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Old 11th Sep 2019, 1:25 pm   #25
PsychMan
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Join Date: Jun 2013
Location: Fleet, Hampshire, UK
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Default Re: Digital 'cassette' recorder

Quote:
Originally Posted by Karen O View Post
PsychMan,
Good question!

I was aiming for a similar frequency response and SNR to an ordinary cassette recorder, back in the day. I chose a sample rate of 31.25kHz to achieve a 10kHz bandwidth (with a little room for filter roll-off), and an SNR of 50dB or so. I used 10 bit samples, mostly because the PIC's ADC is ten bits.

Although 8 bits would give theoretically 48dB SNR, there is an undesirable effect whereby the noise seems to 'come up' as a sound decays. It's kinda like a 'fffffff' sound during the decay of say, a piano note. 10 bits seems to stop that.

Oh, and it's mono of course!
Thanks Karen, I bet it sounds pretty good, and again love the idea and the build quality of what you've made.

Its inspiring stuff. I might have to have a go at something similar myself with Arduino boards. I have used PICs a long time ago, and might revisit, but I find Arduinos a lot simpler to throw things together if you have less patience

I hadnt considered using them for audio before, but with ethernet modules as well, Id be interested to experiment with sampling audio and sending it over ethernet to a device for playback
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