Hi David,
There is no logic in CRCR, it is just an affordable alternative. My experience so far, hope those in the "know" can correct me here, digital ps has the least beneficial from exotic caps and chokes, unlike the picky analog ps.
Here is what PET-240 has came up for me based on a single audio grade EI Tranny.
An externally hosted image should be here but it was not working when we last tested it.
Very similar to mine but I have both negatives connected together with no connection to ground
David
Hi David,
There is no logic in CRCR, it is just an affordable alternative. My experience so far, hope those in the "know" can correct me here, digital ps has the least beneficial from exotic caps and chokes, unlike the picky analog ps.
Here is what PET-240 has came up for me based on a single audio grade EI Tranny.
An externally hosted image should be here but it was not working when we last tested it.
Hi,
Seeing this on a proper size screen I see you've used choke input. I used capacitor input so CLC for the analogue supply and CLC for the digital supply. I use 5,600 Panasonic FCs before the chokes and 11,200 Panasonic FCs after the chokes, along with Schottky diodes.
David
Warning...! Do not try Choke input on ya analog ps! Otherwise, you will never go back to CLC..., ever again!
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please , be serious .......
When I read 12AX7 I knew I could not take it seriously.
My single board DAC will be connected to Dave Davenport's line stage which he made for his DAC which also uses the PCM1794 - not that that makes a big difference.
I have changed the input resistors to 133R since Doede has found this to be optimum for his DAC.
Working on the nige2000 inspired battery supply and on ZM's CCS before I get to listen to it.
Dave's circuit in various iterations has been around for quite awhile. Mine is almost current - he has made a few changes since mine was last treated.
Uses a pair of 6h30s.
We need to differentiate between a real Active circuit for I-V conversion, where the dac out put stays at zero volt compliance and a passive IV output followed by a tube amplifier stage.
If you add a tube amplifier behind the dac after the Rload, so the "133" ohm ones, you just amplify that signal. That is totally different than using a tube circuit as current to voltage converter (again, where output voltage compliance of the current output is kept zero, or almost zero.)
By the way nothing wrong following the dac with a tube amplifier. That is exactly what I do with my CLEO 6 from Triodedick ....
If you add a tube amplifier behind the dac after the Rload, so the "133" ohm ones, you just amplify that signal. That is totally different than using a tube circuit as current to voltage converter (again, where output voltage compliance of the current output is kept zero, or almost zero.)
By the way nothing wrong following the dac with a tube amplifier. That is exactly what I do with my CLEO 6 from Triodedick ....
Dear Mr. Doede Douma,
First, thank you so much for sharing this Pcm1794 Nos Dac project.
I followed your guide through your attached pdf 4.2 version file. I've built my Dac using 2x pcm1798 (same specs and pin out, just little lower SNR ratio than 1794 chips) and wm8805 as spdif receiver.
This Dac sounds so sweet, I chose IV resistors 133Ohm as your guidance, then tubed output.
But now I met 2 problems,
1, Hiss noise on both channels :
- if there is no signal (coax not connected or pause music on transport) the hiss sound cannot acceptable, even output directly through 2 uF Gudeman caps.
- with tube this hiss sound even louder and become noisy.
- switch i2s to external (without any signal connected), no hiss sound (of course no sound)
- HF caps coupling are 4.7nF ceramic.
- remove 2x 133Ohm IV resistors and replace with IV using 3 Opamps (with low pass filter), same hiss sound.
- turned it back to 5V analog and 10k Rref as pcm's datasheet but same problem.
2, Dac often hangs up when powered on, or not stable :
- maybe it muted, or only left or right channel sounded.
- power off and on 2-3 times until it sounds both of 2 channels.
- if there is no sound, slide i2s selector switch until it ok.
- sometime I checked power volt, just touch the VOM tips to Dc terminal, Dac hangs up, need to reset following that tricks.
Parts I used for this Dac :
- Clock 12.000 000MHz from industrial servo controller board.
- all logic chips are HC (I cannot find any VHC series in my country), 74HCT244 from Philips that I picked it from industrial inverter board (maybe hang up problem comes from this chip)
- 74HC04 replaced by 74HC14
- 74HC244 replaced by 74HCT244
- caps are Cerafine, Pana FC, Teapo.
- Asm1117 for 3.3V digital, tcxo, LT1963 for 8V analog.
I've built 2 separated power board and feed 2 sections but same 2 problems.
Can you give me some advices ?
Thank you !
First, thank you so much for sharing this Pcm1794 Nos Dac project.
I followed your guide through your attached pdf 4.2 version file. I've built my Dac using 2x pcm1798 (same specs and pin out, just little lower SNR ratio than 1794 chips) and wm8805 as spdif receiver.
This Dac sounds so sweet, I chose IV resistors 133Ohm as your guidance, then tubed output.
But now I met 2 problems,
1, Hiss noise on both channels :
- if there is no signal (coax not connected or pause music on transport) the hiss sound cannot acceptable, even output directly through 2 uF Gudeman caps.
- with tube this hiss sound even louder and become noisy.
- switch i2s to external (without any signal connected), no hiss sound (of course no sound)
- HF caps coupling are 4.7nF ceramic.
- remove 2x 133Ohm IV resistors and replace with IV using 3 Opamps (with low pass filter), same hiss sound.
- turned it back to 5V analog and 10k Rref as pcm's datasheet but same problem.
2, Dac often hangs up when powered on, or not stable :
- maybe it muted, or only left or right channel sounded.
- power off and on 2-3 times until it sounds both of 2 channels.
- if there is no sound, slide i2s selector switch until it ok.
- sometime I checked power volt, just touch the VOM tips to Dc terminal, Dac hangs up, need to reset following that tricks.
Parts I used for this Dac :
- Clock 12.000 000MHz from industrial servo controller board.
- all logic chips are HC (I cannot find any VHC series in my country), 74HCT244 from Philips that I picked it from industrial inverter board (maybe hang up problem comes from this chip)
- 74HC04 replaced by 74HC14
- 74HC244 replaced by 74HCT244
- caps are Cerafine, Pana FC, Teapo.
- Asm1117 for 3.3V digital, tcxo, LT1963 for 8V analog.
I've built 2 separated power board and feed 2 sections but same 2 problems.
Can you give me some advices ?
Thank you !
DDDAC & S03 dual clocking and BBB
I have now able to get Acko S03 up and running. S03 unit added the purity to the sound, dead quiet dark background. This front end is no doubt worthed setting up. Here on my digital journey is competed for sometime unless R2R is coming out soon. Would like to thanks Doede and those contributed so much into DDDAC, tweaking exercises, feedback,.....
Here, may I concluded that "words will never do it any justice but a practical listenning certainly shall".
Happy Listenning!
Chanh
I have now able to get Acko S03 up and running. S03 unit added the purity to the sound, dead quiet dark background. This front end is no doubt worthed setting up. Here on my digital journey is competed for sometime unless R2R is coming out soon. Would like to thanks Doede and those contributed so much into DDDAC, tweaking exercises, feedback,.....
Here, may I concluded that "words will never do it any justice but a practical listenning certainly shall".
Happy Listenning!
Chanh
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
There is one more tweak to come and that is getting the S03 with its three +5VDC inputs and BBB to be powered by these two super regulators SSR03 from Per-Anders.
Promised, this will be final and then the case.
Now I worry how to fit them all in?!?
An externally hosted image should be here but it was not working when we last tested it.
