After a period of health issues and thinking diyaudio should better be left to fresh new DIYers (where are they?) I decided to ask if my diyaudio.com account could be enabled again. As doing nothing and not being able to do much creates boredom one returns to old habits but then adapted to the situation. A brand new but damaged AK4493SEQ based SMSL SU-1 (defective output stage) was about to be recycled but then I thought to do something useful with it. Also left were a pair of Haufe quality 1:1 line transformers worth more than the entire DAC. This way the output stage is nearly completely passive and also now the possibility occurred to have balanced outputs via XLR. I added a SPDIF transformer and of course USB bus power was interrupted and a very good ultra low noise linear PSU was used instead. Since there was no opamp output stage anymore the original internal +/- 12V switcher was sent to where it belongs. On the 5V input pins of the retired switcher a Molex KK was fitted to power the power on LED.
All work was done with hand tools. All functionality of the SU-1 is retained except the source indication LEDs that are located on the main PCB are now invisible. The power switch switches the device from standby to powered on with a white glowing ring and a short touch switches inputs.
Publishing is only to show what can be done to make a SU-1 really shine. Due to my non optimal situation a perfect esthetical finish was not possible. SU-1 absolutely benefits from an external linear PSU anyway. Although it is still in testing phase (and not 100% electrically safe, I know) it already sounds better than an Eversolo DMP-A6. To solve is a slight humming issue when no music is playing.
All work was done with hand tools. All functionality of the SU-1 is retained except the source indication LEDs that are located on the main PCB are now invisible. The power switch switches the device from standby to powered on with a white glowing ring and a short touch switches inputs.
Publishing is only to show what can be done to make a SU-1 really shine. Due to my non optimal situation a perfect esthetical finish was not possible. SU-1 absolutely benefits from an external linear PSU anyway. Although it is still in testing phase (and not 100% electrically safe, I know) it already sounds better than an Eversolo DMP-A6. To solve is a slight humming issue when no music is playing.
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Really glad you’re back Jean-paul!
All the knowledge you shared is always valuable!
Take care of yourself ! 👍
All the knowledge you shared is always valuable!
Take care of yourself ! 👍
Thank you!
I can not say anything if I will be here often. Still in healing mode. Since I had nothing else to do I spent many a night with KiCAD to teach myself drawing PCBs again. Maybe some real DIY stuff to share.
I can not say anything if I will be here often. Still in healing mode. Since I had nothing else to do I spent many a night with KiCAD to teach myself drawing PCBs again. Maybe some real DIY stuff to share.
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Welcome back jean-paul. 🙂
Really good that you are back, and you should change your avatar picture.
Really good that you are back, and you should change your avatar picture.
Hi Tombo56, thank you. I think you will like the fact that I built your R21. Not a cheap design to build and I was about to draw a new PCB for it but I persevered. Still contemplating to redesign with onboard rectifier and filter caps so as a standalone 1 board LDO.
edit: yes embedded would be best but we are not living in Utopia 🙂 My idea was Schottky rectifiers, CLC filtering and of course output caps. Just a low drop low loss amplifier PSU.
edit: yes embedded would be best but we are not living in Utopia 🙂 My idea was Schottky rectifiers, CLC filtering and of course output caps. Just a low drop low loss amplifier PSU.
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That’s great to hear. As an add-on module, new PCB is not required, but for embedded design it would bring better performance because of better grounding.
Edit: I’m contemplating new design as well, with complete active rectification and regulators on one PCB. It will have brutal PSRR up to MHz range.
Edit: I’m contemplating new design as well, with complete active rectification and regulators on one PCB. It will have brutal PSRR up to MHz range.
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The minimum to have SU-1 performing better (arguably as many things are already excellent measurement wise) is to interrupt USB bus power and to add an external linear 5V PSU preferably with excellent connectors and not the miscast DC jacks "because these are standard". They are standard because they are cheap, not because they are good. Just like USB bus power is cheap and not the best way, switchers are cheap but often not the best way etc. etc. The influence of having clean power in the total should not be underestimated.
On the other hand even simple quality parts today are often more expensive that the device itself. At least that is the situation here. It all depends what challenge the owner sees in getting the best out of a device.
On the other hand even simple quality parts today are often more expensive that the device itself. At least that is the situation here. It all depends what challenge the owner sees in getting the best out of a device.
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Nice to see you back!
What can be done to this one do you think... compared to SU-1... ?
https://www.diyinhk.com/shop/outlet/189-768khz32bit-ak4493seq-dac-bare-pcb-i2sdsd-input-65x65.html
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What can be done to this one do you think... compared to SU-1... ?
https://www.diyinhk.com/shop/outlet/189-768khz32bit-ak4493seq-dac-bare-pcb-i2sdsd-input-65x65.html
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This one too, also sleeps in my garage with good Vref it should be GOOD....🙂
The card allows all the possibilities .....power supply output stage... Super good base for DIY!
And..... good sound from AKM
The card allows all the possibilities .....power supply output stage... Super good base for DIY!
And..... good sound from AKM
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Welcome back, Jean-Paul, and all the best to you!
Nice project, well done as usual
Claude
Nice project, well done as usual
Claude
HI J-P. Glad to read you.
Same story than your here with Kickad at nigth 🙂 !
Easy to learn, has just some rare limitations like yo remove the solder mask of a guard ring or link different gnd layers w/o big jumpers. The through holes interfaces between layers is also not very straigth forward. But anyway micro vias are not accepted at JLPCB 🙂
Permitted me to "publish" here my first pcb shared with others. Subbu dac inspired me 🙂
Same story than your here with Kickad at nigth 🙂 !
Easy to learn, has just some rare limitations like yo remove the solder mask of a guard ring or link different gnd layers w/o big jumpers. The through holes interfaces between layers is also not very straigth forward. But anyway micro vias are not accepted at JLPCB 🙂
Permitted me to "publish" here my first pcb shared with others. Subbu dac inspired me 🙂
What is the reason for this? Removing the mute chip from the signal path? And in general, how does the SU-1 behave without this chip: any noise, clicks when switching frequencies, something else? Thanks.
I've had a similar idea to use(repurpose) the little SU-1 DAC. I'm toying with the idea of incorporating it into a custom preamp that would then allow for digital inputs, along with analog. It's so small it would comfortably fit into another enclosure as well. I could then include a better analog PSU into the design. Maybe I'll make it a 2024 holiday project. 🙂 At $79USD it's a true bargain. BTW, tariffs (consumer tax) are likely coming (to USA) so better buy our China parts now. 🙁
To clean up the signal path and as things was broken between the output and the dac chip on his DAC, this had to go also. A semiconductor relay at the outputs are never welcome but sometimes necessary due to blips and blopps when e.g, changing Fs or switching off an on the unit - thats why they are there. And thats what you will get most probable if you remove them.
I certenlky concur on the benefit if a silent and steady power source - it is important. I changed the Vref caps to the double size and found that as important as the power source. I also decoupled the power to the OP-amp with a couple of 10uF Wima.
They now sound very nice indeed - I use two in an active 2-way system.
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