DIY DAC with premade PCBs, some questions

Jump to Latest
G

Ghoostknight

Member
Joined 2022
#1
Hello,

i would like to know if people who tried to build a dac with multiple standalone pcb's (spdif to i2s converter board, i2s to dac board... etc) what the expierence is and specially if they compared these dacs with readymade dac's, is it worth it?
Are there particular links/pcb's/vendors you can recommend?

in my mind i have a concept of -> usb to i2s board -> i2s to NOS dac board plus some nice power supplys, preferably battery or super capacitor
i also saw the protodac (its a nos dac) which i thought of making my own pcb with amanero card support, might be even the perfect starter project

best regards
 
#3
All my DACs are built like this, from multiple sub-boards. Definitely worth it.

Protodac uses multiple paralleled TDA1387s, you might find - as I have on similar designs - that using TDA1545s instead allows you to get better sound as they're capable of higher output current (hence improved SNR). DACs using those cheap 8pin DACs do make excellent starter projects as they do punch above their modest weight, sonically. My blog post on TDA1387 vs TDA1545 you might find relevant.
 
#4
I used an SPDIF to I2S board from eBay and read the I2S data with an SPI port on a PSOC4 which then directly drove a R - 2R resistor ladder. It made for a decent DAC with high jitter and about 12 bits of real resolution. I had many people in the local club that wanted to build one after listening to it.
 
#5
abraxalito said:
All my DACs are built like this, from multiple sub-boards. Definitely worth it.
Click to expand...
well for me the step to start doing it is that i can indiviually upgrade one unit instead of buying one overpriced readymade unit


abraxalito said:
Protodac uses multiple paralleled TDA1387s, you might find - as I have on similar designs - that using TDA1545s instead allows you to get better sound as they're capable of higher output current (hence improved SNR). DACs using those cheap 8pin DACs do make excellent starter projects as they do punch above their modest weight, sonically. My blog post on TDA1387 vs TDA1545 you might find relevant.
Click to expand...
thanks i will look into your comparison

----

i started hqplayer since a few days ago, the filters actually matter and upsampling pcm or even upsampling to dsd improves also sound quality... so now im kinda looking into a new setup somewhat preferably DSD optimized (or atleast trying out NOS dacs, i dont think the lost bit resolution outweights the sonic improvement by no crappy filter or pcm to dsd conversion inside sigma delta chips)
 
#8
abraxalito said:
DSD and NOS are pretty much polar opposites in the digital audio world. DSD is heavily OS so a DAC board which is NOS and can accept DSD would probably be two separate DAC designs on a single PCB.

I think the original DSC1 (a FIR-DAC back-end for DSD) had an AD844 on-board so would qualify as 'DSD with one opamp' : https://www.audiodesignguide.com/DSC1/index.html
Click to expand...
oh... hmm im not sure on the dac yet
im kinda unsure wether the nos vs os is the only factor or if R2R or something similar also has its own flaws (beside bits..) and it would still be more beneficial to go with something new for other reasons than nos vs os

if i would use this board: https://www.ebay.de/itm/255930571388 .... could i remove the clocks and feed external clock signals to the right pad, so i dont need to reclock later? or would a ian canada fifopi still be beneficial?
i guess this would also eliminate the need for the more expensive amanero modules with better clocks?
 
#10
Ghoostknight said:
...unsure how good all these chinese pcb's are...
Click to expand...
Not very good. DACs need to be on at least a 4-layer PCB, but the low-cost Chinese boards are usually only 2-layer. A dac also needs two precision references: a clock, and a reference voltage. Low cost dac boards usually don't do very well in either regard. Its more like in order to make DAC boards that can sell for a few 10's of dollars, the designers have to cut corners any way and every way they can possibly think of. All the parts except the dac chip are either the cheapest possible and or fakes of respected brands. Generally the low-cost boards can take substantial time, effort, and money to get sounding decent. Usually in the end its cheaper and better to get a Topping or SMSL as your budget allows. OTOH, if you want to start learning about dac building and reverse engineering, the low-cost dacs can sometime be a useful starting point for learning. Need a scope though, which is essential.
 
#12
There are some dac projects here in the forum. There are Abraxalito's designs, there is the AD1862 thread, and there is MarcelvdG's RTZ FIRDAC. IIUC, boards and or Gerbers are available for all of them.

Regarding DIYINHK, some of their boards were pretty bad in the past. Since then a few people have reported that the newer 4-layer boards are better sounding.
 
#13
Markw4 said:
Regarding DIYINHK, some of their boards were pretty bad in the past. Since then a few people have reported that the newer 4-layer boards are better sounding.
Click to expand...
yea i heared some of the bad reviews

i think i might get happy with http://jlsounds.com/ak4493.html + ian canada's output stage... this also allows me to look to maybe design my own dac or output board in the future, this seems like a good way to not rely on china boards, tho i dont know how either measures, same as with china boards but better reputation

thanks for the "simple dsd converter" tip, this seems like the second revision of DSDit with a FPGA... im looking into getting one board

with the usb im not sure yet, i still have todo some research on how the fpga board works, either the cheapest amanero board from aliexpress + reclocking or also the jlsound usb board, many seem to like it and its one of the only ones offering isolation

Then the big question... power supply... this gets messy quick with a few boards... i need probably 3-4x 5V and +/- 12V
whats your expierence with power supplys @Markw4 ? i have some china supercapacitor filters i kinda like and also a fan of battery operated tho cheaper is probably the transformer + regulators
 
#14
Ghoostknight said:
...i still have todo some research on how the fpga board works...
Click to expand...
I use it along with I2SoverUSB. What do you want to know? Or what will you "research?"

If you are thinking you can use a cheap USB board along with the FPGA DSD converter, then reclock to make it all good, it won't work. Asynchronous USB along with a synchronous PCM->DSD256 converter needs to be on a single clock domain. The clocks in the USB board, or else external clocks fed into the USB board will determine the quality of the clock domain. You can only reclock to the master clock of that domain. If its a clock that came with a Chinese USB board then that will be the master clock you use to reclock with. Easy to fix though, just throw away the cheap USB board and get a proper one.

In addition, if you would do some "research" you would know that only I2SoverUSB includes galvanic isolation from the USB bus. Did you read what a difference that isolation made to Marcel's RTZ FIRDAC? Switching from Amanero to I2SoverUSB made what sounded like about 95% of the distortion or noise that sounds like distortion go away. Very substantial improvement.

Regarding power supplies, I use transformers and regulators. However IME it has to be done a certain way for best results. So far I get the impression you would like to find a way to get by doing it for cheap? If so, you can use transformers, batteries, super caps, whatever, and it will still sound bad. Again, how good a dac sounds depends mostly on the surrounding circuitry, and that's where much of the cost is. Maybe it will be best if I leave off here and you can get other people's opinions about that.
 
Last edited:
#15
Markw4 said:
If you are thinking you can use a cheap USB board along with the FPGA DSD converter, then reclock to make it all good, it won't work. Asynchronous USB along with a synchronous PCM->DSD256 converter needs to be on a single clock domain. The clocks in the USB board, or else external clocks fed into the USB board will determine the quality of the clock domain. You can only reclock to the master clock of that domain. If its a clock that came with a Chinese USB board then that will be the master clock you use to reclock with. Easy to fix though, just throw away the cheap USB board and get a proper one.
Click to expand...
yea that was one of the things, tho i can still FIFO/Reclock after the pcm2dsd fpga board, no?

Markw4 said:
In addition, if you would do some "research" you would know that only I2SoverUSB includes galvanic isolation from the USB bus. Did you read what a difference that isolation made to Marcel's RTZ FIRDAC? Switching from Amanero to I2SoverUSB made what sounded like about 95% of the distortion or noise that sounds like distortion go away. Very substantial improvement.
Click to expand...
yea i noticed this... question is if a i2s isolator after the usb receiver would be similar?

Markw4 said:
Regarding power supplies, I use transformers and regulators. However IME it has to be done a certain way for best results. So far I get the impression you would like to find a way to get by doing it for cheap? If so, you can use transformers, batteries, super caps, whatever, and it will still sound bad. Again, how good a dac sounds depends mostly on the surrounding circuitry, and that's where much of the cost is. Maybe it will be best if I leave off here and you can get other people's opinions about that.
Click to expand...
no not for "cheap" lets just say i try to find something that can compete with much more expensive dacs for way less (specially speaking about supercapacitors and battery power supplys here, i probably go with ian canadas modules but i have to see)

what i wanna avoid tho.... is spending 2/3 of the money on the power supply, which is quiet easy todo
 
#16
Ghoostknight said:
...can still FIFO/Reclock after the pcm2dsd fpga board, no?
Click to expand...
If you use I2SoverUSB you can optionally clock it from external clocks, or else you can run it through a FIFO buffer in a different but very close frequency clock domain. IME that can work very well, but its probably something down the road for you. More money and more complications.

However, I2SoverUSB has pretty decent clocks and can export those clock signals so you can use them for reclocking if you want.

As an aside, recently I designed an experimental external clock board that uses Accusilicon clocks divided by 2 to produce 22/24MHz audio clock frequencies. Clock frequencies can be switched remotely by the USB board as needed. There are multiple clock outputs so that, say, for example, a separately buffered clock signal can be used for things such as reclocking. It can also export buffered 45/49MHz clocks in order to clock I2SoverUSB with external clocking. Not clear if I will be able to post that design to the forum, will have to check to see if it would be allowable under my NDA. If I can maybe I will post the KiCad files. The concept is pretty obvious thing to do, don't know why nobody hasn't done one of this particular type before. Among other thing there are no ferrites, and no C-II bypass caps. It sounds pretty much like SOA clocks except for a little more blur effect due to the less than SOA phase noise. IME its probably closer to the sound of SOA clocks than any other off-the-the shelf audio clock design I have tried so far. That said, I am not equipped to take phase noise measurements here so what I am describing is subjective opinion only. One other thing about the board is that it could probably also work with Iancanada 45/49MHz clocks (which I have not tried). If someone wants better than a clock board such as the one I just described, then there are always higher end solutions that can be incorporated down the road when maybe there is more budget for clocking. TheWellAudio and AckoLabs are two sources of SOA clock stuff that I have tried and still use.

Regarding power supplies, for certain critical things such as DAC Vref you might want to use good shunt regulators, but they need to VERY close to the dac chip. For most things that isn't necessary. For most things I use low cost Aliexpress regulator boards for primary regulation, then use local secondary regulators on the dac board for specific groups of loads. Each primary regulator needs its own dedicated transformer winding. Each primary regulator has its own dedicated ground or common terminal that is only connected to other power supplies ONLY at the load (the dac board). No transformer windings with center taps are used. No negative regulators are used either. Negative rails, where needed, are implemented with positive regulators used "up side down." That is to ensure that + and - rails have the same power supply characteristics, such as output impedance versus frequency, etc. Matched rail characteristics are believed by some people to provide better performance with music signals.
 
Last edited:
  • Like
Reactions: mamocel
#17
Markw4 said:
Regarding power supplies, for certain critical things such as DAC Vref you might want to use good shunt regulators, but they need to VERY close to the dac chip. For most things that isn't necessary. For most things I use low cost Aliexpress regulator boards for primary regulation, then use local secondary regulators on the dac board for specific groups of loads. Each primary regulator needs its own dedicated transformer winding. Each primary regulator has its own dedicated ground or common terminal that is only connected to other power supplies ONLY at the load (the dac board). No transformer windings with center taps are used. No negative regulators are used either. Negative rails, where needed, are implemented with positive regulators used "up side down." That is to ensure that + and - rails have the same power supply characteristics, such as output impedance versus frequency, etc. Matched rail characteristics are believed by some people to provide better performance with music signals.
Click to expand...
which aliexpress regulator you use? i probably would aim for LT3045

Markw4 said:
If you use I2SoverUSB you can optionally clock it from external clocks, or else you can run it through a FIFO buffer in a different but very close frequency clock domain. IME that can work very well, but its probably something down the road for you. More money and more complications.

However, I2SoverUSB has pretty decent clocks and can export those clock signals so you can use them for reclocking if you want
Click to expand...
i have to see how i would do it but probably step by step

Markw4 said:
As an aside, recently I designed an experimental external clock board that uses Accusilicon clocks divided by 2 to produce 22/24MHz audio clock frequencies. Clock frequencies can be switched remotely by the USB board as needed. There are multiple clock outputs so that, say, for example, a separately buffered clock signal can be used for things such as reclocking. It can also export buffered 45/49MHz clocks in order to clock I2SoverUSB with external clocking. Not clear if I will be able to post that design to the forum, will have to check to see if it would be allowable under my NDA. If I can maybe I will post the KiCad files. The concept is pretty obvious thing to do, don't know why nobody hasn't done one of this particular type before. Among other thing there are no ferrites, and no C-II bypass caps. It sounds pretty much like SOA clocks except for a little more blur effect due to the less than SOA phase noise. IME its probably closer to the sound of SOA clocks than any other off-the-the shelf audio clock design I have tried so far. That said, I am not equipped to take phase noise measurements here so what I am describing is subjective opinion only. One other thing about the board is that it could probably also work with Iancanada 45/49MHz clocks (which I have not tried). If someone wants better than a clock board such as the one I just described, then there are always higher end solutions that can be incorporated down the road when maybe there is more budget for clocking. TheWellAudio and AckoLabs are two sources of SOA clock stuff that I have tried and still use.
Click to expand...
let me know if you publish it 🙂 else i probably look or make something that cane take a DIP16 clock and feeds the signal either to the usb board, or reclocks the signal with it

i already have a ian canada transport pi digi, which can reclock but i think it doesnt work with DSD...
 
#19
https://www.diyaudio.com/community/threads/dac-ad1862-almost-tht-i2s-input-nos-r-2r.354078/

Don't waste your time, make something of this. I made several pieces myself and everything sounds great. JLS I2SoverUSB card, and AK4118 Chinese receiver card with I2S input and output do the job for you. If you want just a USB input, you have a stackked PCB with AD1862+I2SoverUSB. Even the Chinese Amanero USB/I2S card with SITIME oscillators sounds very close to this. All those on ebay can't handle this. Put on the Burson V6 Classic OPA and enjoy. If you don't want AD1862, you have AD1865, PCM1702, PCM56, PCM58 and PCM63 options.
 
#20
NIXIE62 said:
If you don't want AD1862, you have AD1865, PCM1702, PCM56, PCM58 and PCM63 options.
Click to expand...
what about tda1387 or tda1541? they are both quiet easy to implement and i probably would build something similar to the protodac, this might get my feet wet in terms of NOS

actually i could probably build with a little help this:
ian canadas i2s to pcm module which splits L and R , so you can route the signal to discrete nos chips that run in differential mode...
so i could make a dual 8x TDA1387 custom board
then i could mate it to one of ian canadas output stages

tho overall pricewise this is definitely comparable to RTZ dac... so im not sure
 
You must log in or register to reply here.
Top Bottom