@TNT
schematic is not in a state that can be judged right now.
output stage is not much different from what altor suggested.
We need to think about the Analog Switch IC VS Relay to be used for conversion, (I think relay is better.)
and it has not been decided which of the two functions to add (XLR or HP AMP).
I will post the full schematic once the component selection is confirmed.
schematic is not in a state that can be judged right now.
output stage is not much different from what altor suggested.
We need to think about the Analog Switch IC VS Relay to be used for conversion, (I think relay is better.)
and it has not been decided which of the two functions to add (XLR or HP AMP).
I will post the full schematic once the component selection is confirmed.
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Some of the partial schematics that you do post are hard to read because of their poor resolution and black background.
There is a problem printing pdf. I've moved this project to ORCAD X and I'm not yet familiar with it.
Should the holes for mounting on the CNC case be connected to the AGND plan? If anyone knows, please advise.
Not understanding the question and drawing 100% but I take you mean if metallized through PCB mounting holes should be connected to xGND? Will it be a class I or a class II device? Normally DIY and a metal casing means class I. Either choice has implications for the grounding scheme. Normally one leaves connectors floating from the casing and arranges grounding scheme on the PCB.
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@jean-paul I would say it's Class 2 since we'll be using a 5VDC supply that doesn't have a ground pin.
Can’t help with metal casing and class II. Sorry. Make sure you will have a way to direct leakage current to. No PE pin on PSU is awkward in cases when plugging stuff in and out. Just think of consequences of hot plugging hot pluggable HDMI 🙂 Also not the best scheme for mains filtering.
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Usually no. The best connection to the case is in the area of the output connectors.
But you can connect the mounting holes on the board through separate resistors (or solder bridges) and experiment - putting either 0 Ohm or nothing there.
Alex.
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The project was delayed due to personal reasons.
power supply Schema.
Added EMI filter module and diodes for prevent board destruction. Are there enough devices for safety?
(Reference error: RTC1->PTC1)
power supply Schema.
Added EMI filter module and diodes for prevent board destruction. Are there enough devices for safety?
(Reference error: RTC1->PTC1)
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PCBs are now being designed by experts.
@altor
Dear alex, I'd like to know a little more about the output stage. I bought Douglas' book to better understand small signal control,
and found some material on resistor noise and distortion.
What parts did you use? According to the a10s board pictures you posted,
some of the resistors look like they were specifically selected for different parts. (no values shown)
ps
I have some difficulty using high quality resistors for 1k33 or 1k78. Would it be okay to standardize all of them to 1k5 except 250R and 510R? (G=1)
@altor
Dear alex, I'd like to know a little more about the output stage. I bought Douglas' book to better understand small signal control,
and found some material on resistor noise and distortion.
What parts did you use? According to the a10s board pictures you posted,
some of the resistors look like they were specifically selected for different parts. (no values shown)
ps
I have some difficulty using high quality resistors for 1k33 or 1k78. Would it be okay to standardize all of them to 1k5 except 250R and 510R? (G=1)
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Input filter. Also made it possible to debug the snubber circuit for the switch node of the boost converter.
https://www.digikey.com/en/products/detail/panasonic-electronic-components/ERA-6AEB1781V/2025684
https://www.digikey.com/en/products/detail/susumu/RG2012P-182-B-T5/1240697
https://www.digikey.com/en/products/detail/susumu/RG2012P-1331-B-T5/1240674
https://www.digikey.com/en/products/detail/panasonic-electronic-components/ERA-6AEB1331V/2025673
Thin film 0.05-0.1% 0805
Alex.
Regarding Susumu RG, in my personal subjective opinion they are not always good for audio. In a 32-bit FIRDAC using RG resistors in the output array produced very weird sound, especially at bass frequencies. Really blurred bass. My best guess is that the resulting sound was of 1/f current noise intermodulated with the audio signal. Yageo RT sounded much better, and was one of the best. SMD metal foil sounded the most clear by a slim margin over the Yageo. It seems like metal film resistors like other things involve engineering tradeoffs. Lowest current noise may not the most important spec for RG, especially since Susumu has a line of low noise resistors aimed specifically at audio applications. However, those audio resistors aren't claimed to be especially optimized other than for low current noise.
Thanks. I also read the thread about FIR DACs and remember the content.
Foil resistors would be nice, but they are too expensive.
Someday I'd like to build a DAC using Texas Components foil resistors.
I agree. The public information is too sparse to specify a special purpose.
Foil resistors would be nice, but they are too expensive.
Someday I'd like to build a DAC using Texas Components foil resistors.
The build delay is entirely due to the PCB layout.
I chose someone with enough experience and was confident he would do a better job than me.
However, the layout was not optimized for performance and the placement of all components,
including R and C for symmetrical circuits, is not symmetrical or has mismatched spacing. I am spending almost 3 weeks to direct everything.
I've seen countless PCBs and I've never seen one with such a disorganized component layout.
It's as if it was blown in by the wind and stuck...
with the grid feature I don't think it's going to be disorganized at all.
I chose someone with enough experience and was confident he would do a better job than me.
However, the layout was not optimized for performance and the placement of all components,
including R and C for symmetrical circuits, is not symmetrical or has mismatched spacing. I am spending almost 3 weeks to direct everything.
I've seen countless PCBs and I've never seen one with such a disorganized component layout.
It's as if it was blown in by the wind and stuck...
with the grid feature I don't think it's going to be disorganized at all.
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