Hi Forum!
I am looking at 'coming back' to electronics after 30 years...!
As a hobby, I want to build an optical in to RCA/Phono out DAC
Ideally a pre-soldered eBay board that can be 'improved' via a little 'tinkering': improving the power supply / adding better capacitors / upgrading op-amps perhaps - I can do some soldering if needs be!
Quality of the output sound is my priority.
I don't want to spend more than £250/$300 in total including case and power supply ideally - but - if quality will be noticeably increased I can sell something on eBay and up the budget!
So far, extensive research has lead me to many possible paths:
1: WM8741 v SABRE v AK4xxx
2: Dual/parallel or single DAC
I don't want a microcontroller / display though: just a simple opt/coax in and RCA/Phono out with the 'purest' sound possible.
I know that a lot of my questions are highly subjective - please be kind!
Priorities:
opt in / phono out
pure high quality sound
Questions:
Which DAC / board?
single DAC or parallel / dual?
Thank you very much for any help: taking the time to read and most importantly comment 🙂
I am looking at 'coming back' to electronics after 30 years...!
As a hobby, I want to build an optical in to RCA/Phono out DAC
Ideally a pre-soldered eBay board that can be 'improved' via a little 'tinkering': improving the power supply / adding better capacitors / upgrading op-amps perhaps - I can do some soldering if needs be!
Quality of the output sound is my priority.
I don't want to spend more than £250/$300 in total including case and power supply ideally - but - if quality will be noticeably increased I can sell something on eBay and up the budget!
So far, extensive research has lead me to many possible paths:
1: WM8741 v SABRE v AK4xxx
2: Dual/parallel or single DAC
I don't want a microcontroller / display though: just a simple opt/coax in and RCA/Phono out with the 'purest' sound possible.
I know that a lot of my questions are highly subjective - please be kind!
Priorities:
opt in / phono out
pure high quality sound
Questions:
Which DAC / board?
single DAC or parallel / dual?
Thank you very much for any help: taking the time to read and most importantly comment 🙂
You could probably manage Soekris dam1021-05 for 300$.
Soekris Engineering ApS, Products dam1021
Just add a cheap linear pot, 8V transformer and a Toslink receiver from DIYinHK (Not necessary, but a PCB is a bit more easy to wire than a lose receiver module from your local big component distributor). Lots of options for tinkering, especially in the digital domain, but works quite nicely out of the box.
Just an option.
Soekris Engineering ApS, Products dam1021
Just add a cheap linear pot, 8V transformer and a Toslink receiver from DIYinHK (Not necessary, but a PCB is a bit more easy to wire than a lose receiver module from your local big component distributor). Lots of options for tinkering, especially in the digital domain, but works quite nicely out of the box.
Just an option.
Thanks T129 - do you mean like this:
192K Optical SPDIF receiver - DIYINHK
Does this opt receiver feeb into all i2s inputs??? (Apologies for my ignorance)
192K Optical SPDIF receiver - DIYINHK
Does this opt receiver feeb into all i2s inputs??? (Apologies for my ignorance)
Exactly the board I meant. It is actually a S/PDIF signal. As in normal "coax". It could be used on most coax input devices for adding a toslink connection. Just needs 3,3V of electricity to do it's thing. Which is available on the Soekris DAM board. Twisted Pear has one too with a local regulator. Could be handier with places for consumer or TTL resistors. Soekris can take both, preferes TTL.
TOSLINK Optical Input Module
Do a search for Soekris on this forum and you'll find a massive amount of discussion about the DAM. It is a bit hard to sieve out the important info. Most of the talk is about the first and second versions. The product bought today would be revision 4. Read up and remember that problems and the need for modding is significantly reduced by every update.
Excellent starting point: Soekris dam1021 Sign Magnitude R-2R DAC | Dimdim's Blog
Hi T129 - thanks for that info 🙂
What an exquisite design - I love it!
However; I feel that this is too advanced for me at this stage and is something that I will work towards after my first couple of attempts - which will hopefully shake the dust off and get me back up to speed!
At the moment, I am looking at the following boards:
Assembled DAC7 parallel dual WM8741 + WM8805 + CM6631A +AD627 board | eBay
Assembled AK4495SEQ+NE5532 Two-chip decoder board | eBay
16 Assembled AK4399+PCM2706+WM8805+OPA627AU Audio DAC Boad (include USB card) | eBay
and I like the idea of the dual AK4399, just not with a display/microcontroller: Assembled AK4399 DAC software control high-end dual-parallel decoder | eBay
I'd really like to understand the relationship between digital audio in - DAC - analogue stage. I keep searching Google but have very 'partial' answers....
Can the output of the DAC be fed into a Valve pre-amp instead of opamps for example....
Is there a good article to explain the design / steps that anyone knows of please?
Anyway - thank you for your help and any feedback on the above boards would be a great help!
🙂
What an exquisite design - I love it!
However; I feel that this is too advanced for me at this stage and is something that I will work towards after my first couple of attempts - which will hopefully shake the dust off and get me back up to speed!
At the moment, I am looking at the following boards:
Assembled DAC7 parallel dual WM8741 + WM8805 + CM6631A +AD627 board | eBay
Assembled AK4495SEQ+NE5532 Two-chip decoder board | eBay
16 Assembled AK4399+PCM2706+WM8805+OPA627AU Audio DAC Boad (include USB card) | eBay
and I like the idea of the dual AK4399, just not with a display/microcontroller: Assembled AK4399 DAC software control high-end dual-parallel decoder | eBay
I'd really like to understand the relationship between digital audio in - DAC - analogue stage. I keep searching Google but have very 'partial' answers....
Can the output of the DAC be fed into a Valve pre-amp instead of opamps for example....
Is there a good article to explain the design / steps that anyone knows of please?
Anyway - thank you for your help and any feedback on the above boards would be a great help!
🙂
I'm a bit out of depth here and hopefully somebody else will chime in.
But one fundamental thing about different DAC architectures is the fact if it is Voltage or Current output. If the chip is current-out (as for example the Sabres are designed to be), you will need a I-V stage (current to voltage + usually filtering and buffering). This doesn't have to be op-amp based (check Twisted Pear Legato), but usually is for excellent measured performance.
For voltage out (WM8741 seems to be such), you can often just connect to a pre-amp (tube or otherwise). Assuming short cables and a high input impedance on the pre. The DAC chip can usually output such a measly amount of current that it needs as benign load as possible. The low level signal is also very susceptible to noise. A buffer amp of some sort might be advisable if the pre-amp is not very close (or preferably even in the same case).
All this is AFAIK, I have no real background in signal electronics.
For actual information on dac architecture, refer to Analogs teaching material, even though it doesn't really answer any questions, just teaches you to ask the originals a bit better (and hopefully receive answers from somebody who knows these things, and not just a lost mechanical engineer):
Electronics I & II | Education | Analog Devices
And the little bit deeper end:
ADI - Analog Dialogue | Data Conversion Handbook
Edit: PS. I'm not familiar with the Chinese dac boards you mention, sorry.
But one fundamental thing about different DAC architectures is the fact if it is Voltage or Current output. If the chip is current-out (as for example the Sabres are designed to be), you will need a I-V stage (current to voltage + usually filtering and buffering). This doesn't have to be op-amp based (check Twisted Pear Legato), but usually is for excellent measured performance.
For voltage out (WM8741 seems to be such), you can often just connect to a pre-amp (tube or otherwise). Assuming short cables and a high input impedance on the pre. The DAC chip can usually output such a measly amount of current that it needs as benign load as possible. The low level signal is also very susceptible to noise. A buffer amp of some sort might be advisable if the pre-amp is not very close (or preferably even in the same case).
All this is AFAIK, I have no real background in signal electronics.
For actual information on dac architecture, refer to Analogs teaching material, even though it doesn't really answer any questions, just teaches you to ask the originals a bit better (and hopefully receive answers from somebody who knows these things, and not just a lost mechanical engineer):
Electronics I & II | Education | Analog Devices
And the little bit deeper end:
ADI - Analog Dialogue | Data Conversion Handbook
Edit: PS. I'm not familiar with the Chinese dac boards you mention, sorry.
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Thank you so much T129 !
That is such a helpful post - very kind. 🙂
I am now wondering if I should spend my budget/money on one of these Twisted Pear Board combos....
Please let me know your thoughts - in the meantime I am going to read the manuals 🙂
That is such a helpful post - very kind. 🙂
I am now wondering if I should spend my budget/money on one of these Twisted Pear Board combos....
Please let me know your thoughts - in the meantime I am going to read the manuals 🙂
whinge
I recommend an akm based DAC and a pair of 1:1 transformers. You just connect the primary windingnof the transformer directly to the DAC chip. Put a 18k resistor across the secondary winding and connect to RCA output sockets. It's highly effective at reasonable cost. You can use edcor wsm600/600 transformers which is very cheap.
I recommend an akm based DAC and a pair of 1:1 transformers. You just connect the primary windingnof the transformer directly to the DAC chip. Put a 18k resistor across the secondary winding and connect to RCA output sockets. It's highly effective at reasonable cost. You can use edcor wsm600/600 transformers which is very cheap.
quantran
Thank you for that - it's very interesting that you choose the AKM over the Wolfson - any reason or shall we 'move on' and not get in too deep over which DAC, more, the design 🙂
Please could you give me a little more info about the type of 1:1 transformers please / perhaps some recommended links so that I can learn and make an informed choice?
I really like the idea of the transformer option over an opamp (if I am understanding you correctly).... So with the boards I have linked to: do I drill out the link to the opamps and solder the transformer primary to there?
Are there more modular board options where I can buy a completed DAC with no output/analogue/opamp stage and fit a transformer to the output - and also choose the input etc....
I'm learning so much from the replies that I have already had: sincere thanks to everyone for all your comments so far - I am loving this - I was stagnated before posting on this forum!
Thank you for that - it's very interesting that you choose the AKM over the Wolfson - any reason or shall we 'move on' and not get in too deep over which DAC, more, the design 🙂
Please could you give me a little more info about the type of 1:1 transformers please / perhaps some recommended links so that I can learn and make an informed choice?
I really like the idea of the transformer option over an opamp (if I am understanding you correctly).... So with the boards I have linked to: do I drill out the link to the opamps and solder the transformer primary to there?
Are there more modular board options where I can buy a completed DAC with no output/analogue/opamp stage and fit a transformer to the output - and also choose the input etc....
I'm learning so much from the replies that I have already had: sincere thanks to everyone for all your comments so far - I am loving this - I was stagnated before posting on this forum!
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I believe wolfson chips are fine. I chose akm chip because they are saif to have lower high frequency noise so less filtering is needed at the analog stage. the output transformers would do enough filtering.
I use the transformers at the below link
https://www.don-audio.com/Edcor-WSM600-600?mt=1
There are better transformers but they are quite expensive and the difference in sound quality may not justifies the cost.
connection is really simple. you just connect two ends of the primary to the +/- pin of the dac chip.
Most dac have four resistors connecting the dac chip to the opamp. just pull out these resistors and connect the transformers to these points.
I use the transformers at the below link
https://www.don-audio.com/Edcor-WSM600-600?mt=1
There are better transformers but they are quite expensive and the difference in sound quality may not justifies the cost.
connection is really simple. you just connect two ends of the primary to the +/- pin of the dac chip.
Most dac have four resistors connecting the dac chip to the opamp. just pull out these resistors and connect the transformers to these points.
It is my recommendation based on my actual experience. I have used opamp and I also have brand name products with opamps in the analog stage and they measured pretty well but they don't sound as good as a pair of transformers in this particular type of DAC (Vout).
decent transformers are totally transparent. Most quality studio equipment have line transformers inside. opamp performance is influenced by various factors most importantly the power supply for the opamp.
Current output DACs are different story.
FYI the edcore transformers have very suitable frequency response to use in the analoge stage of a Vout DAC and it form a natural low pass filter. This save you from having additional filter network that are normally added to the opamp.
The edcore transformer is down by -0.75db at 20khz and roll off quickly above 20khz. Using transformers with a much wider bandwidth then you loose this benefits of the natural LPF.
The edcore transformer is down by -0.75db at 20khz and roll off quickly above 20khz. Using transformers with a much wider bandwidth then you loose this benefits of the natural LPF.
Are you sure that your DAC chip is OK with you almost shorting out its DC output with your transformer?
Also, are you sure that your transformers are OK with having DC applied to their coils? Is that not compromising their performance?
Also, are you sure that your transformers are OK with having DC applied to their coils? Is that not compromising their performance?
The +/- output pins of the chip have the same DC potential relative to ground therefore there is no dc running through the transformer primary. You can measure it if you have an ak4396 DAC
Hi quantran,
Thank you so much for your posts: do you have any larger photos so that I can analyse 'what's going on' please?
Are you using this board: NEW LJM CS8416 + AK4396 + NE5532 2496 DAC Kit 24BIT 192K J163 | eBay ?
Could you briefly explain / give me links to details for buying/building/using the board possibly?
Thanks again - I have another post to follow addressing your other kind answers... 🙂
Thank you so much for your posts: do you have any larger photos so that I can analyse 'what's going on' please?
Are you using this board: NEW LJM CS8416 + AK4396 + NE5532 2496 DAC Kit 24BIT 192K J163 | eBay ?
Could you briefly explain / give me links to details for buying/building/using the board possibly?
Thanks again - I have another post to follow addressing your other kind answers... 🙂
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