You did make some basic changes in the PSU. E.g. relocated the voltage regulators. Perhaps the minor problems you describe are related to those changes.
I myself kept that part of the circuit almost as-is, but with some changes in electrolytes values.. The only thing I changed was to relocate the rectifier bridge and add larger caps. I just use a 15Vac x2 transformer. The digital supply is connected by a choke to filter out HF.
This might be caused by asymmetrical discharge of the PSU. You could use a small relay to short-circuit the output when powered-off.
I think potentially you have got the posts mixed up 🙂
Mine doesn't have any issues. It's completely silent and sounds amazing.
I suggest double checking your spdif connection on the board. Make sure ground is soldered properly. The one with papery crackle could be a dead dac chip. This is the common symptom of a failing ak4393/6 chip. The one with hum sounds like an analogue stage problem. Possibly wiring or soldering of your rca connectors. If you had a scope fault finding would be fairly easy.
This is my DAC based on the core board as used by the other members here but the power supplies are totally different. I also use a transformer for digital input. digital signal is upsampling to 192 khz using CS8421. The output stage is a minimalist style which includes only a pair of 1:1 transformers.
The power supplies include:
a R core transformer with 4 separate secondary windings;
two LT3042 (ultra low noise 0.8uV) one opwering the upsampling board and the other powering the analog section of the ak4396 chip
two LT1962 for preregulator and three LT1762 after them.
Are these overkill? 😀
The power supplies include:
a R core transformer with 4 separate secondary windings;
two LT3042 (ultra low noise 0.8uV) one opwering the upsampling board and the other powering the analog section of the ak4396 chip
two LT1962 for preregulator and three LT1762 after them.
Are these overkill? 😀
Attachments
All bypass caps are panasonic PPS smd caps solders under the pcb.
electrolytic caps for digital section are Sanyo oscon
other small caps are pana C0G
Some black gate, nichicon muse kz, elna silmic II , all left over from other projects.
electrolytic caps for digital section are Sanyo oscon
other small caps are pana C0G
Some black gate, nichicon muse kz, elna silmic II , all left over from other projects.
Hi , i have a r core transformer like that , how do you know wish of the yellow and brown wires are the start of the secondary windings ?
I think it doesn't matter because they are all independent windings. This matters only if you connect two or more windings together for parallel operation or to make a dual power supply.
Join one of the yellow to one of the brown, then measure the ac voltage accross the ones you haven't joined - should equal 30v. if it doesn't, change one of the ones you have to joined to the other one and measure again.
Has any one tried to feed the digital section of the ak4396 chip with 5v supply? seems to sound better. The original design was 3.3v for digital section of the ak4396. The datasheet recommends 5v supply for both digital and analog section.
Warning: 5v should be for the ak4396 chip only. theother IC can only run up to 3.3V. In order to do the above it's necessary to remove the ferite bead that connects the 3.3v supply to the ak4396 then put in a separate 5v supply.
Warning: 5v should be for the ak4396 chip only. theother IC can only run up to 3.3V. In order to do the above it's necessary to remove the ferite bead that connects the 3.3v supply to the ak4396 then put in a separate 5v supply.
From: quantran
Has any one tried to feed the digital section of the ak4396 chip with 5v supply? seems to sound better. The original design was 3.3v for digital section of the ak4396. The datasheet recommends 5v supply for both digital and analog section.Warning: 5v should be for the ak4396 chip only. the other IC can only run up to 3.3V. In order to do the above it's necessary to remove the ferrite bead that connects the 3.3v supply to the ak4396 then put in a separate 5v supply.
This is an old post from the board's designer:
Has any one tried to feed the digital section of the ak4396 chip with 5v supply? seems to sound better. The original design was 3.3v for digital section of the ak4396. The datasheet recommends 5v supply for both digital and analog section.Warning: 5v should be for the ak4396 chip only. the other IC can only run up to 3.3V. In order to do the above it's necessary to remove the ferrite bead that connects the 3.3v supply to the ak4396 then put in a separate 5v supply.
This is an old post from the board's designer:
So.....?????
Now I am using 5v supply to feed the digital section of the ak4396. I feel that it sound better this way but it's hard to be sure since I can't really A/B the results. However since the manufacturer recommend 5v supply I would keep using it this way.
All my power supplies are off the board and they are sourced from separate transformer windings.
I agree. Since the AK4396 datasheet implies +5v Dvdd usage, I am going to do that as well. Adding a $0.41 7805 is cheap & easy. I am using a separate +/- 17v supply for my LM4562 output opamp. Parts list total is now about $15, following Dario's replacement recommendations (mostly)----not too bad.
I am assembling a preamp for a friend, and this time I will try an idea I always had, but never used for myself: putting a DAC inside the preamp box.
The reliable AK4393 now seems to have been replaced by the AK4396, hopefully with audio quality gains, right?
You seem to be using Dario's BOM parts too for this kit. AK4393 kit suppliers did sell the pcb just with the SMD parts soldered in. Then you would not waste any money on passive parts you are going to upgrade.
Do they still do that?
The reliable AK4393 now seems to have been replaced by the AK4396, hopefully with audio quality gains, right?
You seem to be using Dario's BOM parts too for this kit. AK4393 kit suppliers did sell the pcb just with the SMD parts soldered in. Then you would not waste any money on passive parts you are going to upgrade.
Do they still do that?