I have 2 OPPO Sonica DAC's. In general, I really like the DAC and she plays beautifully w/DSF files from the hard drive.
Background: One of the Sonica's suddenly sound's slightly muddy or more like listening through a veil, lacking authority or punch. Frankly if I heard this DAC standalone for the first time, I would have assumed "meh, nice but not that impressed".
Performing an A-B swap out of one Sonica for the other, clearly demonstrates it's the DAC.
Question: Any idea what to check?
Thanks for any guidance.
Background: One of the Sonica's suddenly sound's slightly muddy or more like listening through a veil, lacking authority or punch. Frankly if I heard this DAC standalone for the first time, I would have assumed "meh, nice but not that impressed".
Performing an A-B swap out of one Sonica for the other, clearly demonstrates it's the DAC.
Question: Any idea what to check?
Thanks for any guidance.
Do you have an oscilloscope and know how to use it? Are you familiar with ESS Sabre dac circuitry? Maybe a simple logic analyzer?
If yes to the above, then start comparing power supply rails, clock and I2S waveforms, I2C bus programming, etc. Eventually you will find something different between the two units. When you do then focus in on that area to find the problem.
A close up of the dac section of the unit attached below. Looks pretty straightforward to go through.
If yes to the above, then start comparing power supply rails, clock and I2S waveforms, I2C bus programming, etc. Eventually you will find something different between the two units. When you do then focus in on that area to find the problem.
A close up of the dac section of the unit attached below. Looks pretty straightforward to go through.
Attachments
Thank you Mark for the pointers. I have a scope and know how to use it, but not a logic analyzer. I assumed the issue was likely in the analog section and possible an OpAmp or capacitor since the sound was fine, just lacking punch or the authority it used to have and as currently A-B tested with my other Sonica.
I'm not sure the march of bits on the digital side is and issue.
Curious no one else has experienced this issue.
I'll look at measuring one against the other.
I'm not sure the march of bits on the digital side is and issue.
Curious no one else has experienced this issue.
I'll look at measuring one against the other.
Chances are you can find the problem without needing to use a logic analyzer. However, logic analyzers that can capture I2C bus commands are available for around $10 (new price), and there is always a chance that one dac is having audible problems because of I2C settings in the dac chip. KeeYees USB Logic Analyzer Device with 12PCS 6 Colors Test Hook Clip Set USB Cable 24MHz 8CH 8 Channel UART IIC SPI Debug for Arduino ARM FPGA M100 SCM: Amazon.com: Industrial & Scientific
The things you would probably be looking for with the scope would be general quality of I2S bus and clock signals. With a 100MHz scope they will not look perfectly square, but they should all have similar looking rise times.
Mostly the scope can be used to trace analog signals from the dac outputs through the output stage processing and to the output connectors. Comparing the good dac and the bad dac using test tone signals might reveal some problem. The scope can also be used to check power supplies rails for noise and for normal turn-on/turn-off transient behavior. The important thing when you have a good reference dac is just to look for differences to start with. Same thing with a DVM. Measure DC voltages everywhere and compare values. AVCC is critical as are power rails for the output stage. The clock rails may be important too since clocks are considered part of the analog circuitry. I would check rails that power digital circuitry too, they probably just don't affect output sound quality in as a direct a way as the analog power rails do.
The things you would probably be looking for with the scope would be general quality of I2S bus and clock signals. With a 100MHz scope they will not look perfectly square, but they should all have similar looking rise times.
Mostly the scope can be used to trace analog signals from the dac outputs through the output stage processing and to the output connectors. Comparing the good dac and the bad dac using test tone signals might reveal some problem. The scope can also be used to check power supplies rails for noise and for normal turn-on/turn-off transient behavior. The important thing when you have a good reference dac is just to look for differences to start with. Same thing with a DVM. Measure DC voltages everywhere and compare values. AVCC is critical as are power rails for the output stage. The clock rails may be important too since clocks are considered part of the analog circuitry. I would check rails that power digital circuitry too, they probably just don't affect output sound quality in as a direct a way as the analog power rails do.
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