A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

I would skip ECC83 and the like for the buffer. I would only use these tubes for Phono preamp because of the large mu, and nothing else. Also, no gain is required for DDDAC in balanced mode, and for SE mode a voltage gain of 2 is sufficient, as is achieved with a transformer for example. Of the cheap tubes that sound good as a unity gain buffer (all tested) I would highlight the 6E5P-EV (in triode mode), 6N1P-EV, 6N3P-EV and 6CC42. And they all have a lot of gain (mu=22-36), but they sound a lot better than the cheap ECC83.
 
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Not sure what this brings. The Cathode follower has similar or even higher output impedance and you are using two times a capacitor.

indeed no gain, but still lots of pain ;) I stand my ground the DDDAC does not "need" this.

If you like the sound of it, fine, no problem, but I want to make clear there is no need for a buffer after the DDDAC output.
 
I agree, capacitors or a transformer should be placed at the DDDAC output. If you want to have a certain "color" of the sound, then tubes, but some fine details will be lost, that's for sure. An the price i similar.

PS

I have a tube buffer, but as a separate device for all audio sources, not just DDDAC. I’m just used to the sound of tubes, and it’s my only device of its kind, everything else is SS.
The buffer is a practical thing, it has an input selector and volume control and it colors the sound a bit, but just as much as it should. Schematic is Aikido cathode follower.
It is universal, by switching cathode resistors with jumpers, it can be used with E88CC, 6922, ECC85, 6N1P-EV, 6N23P-EV, 6N6P-EV and with adapters it also accepts 6N3P-EV, 5670, 6CC42 and similar.
So when I'm bored, I just replace the tubes.
 
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I agree, capacitors or a transformer should be placed at the DDDAC output. If you want to have a certain "color" of the sound, then tubes, but some fine details will be lost, that's for sure. An the price i similar.

PS

I have a tube buffer, but as a separate device for all audio sources, not just DDDAC. I’m just used to the sound of tubes, and it’s my only device of its kind, everything else is SS.
The buffer is a practical thing, it has an input selector and volume control and it colors the sound a bit, but just as much as it should. Schematic is Aikido cathode follower.
It is universal, by switching cathode resistors with jumpers, it can be used with E88CC, 6922, ECC85, 6N1P-EV, 6N23P-EV, 6N6P-EV and with adapters it also accepts 6N3P-EV, 5670, 6CC42 and similar.
So when I'm bored, I just replace the tubes.

Now that is a nice solution. Very practical and great you can easily change your sound texture :)
 
thank you everyone! i will just use 2 dac boards, a capacitor, and live with it. i am primarily using headphones, so i will just make a tube amp for that tube sound

Maybe….. if your headphone is a 32 ohm version with a nice straight impedance curve, like most have, you could connect the headphone directly between POS and NEG output. If it has a high efficiency, the sound level could be high enough and the small DC mVolt difference not be an issue for the headphone.

I tried this with my MEZE empyrean and it worked great. Loud enough for most music.
 
i have a 120ohm sennheiser hd560s powered by diy single ended dynalo class A amp by kevin gilmore and pcm1794a dac both in the same case. a single dac chip in stereo mode, powered by 8 volt salas shunt and pin 20 ccs (2sk208). amp output impedance is less than 0.1ohm, output power is 1.5W for 32ohm. dac output stage is one opamp per channel (differential amp). pcb, modifications and all other things are made by me.

sound is extra precise, bit warm because of amp, transparent and powerfull, but i am working on balanced dynalo and balanced dddac.

i am not interested in selling these, so no worries about that. also i want to try tubes, so maybe i will build a tube headphone amp. i think in the end it is better to build a separate tube amp than put tubes between dynalo amp and dddac.

i attached pictures of amp/dac. of course i replaced a cm6631 with xmos :D:D:D:D
 

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I like it, you did a really nice job. If you want better sound from that device, replace the mains cable with something better.

Cheap solution:
3 x VDHCS12 (slightly spirally wrapped)
1 x wrap with teflon tape
2 x PET snake skin (doubled for safety)
1 x Martin Kaiser schuko connector standard or silver plated
1 x Martin Kaiser IEC connnector standard or silver plated
and some heat shrink tubing
 
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Just give it a try if you want to experiment. I repeat, the dddac does not need any buffering.

Building a buffer introduces more power supply work, drives expenses up etc. and there is not gain (pun intended ;) )

It could influence sound print and you may like it, than all is fine. But it will not be “better” by definition - like tweaking with Fifopi, better clocks, better couple capacitors and improved power supplies
 
you are fine with the 5v PSU at j3 If you didnt short the ldo's (you have to solder this bridge, its in the manual too, then you only can connect 3,3v +x ( i think x= something Like 0.2v))
I cant remember the 4V but i guess the ldo's on the fifopi can handle 4v to get the 3,3v needed at their end If DD had 4V on his j3 somewhere
 
Hi DD/All - quick question: Is there any harm if I try to use a 5V supply, say from a mobile power bank, at J3 of the FifoPi? Secondly, why and how did you come to the conclusion that a 4V supply is required instead of the prescribed 5V as per the FifoPi manual?

Manual available here: DocumentDownload/FifoPiQ3UltimateManualV3.2.pdf at master * iancanada/DocumentDownload * GitHub

See section E, point 5.

J3 was answered already. The 4 volt is discussed a few times now. I strongly suggest to always read the updates. It had to do with the WaveIO which outputs 5 volts and that side needed 4 volts to be compliant with the Fifopi which does not allow anything close to or over 5 volt
 
Hi! I have some trouble understanding I2S buffer part. I am making smaller mainboard without SPDIF and only for two boards, so I think I don't need I2S buffer (74VHCT244AM). I attached a scheme of this buffer and there are two BCK signals (left and right). I assume they are the same signal but separately buffed. Am I correct? I know I2S signals are 3.3V logic and I want to ask if I would need to change shift registers supply voltage from 5V to 3.3V or can the voltage stay at 5V anyway? I assume that registers will convert 3.3V to 5V, but I am not 100% sure
 

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