attempting 44.1khz 16-bit digital audio

[bahstrike]

hi all,

i dont know much about audio circuit design, but i am attempting to make a basic stand-alone digital speaker to be connected to a larger system. the speaker itself needs no indicators or knobs/buttons:  only receives audio data and few simple commands (such as volume control).  the source for digital audio has not been prescribed, but imagine it may be wireless, ethernet.

the logic and signal processing circuitry is intended to run on 5v, but the 20 watt audio amplifier (http://www.st.com/stonline/books/pdf/docs/1469.pdf) is for car applications and its voltage should be 12-14v or so.


will I need to stretch the audio circuit's 5v signal up to 12v for this amplifier's input??

please help me if obvious errors exist in the schematic (login to view)

[Alex Tsekenis]

No, you dont need to do that. The 12V of the amplifier is the power supply required, not the minimum input voltage. You are good to go.

[bahstrike]

really?  awesome!

i am hoping there aren't any critical issues in the whole audio circuit.


it will leave me to explore ideas for implementing a "sample pump" for the DAC,  probably a simple microcontroller to drive DAC clock lines and fetch samples from a queue in a hunk of external ram (a single 128kb RAM IC should provide a 1.486 second buffer of raw 44100Hz 16-bit audio samples  (44100*2 * 1.486)/1024 = 128kb)

and another "master" MCU for decoding the digital source and fill RAM with audio samples, to generate logarithmic values into digital pot for volume control, and to act as an identity in the speaker control system

[Alex Tsekenis]

Consider a microcontroller with a DMA channel. Good luck!