Clarifications on the "noDAC" DSD DAC from hdmi input

[merlin el mago]

nautibuoy uses third order Butterworth in his version of the valve DAC and hasn't had any tweeters go up in smoke yet./QUOTE]

What's the cut-off frequency?
Series first or shunt first?

 

[MarcelvdG]

For the reconstruction filters of his raw DSD valve DAC, Ray has used RM8 inductors from Don Audio, Custom Inductor RM8 Core, 35,47 €
He uses the filter schematic from post #215 of the valve DAC thread, https://www.diyaudio.com/forums/dig...-linear-audio-volume-13-a-22.html#post5872031 , with R1 and R4 combined into a single 806 ohm resistor. It's supposed to be a third-order Butterworth filter at 42.9 kHz, but I don't know to what extent transformer parasitics affect the response.

 

[Kindofblue]

Doesn't the SACD player have to be master? Unless you manage to modify it appropriately, it can't synchronize to an external clock.

You're probably right, and since I don't want to open the case of my SACD player, I just have to deal with what I have... You see I often get confuset because many projects using this approach use an amanero usb or other kind of board to get the dsd stream. I don't have it, and at the moment I'm not intrested, nor ready, to stream from my PC. I just have an SACD collection which I can't listen to very nicely.

Could I maybe improve something in the dsd/i2s extractor? Just to know

 

[MarcelvdG]

Addition to post #22 Mind you, the first capacitors (two capacitors to ground) are on the main board, and the filter is designed to be driven from a high impedance, so it would be useless for a simple CMOS flip-flop DAC.

 

[Kindofblue]

Meanwhile, I'm soon going to buy the extractor which is necessary, and, for a comparison (or a backup if the main plan doesn't work ) I think I'll buy an ES9023 (which is compatible with direct dsd right?)...

I also see people praise the 9038... Any thoughts?

While I wait for delivery I'll start to think about the diy DAC, maybe by choosing and starting to realise one of the projects you kindly suggested

 

[merlin el mago]

For the reconstruction filters of his raw DSD valve DAC, Ray has used RM8 inductors from Don Audio, Custom Inductor RM8 Core, 35,47 €
He uses the filter schematic from post #215 of the valve DAC thread, https://www.diyaudio.com/forums/dig...-linear-audio-volume-13-a-22.html#post5872031 , with R1 and R4 combined into a single 806 ohm resistor. It's supposed to be a third-order Butterworth filter at 42.9 kHz, but I don't know to what extent transformer parasitics affect the response.

The single 806 ohm resistor is the output impedance of the source so the characteristic impedance of your filter?

 

[merlin el mago]

Addition to post #22 Mind you, the first capacitors (two capacitors to ground) are on the main board, and the filter is designed to be driven from a high impedance, so it would be useless for a simple CMOS flip-flop DAC.

Yes I saw the 806 ohm resistor, thanks to note.

Mine 4th order LPF is optimized for 50 ohms output impedance Amanero so hava a charateristic impedance of 50 ohms.

 

[merlin el mago]

For the reconstruction filters of his raw DSD valve DAC, Ray has used RM8 inductors from Don Audio, Custom Inductor RM8 Core, 35,47 €
He uses the filter schematic from post #215 of the valve DAC thread, https://www.diyaudio.com/forums/dig...-linear-audio-volume-13-a-22.html#post5872031 , with R1 and R4 combined into a single 806 ohm resistor. It's supposed to be a third-order Butterworth filter at 42.9 kHz, but I don't know to what extent transformer parasitics affect the response.

Better to buy copper shielded sheet but I don't know if affects capacitance?

 

[MarcelvdG]

The single 806 ohm resistor is the output impedance of the source so the characteristic impedance of your filter?

The filter is designed to be driven from a high impedance (>= 11.2 kohm differential) and loaded with 750 ohm differential (806 ohm in parallel with the input resistance of the amplifier that's connected to the output, neglecting the effect of transformer losses). When you swap the filter, you can drive it from 750 ohm differential and load it with a high impedance.