need some help from the PSU experts, please ...
I'm was running Doedes's 12V PSU for the DAC Board without tweaks for a long time. As I found here some threads where people have changed the C7 and C8 output capacitors of the PSU with a higher capacitive model with success (1000uF was suggested), I gave this a try yesterday.
I had a big 2x 12000uF cap lying around, removed the C7 and C8 (470uF) and installed the big cap with one side (1 x 12000uF). Power was stable with 12V -> OK. DAC attached and sound was impressive. Digital harshness was gone. Bass definition was better. More natural sound. I was very satisfied. But after powering off and on again I had some problems to get the 12V back. sometimes I got a higher voltage (15V), sometimes only 6-7 V. I then needed to regulate to 12V again via the pot. But regulation seemed also to be more difficult as with the standard caps. So my initial idea "as big as possible" seemed not to work!???
Should it be possible to run the big cap generally with this setup? I'm so pleased with the sound that I do not want to remove the cup, but I also do not want to brake the DAC due to a high voltage after startup (without regulating again to 12 V)...
Can I change something in the circuit that I can run this cap? Or do you think that I would get the same sound improvement with the recommended 1000uF model?
Thanks a lot
Michael
I'm was running Doedes's 12V PSU for the DAC Board without tweaks for a long time. As I found here some threads where people have changed the C7 and C8 output capacitors of the PSU with a higher capacitive model with success (1000uF was suggested), I gave this a try yesterday.
I had a big 2x 12000uF cap lying around, removed the C7 and C8 (470uF) and installed the big cap with one side (1 x 12000uF). Power was stable with 12V -> OK. DAC attached and sound was impressive. Digital harshness was gone. Bass definition was better. More natural sound. I was very satisfied. But after powering off and on again I had some problems to get the 12V back. sometimes I got a higher voltage (15V), sometimes only 6-7 V. I then needed to regulate to 12V again via the pot. But regulation seemed also to be more difficult as with the standard caps. So my initial idea "as big as possible" seemed not to work!???
Should it be possible to run the big cap generally with this setup? I'm so pleased with the sound that I do not want to remove the cup, but I also do not want to brake the DAC due to a high voltage after startup (without regulating again to 12 V)...
Can I change something in the circuit that I can run this cap? Or do you think that I would get the same sound improvement with the recommended 1000uF model?
Thanks a lot
Michael
T3 ain't gonna like that amount of capacitance at C7 and / or C8. Put the original caps back and experiment with C1 and C3...
Nick
Nick
Do what some of us have done to great effect: run the boards from an unregulated supply. Just make sure the voltage under load is close to the target 12v or 5v. Even the stock regs react favourably to this change. This is what you've in effect created with your big cap, but also you've run into T3 issues
Sent from my XT1039 using Tapatalk
You're true, I hesitate to buy Belleson regs for replace them, I'm asking myself is this 300$ tweak will really be an improvement ?
Same for the WaveIO, does someone who as replace it by chronus are happy now ? I actually use BBB -> WaveIO -> DDDAC and I think to change the Waveio for Chronus + Hermes, is it a good idea ?
Save your money. Just do choke power supplies, separate for analogue and digital, with the standard regs and get 90% of the benefit and save approx $250. The standard regs or super regs do not like pre regulated current
The power supply mods I have done and had success with are:
1, Change C7 + C8 to Vishay RVI136 63 v versions but still 470uf.
2, Change C1 + C3 to Mundorf 10,000uf 40v
3, Use a 225VA 2 x 15v transformer
3, Use a 2A Fuse.
I am in the process of changing the R1 and R2 smoothing resistors to chokes which will need about 21v transformer secondarys, but I will let you know how it goes. 🙂
Ok, for the moment, it is like this:
An externally hosted image should be here but it was not working when we last tested it.
So you suggest me to cut the line wich go to the LF33 and suplly it with the 5V PS ? Or make a third PS line only for the digital line ?
DDDCA and passive pre
Hello all. I am sure someone has detailed there experiences with incorporating a passive volume and input selector for the DDDAC but there are a lot of replies to the original thread and I think there would be twice as many by the time I read all the existing ones so could someone point me in the right direction or give me there wisdom on the topic?
many thanks
Hello all. I am sure someone has detailed there experiences with incorporating a passive volume and input selector for the DDDAC but there are a lot of replies to the original thread and I think there would be twice as many by the time I read all the existing ones so could someone point me in the right direction or give me there wisdom on the topic?
many thanks
Thank you all for the information !!! In meantime I have installed a 1200uF Audio Cap together with one of the standard Cap. 12V is then stable also after a restart (Not with the audio cap only!??). SQ is not as good as the big Cap version but better than standard version. So I think I will go for an unregulated PSU to get best SQ.
Thanks again for your help.
Michael
Thanks again for your help.
Michael
Before you get into too many mods, leave C7 and C8 at 470uf, I did try 1000uf and lost sound quality. Put them back to 470f but try the larger values just after the rectifiers, 10000uf works fine.
Hello,
The last few weeks i did do some modifications to my tube line amplifier and my Curcio dac.
In some areas i had to use higher currents chokes and in some areas i could use the lundahl chokes that were designed to be used as anode chokes. Like the LL2743 which can be found at Jac music in Germany depending on the current (70mA, 90mA or 110mA) you will get 64,50 or 41 Henry!!
So far the connection with one coil in tte plus and one coil in the min did give me the best results. You will need them like it is shown on some of their datasheets.
Both coils have one end that is pictured with a dot. If you have the two wires comming from the rectifier one of them must enter at the dot and the other one will enter where there is no dot.
You also need to look at the dots when you wanna put the 2 coils in series or in parallel.
In my dac the value of the cap[s in the power supply did go down 50% or more. Adding the 64Henry input choke did give me much more '' authority '' than tripling the value of the caps.
AND using a choke input will give your transformer, rectifier and caps a much easier life.
Greetings, Eduard
The last few weeks i did do some modifications to my tube line amplifier and my Curcio dac.
In some areas i had to use higher currents chokes and in some areas i could use the lundahl chokes that were designed to be used as anode chokes. Like the LL2743 which can be found at Jac music in Germany depending on the current (70mA, 90mA or 110mA) you will get 64,50 or 41 Henry!!
So far the connection with one coil in tte plus and one coil in the min did give me the best results. You will need them like it is shown on some of their datasheets.
Both coils have one end that is pictured with a dot. If you have the two wires comming from the rectifier one of them must enter at the dot and the other one will enter where there is no dot.
You also need to look at the dots when you wanna put the 2 coils in series or in parallel.
In my dac the value of the cap[s in the power supply did go down 50% or more. Adding the 64Henry input choke did give me much more '' authority '' than tripling the value of the caps.
AND using a choke input will give your transformer, rectifier and caps a much easier life.
Greetings, Eduard
Oh, thank you, I will do a third PS line in that case (my main transformer is not ever built 😱) The current is 10 mA by 1794 ? So for my four module, I need 80mA for digital supply ?
Please note that the current is 100ma for the dac board and 10 ma for the main board 🙂
Thank you Alex, I am going to separate Digital from Analog PS, that why I ask if the current for digital only is 10mA ;o)
I first used CRC filter to get the volts right basing my first test on 50 ma digital /50 ma analogue. Once I'd fine-tuned the volts I then ordered chokes of the correct resistance /inductance and transformers to give me the right end results