I noticed there seems to be interest in the regulation of the MK3 and use of Chokes.
As I like to avoid wild speculations, I can spend a few words on the "regulation."
I will not go into deep detail (yet) on my developments for the DDDAC 1794-MK3. - this is a wider theme than only a linear or shunt regulator instead of the Tent Shunt.
There is suite of ideas and measures I took for the next generation.
These are all based on years of feedback, experiments from me and other enthusiasts and some deep insights from experts, I happen to have had contact with, in digital design (PCB design and voltage rail requirements)
So below is a kind of sneak preview....
Please see the two measurements I made in terms of improved low frequency noise and output impedance of the on-board regulation solution.
Doede
.
As I like to avoid wild speculations, I can spend a few words on the "regulation."
I will not go into deep detail (yet) on my developments for the DDDAC 1794-MK3. - this is a wider theme than only a linear or shunt regulator instead of the Tent Shunt.
There is suite of ideas and measures I took for the next generation.
These are all based on years of feedback, experiments from me and other enthusiasts and some deep insights from experts, I happen to have had contact with, in digital design (PCB design and voltage rail requirements)
So below is a kind of sneak preview....
- The well-known DDDAC power supplies will be a double version, one for the digital and one for the analog section. It will also be a nice mechanical fit to the DAC Board...
- PSUs are more flexible with the transformer used (it will be external with two Independent or one transformer with double windings) - bigger is better...
- There are no rectifying diodes used, but an electronic solution with MOSFETs doing the rectifying.
- There is a connector option to add a Choke. There will be a separate blog on this theme. I have three Chokes for testing: Hammond 159ZC, DDDAC Amorph core Choke, Lundahl LL2273 (no need for bigger ones as current is below 400mA for two boards = like 4 decks now) Spoiler: makes a very significant difference!
- On the DAC-Board: 4 layers with separate power and ground plane. Better choice of capacitors, more SMD, improved decoupling of power around the IC’S etc.
- For both analog and digital an out of datasheet context implemented linear regulator. Goal: Lower noise in the very low noise frequencies and lower output impedance over a wider frequency range. Based on my long year discussions with some experts, this targets Jitter, digital signal integrity and analog signal handling.
Please see the two measurements I made in terms of improved low frequency noise and output impedance of the on-board regulation solution.
Doede
.
Hello,
The LL2733 and its bigger brother the LL2771 are well known to just a few people.
Both are serious chokes and because Doede just told us that the current being drawn is just 400 mA with the equivalent of a 4 board Tent shunt DDDAC we can ask Lundahl to adjust the airgap to get the current rating of the choke closer to the actual current resulting in much more mH ( with equal dcr )
We will have to know if Doede uses the LL2733 with the two coils in series ( 2× 1,7 ohm) =3,4ohm
If so i think i have a LL2771 made for 200mA with coils in series so 400mA in parallel ,( 5,6/2= 2,8 ohm). This one would be around 3000mH.
Greetings, Eduard
The LL2733 and its bigger brother the LL2771 are well known to just a few people.
Both are serious chokes and because Doede just told us that the current being drawn is just 400 mA with the equivalent of a 4 board Tent shunt DDDAC we can ask Lundahl to adjust the airgap to get the current rating of the choke closer to the actual current resulting in much more mH ( with equal dcr )
We will have to know if Doede uses the LL2733 with the two coils in series ( 2× 1,7 ohm) =3,4ohm
If so i think i have a LL2771 made for 200mA with coils in series so 400mA in parallel ,( 5,6/2= 2,8 ohm). This one would be around 3000mH.
Greetings, Eduard
Hello,
The LL2733 with 400mA rating windings in series would give you around 1,6H at 3,4 ohm dcr. A 400 mA rating with windings in parallel would give you 800mH at 0,85 ohm dcr.
One could simulate the results if the ll2771 i have could be better or i just send it to Doede.
Greetings,Eduard
P.s attachment are powerlines, communication cables as seen from a Vietnamese hotelroom
The LL2733 with 400mA rating windings in series would give you around 1,6H at 3,4 ohm dcr. A 400 mA rating with windings in parallel would give you 800mH at 0,85 ohm dcr.
One could simulate the results if the ll2771 i have could be better or i just send it to Doede.
Greetings,Eduard
P.s attachment are powerlines, communication cables as seen from a Vietnamese hotelroom
Hello
After receiving some useful advice on here earlier in the year, I took the plunge and purchsed my first dddac.
I have the basic single dac with a single ended standard capacitor output, a WaveIO usb board and a 12v dddac psu. I am very impressed, and more than happy with my purchase.
I am now looking at some upgrades (with a limited budget!) and have many questions to ask.
Firstly I decided to move to a 2 dac solution. I initially considered purchasing an additional dac board in your 'last build buy' earlier this month, but I managed to buy secondhand, a complete single board dddac with 12v psu for roughly the same cost.
Now I'm thinking I either use the dac board to convert mine to 2 dac, I'll have a spare psu to use elsewhere, and the mainboard is redundant.
Or, is it possible to convert each single dac unit to a 2 dac mono and have a dual mono with a separate psu for each channel, and if it is possible would there be any great benefit?
Ps - the dac board I've just bought is version 4.5, mine original one is 4.7. Is there much difference? Both mainboards are 4.2.
Any help much appreciated
Richard
After receiving some useful advice on here earlier in the year, I took the plunge and purchsed my first dddac.
I have the basic single dac with a single ended standard capacitor output, a WaveIO usb board and a 12v dddac psu. I am very impressed, and more than happy with my purchase.
I am now looking at some upgrades (with a limited budget!) and have many questions to ask.
Firstly I decided to move to a 2 dac solution. I initially considered purchasing an additional dac board in your 'last build buy' earlier this month, but I managed to buy secondhand, a complete single board dddac with 12v psu for roughly the same cost.
Now I'm thinking I either use the dac board to convert mine to 2 dac, I'll have a spare psu to use elsewhere, and the mainboard is redundant.
Or, is it possible to convert each single dac unit to a 2 dac mono and have a dual mono with a separate psu for each channel, and if it is possible would there be any great benefit?
Ps - the dac board I've just bought is version 4.5, mine original one is 4.7. Is there much difference? Both mainboards are 4.2.
Any help much appreciated
Richard
Hello,
To me it would seem strange to have a different board for the left and the rIght channel.
The boards you have are the one with the Tent shunt installed?
Spring or a little later next year there will be boards available from people buying the mk3 version
There are some things you could do to the power supply without spending to much.
Doede wrote about it in his blog.
Greetings Eduard
To me it would seem strange to have a different board for the left and the rIght channel.
The boards you have are the one with the Tent shunt installed?
Spring or a little later next year there will be boards available from people buying the mk3 version
There are some things you could do to the power supply without spending to much.
Doede wrote about it in his blog.
Greetings Eduard
The usual: more DAC boards! Balanced output, not single ended! Beef up the power supply!
Thanks for the replies
Thanks for your patience, I'm quite a novice at diy electronics and probably 10 years behind most of you on your dddac travels! but I'm keen to experiment and learn!
Thanks, Richard
Thanks for your patience, I'm quite a novice at diy electronics and probably 10 years behind most of you on your dddac travels! but I'm keen to experiment and learn!
I will first just convert my single dac to a 2 dac in the normal way. I'm assuming that I just need to desolder the 19 links, add the 2nd board, add new links between the 3 boards, replace the 4x 133R load resistors with 68R. Will any good quality 0.5W resistor be ok?
My original board definitely is (version 4.7 2021). The one I bought secondhand looks identical but is 4.5 2017, will this also have the Tent shunt?
I've read the blog and will probably attempt this next, once I've appreciated the change to 2 dac.
Thanks, Richard
Hello,
The ones with Tent shunt will also have two small blue coloured multi turn Bourns pots installed.
If i am right you can combine the two boards but the newer board is better than the old one.
The current one old plus one shunt board draws is rather modest so a choke wont be that expensive.
Some resistors sound better than others.
With two boards you can use a smaller output capacitor
With the cap you can also " tune " the sound to your flavour.
Greetings Eduard
The ones with Tent shunt will also have two small blue coloured multi turn Bourns pots installed.
If i am right you can combine the two boards but the newer board is better than the old one.
The current one old plus one shunt board draws is rather modest so a choke wont be that expensive.
Some resistors sound better than others.
With two boards you can use a smaller output capacitor
With the cap you can also " tune " the sound to your flavour.
Greetings Eduard
Hi @eduard and @dddac - I have gotten a custom 105VA R-Core trafo wound for 12V PSU so I can make the alterations/improvements that Doede suggested and even @maxiFi implemented.
My query is that if I have this big a power transformer, what is the max DCR of the choke that I can accommodate which can still let me receive a 12V output at the end of the PSU? Or have I not understood the concept and just the increase of VA of the power transformer wont take care of added DCR in the choke?
Thanks in advance.
My query is that if I have this big a power transformer, what is the max DCR of the choke that I can accommodate which can still let me receive a 12V output at the end of the PSU? Or have I not understood the concept and just the increase of VA of the power transformer wont take care of added DCR in the choke?
Thanks in advance.
Please read my blog post on the dddac power supply - it is all explained in detail. You can do the calculation yourself.
Dddac power supply blog post
Dddac power supply blog post
So I managed to find a 0.4R DCR 20mH/3A choke for the PSU. I got the 12V pcb from Audio Creative today and I populated the whole board. I did not go for the Blue Talema transformer and got a custom 15-0-15V transformer made. Here is the picture of my transformer. Can anyone guide me how to wire the secondary of this transformer (15-0-15) to the PSU PCB?
You were close to making a mistake.
15-0-15 is different than 2*15v.
Luckily, Doede's PSU are designed with a full wave bridge with two diodes, so creating a centre tap.
Verify with your DMM that both "centre" holes for the transformer secondaries are connected together. If so, the violet wires go to the outer holes, and the grey to one of the inner
15-0-15 is different than 2*15v.
Luckily, Doede's PSU are designed with a full wave bridge with two diodes, so creating a centre tap.
Verify with your DMM that both "centre" holes for the transformer secondaries are connected together. If so, the violet wires go to the outer holes, and the grey to one of the inner