The silver 99.99% wire for joining the dac boards is 0.8 Diameter.
I get mine from: wires.co.uk : Round Silver Wire
You cannot just add any transformer to the Output. Two things are important, first can they handle the mall DC offset and id the low freq cut off ok with the output impedance. The Sowters I use, which were specially designed to my specs are 100% fit to the DAC.
Now, I am using the same transformer with 18 TAPs output as TVC Volume control. Works like a charm
My DDDAC has the the stock power supply designed / sold by Doede. And I have a box full of 10'000 µF electrolytics. And I just found two chokes in my parts box (can't read the specs / labels anymore, so I'll have to figure out what it is exactly). So I am wondering if it would be any good to insert a CLC or CLCLC between the original PSU and the DDDAC mainboard. I could compensate the voltage drop across the inductors by adjusting the output voltage of the original PSU boards.
What do you think? Good idea? Useful or stupid?
You cannot just add any transformer to the Output. Two things are important, first can they handle the mall DC offset and id the low freq cut off ok with the output impedance. The Sowters I use, which were specially designed to my specs are 100% fit to the DAC.
Now, I am using the same transformer with 18 TAPs output as TVC Volume control. Works like a charm
Sowter produces a TVC that takes the DC imbalance!? Cool!
How / where can I get a pair?
I started with the 1794 standard TI application notes but along the way I found out about Doede's novel design and I'm certainly curious to try it out.
I used a DSD1794 because it has programmable volume control capability which unfortunately doesn't work anymore when no digital filter is selected but, icing on the cake, the SPDIF receiver CS8416 can be set to output audio data as right-justified so I just had to:
- change the CS8416 and DSD1794 setup by software (I2C)
- cut the tracks going to the I/V active stage and add a small pcb as per Doede's Rload
- connect SCK to BCK
and it works (SPDIF sampling rate is 88200, external clock is 22.5792Mhz).
I'll probably end up building 2 DACs: the standard one and the one along Doede's design and then do a listening compare.
I used a DSD1794 because it has programmable volume control capability which unfortunately doesn't work anymore when no digital filter is selected but, icing on the cake, the SPDIF receiver CS8416 can be set to output audio data as right-justified so I just had to:
- change the CS8416 and DSD1794 setup by software (I2C)
- cut the tracks going to the I/V active stage and add a small pcb as per Doede's Rload
- connect SCK to BCK
and it works (SPDIF sampling rate is 88200, external clock is 22.5792Mhz).
I'll probably end up building 2 DACs: the standard one and the one along Doede's design and then do a listening compare.
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yes , those are sowter 9335 attenuators (occ wired) and i am very pleased with them even with just single dac deck. i measured the 9335 with square wave 1k and did not see any significant resonance up to 100khz !!
according to brian sowter these transformers can handle up to 50 uA. the dcr of 9335 is about 700 ohms so even with 10mv dc offset the current would be in a very safe side (=14 ua). in my case i measure an offset of just 0.3mv (!!) at the dac output.
the music is streamed using bbb-hermes-cronus directly to the dac without the main broad as suggested earlier by jürgen. the whole chain (incl. a 4tb hard drive) is supplied by a single 12v, 20ah lifepo4 battery which lasts for approx 15h of enjoying music ;-) .
please find attached some pics of the current set up.
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I discussed this idea with Doede a long time ago, as I had a set of 9335 Sowters lying around. Doede suggested to run them through his AP tester at the DC level of the DDDAC output. I think this somehow didn't happen until now. Hmmm...
update
Hello,
Back home after 10 weeks in Asia.
Yesterday did visit the audio creative website and come across this information
The DDDAC boards out of stock.
At this moment we are waiting for the new DDDAC boards.
The new boards will have the TENT shunts integreated on the board.
I did not see any info about this in this thread or maybe i did miss it. Doede did tell me he was planning to do this modification in the future long time ago. BUT now because the original boards are out of stock it seems it is actually going to happen soon.
Greetings, Edward
Hello,
Back home after 10 weeks in Asia.
Yesterday did visit the audio creative website and come across this information
The DDDAC boards out of stock.
At this moment we are waiting for the new DDDAC boards.
The new boards will have the TENT shunts integreated on the board.
I did not see any info about this in this thread or maybe i did miss it. Doede did tell me he was planning to do this modification in the future long time ago. BUT now because the original boards are out of stock it seems it is actually going to happen soon.
Greetings, Edward
Yes it will. It is hard to make a smooth transition, so we wil have some dead time.
I am finishing the prototype as we speak and will do listening tests hopefully this week. than order boards and SMD soldering in March. April should be target month. The embedded Tent shunt is for the 8Volt only. The 3,3V stays LF33, with option to mount a shunt replacement (for those who really want to do this. My tests showed that the 8V does the most. I truly hear no real difference with or without shunt on the digital side) It also includes a current source for pin 20. And of course totally back wards compatible with mainboards and old dacs (you could even use them mixed if you want)
I am finishing the prototype as we speak and will do listening tests hopefully this week. than order boards and SMD soldering in March. April should be target month. The embedded Tent shunt is for the 8Volt only. The 3,3V stays LF33, with option to mount a shunt replacement (for those who really want to do this. My tests showed that the 8V does the most. I truly hear no real difference with or without shunt on the digital side) It also includes a current source for pin 20. And of course totally back wards compatible with mainboards and old dacs (you could even use them mixed if you want)
Sounds like an excellent plan and a good way to get the best quality/value balance
Which current source did you choose for the pin20?
James
Also, not sure if it's decided already or open for suggestion, but it would be nice to include 2 of these pps caps per deck to use in the local decoupling of the digital supply for each dac chip in place of the Wima film caps.
http://www.mouser.de/Search/m_ProductDetail.aspx?qs=9OvERMBOKbZ8CMwlBytcjw==
It seems a few people have found that a nice pps decoupling cap on the digital supply can give more magic than a fancy regulator for a much cheaper cost
http://www.mouser.de/Search/m_ProductDetail.aspx?qs=9OvERMBOKbZ8CMwlBytcjw==
It seems a few people have found that a nice pps decoupling cap on the digital supply can give more magic than a fancy regulator for a much cheaper cost
Ciao Doede,
I am really curious to see your new board
Hmm... how do you trim the CCS if is directly mounted in the board? Also, there is any chance to connect to a separated PSU instead of the +VB?
Also, not sure if it's decided already or open for suggestion, but it would be nice to include 2 of these pps caps per deck to use in the local decoupling of the digital supply for each dac chip in place of the Wima film caps.
SMR5683J100J03L4BULK Kemet | Mouser
It seems a few people have found that a nice pps decoupling cap on the digital supply can give more magic than a fancy regulator for a much cheaper cost
Another option would be a COG/NPO ceramic directly at the supply pin. Has been quite an improvement for my DDDAC.
Attachments
For me it is highest priority to make the design so, that there is an excellent result to be obtained from the standard design (and the standard DIY kit) at an acceptable price. This is the reason; there are no expensive type capacitors or bulky transformers and exotic resistors in the kit. This is NOT as I might not believe it (can) make a difference. Now exactly at this point comes the fun of the DIY hobby. Tweaking the design to you own taste and ideas. Besides the ideas listed in this thread (that's why it has 5000 pages (Actually.. this is 5000 ) I have got many many by email (always feel free to send me mail!!) and they are sometimes in contradiction or just many ways to Rome.
Hence I stick to my principle and make it worthwhile out of the box. From there every one can decide for himself what to do next
So the new board will be based on the most important "tweaks" which are very difficult to do afterwards. The Shunt and the pin 20 thingy. All others, like components change are much easier to implement and are real fun as well
) I have got many many by email (always feel free to send me mail!!) and they are sometimes in contradiction or just many ways to Rome.Hence I stick to my principle and make it worthwhile out of the box. From there every one can decide for himself what to do next
So the new board will be based on the most important "tweaks" which are very difficult to do afterwards. The Shunt and the pin 20 thingy. All others, like components change are much easier to implement and are real fun as well