@Nightpuma and mbrennwa...
Thank you for your comments. I think I will go for the new Audio Creative O.P.T's and an extra DAC-board. The TVC solution does indeed sound interesting, but presently I'm quite satisfied with my Tube preamp (and its volume control)... Maybe later at some point.
@Doede
Have you heard anything about the Audio Creative O.P.T's and if they are significantly better than the Cinemags? I don't know how close affiliation you have with Audio Creative, and if they have told you anything.
Regards...
Thank you for your comments. I think I will go for the new Audio Creative O.P.T's and an extra DAC-board. The TVC solution does indeed sound interesting, but presently I'm quite satisfied with my Tube preamp (and its volume control)... Maybe later at some point.
@Doede
Have you heard anything about the Audio Creative O.P.T's and if they are significantly better than the Cinemags? I don't know how close affiliation you have with Audio Creative, and if they have told you anything.
Regards...
I do not know, as I have not heard them. It is an offering from Audio Creative Shop only. I am using the special DDDAC Sowters myself as TVC version (18 steps). Dick from AC for example is using a separate TVC "pre amplifier" which is of highest standards. Read his website for details.
Just want to clarify something:
The "4 boards" need for the dddac Sowters (which have 1:1 and 1:2) has nothing to do with the load by the way, but all with the very low primary inductance of the DDDAC Sowters. Brian designed them specially for the DDDAC to make them high bandwidth and excellent impulse / transient behavior. The DDDAC Sowters, as they have very few windings come close to an ideal transformer with a very high headroom for saturation and they are not very receptive for DC (offset) at the input - This also helps Bass reproduction to be very tight, deep and dynamic. So quit special, not really useful as general purpose transformer. They sound fantastic - but it comes at a cost - technically that the inductance is low, hence it need to be driven by a low impedance to create a reasonable low frequency cut off - They need a source impedance like below 100 Ohm, so you need 3-4 boards. And also the price is higher as a normal of the shelf transformer of course…
Hello,
You see, as we all know perfect things dont come cheap.
If you go for a two board dddac with the new audio creative transformers it will surely be good!
The luxury power supply audio creative is selling is using a choke too.
If you are going for a two board dddac you can get the ll2771 6000mH 500mA combine it with a Triad split bobbin to create a very good power supply. Maybe you know some people living close by that are willing to lend you a choke. I might have one ll2733 700mA 1000mH but it would be wiser to get the best one right away.
Greetings, Eduard
You see, as we all know perfect things dont come cheap.
If you go for a two board dddac with the new audio creative transformers it will surely be good!
The luxury power supply audio creative is selling is using a choke too.
If you are going for a two board dddac you can get the ll2771 6000mH 500mA combine it with a Triad split bobbin to create a very good power supply. Maybe you know some people living close by that are willing to lend you a choke. I might have one ll2733 700mA 1000mH but it would be wiser to get the best one right away.
Greetings, Eduard
Hi Eduard.
It is quite clear that you "love" choke PSU's ;-)
Unfortunately, my knowledge about electronics are somewhat limited and I will need a more precise build description to make such thing. I will definitely have to research this topic more at some time. Also power supplies using lifepo4's and SuperCaps...
At the moment my DDDac uses plain DDDac 5V and 12V PSU's (and a third homebuild 5V Linear PSU for the Raspberry Pi 2 board.
If you have a link with good (and detailed information) about Choke PSU's I would be interested 🙂
Regards...
It is quite clear that you "love" choke PSU's ;-)
Unfortunately, my knowledge about electronics are somewhat limited and I will need a more precise build description to make such thing. I will definitely have to research this topic more at some time. Also power supplies using lifepo4's and SuperCaps...
At the moment my DDDac uses plain DDDac 5V and 12V PSU's (and a third homebuild 5V Linear PSU for the Raspberry Pi 2 board.
If you have a link with good (and detailed information) about Choke PSU's I would be interested 🙂
Regards...
Hello,
Found a drawing on my tablet.
This shows a choke input for a 4 board dddac so drawing around 1A
It is a LCLC with a 1A rated ll2771 but with two boards better use the 500mA because it will not give you 3 but 6 henry!!!
You will need less than 30 volts ac from the transformer because the voltage drop across the transformer will be less because current demand is the half.
Second lc network can be changed into an rc network but lc will be better.
Of course you must use a bleeder resistor to take care there is always a minimum current running.
You can mount the 4 diodes right onto the secundairy transformer connections and from there two short wires to the ll2771. Some of my photos are from the test set up.
Greetings, Eduard
Found a drawing on my tablet.
This shows a choke input for a 4 board dddac so drawing around 1A
It is a LCLC with a 1A rated ll2771 but with two boards better use the 500mA because it will not give you 3 but 6 henry!!!
You will need less than 30 volts ac from the transformer because the voltage drop across the transformer will be less because current demand is the half.
Second lc network can be changed into an rc network but lc will be better.
Of course you must use a bleeder resistor to take care there is always a minimum current running.
You can mount the 4 diodes right onto the secundairy transformer connections and from there two short wires to the ll2771. Some of my photos are from the test set up.
Greetings, Eduard
Attachments
Thanks to mbrennwa and Eduard 🙂
PSU improvements sounds interesting but I have chosen to upgrade my DDDac in smaller steps.
Next thing will be output transformers and possibly a second Dac-board. I will also soon change my Allo Kali to an Ian Canada FiFoPi with high-accuracy clocks. These are all fairly easy to implement.
PSU-upgrades will come later but requires much more research from me, if I want my DDDac (and myself) to survive the "experience". It is somewhat different to follow a proper guide with well-labeled PSU PCB-boards compared to pictures and handwritten diagrams.
Hopefully Eduards instructions can help other more experienced DIY'ers.
Am I completely wrong prioritize my upgrades like this?
Regards
PSU improvements sounds interesting but I have chosen to upgrade my DDDac in smaller steps.
Next thing will be output transformers and possibly a second Dac-board. I will also soon change my Allo Kali to an Ian Canada FiFoPi with high-accuracy clocks. These are all fairly easy to implement.
PSU-upgrades will come later but requires much more research from me, if I want my DDDac (and myself) to survive the "experience". It is somewhat different to follow a proper guide with well-labeled PSU PCB-boards compared to pictures and handwritten diagrams.
Hopefully Eduards instructions can help other more experienced DIY'ers.
Am I completely wrong prioritize my upgrades like this?
Regards
No i think your upgrade path is reasonable (although i would upgrade to 4 boards first bc it's a bit more hassle to add boards later than to change something else like the reclocker. That said, you probably get more bang for the bug your way)
Greetings
Greetings
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I simulated this using the Duncan PSUD2 tool, assuming a constant current of about 1 A. Note that your circuit is "symmetric", and PSUD can't do that. I therefore included only the "upper" half of your circuit. The voltages are therefore only half of what they would be in your real circuit. Imagine the second half (mirrored) stacked below the one included in the simulation. See attachments.
Results:
- The circuit has a tendency for instability (see overshoot during start up)
- The output voltage of the "upper half" is about 4.2 VDC, which means the full circuit would have 8.4 VDC.
- The peak-to-peak ripple voltage comes out as 312 nV (!!!!) for the "upper half". The full circuit would be 624 nV(pk-pk), or about 220 nV-RMS.
I don't think the ripple will work out so low in reality, but it does seem like an impressive result!
To avoid the oscillation (overshoot) you'd have to use much larger caps. Say 100 uF each.
How variable is the current consumed by the DDDAC?
Attachments
Hello,
This was a circuit i send to some other member in my country.
The actual circuit i am using in my dddac was simulated by Doede himself and he told me it looks very good.
There are a number of people here on this site who say we should pay attention at what happens at start up. I am no technician but i tend to believe them because the choke can behave " a bit strange " when there is no steady load present, Some people are concerned by the high dcr of the first choke. But if i remember well Doede confirmed that because of the shunts the load will be steady so dcr is not that important..
What will give the highest return on investment nobody knows. I started with 4 decks and Sowter right away. The choke input was also there from the start just moved to a much bigger choke.
Moving from a choke most people use and the one i am using is a small investment so once you go for choke input and you know how much current it needs to handle better get the best one right away.
Greetings, Eduard
This was a circuit i send to some other member in my country.
The actual circuit i am using in my dddac was simulated by Doede himself and he told me it looks very good.
There are a number of people here on this site who say we should pay attention at what happens at start up. I am no technician but i tend to believe them because the choke can behave " a bit strange " when there is no steady load present, Some people are concerned by the high dcr of the first choke. But if i remember well Doede confirmed that because of the shunts the load will be steady so dcr is not that important..
What will give the highest return on investment nobody knows. I started with 4 decks and Sowter right away. The choke input was also there from the start just moved to a much bigger choke.
Moving from a choke most people use and the one i am using is a small investment so once you go for choke input and you know how much current it needs to handle better get the best one right away.
Greetings, Eduard
I have a single board dac. If you want a taste of balanced operation you can simply wire up capacitors to the +and- dddac outputs and run into a balanced preamp. That is what I am currently doing. I found huge improvements in soundstage depth and width, bass, dynamics and resolution by simply doing this “upgrade. I only recently completed a balanced preamp (First watt-Balanced ba3 front end based) which allowed me to try this upgrade. The advantage of a transformer would be that even if you only have a single ended preamp the dac still sees a balanced load from the transformer.
I’m not sure how much improvement switching to transformers would yield, given that I am running a fully balanced preamp. I have 0 noise issues and even with 1 board it sounds very good. I am hoping to increase the number of boards and get transformers eventually. In the meantime I am enjoying much better sound than when running single ended.
I’m not sure how much improvement switching to transformers would yield, given that I am running a fully balanced preamp. I have 0 noise issues and even with 1 board it sounds very good. I am hoping to increase the number of boards and get transformers eventually. In the meantime I am enjoying much better sound than when running single ended.
Hello,
At post number 6812 you can see my actual circuit. Because i had some not used lundahls it was easy to add another lc stage without spending much extra.
I think the biggest benefit is coming from the big input choke. If you are only using two boards it will be easier to obtain more henries of course.
Greetings, Eduard
At post number 6812 you can see my actual circuit. Because i had some not used lundahls it was easy to add another lc stage without spending much extra.
I think the biggest benefit is coming from the big input choke. If you are only using two boards it will be easier to obtain more henries of course.
Greetings, Eduard
Well, I have to apologize...
The Tent application note, does not cover the 3.3v Doede version of the shunt regulator. It turned out that Guido was awake when I ordered, and sent me the version adapted for the DDDAC boards. This version draws less current, and is " plug and play"
Nevertheless... as I have a lc-regulated psu before the mainboard...I will
lower V in and skip all the 7810's
Hello,
As usual there have been posted several circuits that can do the job.
There are however a few things that they have in common and i think one should pay attention to those.
With choke input the power rating of the transformer can be a great deal smaller.
A lundahl is nice but according to a few people maximum isolation should be realized by using a static shield or split bobbin transformer. ( the Triad ones are cheap and work well, i had one a little noisy but that can be solved easily)
Go for the ll2771 as choke input. Look what current you need . For 4 boards get the 3H 1A for two boards get the 6H 0,5A.
Use SBYV28 diodes or very similar.
You can solder the diodes directly at the transformer secundairy. From there two short wires to the input side of the choke and from the output side of the choke two short wires to the first cap with a permanent bleeder mounted on it. You can also mount a 5 watt zener to stop the voltage from rising if you are using 25 voltage rated caps.
From the first cap you can go to a second lc network or an rc network.
Normally you could use an ll1694 or an ll2733 there. Maybe there are other lundahls that could be used if you only use two boards. Of course an rc network is cheaper.
BUT i seriously think that if you have only a limited amount of money to spend a 20 euro Triad plus the big ll2771 and a rc network will sound much better than spending the same money on a big toriodal transformer and two smaller chokes. If you dont believe you better try it your way. Remember i went from a 500va r core back to a little transformer with bigger chokes. You can take a look at pictures i posted before. Greetings, Eduard
As usual there have been posted several circuits that can do the job.
There are however a few things that they have in common and i think one should pay attention to those.
With choke input the power rating of the transformer can be a great deal smaller.
A lundahl is nice but according to a few people maximum isolation should be realized by using a static shield or split bobbin transformer. ( the Triad ones are cheap and work well, i had one a little noisy but that can be solved easily)
Go for the ll2771 as choke input. Look what current you need . For 4 boards get the 3H 1A for two boards get the 6H 0,5A.
Use SBYV28 diodes or very similar.
You can solder the diodes directly at the transformer secundairy. From there two short wires to the input side of the choke and from the output side of the choke two short wires to the first cap with a permanent bleeder mounted on it. You can also mount a 5 watt zener to stop the voltage from rising if you are using 25 voltage rated caps.
From the first cap you can go to a second lc network or an rc network.
Normally you could use an ll1694 or an ll2733 there. Maybe there are other lundahls that could be used if you only use two boards. Of course an rc network is cheaper.
BUT i seriously think that if you have only a limited amount of money to spend a 20 euro Triad plus the big ll2771 and a rc network will sound much better than spending the same money on a big toriodal transformer and two smaller chokes. If you dont believe you better try it your way. Remember i went from a 500va r core back to a little transformer with bigger chokes. You can take a look at pictures i posted before. Greetings, Eduard
Thanks for this reminder -- the 40mV bias.
Yes, I'm accustomed to digital volume in 0.5 db steps. As we know, sound pressure levels are very nonlinear and within certain ranges we are extremely sensitive. Even more so if you're lucky enough to have a listening room with a very low noise floor. Living with 2 db steps would be like a sad Goldilocks for me; a little too loud, a little too soft, but never just right...
Hello ,
Waiting for my driver to arrive so i have some time to write down some information on lundahl chokes. For the dddac there are 3 that can be used.
LL2771 The BIG one 3H 1A or 6H 0,5A 2 times 5,6 ohm dcr 131,99 euro
LL2733 The not so big one 0,4H 1,7A 2 times 1,7 ohm dcr 96,53 euro
LL1694 The little one ( the one most people use for the dddac) 0,16 H 2 times 0,9 ohm 75,31 euro
My honest opinion is that you should use the BIG one as the first choke. The higher the number of Henry the less current it needs to work perfectly. Some people say the Tentlabs shunts will start using current right after switching on. I want to have some extra safety so that is why i use a resistor across the first capacitor to make sure there is ALWAYS a minimum current taken from the power supply .
Some people will worry about the dcr of 5,6 ohm of the big choke but because the Tentlabs shunt will give the power supply a constant load i dont think this a big problem.
If you have doubts about that you could use a choke with lower dcr as the input choke but the you will have to use another transformer as well because the ll2771 will give much higher voltage drop than tne two other lundahl chokes.
By the way i have a vietnamese friend who use the ll2733 for a choke input power supply for a Nelson Pass class A power amp. One might think that there there the two times 1,7 ohm would be a problem but probably because it is a single ended class A amp with an output transformer there is no problem at all.
Greetings, Eduard
Waiting for my driver to arrive so i have some time to write down some information on lundahl chokes. For the dddac there are 3 that can be used.
LL2771 The BIG one 3H 1A or 6H 0,5A 2 times 5,6 ohm dcr 131,99 euro
LL2733 The not so big one 0,4H 1,7A 2 times 1,7 ohm dcr 96,53 euro
LL1694 The little one ( the one most people use for the dddac) 0,16 H 2 times 0,9 ohm 75,31 euro
My honest opinion is that you should use the BIG one as the first choke. The higher the number of Henry the less current it needs to work perfectly. Some people say the Tentlabs shunts will start using current right after switching on. I want to have some extra safety so that is why i use a resistor across the first capacitor to make sure there is ALWAYS a minimum current taken from the power supply .
Some people will worry about the dcr of 5,6 ohm of the big choke but because the Tentlabs shunt will give the power supply a constant load i dont think this a big problem.
If you have doubts about that you could use a choke with lower dcr as the input choke but the you will have to use another transformer as well because the ll2771 will give much higher voltage drop than tne two other lundahl chokes.
By the way i have a vietnamese friend who use the ll2733 for a choke input power supply for a Nelson Pass class A power amp. One might think that there there the two times 1,7 ohm would be a problem but probably because it is a single ended class A amp with an output transformer there is no problem at all.
Greetings, Eduard