iron_attorney
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Raspberry Pi 2 Audio DAC

Fri Apr 24, 2015 8:28 pm

Hi there, this is my first post in this forum. Just picked up a raspberry pi 2. Appologies if this isn't quite the right place for this question, but it's the closest I could find.

My main purpose for the pi is audio processing and synthesis, so I have been wondering about the onboard DAC. I have read about people with older Pi models doing similar things who say the onboard DAC isn't high enough quality, and so they have always used a USB soundcard instead. Is this the same with the Pi 2? What is the onboard DAC and what are the specs?

Cheers in advance for any help,

Pete

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DougieLawson
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Re: Raspberry Pi 2 Audio DAC

Fri Apr 24, 2015 8:32 pm

There isn't any on-board DAC!
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mahjongg
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Re: Raspberry Pi 2 Audio DAC

Fri Apr 24, 2015 8:34 pm

the PI uses HDMI for good sounding audio, the analog sound output is a backup solution, which uses a simple PWM output, not an "audio DAC", its only good for basic sound effects and such, not high end audio.

But the PI also has an I2S digital audio output, which you can connect a professional Codex to, or an optical sound output device, none of these are "on board" though.

iron_attorney
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Re: Raspberry Pi 2 Audio DAC

Sat Apr 25, 2015 6:02 pm

Would that output be any use while prototyping and testing the audio device that I'm making? Just enough to know it works and that while I work out my perminant audio output solution?

Also, surely anything that takes a digital signal, and turns it into an analogue signal that can drive a speaker is a DAC, even if it's crap.

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mahjongg
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Re: Raspberry Pi 2 Audio DAC

Sat Apr 25, 2015 8:14 pm

Yes, literally its a "digital to audio converter" or DAC, but that wasn't the use of the meaning of the term that I was reading into the title , as the "audio" in front of it changes the meaning to something like this: http://www.ti.com/lsds/ti/audio-ic/audi ... oduct.page

also "on board" normally means a separate function (chip), and the PI hasn't one, it only has a few capacitors and resistors, that are used to convert two standard PWM signals to stereo sound.

I2S is the real audio DAC output so you can connect an "audio DAC", or the more commonly used term Codex.

there are several codex solutions for the PI, the mayor player being Wolffson, there is also at least one device that uses I2S to create an optical audio output.

iron_attorney
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Re: Raspberry Pi 2 Audio DAC

Sat Apr 25, 2015 10:26 pm

Cool! Cheers very much man, I'll check them out. I'm still gonna have to be annoying and picky about the DAC thing though. An R2R ladder DAC is a DAC, and that's just a bunch of resistors.

Sorry about being a pedant, people in my real life hate me for it too, haha! I am genuinly thankful for both of your help!

Pete

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Re: Raspberry Pi 2 Audio DAC

Sun Apr 26, 2015 10:56 am

mahjongg wrote: there are several codex solutions for the PI, the mayor player being Wolffson.
Err, I think there would be a host of people who's suggest otherwise. :-)

gordon@iqaudio.com

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DougieLawson
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Re: Raspberry Pi 2 Audio DAC

Sun Apr 26, 2015 1:34 pm

Gswg wrote:
mahjongg wrote: there are several codex solutions for the PI, the mayor player being Wolffson.
Err, I think there would be a host of people who's suggest otherwise. :-)

gordon@iqaudio.com
There's even some folks who've got a Wolfson on a model B who'd agree with you. (Bad choice.)
Languages using left-hand whitespace for syntax are ridiculous

DMs sent on https://twitter.com/DougieLawson or LinkedIn will be answered next month.
Fake doctors - are all on my foes list.

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