here are the specs on the codec then:
Stereo Audio DAC
100 dB A Signal-to-Noise Ratio
16/20/24/32-Bit Data
Supports Rates From 8 kHz to 96 kHz
3D/Bass/Treble/EQ/De-Emphasis Effects
Stereo Audio ADC
92 dB A Signal-to-Noise Ratio
Supports Rates From 8 kHz to 96 kHz
Six Audio Input Pins
Six Stereo Single-Ended Inputs
Six Audio Output Drivers
Stereo 8 , 500 mw/Channel Speaker Drive Capability
Stereo Fully-Differential or Single-Ended Headphone Drivers
Fully Differential Stereo Line Outputs
Low Power: 14-mW Stereo 48-kHz Playback With 3.3-V Analog Supply
Programmable Input/Output Analog Gains
Automatic Gain Control (AGC) for Record
Programmable Microphone Bias Level
Programmable PLL for Flexible Clock Generation
I2C Control Bus
Audio Serial Data Bus Supports I2S, Left/Right-Justified, DSP, and TDM Modes
Extensive Modular Power Control
Power Supplies:
Analog: 2.7 V - 3.6 V
Digital Core: 1.525 V - 1.95 V
Digital I/O: 1.1 V - 3.6 V
Available Packages: 5 × 5 mm, 32 QFN
Nice. It looks like everything, including the headphone amp!, is in that chip. Seems pretty good quality too. Does anyone know how the TI/Burr-Brown stuff compares to the AKM in terms of the converter quality?
Let me just add to that, after skimming the docs, what the preamp is doing. There is a plot showing that if I put in a signal at -65dB wrt line level, what the SNR is as I add (mic pre) gain. If I add 0dB gain I get an SNR of ~27dB, which is just down to the noise floor of -92dB. It I add 20dB of gain, I get an SNR of ~37dB. So, adding 20dB of gain added about 10dB to the noise floor. If I were using "hot" mics, maybe 20dB is enough gain, and then my *maximum* SNR would be 92-20 = 72dB. I'll have to look at MD, but I think it is comparable.
Of course, this is all on paper. I've got to hear how it sounds.
Thanks again Neutrino for the brave disassembly! I hope you get it back together safely...
Richard