OPA861 fully balanced I/V stage for RPi ESS DAC HAT
OPA861 fully balanced I/V stage PCB samples arrived last week. After a quick listening test, I have to say it's really really good. I never thought those small things can sound as good as that.
Actually OPA861 is very special, it's almost the perfect solution I can ever found for I/V stage:
1. Zero feedback, similar to passive solutions such I/V transformers or I/V resistors
2. True current input mode with impedance only around 10 ohm. ( 0 Ohm is the is the ideal input impedance of a current mode I/V stage, but it doesn't exist in the real world.)
3. 80Mhz high bandwidth and 900V/us slew rate. The speed is very good for a ESS DAC running at 50-100MHz MCLK.
OPA861 was very successful as I/V stage for TDA1541. And there are a lot of good reviews from audiophiles.
Mono and Stereo High-End Audio Magazine: Interview with Pedja Rogic of Audial
OPA861 for I/V
OPA861 zero-feedback output stage of AYA II – Audial
K&K Audio / Lundahl Transformers
I think it was overlooked by people in recent years however.
In picture is the first balanced OPA861 I/V stage for ESS DACs. I hope very soon I'll run another full listening test to get it compare with Transformer I/V, OP amplifier I/V and the coming OPA1632 I/V.
http://www.diyaudio.com/forums/pc-b...i2s-dac-hats-raspberry-pi-37.html#post5454403
OPA861IV_1 by Ian, on Flickr
Regards,
Ian
OPA861 fully balanced I/V stage PCB samples arrived last week. After a quick listening test, I have to say it's really really good. I never thought those small things can sound as good as that.
Actually OPA861 is very special, it's almost the perfect solution I can ever found for I/V stage:
1. Zero feedback, similar to passive solutions such I/V transformers or I/V resistors
2. True current input mode with impedance only around 10 ohm. ( 0 Ohm is the is the ideal input impedance of a current mode I/V stage, but it doesn't exist in the real world.)
3. 80Mhz high bandwidth and 900V/us slew rate. The speed is very good for a ESS DAC running at 50-100MHz MCLK.
OPA861 was very successful as I/V stage for TDA1541. And there are a lot of good reviews from audiophiles.
Mono and Stereo High-End Audio Magazine: Interview with Pedja Rogic of Audial
OPA861 for I/V
OPA861 zero-feedback output stage of AYA II – Audial
K&K Audio / Lundahl Transformers
I think it was overlooked by people in recent years however.
In picture is the first balanced OPA861 I/V stage for ESS DACs. I hope very soon I'll run another full listening test to get it compare with Transformer I/V, OP amplifier I/V and the coming OPA1632 I/V.
http://www.diyaudio.com/forums/pc-b...i2s-dac-hats-raspberry-pi-37.html#post5454403
OPA861IV_1 by Ian, on Flickr
Regards,
Ian
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Ian,
That looks great.
I am really hoping you will enable a way to use multiple of these with your MC FIFO for a multichannel DAC solution.
In fact a single board hosting 4x IV could offer incrementally better performance due to increased board space and larger shared power planes.
PC based DSP is very flexible and there is a need for good quality multichannel DAC.
I know you are primarily focused on Rasp Pi based stereo systems, but you have developed so many sub blocks that enabling DSP based systems also is possible now.
Thanks for sharing your work.
JP
That looks great.
I am really hoping you will enable a way to use multiple of these with your MC FIFO for a multichannel DAC solution.
In fact a single board hosting 4x IV could offer incrementally better performance due to increased board space and larger shared power planes.
PC based DSP is very flexible and there is a need for good quality multichannel DAC.
I know you are primarily focused on Rasp Pi based stereo systems, but you have developed so many sub blocks that enabling DSP based systems also is possible now.
Thanks for sharing your work.
JP
It's amazing for so fast that PCB design has been completed. hoping it has good results.
Hi Guys,
I brought DAC board ES9028Q2M board from china as Ian has good opinion on that DAC chip. It has JRC5532DD opamp. I am going to buy Raspberry pi 3 B+ model. Can I use raspberry universal power supply or power bank to power up the Raspberry.
any mods suggested. I want to play flac and mp3 files.
Thanks,
Nag.
I brought DAC board ES9028Q2M board from china as Ian has good opinion on that DAC chip. It has JRC5532DD opamp. I am going to buy Raspberry pi 3 B+ model. Can I use raspberry universal power supply or power bank to power up the Raspberry.
any mods suggested. I want to play flac and mp3 files.
Thanks,
Nag.
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The best mod you can do from here is to get es9038q2m Ian board for Pi
I really mean it. There is bunch of things you would have to do to your board to get good sound starting from replacing chip for es9038q2m, then clean 3.3V for avcc, then replacing clock to low phase noise one with clean 3.3V supply, better I/V stage ... why bother? unless you have plenty of time and you want to play ...
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I understand Ian,thank.Have you also planned the design of an ultracapacitor power supply for feed your clock card and I2S to PCM board.
Hi,
I just bought the following I2S card from Audiophonics :
ESS ES9028Q2M Module DAC I2S 32bit 384khz DSD Symetrique Regulateurs 1x LT1963 - Audiophonics
It is powered using the recommended toroidal transformer.
Used on my new Raspberry 3 B+ along with the Allo Kali reclocker.
I installed Volumio following the install instructions : without the DAC, it plays flawlessly my music on the jack output and also through AirPlay (although I still have indexing problems : about 1/10th of my music Library stored on my 1 To hard drive is available) .
But when I connect the DAC board I cannot stream music through Airplay, it is mixed with some sort of white noise. Also the startup sound is distorted.
Curiously on the other hand, music stored on the local hard drive directly connected to the RPi plays well (really well!!) out of the RCA outputs.
I already installed the last plugin through ssh and tried different DACs in the Playback menu. I also set 32 bit resampling (otherwise neither 16 bit nor 24 bit Flac are played, or again with this white-noisish music).
Is there anything I'm missing?
Do I need a different plugin for this board?
Shall I go to another player (Moode,? DietPi?) with more chances of succes?
Any help will be very appreciated!!
I just bought the following I2S card from Audiophonics :
ESS ES9028Q2M Module DAC I2S 32bit 384khz DSD Symetrique Regulateurs 1x LT1963 - Audiophonics
It is powered using the recommended toroidal transformer.
Used on my new Raspberry 3 B+ along with the Allo Kali reclocker.
I installed Volumio following the install instructions : without the DAC, it plays flawlessly my music on the jack output and also through AirPlay (although I still have indexing problems : about 1/10th of my music Library stored on my 1 To hard drive is available) .
But when I connect the DAC board I cannot stream music through Airplay, it is mixed with some sort of white noise. Also the startup sound is distorted.
Curiously on the other hand, music stored on the local hard drive directly connected to the RPi plays well (really well!!) out of the RCA outputs.
I already installed the last plugin through ssh and tried different DACs in the Playback menu. I also set 32 bit resampling (otherwise neither 16 bit nor 24 bit Flac are played, or again with this white-noisish music).
Is there anything I'm missing?
Do I need a different plugin for this board?
Shall I go to another player (Moode,? DietPi?) with more chances of succes?
Any help will be very appreciated!!
Thanks Do, sometimes I just couldn't help doing so
Hi Frank
You guessed it
Ian
Hope you have some time left, to sleep
Frank
Thanks Do, sometimes I just couldn't help doing so
Hi Frank
You guessed it
Ian
Maybe a litte bit off topic...... 😇
Engineers often run on coffee.
That's my business.....
I import coffee from a very small French coffee roaster. A family business since 1921. The very best you can get.
I hear you thinking......French⁉️ Wine come from France, but coffee?
I'll tell you a secret....Espresso and the Espresso machine are developed in ...France in 1866
have a look at Home Koffie en Chocolade - Cafes-Canton.nl
Regards,
Frank
3000F Maxwell ultracapacitors
The monster Maxwell 3000F ultracapacitors arrived yesterday. They are really really bigger than I thought. Looks a bit crazy. But the good thing is that they are not heavy.
It's supposed to be the best power supply in the world due to the 0.29 mOhms output impedance and 210A (RMS) continues output current.
For now, I'm just curious how good they are by comparing with the 350F ultracapacitors as my ESS DAC HAT power supply.
If I'm happy with the result, I'll open a new thread to discuss developing the big high power isolated ultracapacitor power supply, maybe +3.3V,+5V and +(-) 15V. But to my opinion they are too big for RPi audio applications.
In this thread, I'll keep focus on ESS DAC HATs, corresponding I/V stages, ESS controller and RPi ultracapacitor power supply solutions.
Pursuing sound quality will always be unlimited
Maxwell300FultraCapacitor by Ian, on Flickr
Ian
The monster Maxwell 3000F ultracapacitors arrived yesterday. They are really really bigger than I thought. Looks a bit crazy. But the good thing is that they are not heavy.
It's supposed to be the best power supply in the world due to the 0.29 mOhms output impedance and 210A (RMS) continues output current.
For now, I'm just curious how good they are by comparing with the 350F ultracapacitors as my ESS DAC HAT power supply.
If I'm happy with the result, I'll open a new thread to discuss developing the big high power isolated ultracapacitor power supply, maybe +3.3V,+5V and +(-) 15V. But to my opinion they are too big for RPi audio applications.
In this thread, I'll keep focus on ESS DAC HATs, corresponding I/V stages, ESS controller and RPi ultracapacitor power supply solutions.
Pursuing sound quality will always be unlimited
Maxwell300FultraCapacitor by Ian, on Flickr
Ian
OMFG they are huuuuuge, I love it. My wife would never stand for it but I love the absurdity of it all. ;D
Now, if practical considerations matter, the smaller brethren are probably preferable for a RPi solution.
Personally I always consider true audibility and diminishing returns. If I can’t tell a difference between big expensive gear and smaller cheaper dittos, I’ll go for small and cheap every time. OTOH if there is a clear difference, it becomes a much tougher decision.
P.S. After digesting the initial shock... if using a regular “full size” cabinet there is usually a lot of air inside, maybe this could be a good way of filling some of that air?
Now, if practical considerations matter, the smaller brethren are probably preferable for a RPi solution.
Personally I always consider true audibility and diminishing returns. If I can’t tell a difference between big expensive gear and smaller cheaper dittos, I’ll go for small and cheap every time. OTOH if there is a clear difference, it becomes a much tougher decision.
P.S. After digesting the initial shock... if using a regular “full size” cabinet there is usually a lot of air inside, maybe this could be a good way of filling some of that air?
Watching with great interest... Size isn't an issue for me either. Currently I am using 4x linear supplies (thanks GStew), one for each board in my Pi stack, and those dwarf the Pi as well.
Mark, I have the same idea as you--eventually I will case everything up when I find the sound I am after.
Mark, I have the same idea as you--eventually I will case everything up when I find the sound I am after.
The monster Maxwell 3000F ultracapacitors arrived yesterday. They are really really bigger than I thought. Looks a bit crazy. But the good thing is that they are not heavy.
It's supposed to be the best power supply in the world due to the 0.29 mOhms output impedance and 210A (RMS) continues output current.
For now, I'm just curious how good they are by comparing with the 350F ultracapacitors as my ESS DAC HAT power supply.
If I'm happy with the result, I'll open a new thread to discuss developing the big high power isolated ultracapacitor power supply, maybe +3.3V,+5V and +(-) 15V. But to my opinion they are too big for RPi audio applications.
In this thread, I'll keep focus on ESS DAC HATs, corresponding I/V stages, ESS controller and RPi ultracapacitor power supply solutions.
Pursuing sound quality will always be unlimited
Maxwell300FultraCapacitor by Ian, on Flickr
Ian
3000F ?! Isn't this necessary? Pi or the clock board isn't a very power-consuming device.