Guys if I pick up the signal at opamp pins 2 and 3 and leave the Riv Insitu (R8/9) , have I bypassed the Riv and so no need to remove?
You really only have to lift, disconnect, the sides, or leads, of R8/9 and C31/36 that touch pin 2, to experiment.
Presenting a minimalist version of AD1862 DAC.
Based on JLSounds version of Miro DAC.
1. DAC works on +/-12v rails simplifying power supply requirements
2. Digital and Analog Grounding is in line with Spec sheet
3. Removed MSB trimmer and u.fl connectors as they seem to have been used very little.
4. Moved I/V conversion out of the board to enable tweaking.
Can be turned into a dual mono version if anyone is interested
Credits to Miro for original design.
Thanks
Mallik
Based on JLSounds version of Miro DAC.
1. DAC works on +/-12v rails simplifying power supply requirements
2. Digital and Analog Grounding is in line with Spec sheet
3. Removed MSB trimmer and u.fl connectors as they seem to have been used very little.
4. Moved I/V conversion out of the board to enable tweaking.
Can be turned into a dual mono version if anyone is interested
Credits to Miro for original design.
Thanks
Mallik
Attachments
Joined the PCM56P club now as well. Mounted most of the caps on the underside but will take a break before I do any I/V experiments. Used the opportunity to try out T-962 reflow oven to solder the level shifters, which worked out very nicely but you have to be sure to clean up solder balls afterward. Thinned out the solder paste and applied in strips and didn't get any bridges but touched up a few pads on the end of 3 rows. Fired up on first try so I'm very 😊
Thank you miro1360!



Thank you miro1360!



In the last few days I have been testing the promised TDA1540P 
It works nicely, no audible digital distortion, no glitches. The sound is very dynamic (slightly harder with strong bass, the bass guitar is very much alive
)
Power supply is compact and stackable. The input is standard I2S as always (but you need to programm the CPLD converter with my VHDL program, no worries - step-by-step tutorial will be included).

It works nicely, no audible digital distortion, no glitches. The sound is very dynamic (slightly harder with strong bass, the bass guitar is very much alive

Power supply is compact and stackable. The input is standard I2S as always (but you need to programm the CPLD converter with my VHDL program, no worries - step-by-step tutorial will be included).
Attachments
Is it possible to us a unity gain buffer as an output for AD1862?
Am I correct that I can use a resistor, say 2.7k, from pin 11 output to ground then use the voltage across this resister as input of the buffer?
Am I correct that I can use a resistor, say 2.7k, from pin 11 output to ground then use the voltage across this resister as input of the buffer?
Nice work Miro. So NXP 1540, is that a current production chip? Or atleast more recent than Philips.?
I am surrounded by Miro projects. 56,68, 1541A, 1862 stop clock!
Not sure if the PCM68 has been built yet but I have some ex military chips and the boards are on their way from JLC.
Yesterday I added to my current AD1862 the EUVL FC CeN IV. Has taken me some getting working correctly but thanks to Fran I have it plating music 🎶! Need to give it/me some time but it naturally sounds amazing. More to come. I think I ought to try a different digital front end. Been feeding my AD1862 with AK4118 from optical (Google Chromecast.) The convenience is killer but I may try an Rpi and Fifi soon.
My brother wants to try Qobuz 24/192 via USB. Can this be done on any of the NOS R2R chips here?
I am surrounded by Miro projects. 56,68, 1541A, 1862 stop clock!
Not sure if the PCM68 has been built yet but I have some ex military chips and the boards are on their way from JLC.
Yesterday I added to my current AD1862 the EUVL FC CeN IV. Has taken me some getting working correctly but thanks to Fran I have it plating music 🎶! Need to give it/me some time but it naturally sounds amazing. More to come. I think I ought to try a different digital front end. Been feeding my AD1862 with AK4118 from optical (Google Chromecast.) The convenience is killer but I may try an Rpi and Fifi soon.
My brother wants to try Qobuz 24/192 via USB. Can this be done on any of the NOS R2R chips here?
Attachments
Any official BOM yet?😆In the last few days I have been testing the promised TDA1540P
It works nicely, no audible digital distortion, no glitches. The sound is very dynamic (slightly harder with strong bass, the bass guitar is very much alive)
Power supply is compact and stackable. The input is standard I2S as always (but you need to programm the CPLD converter with my VHDL program, no worries - step-by-step tutorial will be included).
TDA1540 NOS DAC
I2S to TDA1540 converter for this DAC: I2S-TDA1540
Power supply is shared in the next post and PCB has the same dimension (can be stacked).
Null DC output voltage:
1. be sure that programmed I2S to TDA1540 converter is connected with TDA1540 DAC and I2S input source is turned ON
2. turn-on DAC and play some music, stop the music
3. measure DC offset between tpL and GND, null it with trimmer TR1
4. measure DC offset between tpR and GND, null it with trimmer TR2
5. the green LED should light up (output is active == no DC voltage on the output is present)
6. try the music on speakers or headphones
Measure it again after warm-up and check it in the future.
DC output voltage can fluctuate a few mV.
If TDA1540 DAC is turned ON with disconnected I2S input source (or the I2S source connection is lost), then DC on the output is present and DC protection kicks in (do not adjust the voltage this time, just connect the I2S input source and it resets to zero, this is normal function of TDA1540).
BOM example:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=495d7a1474
connectors 2-Pin, 3-Pin: https://www.aliexpress.com/item/4000867583795.html
R-Core transformer: https://www.aliexpress.com/item/4001293182295.html
relay if not available on mouser: https://www.tme.eu/sk/en/details/az850-12/miniature-electromagnetic-relays/zettler/

- NOS, without digital filter
- simultaneous input (with external I2S to TDA1540 converter)
- integrated DC output protection
I2S to TDA1540 converter for this DAC: I2S-TDA1540
Power supply is shared in the next post and PCB has the same dimension (can be stacked).
Null DC output voltage:
1. be sure that programmed I2S to TDA1540 converter is connected with TDA1540 DAC and I2S input source is turned ON
2. turn-on DAC and play some music, stop the music
3. measure DC offset between tpL and GND, null it with trimmer TR1
4. measure DC offset between tpR and GND, null it with trimmer TR2
5. the green LED should light up (output is active == no DC voltage on the output is present)
6. try the music on speakers or headphones
Measure it again after warm-up and check it in the future.
DC output voltage can fluctuate a few mV.
If TDA1540 DAC is turned ON with disconnected I2S input source (or the I2S source connection is lost), then DC on the output is present and DC protection kicks in (do not adjust the voltage this time, just connect the I2S input source and it resets to zero, this is normal function of TDA1540).
BOM example:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=495d7a1474
connectors 2-Pin, 3-Pin: https://www.aliexpress.com/item/4000867583795.html
R-Core transformer: https://www.aliexpress.com/item/4001293182295.html
relay if not available on mouser: https://www.tme.eu/sk/en/details/az850-12/miniature-electromagnetic-relays/zettler/
Attachments
PSU 1 for DAC TDA1540
78/79xx regulators from onsemi (MC78xx/MC79xx, be sure you get these).
You are working with mains voltage, so very careful because it can be deadly and no one is here responsible for your life and health
Build hints:
BOM example:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=49b4bec728
heatsink: I have this D01A https://www.avelmak.sk/index.php?lm=1435&pg=det&article=38184 (13.2 x 12.7 x 19 mm, 21K/W) ... you can find alternative on aliexpress or from another local distributor
connectors 2-pin, 3-pin: https://www.aliexpress.com/item/4000867583795.html
https://www.aliexpress.com/item/1005002952338852.html (30mm or 35mm M3 screw spacer)
https://www.aliexpress.com/item/1005004127890102.html (15mm M3 screw spacer)
https://www.aliexpress.com/item/1005003411992910.html (M3 screws)
maybe a few M3 gaskets ...
missing components can be found on tme.eu or from another distributor
- PCB has the same dimensions as DAC, so it can be stacked
- Grounds are already separated for best results (connected in DAC PCB)
78/79xx regulators from onsemi (MC78xx/MC79xx, be sure you get these).
You are working with mains voltage, so very careful because it can be deadly and no one is here responsible for your life and health

Build hints:
- start with diodes, resistors, connectors, LEDs, foil capacitors, big electrolytes
- install heatsinks on regulators and put them into PCB (let a small space between heatsink and PCB)
- triple check electrolytic capacitors polarity
- install AC wires from transformers (you can first try them and measure AC voltages)
- triple check everything (especially solder joints (cold joints, bridges), regulator ICs positions)
- put on safety glasses, turn it on and hide for a while (watch for smoke or explosions LOOL 🤣)
- if nothing bad happens, touch electrolytic capacitors if they are cold (touch also heatsink - it can be warm because there is small current consumption, but not very hot)
- now measure DC output voltages (and also AC input voltages)
- turn it on and off a few times, everything should work without further settings
BOM example:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=49b4bec728
heatsink: I have this D01A https://www.avelmak.sk/index.php?lm=1435&pg=det&article=38184 (13.2 x 12.7 x 19 mm, 21K/W) ... you can find alternative on aliexpress or from another local distributor
connectors 2-pin, 3-pin: https://www.aliexpress.com/item/4000867583795.html
https://www.aliexpress.com/item/1005002952338852.html (30mm or 35mm M3 screw spacer)
https://www.aliexpress.com/item/1005004127890102.html (15mm M3 screw spacer)
https://www.aliexpress.com/item/1005003411992910.html (M3 screws)
maybe a few M3 gaskets ...
missing components can be found on tme.eu or from another distributor
Attachments
Nice work!! 😊So NXP 1540, is that a current production chip? Or atleast more recent than Philips.?
I am surrounded by Miro projects. 56,68, 1541A, 1862 stop clock!
My brother wants to try Qobuz 24/192 via USB. Can this be done on any of the NOS R2R chips here?
I am not sure about this NXP print, it can be salute from "china clean factory" 🤣 I bought it on ebay, but works.
In my opinion it 24/192kHz will work on most DACs here, but only specified bits will be played (AD1862 and PCM63 plays 20-bits, AD1865 18-bits, PCM56 and TDA1541A only 16-bits, PCM TDA1540 only 14-bits of that recording 😊)
You can add unity gain buffer with passive I/V resistor to the GND (as you specified) ... but this approach does not have high reputation 🙂Is it possible to us a unity gain buffer as an output for AD1862?
Am I correct that I can use a resistor, say 2.7k, from pin 11 output to ground then use the voltage across this resister as input of the buffer?
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