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OLD THREAD DAC End by Andrea Ciuffoli

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#942
adamus said:
me too, exactly.

that rules out a short or leaky cap i think. You know what, i think i will just leave it. The 5v lines look clean on the scope, nothign is gettign hot. If i adjust the salas shunt just below its max then it regulates well. Sounds great.
Click to expand...

They could be fighting for setting V on the lines with the successive little 431 shunts and its just a matter of tolerances on their integrated Vrefs.
 
#943
Salas said:
They could be fighting for setting V on the lines with the successive little 431 shunts and its just a matter of tolerances on their integrated Vrefs.
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Salas, I know you cannot express concerns about the use of the 431 after your beauty PSU. And at the same time the author of the DAC in early stages of DAC end excluded the TL431 shunt as it did not sound well. Now the TL431 is back. Interesting to know why.
 
#946
apelizzo said:
Salas, I know you cannot express concerns about the use of the 431 after your beauty PSU. And at the same time the author of the DAC in early stages of DAC end excluded the TL431 shunt as it did not sound well. Now the TL431 is back. Interesting to know why.
Click to expand...

adamus said:
I guess some line sepeartion of sorts. on the scope there is more noise post tl431 than pre, but its not too bad.
Click to expand...

Don't know, I just saw this creation finished as you did. I just wanted to help if there was something wrong with the main LV regs section that I intimately know, because its an expensive DAC set of enough parts and I hate to see an investing member having questions not answered about regs if I am around. I am happy to end up finally knowing that adamus build works as intended by the creators. Happy listening.
 
#947
apelizzo said:
...Obbligato 1uF 630v MKP. I noticed Obbligato somehow sounds with no soul, the detail is grainy. I don't like it, that's just my taste.
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adamus said:
Interesting comments re obbligato. When you say grainy i say resolving.
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Could you both tell us rest of your systems? I have ordered some Obbligato, just wondering if I should try also something else, or just be happy with those. 😛
 
#949
Ekkeri said:
Could you both tell us rest of your systems? I have ordered some Obbligato, just wondering if I should try also something else, or just be happy with those. 😛
Click to expand...

At this point is up to the listener to choose the right cap.
There is a significant difference between Paper In Oil and MKP (Obbligato, Clarity whatever....)
So my suggestion is to buy on ebay also Russian PIO OTK (axial green or silver). Don't need to spend a fortune for Jensen. By comparing the two chemistries you will know where to go. If you like the sound of MKP then Obbligato should be OK. Otherwise Russian PIO is good too.
Don't forget you can play by mixing them. For example I will try PIO and Teflon (small value) in parallel. Teflon is very good for resolution while combining with the sweetness of PIO
 
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#952
apelizzo said:
Break-in setup, I still have to find out how to install the large Sprague.

The only criticism to this project is for the power supply for the heater is a little too compact. In Australia in summer it will get very hot then reliability becomes an issue.
Look the heatsink for DC power to heater on my previous AD1865 DAC (using 6n6P as rectifier, 5670 and 6n6p cathode follower).
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apelizzo

what kinda modification you have done to the I/V stage PSU board from stock circuit? Did you change any values or stick with standard parts in the BOM?
 
#954
gabanyayaya said:
Where can I get the instruction to mod this PCB ?
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Just download the datasheet of both tubes, take note of different pinout.
At this point you have three choices:

A) Cut the tracks needed to be rerouted and wire to the correct socket pin number.
B) Don't need to cut tracks an you can wire the whole socket away from the board if you wish to mount new sockets on chassis.
C) Buy an 9pin socket replicator where inside you can wire as desired. In this case you can leave the PCB as is and solder PCB socket and plug tube on replicator and on PCB. Let me know if you need help and choose A,B or C.
 
#958
apelizzo said:
Just download the datasheet of both tubes, take note of different pinout.
At this point you have three choices:

A) Cut the tracks needed to be rerouted and wire to the correct socket pin number.
B) Don't need to cut tracks an you can wire the whole socket away from the board if you wish to mount new sockets on chassis.
C) Buy an 9pin socket replicator where inside you can wire as desired. In this case you can leave the PCB as is and solder PCB socket and plug tube on replicator and on PCB. Let me know if you need help and choose A,B or C.
Click to expand...

So that meant no new parts or value need to be added, just reroute the solder track according to 6H6P spec right....


apelizzo said:
I only changed R11 that becomes 560R. C5 is 150uf but just because I had it in my stock.
Click to expand...

But what about the voltage? Do I need to reduce to 150V-0 , 0.2mA and 9v-0, 1.5A since I'm going to use 6H6P not E182CC or 5687 (250V 50mA/9v 3A)...?
 
#959
apelizzo said:
At this point is up to the listener to choose the right cap.
There is a significant difference between Paper In Oil and MKP (Obbligato, Clarity whatever....)
So my suggestion is to buy on ebay also Russian PIO OTK (axial green or silver). Don't need to spend a fortune for Jensen. By comparing the two chemistries you will know where to go. If you like the sound of MKP then Obbligato should be OK. Otherwise Russian PIO is good too.
Don't forget you can play by mixing them. For example I will try PIO and Teflon (small value) in parallel. Teflon is very good for resolution while combining with the sweetness of PIO
Click to expand...

There are also significant sound differences between Russians PIO.
I have seen that you used some greenish type, what kind of Russians PIO is it?
 
#960
gabanyayaya said:
So that meant no new parts or value need to be added, just reroute the solder track according to 6H6P spec right....




But what about the voltage? Do I need to reduce to 150V-0 , 0.2mA and 9v-0, 1.5A since I'm going to use 6H6P not E182CC or 5687 (250V 50mA/9v 3A)...?
Click to expand...

looking at the datasheet no changes necessary. the curves are very similar to the 5687. Just the appropriate rerouting needed.

I would say though many people prefer the 6n6p running at more than 8ma. I like at least 15
 
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