To get an idea of this, try listening to a 44.1 file at 48. Better yet, the reverse...
You are right!
What is important is to generate the bitclock to clock the data out. The LRCK (=sample rate) will always be /32x2 for most DACs.
I Wonder how the Broadcom chip in the Rpi does it with the "fractional divisor" trick where it periodically "dropping source clock pulses".
With a 19.2M clock
19200000/64/7=42857
19200000/64/8=37500
I think the "quieter" part comes from the fact that the OS can be configured for audio only. The boards still has a lot of chips. The generated audio-clocks don't seem "ideal" right now. The USB devices are more mature at this point... In a few months things would be clearer.
Maybe Russ is already building a clock board and writing the drivers
This is ONLY a step forward if you go I2S. That's the point of the exercise.
You can get hung up counting ticks if you like, but I am listening to the most revealing, most dynamic and tonally pleasing replay (at rates from 44.1/16 upto 192/24) coming out of a $50 computer.
I'm not saying the clock frequencies are not relevant, but they aren't holding the sound back.
You can get hung up counting ticks if you like, but I am listening to the most revealing, most dynamic and tonally pleasing replay (at rates from 44.1/16 upto 192/24) coming out of a $50 computer.
I'm not saying the clock frequencies are not relevant, but they aren't holding the sound back.
Hi Coris
No magic involved. Start with Russ's opening post on this thread. You'll need a Pi, a Buffalo dac, Volumio or Squeezeplug v7 and the necessary pc tools to create an image on an sd card and SSH into the Pi. A wifi dongle proven to work with the Pi is optional but makes a lot of sense.
Follow the instructions on the software vendor websites to create an SD card image, slot it into the pi and connect up to your network using an Ethernet cable. I guess you could use a keyboard and monitor but SSH works a treat. You'll need a terminal emulator on the pc (Putty works great).
If you use the Squeezeplug image everything is available in the terminal using simple menus. Choose the Hifiberry output option and either MPD or LMS server/client depending on how you wish to render the output.
Volumio and Squeezeplug are preconfigured for ALSA to output bit perfect at all supported rates.
With Volumio or MPD I have used a local USB hard drive with my library on it, with LMS I have used bother local USB and my main LMS running on a PC at the other end of the house, over wifi. (That works fine, but signal strength issues seem to preclude running 192/24 over the wifi link).
Once you have followed the set up steps (and please refer to Russ's config note regarding the /etc/modules config for Volumio) you need to wire up the I2S out from the P5 header on the RPi board (I just soldered short fly leads directly to the board because I didn't have a suitable pin header lying around). Russ's first post has the diagram to follow. Mine are only about 50mm long and the Rpi is positioned right next to the input header on the Buffalo for shortest signal path.
As I'm using wifi to connect to the Pi, I use an Android phone running a variety of client options - Browser or MPDroid for Volumio, Squeeebox controller for LMS.
I am currently using a small wallwart to power the Pi. I am sure a nice linear PSU will be better but the one I tried doesn't seem to deliver enough current to power the Pi, USB drive and wifi dongle as when I tried running the set up from that the Pi would crap out on me randomly - an issue not encountered with the little switchmode jobbie. My Dac is separately powered with some SALAS LV regs feeding the Trident local regulators, all running of a chunky 7amp linear PSU.
I have to say - but appreciate this may not be the place to do so (so Russ feel free to edit/remove) - that both Volumio and Squeezeplug are brilliantly configured packages for an idiot like me who gets the shakes at the thought of a Linux command line. With both packages I was up and running in an hour or less.
And the sound - I'm hearing new things in recordings I have listened to for many years. And it's a very satisfying sound. So try it!
Totally agree. I guess we were only discussing the technical aspects of the solution. Part of the enjoyment of this hobby is to arrive at the best possible engineering solution.
I would be the first one to admit that many of the mods I do myself are below the threshold of my hearing capability. I recently took the Philips golden ear test and was stuck in the 128K MP3 test for a long time...
This is a really interesting thread and the info really appreciated.
I'm headed in the same direction already myself; hoping to hook up a RPi to the i2s inputs on my RAKK DAC shortly.
One area where my furrow is different is the use of UPnP/DLNA; I already stream music to my Denon home cinema amp via this protocol, controlled via BubbleUPnP on my Android tablet. I have a RPi set up with GMediaRenderer-Resurrect so it integrates with my existing setup and it's been working fine connected to some old computer speakers. I've tried Volumio too and it's nice but would be even nicer if it could work as a UPnP renderer too.
I've also ordered a HiFiBerry DAC to use on a second RPi on another setup in the spare room so should be able to compare in due course.
Ray
I'm headed in the same direction already myself; hoping to hook up a RPi to the i2s inputs on my RAKK DAC shortly.
One area where my furrow is different is the use of UPnP/DLNA; I already stream music to my Denon home cinema amp via this protocol, controlled via BubbleUPnP on my Android tablet. I have a RPi set up with GMediaRenderer-Resurrect so it integrates with my existing setup and it's been working fine connected to some old computer speakers. I've tried Volumio too and it's nice but would be even nicer if it could work as a UPnP renderer too.
I've also ordered a HiFiBerry DAC to use on a second RPi on another setup in the spare room so should be able to compare in due course.
Ray
Mark
Why do you need to 3.3v? I power the RPi from a wallwart into the micro usb slot. I power the dac from its own fancy-schmansy setup, no need for 3.3v which is generated onboard the RPi for its own purposes.
Yes I use this wifi dongle - cheap and works well. Wireless USB 11N Nano
Regards
Mark
Why do you need to 3.3v? I power the RPi from a wallwart into the micro usb slot. I power the dac from its own fancy-schmansy setup, no need for 3.3v which is generated onboard the RPi for its own purposes.
Yes I use this wifi dongle - cheap and works well. Wireless USB 11N Nano
Regards
Mark
I don't see any issue. The Buffalo32 does I2S input and runs its own master clock, so should be perfect for this approach.
Hey all - just to chip in my take.
I personally think the RPI is likely perfectly adequate - and I can attest that with the Buffalo it sounds very very good.
The engineer in me likes the BBB better, and so I will probably create a cape with audio master clocks to feed McASP.
I just haven't had a lot of time to throw at it. I did create a layout for an simpler rpi module, if there is interest I will share what it looks like right now.
I personally think the RPI is likely perfectly adequate - and I can attest that with the Buffalo it sounds very very good.
The engineer in me likes the BBB better, and so I will probably create a cape with audio master clocks to feed McASP.
I just haven't had a lot of time to throw at it. I did create a layout for an simpler rpi module, if there is interest I will share what it looks like right now.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.