i2s DAC solutions

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IDM
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Post by IDM » Fri Apr 10, 2015 2:49 pm

I am at work so cannot check which of the I2S options I used. However, I do recall that it didn't work with them all. So I suggest trying them sequentially and rebooting after each change until it works.

I will check my settings when I get home.

Cheers
Ian

Neal
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Post by Neal » Fri Apr 10, 2015 3:41 pm

Cheers Ian, I can only select the one option: ALSA in audio output despite the I2S being enabled, its playing out via the 3.5mm jack...
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IDM
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Post by IDM » Fri Apr 10, 2015 4:39 pm

Right, just got home and checked the web interface. If I look at the playback option I have audio output set as:

sndrpihifiberry

So try the hifiberry options in the I2S options on the systems tab.

Hope that helps.

When you have connected the BCK, LRCK and data, you have also connected the Gnd? If not it wont work (sorry if this question is patronising, you probably know what you are doing better than me.



Cheers
Ian

Neal
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Post by Neal » Fri Apr 10, 2015 4:45 pm

Cheers Ian, no not patronising at all, I've used the twisted pairs from Cat5e cable and have connected the grounds as well to the same point on the Arcam board…

In play back I have the mixer disabled and ALSA as the output...
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Post by Neal » Fri Apr 10, 2015 4:51 pm

Bloody Hell it only actually works! I thought I had tried the HiFiBerry option earlier….many thanks Ian! I feel I'm going senile LOL! :shock:

Edit o/p audio device is now sndprhifiberry
Last edited by Neal on Fri Apr 10, 2015 4:52 pm, edited 1 time in total.
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IDM
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Post by IDM » Fri Apr 10, 2015 4:51 pm

Hmm,

What are your options for activating I2S in the system tab?

Do you get a list of different DAC's?

IDM
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Post by IDM » Fri Apr 10, 2015 4:55 pm

I am going senile as well as I didn't notice that your previous post said that it works!! Any way, great news.

How long are your wires feeding the I2S signals? Mine are about 30mm, apparently it pays to keep them as short as possible.

I will be very interested to hear your impression of the sound quality. As I said previously, I am hugely impressed.

At some point in the future I will follow Ray's lead with the BBB, but for the momement the Pi is pretty damn good.

Cheers
Ian

Neal
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Post by Neal » Fri Apr 10, 2015 5:00 pm

Many thanks for your help Ian! The longest one is about 8cm, the other two 5 and 6cm…its just a lash up at the moment, I'll post a few pics in a mo when I've uploaded them…..
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Post by Neal » Fri Apr 10, 2015 5:11 pm

OK here goes, I attached 3x 10cm of cat5e twisted pairs to the underside of the RPi:

Image

Then I cut them down as short as possible to fit my TDA1541A Board and case:

Image

Image

Caos!

Image
Last edited by Neal on Sat Apr 11, 2015 8:57 am, edited 1 time in total.
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Ray P
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Post by Ray P » Fri Apr 10, 2015 7:35 pm

Neal wrote:...the BBB would appear to have a better clock implementation for audio. Lots of good reports on the RPi sound quality though..
Neal, I think that depends on what you plan to use it for and on your priorities but I think if you are looking to push performance to any degree, and are prepared to spend a little more the BBB is the better solution.

Considering they have similar price points I think as a standalone rendering interface the RPi is a better solution; although it has a relatively ordinary 19MHz clock it uses factional division to derive clock signals that preserve the native sample rate of the incoming data. That seems a better compromise than the BBB and it's single 22MHz clock, which is great for 48KHz family data (48KHz, 96KHz, 192KHz) but requires that 44.1KHz family data is resampled to 48KHz rates - that may be audible.

I've used RPi based solutions and they sound pretty good, especially when you consider the outlay required.

The BBB comes into its own once you start to consider using offboard clocks, which it can readily utilise. Using something like the Botic Linux distribution and off board clocks the BBB can detect the sample rate of the data being received, select the correct offboard clock oscillator for that sample rate and use that offboard clock to process the data at the native rates. You can, of course, use high quality clocks with their benefits.

As far as I know you cannot use external clocks with the RPi.

In my DAC setup I use an Acko SO3 isolator reclocker. This has high quality 90/98MHz master clock oscillators. As described above, these clock the BBB, they also clock the fifo data reclocking and provide the master clock signal to the DAC board (TP Buffalo IIIse) so the whole lot is running synchronously. Of course, the outlay is rather more than a simple RPi solution but the results are far better - but how much of the improvement is down to the BBB, how much the data reclocker and how much the DAC I cannot say.

If you're interested in the approach I've adopted check out the Acko website for his SO3 as well as Twisted Pear Audio's Chronos/Hermes modules - they're not as expensive as you might think.

Ray

Postscript: the BBB/Botic combo has another string to it's bow as it is possible to stream DSD to it. I hope to be able to do this with my DAC very soon.
Last edited by Ray P on Sat Apr 11, 2015 6:34 am, edited 1 time in total.

Tony Moore
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Post by Tony Moore » Fri Apr 10, 2015 9:14 pm

I'm very interested to hear your conclusions...

As you may know I use a SqueezeBox receiver in the same way as you are using the Rpi. The only difference being I am able to clock the SBR with the Tent clock and I reclock the I2S signals using the same clock.

Neal
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Post by Neal » Sat Apr 11, 2015 11:52 am

Tony it's good, very good. I'd forgotten what a well implemented TDA DAC sounds like, this may stay a while! I've ordered a second RPi as I'm going to mount this one permanently in place of the CS SPDIF board and add a linear 5v supply.

I'm not that impressed with Volumio, I know it's free and in development but it has too many bugs at the moment, radio stream management is not good and besides I much prefer using iPeng and LMS.

I've now just got to work out how to configure Squeezeplug to output on the I2S bus!
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IDM
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Post by IDM » Sat Apr 11, 2015 2:30 pm

Hi Neal,

I would be interested to hear about the bugs. I had read that Volumio for the pi2 did have more issues than the older software for the pi B.

Have you tried Rune Audio, that might be better for your needs.

I have to say I have only used the radio streams (as presented by Volumio) a few times so have little experience of them. For radio I currently use Ministreamer on a seperate Pi that streams high res BBC to Volumio and this works ok.

Neal
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Post by Neal » Sat Apr 11, 2015 6:03 pm

I've not tried it Ian, Chris(krisbee) over on TAS has put me onto tcmods.org which looks like a more complete development of a Volumio style interface. I'll give it a try at some point but in the mean time I've been playing with max2play and have managed to get it working using the hifiberryDAC driver with an edit to /etc/modules and a single line added to the config file. Details are on the HiFiBerry web site.

Max2play implements LMS so I can use iPeng and the BBC iPlayer plugin by Triode. It just works!


The most irritating bug with Volumio is when you clear the play list, the browser loses contact with Volumio and if left long enough reboots. There's no way to test a radio stream or delete one from the GUI if is not working and if you are browsing your media store and have navigated down a longish tree to add a track to play, if you come out of that screen and go back in it puts you right back at the top of the tree which is irritating...
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Post by IDM » Sat Apr 11, 2015 8:21 pm

Some really interesting stuff. I didn't know there were so many different players available, I will have to try some of them at some point.

Currently I just use Volumio with a UPnP music server (Asset on another raspberry pi, or minimserver also on a raspberry pi). The kids sometimes use the airplay feature of volumio which also behaves fine.

How do you find the audio quality of the pi as the I2S source?

Cheers
Ian

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