Direct Drive DSD

[acko]

These are all good, thanks! Commercial designs tend to obscure the concept a bit, so tubes and transformers aside here is something simplified:
[IMGDEAD]https://sites.google.com/site/ackodac/_/rsrc/1426654651702/home/images/DSD%20only%20Audio.png[/IMGDEAD]

The S03 has fairly strong outputs and should be able to drive passive filters directly. Choose cut-off frequency (say, @50/100KHz) to recover the baseband audio and remove the DSD carrier which starts from 2.8MHz DSD64 - fairly spaced apart so a simple LPF will do as shown.

There will be a dc offset of ~1.6V from averaging the unipolar switching and should be blocked using a coupling cap. Usually the Buffer/Amp has one at the input so this taken care off - but don't forget to mute at power on/off !!!

For steeper roll-off. cascaded filters and its associated buffers should be used. I think this is what is done by the triode filters of the Lampizator and the digital filters of ESS DACs, etc

Simply duplicate for the other channel... and that is it!

An implementation:
[IMGDEAD]https://sites.google.com/site/ackodac/home/images/AKDS2.png[/IMGDEAD]

DSD only
Sounds amazing! Connect straight to Amps. More to come ...

 

[acko]

How is the connectivity btw Direct Drive DSD and SO3?

Simply connect the DSD outputs from S03 to these DSD DAC modules

 

[kuribo]

possible to use the dsd board in an active 4 way system?

 

[acko]

possible to use the dsd board in an active 4 way system?

Yes it is scalable for multi-channel applications. So for a 4-way stereo system you will need 8 of these modules (4 for each L/R channel). Of course assuming your DSP produces 8 channels of DSD

 

[kuribo]

Yeah, I need to see if there is anything outputing 8 channels of dsd via computer...My exa21 is not documented to output dsd but have heard it will....

 

[stijn001]

I've done some experimenting with upsampling my FLAC files to DSD using HQ Player; my atom processer based computer couldn't even deliver DSD64 so it's unlikely a BBB will have sufficient processing power.

On the other hand, using gigabit Ethernet connections I have rendered a DSD256 .dsf album on a BBB/Botic (ie, no upsampling, just simple network playback) so it looks like a BBB might be upto the NAA component in a HQ Player setup; I've recently purchased a high spec workstation to explore this further (benchmarks at around 9000 so should be good to upsample to DSD256 - should know pretty soon). I want to try loading the HQ Player NAA component onto a Botic/BBB to see if that is a viable set up.

Since the BBB is in the picture above and we need a source to playback DSD, I hope we can stray a bit off topic .

Continueing here..: I was looking at HQPlayer last night as well, impressive set of conversion options.

Just to keep myself honnest I doublechecked the specc's of the BBB and it Ethernet adapter only supports 10/100Mbps. It's important to remember to deduct a healthy portion off for overhead. Most adapters only achive a mere 60%-80% of actuall application bit rate, worse if other chatty applications are present.

@Acko, you were hinting at the DC offset. What are your thought on that, now that you've spend some time on the board?

 

[acko]

...
Moving back to Acko's new hardware development, I've already achieved excellent direct 'no-dac' DSD playback using a simple LF filter and Acko's design looks as though it will significantly improve on that with properly sorted 'noise' management and digital volume control - I'm really looking forward to this development.

Ray

Thanks Ray, it will be a 256 level digital volume control

 

[nautibuoy]

of the BBB and it Ethernet adapter only supports 10/100Mbps. It's important to remember to deduct a healthy portion off for overhead. Most adapters only achive a mere 60%-80% of actuall application bit rate, worse if other chatty applications are present.

Stijn, strangely, I woke with a nagging doubt about my reference to gigabit Ethernet this morning and checked it out and you are correct. Looking back at my earlier posts around this, I couldn't make DSD256 work when my laptop (which has a beta version of 'native' DSD capable Asset UPnP installed) was connected over wifi but it was fine over a wired connection. No, you'll never achieve the full technical bandwidth but Ethernet is a collision detect protocol so in a home scenario with few devices you should be able to achieve good performance, all else being of suitable quality. Still over a wired 100Mb connection I was able to render a native DSD256 album via my BBB/Botic.

Ray

 

[acko]

.....

@Acko, you were hinting at the DC offset. What are your thought on that, now that you've spend some time on the board?

The dc offset is there but nulled out by a servo so the outputs can be directly coupled. No transformers or caps that you usually see in designs like this but having said that servo does not seem be fast enough at times so needs further tuning.

 

[analog_sa]

Yeah, I need to see if there is anything outputing 8 channels of dsd via computer...My exa21 is not documented to output dsd but have heard it will....

It's been years since i had one, but yes, it does output DSD. For this it required its own software player and an external muting arrangement.

 

[lemon]

How is the connectivity btw Direct Drive DSD and SO3?

Simply connect the DSD outputs from S03 to these DSD DAC modules

Thanks Acko for the answering.

I see that it uses the DSD1 & DSD2 for that purpose. In situation that these u.fl used by an allready dac, can we split the signal of these? One pair to dac and the other pair to Direct DSD? Is it practical?

 

[stijn001]

The dc offset is there but nulled out by a servo so the outputs can be directly coupled...

I know these are personal choices, but if there is no getting around a DC offset a HQ traffo is no sin.

 

[acko]

You can connect the outputs to suitable trafos to cancel out any residual dc and provide isolation. In fact will be supplied without any output connectors mounted. This dc effect is only during track changes when the levels suddenly change but otherwise when music is already playing there are no problems. There is absolutely no background noise.

 

[wlowes]

subscribing to thread

 

[acko]

Ray

Thanks for the information - I have been also thinking about going the HQ direction. I currently use an older MacBook which would not serve to the conversion to DSD in real time. However the idea of remote strikes the appropriate cord. My main system is a quad core i7 iMac. Now I can research "remoteness"

Good luck on that amp !!!!

Best

Bob

Tried HQPlayer 3.10 (licensed version) on my core i7 MacPro running Win7 (dual boot). Transcoded 44.1k pcm right up to DSD512 (the maximum possible with Amanero). Did not break a sweat on the PC and sounded fantastic with this DSD DAC!

Unfortunately, HQPlayer (demo version) on OSX crashes!

Anyway, really happy with the results of the live transcoding.

 

[acko]

Prior to this I tried preconverted files using JRiver (to DSD128 max) but did not quite like the results compared to original PCM
HQPlayer sound is more full bodied and closer to the original PCM. Using defaults only but will play around with other settings soon

 

[acko]

Thanks Acko for the answering.

I see that it uses the DSD1 & DSD2 for that purpose. In situation that these u.fl used by an allready dac, can we split the signal of these? One pair to dac and the other pair to Direct DSD? Is it practical?

Yes, you can do so to create a dual DAC setup, one for PCM and the other for DSD but you will need to figure out how to select the outputs accordingly

 

[flowerpot]

Is J6 an alternate input to the u.fl? One can have a balanced output using 2 boards using the same dsd input but with one input inverted...

 

[acko]

Is J6 an alternate input to the u.fl? One can have a balanced output using 2 boards using the same dsd input but with one input inverted...

Yes, J6 is a header input option
Board already has fully balanced outputs at J1.

 

[flowerpot]

Yes, J6 is a header input option
Board already has fully balanced outputs at J1.

Thats great, that will make things simpler.