I can only "copy that" 
As most of you know, I use the special dddac Sowter version with 18 taps as volume control. What makes it so good, is that specially at lower volumes (which is normally the case) the number of secondary windings are lower and sound quality improves thanks to this - compare this to the normal volume control where "mid-position" is kind of the worst in regard to output impedance to the next stage….
As most of you know, I use the special dddac Sowter version with 18 taps as volume control. What makes it so good, is that specially at lower volumes (which is normally the case) the number of secondary windings are lower and sound quality improves thanks to this - compare this to the normal volume control where "mid-position" is kind of the worst in regard to output impedance to the next stage….
Exactly. If the DDDAC output is nicely balanced, the DC between the two outputs is nearly zero, so there is no DC flowing through the primary of the TVC. If the TVC was particularly picky about DC (the Sowter 9335 isn't), one could use a trimmer pot across the DDDAC out with the wiper connected to signal-GND in order to perfectly zero out the DC.
That is something I have thought about as a possible issue when using transformer outputs. You see some very different listening results when different people try transformers. I wonder if some of this may be de to the interaction between the transformer and the DC offset. I am currently running my single board DAC single ended. My offset is 4 -5mv which could be trimmed to zero. When I had a balanced preamp I ran the DDDac balanced and seemed to sound a bit better that way. I want to add at least one more board and also get balanced output back in use. I am right now neck deep in a home renovation and it will be a couple of months before I can get back at audio projects. My soldering iron is calling me but I just don’t have the time right now. 
Hello,
I need to ask something about the power supply and please excuse me if this has been covered before. I'll be using a different psu and I would like to know if I can feed the tentlabs regulators directly with 12V - omit the 7810 regulator. Also, according to the schematic, the DAC module consumes around 100mA. Am I correct assuming that is for one channel including the tentlabs regulators consumption?
I need to ask something about the power supply and please excuse me if this has been covered before. I'll be using a different psu and I would like to know if I can feed the tentlabs regulators directly with 12V - omit the 7810 regulator. Also, according to the schematic, the DAC module consumes around 100mA. Am I correct assuming that is for one channel including the tentlabs regulators consumption?
The above information is completely incorrect I'm afraid. The Tent regs whether discrete or embedded are specced at a max Vin of over 20. I've run the embedded version since release on 14v in and they never even get warm, even in 30+c ambient temperatures. To my ears, they sound best when fed with a choke regulated supply with no pre electronic regulation.
I can't remember off the top of my head whether the supplied regs are LDO types or not. While LDO types will run down to a headroom of 0.7v or so, the non LDO types need 2.3v according to the spec sheet to function correctly.
The Dac board consumption is given in the DDDAC technical data but the consumption will vary if, as I do, you separate analogue and digital power supplies.
I can't remember off the top of my head whether the supplied regs are LDO types or not. While LDO types will run down to a headroom of 0.7v or so, the non LDO types need 2.3v according to the spec sheet to function correctly.
The Dac board consumption is given in the DDDAC technical data but the consumption will vary if, as I do, you separate analogue and digital power supplies.
I remember Doede saying that the 7810 should always be there in one of many previous posts. Why would Doede include them when he could have omitted them and used +12V DC analog bus to feed 12V directly to shunt regs? I know there is a good reason for 7810, maybe the man himself could chime in...?
The 140mA is the value I measured, per tent board. The old board uses 80mA.
The 140mA is the value I measured, per tent board. The old board uses 80mA.
Tent Shunt Info
OK, guys, let me try to answer all individual posts in one reply
The embedded Tent Shunt is of course tailor made for the DDDAC- so no 100% 1:1 comparison in terms of specs with the stock items…
The power consumption of the Shunt for one channel is approximately 100mA. On top comes the digital supply for the PCM1794, depending on Fs this can be something between 15 and 25mA. So every (2 channel) DAC Board (Deck) consumes between 230mA and 250mA.
The pre regulation is advised for safety of over voltage and power dissipation. That does not mean it cannot be done without the 7810 when care is taken. Everyone knows my motto: It’s a hobby and you should try things to get the best sound to your ears. Knowing, that the 12 Volt supply is not always 12 volt, examples like batteries or choke supplies, you might come to certain limits. Running the dac board at 15 volt is getting already pretty critical in terms of power dissipation
As I wanted the kit to be also ready for less technical DIY – it was (and is) wise to use the pre regulation as long as I don’t know who is building it – And I wanted to have maximum success rates out there …
I know some people experiment(ed) with separate analog power supplies directly to the TENT Shunt and that is fine. I still would like to suggest not go too far above the 10 Volt.
Hope this helps
OK, guys, let me try to answer all individual posts in one reply
The embedded Tent Shunt is of course tailor made for the DDDAC- so no 100% 1:1 comparison in terms of specs with the stock items…
The power consumption of the Shunt for one channel is approximately 100mA. On top comes the digital supply for the PCM1794, depending on Fs this can be something between 15 and 25mA. So every (2 channel) DAC Board (Deck) consumes between 230mA and 250mA.
The pre regulation is advised for safety of over voltage and power dissipation. That does not mean it cannot be done without the 7810 when care is taken. Everyone knows my motto: It’s a hobby and you should try things to get the best sound to your ears. Knowing, that the 12 Volt supply is not always 12 volt, examples like batteries or choke supplies, you might come to certain limits. Running the dac board at 15 volt is getting already pretty critical in terms of power dissipation
As I wanted the kit to be also ready for less technical DIY – it was (and is) wise to use the pre regulation as long as I don’t know who is building it – And I wanted to have maximum success rates out there …
I know some people experiment(ed) with separate analog power supplies directly to the TENT Shunt and that is fine. I still would like to suggest not go too far above the 10 Volt.
Hope this helps
A long term report after building my 16 stack DDDAC.
I am still enjoying it. I have a 300VA 18V transformer feeding the modded standard power supply and I cannot think of anything else to do to it to make it sound even better.
Apart from getting Doede to make me a main board with an SN74AS1034A per channel which would allow the final I2s to be powered by two buffers paralleled before going to feed the Dac boards.
Then hopefully it would have the power to feed 16 Tent powered boards. Anyone want to have a go at PCB designing ?
I am still enjoying it. I have a 300VA 18V transformer feeding the modded standard power supply and I cannot think of anything else to do to it to make it sound even better.
Apart from getting Doede to make me a main board with an SN74AS1034A per channel which would allow the final I2s to be powered by two buffers paralleled before going to feed the Dac boards.
Then hopefully it would have the power to feed 16 Tent powered boards. Anyone want to have a go at PCB designing ?
I have the stock mainboard driving 16 old type Dac boards. I tried to run 16 Tent boards with the stock mainboard and the sound was distorted.
The distortion was the same as when I tried to run 8 old Dac boards with the old type main board.
When I got the latest mainboard it was happy running 8 then 16 old Dac boards but it did not run 16 Tent Dac boards.
So to run the 16 Tent Dac boards it needs more buffering than what the latest main board can offer, that is why I want the hex buffers added to the latest mainboard.
Hi all,
I am interested to build this DAC. However, since pcm1794a does not support DSD and I have many diff/dsf files, what can I do for this case? Should I convert all the DSD to PCM offline or foobar can perform real time conversion for it?
Furthermore, I would like to know the sound quality of PCM converted from DSD. Any audible difference between DSD and converted PCM?
I am interested to build this DAC. However, since pcm1794a does not support DSD and I have many diff/dsf files, what can I do for this case? Should I convert all the DSD to PCM offline or foobar can perform real time conversion for it?
Furthermore, I would like to know the sound quality of PCM converted from DSD. Any audible difference between DSD and converted PCM?
I am running DSD files through a converter inside the audioplayer to PCM. Works absolutely fine.
I also had DSD converted into PCM - I could not really make out so much difference.
DSD will only deploy its full potential when run through a real DSD filter. Which is not a DAC in that sense. I have made a nicely working prototype some years ago and it sounds better than straight PCM conversion. However, it was a separate piece of equipment and I have not pursued further development yet - It was not ripe for straight forward DIY.
A bucket list project from me is to make a dac board version with the PCM1795 - which will be arduino controlled