Question about ADC's and microphone inputs

Hello daisy forum!
I’m looking for a way to make an affordable, high quality sound recorder.
When I tried this on the teensy + audio shield, I ran into a lot of noise issues. I was able to get rid of the worst noise by using the MIC IN instead of LINE IN, but there was still a noticeable white noise hissing, which isn’t okay for my project.

So, I have two questions about the daisy seed:

  1. How noisy is the daisy seed microphone inputs?

  2. Can the ADC pins receive input from a microphone?


Hello @clarkc5 and welcome to the forum!

The Seed only has line level inputs. In my experience they are very quiet.

I haven’t tried this but it should be possible. You probably have to amplify the signal before sampling it.

If I would do a similar project I would run my mic through a microphone amplifier or a mixer with mic inputs, and then feed the Seed from the mixer line level outputs.

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@clarkc5 Daisy includes a hifi audio codec on board, I don’t understand why you’re looking for alternatives to that.

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Okay, thanks for the advice
Is there a limitation on how many adc’s it can process simultaneously? I would like to input 4 microphones if possible.

I’m looking for something which can input 4 microphones at a good quality, for the lowest cost as possible. I was considering building a board with a pre amp and adc, and routing it to digital pins on a microcontroller. But maybe using 2 daisy seed is a better option. It just depends on which one is more cost effective.

Nope, it is all up to your software! :slight_smile:

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Great, thanks! I’ll buy one an tinker with it

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I think it would be easier to answer if you told us a bit more about what you are trying to achieve. :slight_smile:

Normal Daisy input is line level.

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That is the right attitude! :slightly_smiling_face::+1:I don’t think you will be disappointed!

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My goal is to record from a large number of microphones with low noise interference, and able to be portable/not connected to the power grid. At first, 48 microphones for the first version, then add more later, when it works. To keep costs as low as possible for the prototype, I’m planning on using this battery powered camera microphone:

I’m going to make it so that I press a button, and all the microphones begin recording at the same time. I was thinking to make it with 4 microphones per “node”, but now I’d like to connect as many as possible, although 4 would still be okay.

Is the daisy seed capable of inputting 16bit, 44.1kHz (or higher), on all 11 ADC pins simultaneously, and store this info as separate .wav files? I appreciate your help.

In such case, the most suitable approach would be to connect second codec. Current version of Daisy Seed uses WM8731 that is a bit old, but good enough and fairly common. SAR ADC that are internal on MCU are usable for high bandwidth applications, but don’t have sufficient accuracy/signal to noise ratio for processing audio. If they were, there would be no need to include codec on Daisy.

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Interesting, thank you!
And just to make sure, the codec is meant to package many useful functions into one piece? Like adc and dac?

@clarkc5, sounds very interesting, but beyond my capabilities to assist. Sorry.

But I can say, like @antisvin suggested, that using the ADCs of the Daisy will not work for you. They are not made for that kind of application, and lack the resolution that you want. As I see them, they are made for sensors and CV input.

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No problem, thanks for your help. I may have to use external ADCs. Shouldn’t be difficult.

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Remember to update us with your progress! :slight_smile:

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