I have them in... and still impressed by the dac
I know some leave them out, no problems with that. The concept of DDDAC was and is to have room for tweaking and experiments
on "huge", that is personal of course. Me, I am a bit more holding back on the SQ improvements. If I would add up all the "huge" improvements over time, the original DAC must have been a shower radio, haha!
But that is not exclusive to the DDDAC, reading other topics or audio magazines. I understand and appreciate enthusiasm of DIY, when tweaks give nice improvements. It is up to every individual how to describe their experience of course
He he,,huge is not so huge in hifi. Often it take some time to decide if an expected upgrade actually is,over time. Stock dddac is ok sounding, but no doubt that it’s much better with a few changes here and there. It’s also depending on rest of the setup. I’m pretty shure that Leif Christensen’s setup will respond in a way that’s easy to hear almost immediately.
The more than 2v came direct from Guido for the original Tent shunts. The board's have always been billed as 'with embedded Tent shunts' with no reference to any design change. If there was, now we know. But to my ears they sound better with 11-12v input and are merely warm to touch. But of course, the 10v regulator is there for safety and the DDDAC still sounds great, so if in any doubt of your PSU output variation or ability, build as standard.Just to make sure - it is not only about reliability. One wrong voltage applied to the dac and your boards are dead. Not EVERY DDDAC DIY out there is top notch on electronics - so the 7810 are there for safety first.
secondly, 2 volt is more than enough- This is specially designed by me and Guido for the DDDAC, so not sure why you state that 2 Volt is tight? it is not... trust me, all components are in the middle of their linear bias points...
thirdly, with >12 Volts you are driving the parts towards the limit of their thermal specs. That might be ok in individual cases, but I cannot guruantee a safe design for the long run without knowing every single situation
hence, everyone is free to experiment - if you are not sure what you are doing, let the 7810 in, if you like them out, lower the supply voltage. If know what you are doing, well I am good of course
Hello,
I am sure that Doede and Guido ( both being Dutch) surely tried to get the best of the combined use of the 7810 and the 8 volt shunt! I remember a few years back there has been a discussion on this thread ( ask Supersurfer) on how much the minimum voltage for the Tent shunt needs to be. This was when the Tent shunts were not yet embedded.
If with adding a big zener that would protect the shunts from a to high input voltage one could skip the 7810 than it would be ok. But i think then you would need a supply with one or more chokes.
Like Doede wrote you need a foolproof set up in order to prevent frying everything. My DDDAC is always on except when i am outside the country because i know there is hardly any risk because even the 7810 is protected for an input voltage that is to high.
Greetings, Eduard
I am sure that Doede and Guido ( both being Dutch) surely tried to get the best of the combined use of the 7810 and the 8 volt shunt! I remember a few years back there has been a discussion on this thread ( ask Supersurfer) on how much the minimum voltage for the Tent shunt needs to be. This was when the Tent shunts were not yet embedded.
If with adding a big zener that would protect the shunts from a to high input voltage one could skip the 7810 than it would be ok. But i think then you would need a supply with one or more chokes.
Like Doede wrote you need a foolproof set up in order to prevent frying everything. My DDDAC is always on except when i am outside the country because i know there is hardly any risk because even the 7810 is protected for an input voltage that is to high.
Greetings, Eduard
Doede's Dutch now[emoji16]I'll let him answer that! Doede has said several times he did for precautionary reasons. I do the the same if building for other people. But not for optimum SQ. Incidentally the only dddac failure I had was a 7810......
ok, let's solve the riddle….
Born Dutch, moved to Germany 24 years ago - took German Citizenship two years ago, so have two now. Dutch and German
I use a clclc power supply without any regulation. I find unregulated raw power supply to sound much better than with an extra regulator.
My dac boards are fitted with Tent shunts for digital and analog, the voltage before the shunts is around 2v, higher voltage will heat up the shunts too much.
Ps. I use the old dac boards modified (this one was the prototype for the dddac shunt version)
My dac boards are fitted with Tent shunts for digital and analog, the voltage before the shunts is around 2v, higher voltage will heat up the shunts too much.
Ps. I use the old dac boards modified (this one was the prototype for the dddac shunt version)
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On a different note has anyone used a pulse transformer on the S/PDIF input of DDDAC in lieu of the recommended 75 ohm resistor ? You typically see these pulse transformer on Audio Note DAC's
PS - I have a 3 deck DDDAC approximately 44ohm output Z, was wondering if anyone has used 3 decks to drive the Cinmag 600/600 transformer. Currently using the Cinemag 15/15b transformer, very happy with sound, just wondering
Cheers Johno
PS - I have a 3 deck DDDAC approximately 44ohm output Z, was wondering if anyone has used 3 decks to drive the Cinmag 600/600 transformer. Currently using the Cinemag 15/15b transformer, very happy with sound, just wondering
Cheers Johno
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Hello,
Doede took a lot of time to bring the updated boards on the market. I am sure Doede and Guido working as a team will take care it will work as it should be. Greetings, Eduard
P.s i think the required voltage drop can be lower if the 7810 has to supply less current.
And could it be that using it with a bigger voltage drop would have negative side effects on the sound???
Doede took a lot of time to bring the updated boards on the market. I am sure Doede and Guido working as a team will take care it will work as it should be. Greetings, Eduard
P.s i think the required voltage drop can be lower if the 7810 has to supply less current.
And could it be that using it with a bigger voltage drop would have negative side effects on the sound???
It doesn't, but as previously stated SQ is better without the 7810s. Try it and see for yourself
Hello,
I could try when the present project is finished. When power chassis and signal chassis are mounted together it will be 40 kilograms i estimate and to big to move around all the time.greetings, Eduard
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Hello,
It is the VT25 output tube in a DRD power amp. Right now just the parts mounted for one channel.....
What to do if I use another Rload value?
I get sometimes questions on what to do with a different Rload (sometimes nice resistors are not available in 133, 68 or 33 Ohm )
so I did some measurements today to see if I can find a correlation between the Bias voltage at the test point (the one which "should be" 40mV) and the value of the Rload resistors. I did this for one board, but it applies for every number of boards of course with the factor n, where n = the number of boards
The background is, that if you change the bias current (measured by the 40mV point) you change the DC bias output current as well as the AC signal current gain… The Rload makes I-V conversion, so you get a DC bias and a AC signal output. The maximum voltage at the DDDAC you can do before the output starts clipping is roughly 4, 7 volt. The clipping is soft so it depends a bit at which THD% you measure this. I did 1% THD
The measurements and calculation table is below in the image- I understand this is humbug for most of you who are not in the detail of the internal functioning of the PCM1794.... So I looked for a Rule of Thumb correlation and actually found a very simple one which can be used !!
just calculate [Rload in Ohm] x [bias voltage check in mV] x [n-the number of boards]
this will give yo a numeric value and the rule is: STAY BELOW 5500....
For the standard DDDAC with for example 4 boards this is: 33x40x4 = 5280
assuming you only can get 39 Ohm resistors for the Rload and just soldered them in and kept the bias at 40mV?
now you have: 39x40x4=6240 ….. oooopsie: TOO HIGH!! this will distort like hell !!
so what you do is turning the blue trimmers till you have 35mVolt
39*35*4= 5460...… case solved !
You can use the table as well if you want a LOWER signal voltage....
The table is done with ONE BOARD ...
hope this helps…. DD
.
I get sometimes questions on what to do with a different Rload (sometimes nice resistors are not available in 133, 68 or 33 Ohm
)so I did some measurements today to see if I can find a correlation between the Bias voltage at the test point (the one which "should be" 40mV) and the value of the Rload resistors. I did this for one board, but it applies for every number of boards of course with the factor n, where n = the number of boards
The background is, that if you change the bias current (measured by the 40mV point) you change the DC bias output current as well as the AC signal current gain… The Rload makes I-V conversion, so you get a DC bias and a AC signal output. The maximum voltage at the DDDAC you can do before the output starts clipping is roughly 4, 7 volt. The clipping is soft so it depends a bit at which THD% you measure this. I did 1% THD
The measurements and calculation table is below in the image- I understand this is humbug for most of you who are not in the detail of the internal functioning of the PCM1794.... So I looked for a Rule of Thumb correlation and actually found a very simple one which can be used !!
just calculate [Rload in Ohm] x [bias voltage check in mV] x [n-the number of boards]
this will give yo a numeric value and the rule is: STAY BELOW 5500....
For the standard DDDAC with for example 4 boards this is: 33x40x4 = 5280
assuming you only can get 39 Ohm resistors for the Rload and just soldered them in and kept the bias at 40mV?
now you have: 39x40x4=6240 ….. oooopsie: TOO HIGH!! this will distort like hell !!
so what you do is turning the blue trimmers till you have 35mVolt
39*35*4= 5460...… case solved !
You can use the table as well if you want a LOWER signal voltage....
The table is done with ONE BOARD ...
hope this helps…. DD
.
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For all the talk of reclocking and improvements, I would just like to emphasise how good the bog standard DDDAC is. I have a version with two original boards and the original red board and very simple crc power supply in my studio and it never ceases to please sonically when I go back to it from more tweaked versions.
I'd like to say big thanks to Doede who made it all possible and Dick and Marco who run the shop and are super helpful.
I'd like to say big thanks to Doede who made it all possible and Dick and Marco who run the shop and are super helpful.
I never doubted for a moment you´d come up with an answer...