Hello all,
to be honest this is my first real post on diyaudio.com although I'm a passive reader for quite some time.
I have had some spare time due to the current world wide situation.
So I was thinking about to start a project to aquire new skills and I have had laying around some old tubes, housings... which were not in use.
So I downloaded KiCad and Micro-Cap 12 (which is available for free now, as you might know)
At the end I came up with an MM phono stage using 5751 and 6922.
The MC stage will be some sort of Xono MC stage (I'm not quite sure).
For the line stage I decided to use 5687 followed by an Allen Wright SLCF with 6922.
Power supply will be separated and some shunt regs a la Salas will be used if he don't mind.
Since I like it comfortable, I planned to make everything controllable and switchable (source, phono loading, volume etc) with a µC and also via a remote control.
After the first steps in KiCad I finished a "controller board" and sent the gerber files to a PCB manufacturer.
Please keep in mind that I am abolutely not an professional and I am just learning by doing.
Hence any feedback of you is very welcome!
Next step would be to finish the "input board". During the manufacturing process I would have some time to finish the µC routines.
Here I would like to ask for your help 🙂
The "input board" should include source switching, phono loading switching and the volume control with the muses 72320 chip. (You can find the first schematic of the muses chip in the attachment)
Following questions showed up, where I have no clue:
Muses 72320:
1.) How important is quality of the +/-15V supply for the chip?
2.) Would a +/-12V supply have major disadvantages?
3.) Would be some kind of galvanic isolation helpful for the SPI bus? (If so, which chip would you recommend?)
4.) Looks the schematic in general "okay" for you?
Source switching:
I am still thinking about what would be the best way for source selection.
I mean, for example the GND handling. Should I also disconnect the GND of unused sources? If so, which trouble I am running into? (mute relays etc. are already included)
Or would it just be okay to switch unused sources via a defined resistor to GND?
For the beginning this would be my first questions to be able to continue with this project.
I'm sure it will be a long way and I am very exited if I will finish it. 😀
So thank you very much for your help and your support in advance!
Please stay safe!!!
Falk
to be honest this is my first real post on diyaudio.com although I'm a passive reader for quite some time.
I have had some spare time due to the current world wide situation.
So I was thinking about to start a project to aquire new skills and I have had laying around some old tubes, housings... which were not in use.
So I downloaded KiCad and Micro-Cap 12 (which is available for free now, as you might know)
At the end I came up with an MM phono stage using 5751 and 6922.
The MC stage will be some sort of Xono MC stage (I'm not quite sure).
For the line stage I decided to use 5687 followed by an Allen Wright SLCF with 6922.
Power supply will be separated and some shunt regs a la Salas will be used if he don't mind.
Since I like it comfortable, I planned to make everything controllable and switchable (source, phono loading, volume etc) with a µC and also via a remote control.
After the first steps in KiCad I finished a "controller board" and sent the gerber files to a PCB manufacturer.
Please keep in mind that I am abolutely not an professional and I am just learning by doing.
Hence any feedback of you is very welcome!
Next step would be to finish the "input board". During the manufacturing process I would have some time to finish the µC routines.
Here I would like to ask for your help 🙂
The "input board" should include source switching, phono loading switching and the volume control with the muses 72320 chip. (You can find the first schematic of the muses chip in the attachment)
Following questions showed up, where I have no clue:
Muses 72320:
1.) How important is quality of the +/-15V supply for the chip?
2.) Would a +/-12V supply have major disadvantages?
3.) Would be some kind of galvanic isolation helpful for the SPI bus? (If so, which chip would you recommend?)
4.) Looks the schematic in general "okay" for you?
Source switching:
I am still thinking about what would be the best way for source selection.
I mean, for example the GND handling. Should I also disconnect the GND of unused sources? If so, which trouble I am running into? (mute relays etc. are already included)
Or would it just be okay to switch unused sources via a defined resistor to GND?
For the beginning this would be my first questions to be able to continue with this project.
I'm sure it will be a long way and I am very exited if I will finish it. 😀
So thank you very much for your help and your support in advance!
Please stay safe!!!
Falk
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Last edited:
Hi Falk, here my 2cents as I am currently also working on a preamp bases on the Muses chip.
1. I have about the same question. I’m planning for a CRC followed by lm317/337 regulators for +-15v
2.datasheet is mentioning minimum +-8.5v. 12v should be fine
3.I would do this. Search for “muses volume”, thread by Meldano, in his muses circuit manual he is referring to a particular chip to do this.
4. Schematic looks 95% same as what I have currently. I also uses separate audio ground for left and right channel.
Regards
Hi Bensen,
thank you, this already helped me!
I think, I will do the same. Since I still have some space on the "MC-Phono Board" I think I will also implement a headphone amp on it and use the+/-15V for it also.
I am just looking at Meldanos thread to find which SPI isolator he is using.
Looking at the schematic in the documention I can't find an isolator IC.
but I think I will figure it out, will not be a big problem.
May I ask how you realise the source selection for your pre amp?
Best regards,
Falk
thank you, this already helped me!
I think, I will do the same. Since I still have some space on the "MC-Phono Board" I think I will also implement a headphone amp on it and use the+/-15V for it also.
I am just looking at Meldanos thread to find which SPI isolator he is using.
Looking at the schematic in the documention I can't find an isolator IC.
but I think I will figure it out, will not be a big problem.
May I ask how you realise the source selection for your pre amp?
Best regards,
Falk
Adum1250?
Source selection wil likely be a rotary switch combined with a 7segment driver to make the selected channel visible. Have to create the schematic yet, should not be to complex I think.
Source selection wil likely be a rotary switch combined with a 7segment driver to make the selected channel visible. Have to create the schematic yet, should not be to complex I think.
Hi Benson,
sorry for the late reply.
I finished my input board layout with the muses chip so far.
Separate audio GND for left and right channel sounds interesting, but I am not quite sure if it is possible / makes sense with one muses 72320 for unbalanced inputs.
I put left/right channel GND together right at the input.
I am not sure, if I should redesign the board for separeted GNDs
Can you confirm that the muses chip handles the GNDs separated?
How about your progress?
Best regards,
Falk
