ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi

@Markw4 @xaled

Yes, theoretically separated AVCC for both left and right channels would be in better performance. But when I use ultracapacitor power supply or ultracapacitor /LifePO4 hybrid power supply for my DAC, I didn't feel any difference. Because the ESR of those power supplies is very low in just a couple of mohm level. And also, separating AVCC could result in different DC offset in I/V stage, unless the I/V stages are also in dual mono configurations. For two AVCC voltage rails can not be 100% identical. I'll take it into consideration if I got chance to design a AK4499 or ES9038Pro DAC.

Good weekend.
Ian

I use Buffalo and Mercury, so separate AVCC is used on Buffalo. However, the separating AVCC will become very sensitive, as long as the LDO status of the left and right channels is slightly different, it can be immediately noticed from the sound. When I measured the connection terminals between Buffalo and Mercury, and I find that the voltage is slightly different. In other words, even if ESR of those power supplies is very low, when the state of ultracapacitor/LifePO4 deteriorates, it will not be easy to detect.
 
hi IAN.
can i use ll1527 for stage I/V?
 

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@Vavilen

Unless you have a suitable ES9038Q2M Dual Mono Linux driver.

Regards,
Ian

If the two control buses are exposed on the GPIO - surely a modified driver such as this: https://github.com/VinnyLorrin/ES9038Q2M-Linux_Driver/blob/master/hifibunny3-codec.c could be modified with the control register information here: https://www.esstech.com/wp-content/uploads/2021/02/ES9028Q2M_Datasheet_v0.41.pdf

I have a question - I take it the DAC board simply provides ES9038Q2M pin out, the separate output board provides output buffer and filtering?
 
OPA861 Fully Balanced Zero Feedback I/V Stage.

OPA861 is a very special operational transconductance amplifier. It has super-high slew rate up to 900V/us over a wide bandwidth extended to 80MHz. The OPA861's performance is pretty much like a super transistor. In current input voltage output mode with zero feedback, the input impedance can be less than 10 ohms. This very low input impedance (closed to short circuit) and the ultra-high speed make it almost the perfect solution of an I/V converter. Actually, OPA861 was confirmed very successful as the SE I/V stage for TDA1541 DAC.

This is the first OPA861 I/V stage running in fully balanced mode. Different from all other active OP amplifier I/V stages, OPA861 I/V is more closed to passive I/V stages such as a resistor I/V or Transformer I/V but with much better dynamic performance.

The sound style is also totally different from a traditional I/V stage. According to my own listing test, it brings the best clarity so far I have experienced. The sound is very detail and at the same time is also very rich. The soundstage is widely open and focused. The music is vivid and dynamic. It doesn't color the music but just makes it more close to the original. I cannot say it is the perfect I/V stage, but I have to say it's the most impressive one.
This OPA861 would be a great option for the high-performance current mode DACs in balanced configuration such as the ESS9038 Q2M Dual mono, the ES9028Q2M, and ES9038Pro, AK4499, PCM1704, TDA1541 and so on.

https://github.com/iancanada/DocumentDownload/blob/master/RPiDacHAT/IVboards/OPA861IV/OPA861IV.pdf
https://github.com/iancanada/DocumentDownload


OPA861_1
by Ian, on Flickr
 
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Reactions: 1 users
OPA861 Fully Balanced Zero Feedback I/V Stage.

OPA861 is a very special operational transconductance amplifier. It has super-high slew rate up to 900V/us over a wide bandwidth extended to 80MHz. The OPA861's performance is pretty much like a super transistor. In current input voltage output mode with zero feedback, the input impedance can be less than 10 ohms. This very low input impedance (closed to short circuit) and the ultra-high speed make it almost the perfect solution of an I/V converter. Actually, OPA861 was confirmed very successful as the SE I/V stage for TDA1541 DAC.

This is the first OPA861 I/V stage running in fully balanced mode. Different from all other active OP amplifier I/V stages, OPA861 I/V is more closed to passive I/V stages such as a resistor I/V or Transformer I/V but with much better dynamic performance.

The sound style is also totally different from a traditional I/V stage. According to my own listing test, it brings the best clarity so far I have experienced. The sound is very detail and at the same time is also very rich. The soundstage is widely open and focused. The music is vivid and dynamic. It doesn't color the music but just makes it more close to the original. I cannot say it is the perfect I/V stage, but I have to say it's the most impressive one.
This OPA861 would be a great option for the high-performance current mode DACs in balanced configuration such as the ESS9038 Q2M Dual mono, the ES9028Q2M, and ES9038Pro, AK4499, PCM1704, TDA1541 and so on.

https://github.com/iancanada/DocumentDownload/blob/master/RPiDacHAT/IVboards/OPA861IV/OPA861IV.pdf
https://github.com/iancanada/DocumentDownload


OPA861_1 by Ian, on Flickr
nice that's in my 1541, there is a filter too ?
 
you mean they are less prone to be influenced by the good or bad quality of the power supplies?
Because I'm going the way, power supplies wise, with the LifePo4 MKIII as the core of my power supply for the rasp4 and the digital to analog path. With this setup, aka, a good and clean power supply, it would mean I don't "need" the T I/V ?
 
Not entirely clear to this newbie... Regarding powering the OPA861, could I use the PurePi J6 5V terminal block output if I am using the J4 output to power the Raspberry Pi GPIO from the bottom side? Assuming no because of the shared nature as well as only 2 terminals output versus the 3 inputs on the OPA861. Any help clarifying this would be appreciated!
 
Transformer I/Vs are pure passive so they don't need power supplies.
But for OPA861, you with need good +-5V. I use LinearPi Dual with two UcConditioner 5V.

The two I/Vs are totally different. But it up to your decision.
Not entirely clear to this newbie... Regarding powering the OPA861, could I use the PurePi J6 5V terminal block output if I am using the J4 output to power the Raspberry Pi GPIO from the bottom side? Assuming no because of the shared nature as well as only 2 terminals output versus the 3 inputs on the OPA861. Any help clarifying this would be appreciated!
 
@iancanada
Can please give a short inside what the ES9038Q2M DM II will be? Is this a new RPi DAC HAT Board or some extension for the existing ES9038Q2M Dual Mono Plus HAT? Because I already own your ES9038Q2M Dual Mono Plus HAT and the OPA861 Board. At the moment I'm searching for a suitable power supply to power the DAC HAT, OPA861 Board and a RPI4 togehter. What is your recommendation to start tweaking around with the sound and not to break the bank? I wish there was a compact solution like the PurePi, but that's obviously not the case.