A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

So far this is the best the rpi has sounded on my system, your mileage may vary...

I'm looking forward to clivem's wandboard implementation or Russ' cape for the bbb, as they do promise better sound than the rpi. But right now with the rpi, I'm happy!

Is the little piggyback board on the mainboard, what you are referring to as isolator, where did you get it? It looks like you are making your jumper cables yourself where do you get the female connectors? Thanks,
 
Is the little piggyback board on the mainboard, what you are referring to as isolator...
No, that's just a pin to u.fl adapter, since Acko's S03 only has u.fl out (it has pin and u.fl in, but only u.fl out). The S03 is both a reclocker and isolator. The input line isolator is to the right of the black and white twisted cable almost in the middle of the photo, you can see the chip says IL715 (http://www.diyaudio.com/forums/atta...m1794-waveio-usb-input-crystek_100mhz_s03.jpg).

where did you get it?
Ian made it for people wanting to use his FIFO board with a Buffalo III. I had a Buffalo IIISE and didn't need the adapter with it so I had it left over. It was not my idea to re-purpose it, I saw someone else do it in another thread. It's a very simple board, someone else in this thread talked about doing a similar board I think (http://www.diyaudio.com/forums/digi...imate-weapon-fight-jitter-75.html#post3084111).

where do you get the female connectors
Search ebay for "Dupont Jumper Wire Cable Housing Female Pin Connector Terminal 2.54mm" for the connector and "Dupont Jumper Wire Cable Housing Female" for the plastic housing (ebay links don't work most of the time in the forum). You can get nicer, gold plated ones from Mouser/Digikey (i.e., molex), but for testing and short term use, these work ok. From ebay you can also get 10cm and sometimes 5cm "dupont arduino cables", which if you are happy with that length you can buy ready made.
 
.......From ebay you can also get 10cm and sometimes 5cm "dupont arduino cables", which if you are happy with that length you can buy ready made.

Thanks, I'd found the ready made cables I just didn't know what the female connectors where called. I'd like to make some custom length ones when I tidy up the cabling..(eventually). I hope Russ his BBB cape will do all the things you isolator board does. Those U.fl cables are a nice touch.
 
I was able to recap part of my DDDAC to Elna Cerafine and found noticeable SQ improved. However, the sound seems abit harsh or too much resolutions? Hope the edginess will improved after burned in!
I also found tripped the caps' skin improved the openness of the sound abit further. Is the mind playing trick?

All skinless caps are Elna Cerafine, 47uf, 470uf, 1000uf. The two big filter caps are Mundorf MLytic AG 4700uf. I also replaced the stock 0.1Ohm 5W 10% resister to Kiwame 5%.

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hello
I´ve been busy with my new Studer A80, while I´m waiting for a load of Panasonic Fc 47µF for the dac boards.
I also have in transit new low noise reg boards from DIYINHK like James linked to.
glad everybody like the R1&2+fuse bypass....improves dynamics dramatically
sure would have liked to be at the shootout on the horn setup
DD: just one idea
the stacking of the boards makes cap and reg swapping extremely difficult
would it be possible to have som sort of stacking connectorsystem, e.g like the one used by TPA between the dac and the analog boards?they also use it between dac and AVCC reg board
they´re called pin headers and sockets for direct stacking and Mouser no. are 929647-04-36-I and 5-534237-1
These are only for two layers, but I guess other versions are available....
then one could simply plug the stack together and even pick it apart for swapping components or even just adding or subtracting no of boards
I hate the thought of desoldering, cleaning boards etc
best
Leif
 
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32 tent lab 8 stack dddac 1794 board

I have a 8 board dddac 1794 with 32 tent lab regulators. It took quit a bit of work to remove all of the standard regulators. I had to remove 1 each for the 47 uF filter capacitors. I like how DWJames was able to keep all four of the 47 uF capacitors by moving one of the wima to the back side of the board. I plan on doing the same later on after finalizing my dac board modifications.

Along with all of the trouble of removing the parts, I found 1 of the 8 boards was not functioning. I had to chop the silver wire out and find the bad board.

With all of the modifications being posted, I have just 1 board installed to finalize what I will eventually do to all 8 dac boards.

The 8 tent regulated dac takes a lot of power to run. At 12 volts it needed at least 3 amp fuse. 2 amp fuse blew on power up surge of the tent regulators.

I did not have a 2.5 amp fuse to try.

I had to mount a huge heatsink to Doede's darlington transistor's stock heat sink which was warm to touch after this modification.

Doede has been very helpful with lots of emails! I initially had trouble with the Lucian USB board not communicating with my netbook. He sent a new one out while I sent the old one back. Found out a month or so that I had soldered above the board for the USB spdif switch and a very small drop of solder had landed on the pins of the board causing it to not function. Those SMD parts are so small that I did not notice.

I was worried about the damage from my fault and offered to pay for the damaged board. Both Doede and Lucian declined my offer and said enjoy your new Lucian board!!!

Regards, Bill

I have a lot invested in this 32 tent lab regulated dac set up!

I have tried the power supply bypass of the wire wound resistors and found the gain did increase, but it sounded noisier. Not as smooth with the resistors. I tried bypassing the fuse and found trying different wire to see how the sound would change. I tried some copper and silver wire and stock fuse. I found the stock fuse sounded okay so decided to leave it in for protection. The silver wire soldered across the fuse seemed to offer finer low level details, but the bass seemed to be weaker or less balanced. The copper had better bass. Surprised at how the sound changed so much...

I found the standard fuse sounded better balanced in my system after bypassing the dac board's inductors. I just bypassed the ones after the 8 volt shunts sofar and found the dac is more spacious. I believe the higher frequency is louder making the dac more brighter or detailed. This seems balanced better with the stock power supply from Doede. Except I am using an 800 Va transformer to handle the 32 tent lab regulators. I would estimate the tent regulators take at least 0.250 to 0.275 amps per dac board! Kind of reminds me of a class A amp. Continuos current draw!!! So, I will try some class A style power supplies to see if the Dac can be improved.

The sound of 1 board is great. Can't wait to finalize 1 board and then doing them to all 8 of my dac boards!

I prefer no output transformer. Better bass and highs compared to my cinemag transformer. Although the dc offset was 3mVolt and 6 mVolt, I can hear some AC hum when I turn my preamp up way loud. At normal listening levels I don't notice any hum.

So, in the future I will try additional filtering prior to either try by itself and feed into my shunt regulated dac boards or also feed into Doede's power supply. I want to try some power supplies that I have used for some class A amps...

Lots of fun experimenting!! Ultimately leaving what I like to my ears!!!



Thanks to many of the forum members postings and Especially Doede and Lucian!
 
hi
I have one new unsoldered each of mother and dac board waiting for the new Fc cxaps
will do like you and optimize one board to start with...then stack
know people whohave tried DIYINHK reg. and they say it sounds fantastic
might be better in front of board instead of changing all the local regs
gives them less noise to start with...
best
Leif
 
DD: just one idea
the stacking of the boards makes cap and reg swapping extremely difficult
would it be possible to have som sort of stacking connectorsystem, e.g like the one used by TPA between the dac and the analog boards?they also use it between dac and AVCC reg board
they´re called pin headers and sockets for direct stacking and Mouser no. are 929647-04-36-I and 5-534237-1
These are only for two layers, but I guess other versions are available....
then one could simply plug the stack together and even pick it apart for swapping components or even just adding or subtracting no of boards
I hate the thought of desoldering, cleaning boards etc
best
Leif

Hi Leif, I have not actually check what pin headers you refering to but it's totally possible to stack the boards up with female pin headers for easy removal especially if you like to fool around or experiment like me and I have actually done just that.
A few pages back I did mention the stacking of dac chips and I am in still in the experimental stages of the idea so still not conclusive yet but so far so good. Still got many things to try so won't be able to say much for now.
20140413_190229_zpsc9uehsg7.jpg
 
Search ebay for "Dupont Jumper Wire Cable Housing Female Pin Connector Terminal 2.54mm" for the connector and "Dupont Jumper Wire Cable Housing Female" for the plastic housing (ebay links don't work most of the time in the forum). You can get nicer, gold plated ones from Mouser/Digikey (i.e., molex), but for testing and short term use, these work ok. From ebay you can also get 10cm and sometimes 5cm "dupont arduino cables", which if you are happy with that length you can buy ready made.

Thanks, Frankie, for this tip. Might help with another project I have yet to finish.:eek: I immediately went on ebay and found some 30cm 2p to 2p that I can cut up to do just that.

Thanks also to Doede for continuing to support discussion of alternative ways to get information to his DAC, in this case from small embedded devices such as the rpi, and, more generally, from I2S sources. The more ways we can learn to skin the cat, the more fun we can have. (No cats were harmed, by the way, in the composing of this post.)
 
@Chahn, yes removing the plastic makes a difference. Plastic is static and because through a capacitor there is a dynamic AC current running, there will also be an electro magnetic field around it. This field will be influenced by plastic, and in turn this will influence rhe flow of current through the cap. So the difference you hear is very real!
That's also why I like my cinch cable more than any other cable with plastic cover.............

@Leif, you can cut out the pins of a DIL socket and solder them on the board, than solder short wires below the pin so they can be pushed into the underlying pin. In this way it will be a removable stack.

@bill, using the 32 shunts is very cool, would love to hear this.

Regards,
 
How would you connect a passive volume control? What size pot should I use?

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Does someone dare to comment on my question? I've come to realise I probably need a 100K pot and leave out the bleeding resistor.

However, I'm still unclear about which negative wiring scheme to use..

Any suggestions would be much appreaciated. I need to order parts hence I can not test this my self and are hoping someone here might have an insight.
 
hi, from your diagram I would use Option 2-I do, with no bleeder resistors. I don't see why you need a 100k pot. Mine works perfectly into a 20k pot.
David

Hi David, Thanks. Good to read someone has gone the same route. Can you confirm you’ve connected POS & NEG and not common like Doede specifies in his schematics? If the pot is 20K and you'd remove the bleeding resistor, your end up with 20k minimum bleeding resistance or am I missing something?
 
Does someone dare to comment on my question? I've come to realise I probably need a 100K pot and leave out the bleeding resistor.

However, I'm still unclear about which negative wiring scheme to use..

Any suggestions would be much appreaciated. I need to order parts hence I can not test this my self and are hoping someone here might have an insight.

yes, option two is the one to pick IMHO :)
no bleeders needed....