**DIY Microphone Amplifier Circuits: A Feasible Alternative?**

When producing videos, one essential piece of equipment is a decent studio microphone to record voiceovers. For about three years, I've been using the T-Bone SC440 USB studio microphone, but then one day, the USB connector broke. As a fitting replacement, I got myself its successor, the SC450, which can be obtained for around 90 euro.

However, if we take apart my broken microphone, we can find two PCBs that utilize the AKM five 7371 Channel analog-to-digital converter as the brains of the organization. If we dig a bit deeper, we can also discover the heart of the microphone – a condenser microphone, also known as a capacitor microphone.

**Condenser Microphones and Electret Condenser Microphones**

In this episode of DIY or Buy, we will have a closer look at different microphone types and create a DIY microphone amplifier circuit to find out whether DIYing a microphone is an adequate alternative to buying a proper studio microphone. For the final showdown, we will compare the microphones by building up a test setup and playing back different music clips.

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**The Job of a Condenser Microphone**

Now, let's get started with the video! The job of such a condenser microphone is to convert sound waves into an electrical signal, which we then can record with for example a computer. To do that, the condenser microphone consists of a thin membrane and solid metal plates, which together pull up a plate capacitor.

When the sound waves hit the diaphragm, it changes its position, and this movement creates a varying voltage across the capacitor. This voltage is what we record as audio.

**Electret Condenser Microphones**

However, there's another type of condenser microphone – the electret condenser microphone. In an electret condenser microphone, the membrane is not movable, but instead, it's fixed in place with a thin layer of electrically charged material called an "electret." This electret creates an electric field that varies with the sound waves, and this varying electric field induces a voltage across the capacitor.

This type of microphone is commonly used in lavalier microphones and other handheld devices. They are often less expensive than condenser microphones but still offer good audio quality.

**Creating a DIY Microphone Amplifier Circuit**

To create a DIY microphone amplifier circuit, I designed this small schematic. The 1k resistor powers the defect, but two parallel 470 nF capacitors remove the DC offset of the audio signal. Then, we have the NJM 5532 low-noise op-amp in an inverting op-amp configuration with a gain of around 21.

The voltage divider on the non-inverting inputs is utilized to create a 2.5V offset voltage at which the output voltage will oscillate around. Last but not least, we have a high-pass filter and a low-pass filter with cutoff frequencies of 3.6 Hz and 15.9 kHz, respectively.

**Testing the DIY Microphone Amplifier Circuit**

With a theory out of the way, I gathered all the required components and started soldering them to a small piece of perf board. After a mere 30 minutes of soldering, these circuits were complete. I then connected the microphone and powered the circuits with 5V power.

It was time for first tests on the oscilloscope. We can see that we now have peak-to-peak voltages of up to 3V, which means that the amp should increase the volume.

**Comparing the Recording Quality**

After reconnecting the right ring to ground and this time only the far-left ring in contact with the output of the amp, it was time for another test recording. But in order to have a proper reference value, I first utilized my usual studio microphone to record a bit of music.

Here's the unedited results, and here's what the small electret microphone delivers. Now both mics fulfill the job without a problem, but to no surprise, the studio microphone offers a better recording quality.

**Conclusion**

Not convinced yet? Well, this is what the voiceover recorded by the electret condenser microphone sounds like. Again, definitely usable, but not nearly as good as the studio microphone. So when it comes to recording voiceovers, deep I option definitely wins in this case.

But if we compare the recording quality of my lavalier microphone with the recording quality of my DIY microphone, it's clear that when the lavalier mic costs around 57 euro, the DIY version for around 4 euro is the winner.

WEBVTTKind: captionsLanguage: enWhen producing videos one by the piece of equipment is a decent studio microphone to record voiceoversFor about three years. I've been using this t-bone SC440 USB studio microphonebut then one day the USB connector broke asthe fitting replacement, I got myself its successor theSC450 which you can get a for around 90 euroBut if we take apart my out broken microphone we can for one find two PCBswhich utilize the aka five three seven one two Channel analog to digital converter as the brains of the organization andIf we dig a bit deeperWe can also discover the heart of the microphoneThis cylinder shaped piece of metal with two wires coming out of it is a so-called condenser microphoneAka condenser capsule aka capacitor microphone. Or ever you want to call itSo in this episode of DIY or buy we will have a closer look at different microphone types and create a DIYMicrophone amplifier circuits in order to find out whether DIY a microphone is an adequate alternativeto buying a proper studio microphone andFor the final showdown we will compare the microphones by building up a test setup and playing back different music clipsWhich brings me to the sponsor of this video.audio blocksThey offer one of the largest stock audio library with over100,000 clips loopsmusic and sound effects and best of all all the audio clips come with a royalty-free agreements so I andpossibly you can use them in YouTube videos without getting in trouble due to copyright claimsthey are currently giving out a seven day trial periodSo you can give it a shot and get access to the massive stock audio library for freeJust visit audioblocks.com/youtube or click the link in the video description to get started with your free trialAnd with that being said let's get started with the videoNow the job of such a condenser microphone is to convert sound waves into an electrical signalWhich we then can record with for example a computer.To do that the condenser microphone consists of a thin membrane and the solid metal platesWhich together pulled up a plate capacitor?when the sound waves hit the diaphragm it changes its distance to the solid plates and thusaccording to the capacitance formula of a plate capacitor the capacitance of the setup changesBut in order to get a proper electrical signal out of this we would need to charge up the capacitor through a bias resistorWith a high voltage of up to 48 volts which is also known as phantom powerThis way since we got an almost constant charge the voltage changes of the capacitorReflect the capacitance changes, and thus the sound wavespretty awesomeOnly problem is that such condenser capsules cannot easily be purchasedexcept of course if you would buy a proper studio microphone, but that would destroy the DIY aspectsInstead we could focus on these electric condenser microphonesThose can be bought for very cheap and almost all small microphones nowadays of such a kindEven the lavalier microphone that I used for my Q&A videos is one of themTheir structure is similar to that of a condenser microphone, but a light the name of this microphone type impliesThere is a film of electret between the two capacitor plateswhich therefore polarizes the capacitor naturally without the needs of phantom power andOnce we take apart such a microphoneWhich is honestly easier said than done?Then we can find an additional field effect transistor connected to one capacitor platesThis FET is used for power amplificationWhich means all we have to do is to add a 1 kilo ohm resistor and a 1 micro farad capacitor?To the circuits and power it with a voltage of above 1.5 volts to get our audio signal on the outputsso I added those components to the capsule applied 5 volts to the circuits book the output up to my oscilloscope andrealized that everything worked like it was supposed to andConnecting such an electret condenser capsule to a computer is even easierWe simply have to plug an audio cable into the mic import connect the right ring to the minus pole of the capsulewhich you can identify by the traces going to the housing andconnect the other two ring contacts to the plus pole of the capsule theWay this works is that these sound cards includes the Manito resistor and capacitor?Which means that by checking the recording devices the microphone should work just fine, but?Make sure to disable all enhancements your sound card offersOtherwise they can mess up the recordingNext I open the software audacityCreated the small test set up and started the recording of a music clipAs you can hear the microphone works just fineBut you should also hear and probably see it due to the audio waveform that the volume is a bit lowOne way to increase this recording volume is to utilize the microphone boost windows providesWhich as you can once again hear and see does work.But the problem is that you simultaneously increase the noise floor.for better understandinghere's a silent recording without boostand here's one with boostAs you could hear the capsule alone is not the best solution yet.Since it only features peak to peak voltages of around 200 millivolts at bestSo obviously we need a decent amplifier. For that, I created this small schematicLike before the 1k resistor powers defects, but two parallel470 nano farad capacitors remove the DC offset of the audio signalThen we got the njm 5 5 3 2 low noise op-amp in an inverting op-amp configuration.We have a gain of around 21The voltage divider on the non-inverting inputs is utilized to create a 2.5 volt offset voltage at which the outputvoltage will oscillate aroundLast but not least we got a high-pass filter and a low-pass filter with cutoff frequencies of 3.6 hertz and15.9 kilo hertz, which should get rid of unwanted frequencies andwith a theory out of the way, I gathered all the required components and started soldering them all to a small piece of perf boardafter a mere 30 minutes of soldering these circuits was complete andafter inserting the ICEAConnecting the microphone and powering the circuits with 5 volt powerIt was time for first tests. On the oscilloscopewe can see that we now got peak to peak voltages of up to 3 volts which means that the amp should increase the volumeSo after reconnecting the right ring to ground and this time only the far left ring in contact to the output of the ampIt was time for another test recordingBut in order to have a proper reference value, I first utilized my usual studio microphone to record a bit of musicHere's the unedited resultsAnd here's what the small electret microphone deliversNow both mics fulfill the job without a problem, but to no surprise the studio microphoneoffers a better recording qualityNot convinced yet. Well. This is what the voiceover recorded by the electret condenser microphone sounds likeAgain definitely usable, but not nearly as good as the studio microphoneSo when it comes to recording voiceovers deep I option definitely wins in this caseBut if we compare the recording quality of my lavalier microphoneWhich sounds like this with the recording quality of my DIY microphone?Which sounds like this it is clear that when the lavalier mic costs around 57 euroThat the DIY version for around 4 euro is the winnerBut what do you think and what future episodes of DIY or buy would you like to see?As always, thanks for watching don't forget to Like share and subscribeStay creative, and I will see you next time