Hi Acko, A couple of thoughts on the project, perhaps slightly provocative but not meant to slight in any way🙂.
Having read back through quite a bit of the thread is there a danger that the beautiful simplicity of where the project started is being lost?
And a suggestion for a slightly different approach, without compromising the work you've already done, that would allow simple or complex to suit personal requirements.
As you're already using a motherboard approach, how about separating the 'direct DAC' board into discrete modules that can be 'plugged' into the motherboard (or omitted as required). How about separate plugin modules for;
Of course, I recognise that you the driver...
Ray
Having read back through quite a bit of the thread is there a danger that the beautiful simplicity of where the project started is being lost?
And a suggestion for a slightly different approach, without compromising the work you've already done, that would allow simple or complex to suit personal requirements.
As you're already using a motherboard approach, how about separating the 'direct DAC' board into discrete modules that can be 'plugged' into the motherboard (or omitted as required). How about separate plugin modules for;
- Digital volume
- LP filter (maybe several varieties)
- DC Offset Nulling
- A variety of output buffers to suit different drive requirements
Of course, I recognise that you the driver...
Ray
I made some final tweaks to my Debian Stretch NAA build today and I think I now have it behaving like a true 'black box' appliance; push the button to turn it on and it's ready to use in a couple of seconds then press the button to turn it off. No need for any commands, it has just worked over quite a number of cycles.
Ray
Ray
- Digital volume
- LP filter (maybe several varieties)
- DC Offset Nulling
- A variety of output buffers to suit different drive requirements
Can I add one more feature to the wishlist?
Variable digital delay for each channel!
Then we can all dump our Multi-channel DSP crossovers but save their most useful feature. It seems to me that upsampling everything to a chosen fixed frequency makes this sort of delay feasible.
Thoughts?
in few pages DSD drive will be transformed to some kind of military swiss knife by functions, and swiss watches by price )))
Ray, thanks for the feedback and suggestions. Just to allay your concerns 🙂 there is no project creep as such. The original design is still the reference. What goes on the board or taken off depends on the outcome of the test results. Some functions are core requirements, others are glue logic for features, so you as can see the motherboard design appearing.
Ordinarily, this type of work will be done on breadboards but there are MHz switching for this case and therefore pcbs with HF layouts even for simple tests. In fact the basic modules shown need further HF layout updates for DSD256 @ 12MHz switching.
Then volume control, and this will be done on a separate module altogether. If it does not compare well then it will be discarded. Btw, the software volume control on HQPlayer is not up to scratch and best disabled (directSDM) and use external attenuator. There are no signs of CPU stress with Volume ON so must be implementation issue or settings. 9018 DAC does a better job here!
The rest, where appropriate, as external modules to suit.
Im not sure if it's the filtering or what with the HQplayer volume control. Compared to SDMdirect, your passing the signal through an extra layer of filtering. I just wish the volume control could be added without that extra layer of filtering. But I think some sort of filter/modulator is required. And may be impossible to make this as transparent at straight bypass.
BTW with further listening, DSD mode with Sonny's DAC is stunning. Comparing it with passing through the modulator section of the chip is night and day. The AK4490 is as close as it gets to chipless in DSD direct mode as a chip can be.
It's the NUC 3815. Very nice little board. Sounds great.
http://ark.intel.com/m/products/78577/Intel-NUC-Kit-DE3815TYKHE#@product/specifications
Driven by linear supply, it sounds much better than my Mac mini used as an NAA. And that's with Windows on SSD. I'm thinking with Linux running on the eMMC, it will be even better. Plus won't need the SSD.
I don't know about you but I can't get the same level of sound quality with SDMdirect disabled so the volume control can be used. It doesn't matter which settings it's on. There's an extra veil over the sound, and resolution is lost.
I haven't tried the HQP volume control so don't have an opinion yet. Will try it over the weekend.
Ray
Same here, during early days of testing this DirectDrive DSD/HQPlayer without external attenuator. Thought this was even more direct... Almost gave up, getting less than favourable sound, until I added this simple ALPS pot, disabled HQPlayer Vol and then bingo!
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Upon further comparison of Audiolinux running the networkaudiod daemon in command line mode in both DoP and native DSD with my fine tuned Windows 8 embedded OS on the same computer, there's definitely a difference in sound.
I'm not sure if I'm liking the Linux better at this point. At first it seemed more raw and direct. But after comparing further, it also may be a bit too raw. Stringed instruments have more edge to them and seem a bit too metallic. Where on Windows they are smoother and more delicate.
It's gonna take some more time to evaluate. I'll update after some more listening.
I think what's going on here may be that it's a bit louder with Linux, and it's causing my weak output stage to work harder. I'll have Sonny's preamp Friday. Better testing can be performed after that.
It's far too loud with them and no volume control. Almost blew the speakers once trying that already. It's making a loud pop when going into native DSD mode. Sonny has to tweak the XMOS firmware a bit more.
Yes, also experienced these pops but now my squelch function on this DirectDrive DSD has taken care of this 🙂
The plan is to make the best possible DSD DAC for the rest of us without having to pay mega bucks like for those commercial ones! So feedback and suggestions are most welcome to steer the development favourably
Ok guys I take back my last comments about the Audiolinux based NAA. I realized after the problem was I was running the USB stick the installation was on from a USB hub while doing the comparison with Windows 8 embedded. The Windows was installed on a SATA SSD. So I unplugged the SATA SSD, disabled the SATA bus in the bios, disabled the mPCI-E slot, and the onboard eMMC drive. Then I plugged the stick into the USB 3 port and booted into command mode.
Wow! I can't believe the difference that made! The sound coming out of this unit is stunning. After hearing this I feel stupid for using Windows and OSX for all these years.
I also compared to running the NAA daemon on my Mac mini. Absolutely horrible. Unlistenable after hearing this. Not bad for a $99 SBC running 29 Euro OS off of a $10 USB stick!
Next I'm going to try running my HQplayer server off this OS as well. I can only see it making an even bigger difference. Although it's hard to imagine it getting much better!
Wow! I can't believe the difference that made! The sound coming out of this unit is stunning. After hearing this I feel stupid for using Windows and OSX for all these years.
I also compared to running the NAA daemon on my Mac mini. Absolutely horrible. Unlistenable after hearing this. Not bad for a $99 SBC running 29 Euro OS off of a $10 USB stick!
Next I'm going to try running my HQplayer server off this OS as well. I can only see it making an even bigger difference. Although it's hard to imagine it getting much better!
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