connectors. (I also want to just use the original usb connector if possible, but I can buy an adapter if I just need to buy the usb c breakout board to follow along.)

But one issue is when it gets to the audio side of the pre-amp all the sudden 4 or 5 wires are gone, not sure which ones, and generally can't see which side of the 2/3pin male connectors the respective wires are going into. I apologize if this is noob stuff and it's covered on the circuit diagram, I can't remember enough about how to read those anymore 😳 Any help anyone can lend is greatly appreciated!!! 

 
Posted : 18/05/2022 8:07 pm
Mike
 Mike
(@mike)
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@thijnmens You can just bridge the connection on the board where the rotary switch normally connects. However, I highly suggest trying different resistors as the microphone is just too sensitive when wired directly.

 
Posted : 19/05/2022 11:22 am
thijnmens and thijnmens reacted
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