Some questions about recording audio

Writing software that inputs and/or outputs audio and performs DSP algorithms such as filters, new codecs or audio effects.
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Some questions about recording audio

Post by asgnpiao » Tue 2017-01-24 9:35

I am trying to record audio using the MAX4466 op-amp and VS1053 shield that I bought from Kynix. I am able to record audio by connecting OUT --> MICP, GND --> MICN, GND -> GND. 

The recorded audio seems to have a very low gain i.e. I am barely able to hear what has been recorded in a room. I tried varying the gain using a potentiometer.  The recordings are generally noisy so I’m not able to listen to what is actually being recorded. 

The recordings are marred by some noise (Link for the sample). While I am not trying to achieve high quality audio using an arduino + a breakout on a breadboard, I would like to record any conversation within a few feet (of course with the consent of people being recorded). 

My questions are: 

a) How do I avoid the noise that is affecting the quality of the recording?
b) How do I improve the gain of the recording so that I am able to hear something when I play the recorded file?
c) If it is not possible using the MAX4466 breakout, is there an alternative to record the audio?

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Re: Some questions about recording audio

Post by pasi » Wed 2017-01-25 12:02

What are the recoding settings? SCI_MODE (line/mic), SCI_AICTRL0 (samplerate), SCI_AICTRL1 (gain / autogain)?

After reset the line input is selected, so unless you clear the SM_LINE bit, you won't have the microphone amplifier active. Although, with the MAX4466 maybe the input is high enough for the line input. Have you measured what peak-to-peak voltage do you get at the MICP/LINE1 pin?

Setting AICTRL1 to 0 will enable autogain.
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