DIY DAC with premade PCBs, some questions

With all these things you can do to tweak performance, many of them are less audible until you fix the biggest problems first. Once you get a pretty clean system, then the smaller level problems start to become more noticeable. Its like, now they are your biggest remaining problems.
i also already expierenced it, specially if you wanna try to filter EMI

If you read through my chronology of powering and driving Marcel's RTZ FIRDAC, you will see the order I recommended for that. Start with power and clean USB. The first example I give is what I called the worst possible. It isn't really. But I explain what's wrong with it, so a reader will hopefully get the right ideas. I suggest to go study that series of posts and pics, since I see no point it writing it all up again here. https://www.diyaudio.com/community/...t-register-firdac.379406/page-94#post-7457164
thanks for reference, i will read trough :)
 
Don't see an electrostatic shield shown on the torriod transformer schematic. There should be one between the primary and secondary to prevent EMI/RFI from coupling capacitively between the windings.

Also, what is the magnetic shield can made of? Soft steel? How thick is the metal, 18 gauge?
 
i think 4 seperated power supplys for digital side should be enough..
You need 2 isolated +5v supplies just for the USB board, if you want to do it right. They don't all need to be expensive but they do need to have their own isolated transformer windings. You can use NJM7805 for the USB board supplies if you want. I2SoverUSB has secondary regulators anyway.

Then if you want an external clock board, you will need another isolated supply for it. Maybe another isolated +5v primary regulator for more of the dac low voltage supplies. The secondary dac regulators should designed into the dac board.

All this stuff doesn't have to be the best, just good enough and wired up properly.

What is critical are the two Vref supplies, one for each channel. Shunts are probably best there. Ideally they should also be designed onto the dac board, or at least very close to the dac board. No more than a few CM of wire if you can help it.

Also if you have a stereo discrete output stage like I do then you need four isolated shunt supplies for that. You can get by with four isolated LT1083 supplies for awhile, but eventually you might want to move up to good shunts for that.
 
ah thank you, the normal audio grade ones seem fairly well priced, i will probably order there

i guess the 50VA 2x10V ones for digital and one double transformer depending on the output stage
i guess i could also use 2x15V universally... so i might change the output stage later and its combatible up to 15V dc

You need 2 isolated +5v supplies just for the USB board, if you want to do it right. They don't all need to be expensive but they do need to have their own isolated transformer windings. You can use NJM7805 for the USB board supplies if you want. I2SoverUSB has secondary regulators anyway.

Then if you want an external clock board, you will need another isolated supply for it. Maybe another isolated +5v primary regulator for more of the dac low voltage supplies. The secondary dac regulators should designed into the dac board.

All this stuff doesn't have to be the best, just good enough and wired up properly.

What is critical are the two Vref supplies, one for each channel. Shunts are probably best there. Ideally they should also be designed onto the dac board, or at least very close to the dac board. No more than a few CM of wire if you can help it.

Also if you have a stereo discrete output stage like I do then you need four isolated shunt supplies for that. You can get by with four isolated LT1083 supplies for awhile, but eventually you might want to move up to good shunts for that.
really curious what the seperate power supplys do tho, do i have to be careful with ground connections to not mess things up? i guess its best to seperate it as much with i2s isolators ?

i kinda wanna keep the size small thats why i preferably wanna do just 3 transformers, unfortunaly toroidy is just available as max 2 secondarys

well in theory for me it would be probably
2x 5V usb card
1x 5V dac
1x5V hardware resampler
(maybe) 1x5 or 3.3V for clocks

2x5 or up to 15v output stage

i guess i could play it safe and reserve 2x 5V for future upgrades or make it 6 in total, would end up being 4 transformators ... not that bad depending on the size
price and size wise i would go for 50VA, i can do the output stage transformer in 100VA, i hope this works out and being not so beefy gets compensated by supercapacitors...
 
regarding the LT1083 board..

i might do a custom board with rectifier and caps on board + 5 or so sockets for all these LM337 combatible regulators like this: https://www.audiophonics.fr/en/volt...17-discrete-voltage-regulator-5v-p-13304.html

this would allow to easly compare different voltage regulators to eachother and i could listen if i hear a difference if i stack more than one, what you think? i kinda like the idea..

maybe yet easier is to buy a rectifier and smoothing board from aliexpress and making just an socket board for these regulators
 
i might do a custom board with rectifier and caps on board + 5 or so sockets for all these LM337 combatible regulators like this:
It might be a wiser idea to start with decent off the shelf boards that are proven to be quite good, this will give you a fast reference baseline, instant satisfaction/dac tests and you can always tinker with custom, boards afterwards, while listening to great music through an existing system. I have never attempted a custom board but even if I could (which currently am ill equipped) I would go the above route anyhow.
 
Also, what is the magnetic shield can made of? Soft steel? How thick is the metal, 18 gauge?
GOSS - grain oriented silicon steel. This manufacturer where I buy wraps a couple of layers around the "belly" of the transformer. I put them very close to the PCBs, there is no trace of hum.
 

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It might be a wiser idea to start with decent off the shelf boards that are proven to be quite good, this will give you a fast reference baseline, instant satisfaction/dac tests and you can always tinker with custom, boards afterwards, while listening to great music through an existing system. I have never attempted a custom board but even if I could (which currently am ill equipped) I would go the above route anyhow.
well i thought there is not much to it other than rectifier and some smoothing caps, which i can choose better quality parts

tho im not sure how i implement the LM337 the best, there seems to be kind of issues parralleling more than one and i have todo a little circuitr around the sockets

PS - Miro and Abraxalito, the latter including good PCM56 & PCM58 boards that are not advertised in a DIYA thread, offer great DIY dacs and are cost effective. Check them out. Best of luck!
yes i already looked trough their boards, still unsure if in wanna go the akm route with hardware resampler route or try nos, a try its definitely worth it in both cases imo
 
i think the aliexpress shield cans are probably steel or iron

i got an nice offer on this case -> https://modushop.biz/site/index.php?route=product/product&path=120_246_248&product_id=89
tho it has steel sides, is this an big issue? ... the deal is to good tho 70 euro including shipping and the inner baseplate, not used
The magnetic armor should be Iron or Steel with as little carbon content as possible.

I have exactly that Modushop box, it is intended for Miro NOS DAC with PCM63P-Y. It is quite large, there is room for a complete DAC with all digital inputs, 3 transformers, many power supplies (aprox. 8pcs) + tube I/V stage. :ROFLMAO:
 
I have exactly that Modushop box, it is intended for Miro NOS DAC with PCM63P-Y. It is quite large, there is room for a complete DAC with all digital inputs, 3 transformers, many power supplies (aprox. 8pcs) + tube I/V stage. :ROFLMAO:
i said before that i search something beside the modushop boxes but the modushop cases seem well designed after all...
is it rigid? how does it resonante once you tap the top? (do you have the steel side/top/bottom/back version?)

i really like the inner baseplate design... way easier to DIY imo, tho im a little concerned about the rigidity of the baseplate... i dont want it to resonate like hell (EDIT: a easy fix might be to put something between baseplate and bottom so the baseplate is under "pressure" from the bottom..)

and i have to see how i modify the 10mm front plate.. i probably will send it somewhere to customize once im done with the build (or i might do all settings in LED with microcontroller so i dont need to make large display cutouts...)
 
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This is how things stand, the front plate and sides are rigid Aluminium, the back, bottom and top are made of thin sheet steel. That can ring. Personally, I prefer thicker plates made of Aluminum, but I got this extra cheap so I'm not complaining. I will reinforce it with Alu L profiles. I also have some Alu U profiles, 10x10mm and 15x15mm, that's also good for reinforcement. I didn't get the perforated bottom plate, I bought the box from a friend.

On the front the NIXIE tube display should come, so the front plate has to go to CNC machining, but we'll see how it turns out. Maybe it won't be NIXIE, I don't know yet. Power switch will be at the bottom plate, invisible. :unsure:

To tell you the truth, I used to buy better boxes from the Chinese (3-4mm Aluminum whole box), but now the postage is abnormally high. For heavier boxes, the postage is more expensive than the box itself. :rolleyes:
 
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This is how things stand, the front plate and sides are rigid Aluminium, the back, bottom and top are made of thin sheet steel. That can ring a bell.
ahh ****.. tho maybe this can be damped with bitumen for the large panels

but the one i bought has also u shaped steel sides from the pics
(edit: it must be this one: https://modushop.biz/site/index.php?route=product/product&path=171_229&product_id=158 )

Personally, I prefer thicker plates made of Aluminum, but I got this extra cheap so I'm not complaining.
yea kinda in the same position :D

im sure it can be tweaked so im not complaining! .. i would have paid ATLEAST 100-120+ for that size of case with shipping etc got it now as new for 70 including the baseplate, including shipping... and i like the looks of it, it looks simple but not "cheap"

and good thing about the modushop cases is they have replacement parts and may can customize something if you really want to...
 
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To tell you the truth, I used to buy better boxes from the Chinese (3-4mm Aluminum whole box), but now the postage is abnormally high. For heavier boxes, the postage is more expensive than the box itself. :rolleyes:
yea i noticed these shipping cost on aliexpress.. they seem to be around 30-100 euro shipping cost, its not really worth it, in general aliexpress isnt "that" much cheaper like few years ago...

but still... aliexpress is atleast 2/3 of what i pay in germany for electronics stuff, it just becomes sketchy with fake parts etc.. (but usually i can buy the exact same board in germany, just more expensive...)
 
There are still a lot of fake parts from the Chinese, and Aliexpress/ebay is to blame for that, which allows such things, that is, allows them to close a notorious company after a while, and immediately open a new one under a different name. And when we catch them in a scam, we only get a refund but no penalty to stop them from doing such things. I am surprised that their big manufacturers of original and licensed parts do not protest because it gives them a bad image. As long as there is no punishment, anyone can do what they want.