Hi
I decided to design a DAC (my first) to use it with W. Colburnes headamp. I've made some starting choices.
-DAC chip: WM8741 - great DAC, a bit forgotten now
-LT1763 power regs, CLC at DACs power inputs, preregulation on capacitance multipliers.
-Amanero input (with isolator?)
Disrette output stage, mainly for buffering and filtering. (LTP, one gainstage and buffer, FETs runned hot).
What do you think? I wanted to get any opinions before drawing a schematics
I decided to design a DAC (my first) to use it with W. Colburnes headamp. I've made some starting choices.
-DAC chip: WM8741 - great DAC, a bit forgotten now
-LT1763 power regs, CLC at DACs power inputs, preregulation on capacitance multipliers.
-Amanero input (with isolator?)
Disrette output stage, mainly for buffering and filtering. (LTP, one gainstage and buffer, FETs runned hot).
What do you think? I wanted to get any opinions before drawing a schematics
First steps
Okay, so I did a few things.
WM8741 works in HW mode. Filters are switchable, no deemphasis, nor attenuation. Configured for 176.4/192kHz inputs.
LT1763s in SOIC8 for power supply (yes I know bypass cap should be 10nF). No inductors yet, they will be there, no worries.
Zero Flag tied to the GND (I don't see any use for it).
If somebody could check the HW settings
Okay, so I did a few things.
WM8741 works in HW mode. Filters are switchable, no deemphasis, nor attenuation. Configured for 176.4/192kHz inputs.
LT1763s in SOIC8 for power supply (yes I know bypass cap should be 10nF). No inductors yet, they will be there, no worries.
Zero Flag tied to the GND (I don't see any use for it).
If somebody could check the HW settings
Attachments
The resistor values in the filter are extremely low in order to get lowest noise (see note 1 on p63 of the datasheet). However you're using FET opamps which contribute significantly more noise than these low resistor values.
I suggest giving up the aim to get the very lowest noise as recording noise is going to dominate over DAC noise in the majority of cases. After all the vast bulk of digital recordings are still 16/44.1.
I suggest giving up the aim to get the very lowest noise as recording noise is going to dominate over DAC noise in the majority of cases. After all the vast bulk of digital recordings are still 16/44.1.
Those are only stock models. I'll use other, low noise opamps, probably from TI.
"I suggest giving up the aim to get the very lowest noise as recording noise is going to dominate over DAC noise in the majority of cases. After all the vast bulk of digital recordings are still 16/44.1."
So what do you propose Abraxalito? Maybe go for normal, low noise 0805 resistors, instead of MELFs?
"I suggest giving up the aim to get the very lowest noise as recording noise is going to dominate over DAC noise in the majority of cases. After all the vast bulk of digital recordings are still 16/44.1."
So what do you propose Abraxalito? Maybe go for normal, low noise 0805 resistors, instead of MELFs?
I upgraded a WM874x DAC with a 100X rise in the impedance of the filter networks following the chip itself. This gave a very large improvement in bass dynamics (the treble is still less than squeaky clean though). So I suggest scale up the given resistor values by a factor of at least 20, up to 100. Scale down the caps by the same factor. I haven't done a comparison of MELFs vs thick film so have no suggestions on that front.
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