This tutorial will help you modify the sound of your microphone in order to transform the sound of your microphone into the accurate copy of the sound of a better microphone. You can also transform a pair of identical (same model) microphones into a matched pair of microphones for stereo recording. The proposed digital mod is simpler than an electrical or mechanical mod, and in the same time it ensures incomparably higher accuracy.
It is known that the sound quality of a microphone mainly depends upon its frequency response. High quality microphones have better frequency responses than low quality mics. MathAudio Microphone EQ is a VST effect plug-in which corrects the frequency responses of microphones. In fact, you can take your medium quality microphone and transform it into an acoustic replica of a high quality microphone. The process of replication takes a few minutes. After that the sound of your medium quality microphone will be very similar to the sound of the high quality microphone. Listen to the sound samples.
There is an important restriction: MathAudio Microphone EQ doesn't reduce the self-noise of microphones. If you buy a microphone for using it with MathAudio Microphone EQ, make sure that the microphone is not noisy. Usually condenser microphones have a smaller self-noise than dynamic ones.
MathAudio Microphone EQ is also able to transform a pair of identical (same model) microphones into a matched pair of microphones for stereo recording. Such matching can increase the quality of stereo recordings. If the microphones acted differently, your left and right channels would not sound exactly the same, which could result in timbre anomalies between them and a smearing of the stereo image. MathAudio Microphone EQ can match your microphones much better than they were matched at the factory. Use MathAudio Microphone EQ to transform you right microphone into the replica of the left one. It is also possible to transform both left and right microphones into replicas of a third microphone.
The Microphone EQ set includes two VST plug-ins: Microphone EQ VST (mono) and Microphone EQ Measurement VST (stereo). Microphone EQ Measurement VST generates correction files, and Microphone EQ VST transforms the sound of your microphone into the sound of the desired microphone.
MathAudio Microphone EQ Measurement VST is a sort of a self-learning system: it first compares the signal of your target microphone with the signal of your reference microphone. Then it creates a mathematical algorithm which changes the spectrum of the signal of your target microphone to make it similar to the spectrum of the signal of your reference microphone. Please note that the microphone which will be corrected is referred to below as the target microphone.
There are two methods of generation of the correction files: direct method and postponed method. The postponed method includes recording of the microphones in one place (e.g. in recording studio) and analysis of the sound file in another place (e.g. on your home computer). The postponed method will be discussed near the bottom of this page.
The direct method includes the following steps:
1. Install the Microphone EQ plug-in set to you computer
Choose the right installer. If you use the x32 version of your VST host, use the x32 version of the Microphone EQ installer. If you use the x64 version of your VST host, use the x64 version of the Microphone EQ installer.
The installer will install two VST plug-ins to your computer: Microphone EQ VST and Microphone EQ Measurement VST.
2. Connect your target microphone to the sound card of your PC
3. Connect the reference microphone to another input of the sound card
Both target microphone and reference microphone must be connected to your sound card simultaneously. They must be connected to the different inputs of your sound card. For example, connect your target microphone to the right input of your sound card and connect the reference microphone to the left input.
4. Place the microphones at the preferable distance
Both microphones must be placed at the same distance from the source of the sound. If you correct a vocal microphone - place both microphones at a preferred distance from your mouth. If you correct an instrumental microphone - place it at the preferable distance from your musical instrument.
5. Switch off your speakers
Your speakers must be switched off to avoid the acoustic feedback. Use headphones to monitor the sound of the microphones.
6. Open and adjust your VST host program (Reaper, Cubase, Nuendo, etc)
Your VST host program must work in stereo mode. Adjust the direct monitoring of the microphones. Make sure that you hear the sound of both microphones in your headphones. Touch the microphones with your finger to make sure that the stereo mode is activated and you hear the sounds of microphones in different ear cups.
7. Include the Microphone EQ Measurement VST plug-in to the stereo signal path
Open the editor of the plug-in. You will get the window shown in Fig.1.
Fig.1. Screenshot of the MathAudio Microphone EQ Measurement VST plug-in.
Check the state of the radio buttons in the Inputs tab of the plug-in. The selected inputs must correspond to the inputs of your sound card that were used for connecting your microphones. Then switch the Reference Mic and Target Mic radio buttons and touch the microphones to make sure that you hear the corresponding microphone.
9. Adjust for comfortable sound volume
Use headphones to monitor the microphone signals. Select the "Reference Mic" radio button. Use the volume control of your VST host program to adjust for comfortable sound volume. Then select the "Target Mic" radio button and listen to the sound of your target microphone. A volume control knob will appear. Use the knob to adjust for comfortable sound volume.
10. Start the measurement
Click the "Start" button. You will get the window shown in Fig.2. You have 10 seconds to speak to the microphones (if you replicate a vocal microphone) or play all the notes of your musical instrument (if you replicate an instrumental microphone). Don't bother about the quality of your speaking or playing. The progress bar in the MathAudio Microphone EQ window will show you your progress. Fill the full 10 seconds with the sound of your voice or the sound of your musical instrument. The signal correction algorithm will be generated automatically in a second after the end of the measurement process.
Fig.2. Screenshot of the MathAudio Microphone EQ Measurement program with the progress bar.
11. Save the correction file
You will be automatically prompted to save the correction file when the correction algorithm will be ready. Type in the name of the correction file and save the signal correction algorithm as an .alg file.
12. Listen to the processed sound of your microphone
Click the "Corrected Target Mic" radio button. Speak to your target microphone or play your musical instrument. You will hear the processed sound. Then click the "Reference Mic" radio button to compare the processed sound of your target microphone with the original sound of your reference microphone. The sounds must be very similar.
13. Close the Microphone EQ Measurement VST plug-in window and remove it from the signal path.
If the correction file is ready, you don't need the measurement plug-in any more. Remove it from the signal path.
14. Include the Microphone EQ VST plug-in to the mono signal path
Use the Microphone EQ VST plug-in to permanently process the signal of your microphone. Run your VST host program and insert the plug-in into the mono channel corresponding to the target microphone. Open the Microphone EQ VST plug-in editor. You will see the plug-in window shown in Fig.3.
Fig.3. MathAudio Microphone EQ plug-in window.
15. Load the correction file
- Click the "Load corr. file" button in the MathAudio Microphone EQ plug-in window and open the saved .alg file. The name of the loaded .alg file will be indicated in the plug-in window.
- Adjust the volume of the microphone sound, as necessary, by means of the volume control of your host software.
Sometimes it is more convenient to record the sound of the microphones in one place (e.g. in recording studio) and generate the correction file in another place (e.g. on your home computer). In that case you can make a short (20-25 seconds) stereo recording of your voice (right channel - your target mic, left channel - the reference mic) and save it as a WAV file. Then open that file by means of your VST host software and include the Microphone EQ Measurement VST plug-in to the stereo signal path. Start the playback of the recorded sound, then click the "Start" button in the measurement plug-in window and save the resultant correction file. Of course, you don't need to use microphones and speak to them because the recorded sound replaces the sound of microphones. The postponed method allows you to get exactly the same result as the direct method.