Raspberry Pi - Addressing a Weakness?

Ray P · Post by **Ray P** » Tue Feb 25, 2014 9:31 pm

I perceive that a weakness with the use of 'mini' computers like the RPi, BeagleBone and, for that matter, squeezeboxes, might be the native onboard clocks which can only have been designed down to a price.

With my specific RPi interest I've been reading a very interesting project thread over on DIY Audio that addresses the clock issue by buffering and reclocking the i2s streams. There is also a group purchase running periodically and I'm now on the current waiting list; the whole project is very well designed and engineered with top-notch boards. I thought there might be one or two here who might find it interesting too. Here are two links, one to the general discussion and the other to the group purchase thread. There's a lot of reading but I think I've got a good handle on it now if anyone needs a simple explanation...

http://www.diyaudio.com/forums/digital- ... itter.html

http://www.diyaudio.com/forums/group-bu ... p-buy.html

Ray

IDM · Post by **IDM** » Wed Feb 26, 2014 5:18 pm

Hi Ray,

Fascinating stuff. I just wish there weren't over 300 pages to read! I think I am right in thinking that to simply reclock the I2S to a local DAC (all in one box) I just need the FIFO board?

I will have to get reading and probably join you in the queue for the boards.

Cheers
Ian

Paul Barker · Post by **Paul Barker** » Wed Feb 26, 2014 6:12 pm

Let me know if it's a goer and I'll join. No chance I have the mental capacity to understand such a thread.

Ray P · Post by **Ray P** » Wed Feb 26, 2014 7:37 pm

IDM wrote:I think I am right in thinking that to simply reclock the I2S to a local DAC (all in one box) I just need the FIFO board?

Well, yes and no....

It's developed quite a lot since the initial post for the group buy.

The basic FIFO board includes a single clock board and will enable you to work with a single sampling rate. If you want to auto switch sampling rates you'll need the dual clock or SIL570 board upgrade.

If you want to take the performance up a level you'll need to add the isolator board between the FIFO and clock boards.

There are also upgraded clock power supply modules and battery management modules if you want to experiment with those options.

If you want conventional inputs you'll need the spdif input module.

Oh, and you'll need good power supplies for it as well (I've ordered some Salas shunt regulators in anticipation).

Sounds a lot but it's all incremental and flexible and costs are still very reasonable.

Download the user documentation, it's very easy to read.

Ray

IDM · Post by **IDM** » Sat Mar 15, 2014 1:17 pm

Hi Ray,

I am still ploughing through the DIY audio thread. As ever there seem to be people suggesting that the FIFO board will introduce as many jitter problems as it solves and I am in absolutely no position to judge where the truth lies. As you may have seen on another computer thread I have got the Pi I2S to work and feed my TDA1541A DAC. I am currently listening to it with WAV music files on a USB stick plugged into the Pi and I am starting to think it might sound better than my Philips CD-Pro2M transport, which cost alot of money! So I am currently wondering whether to bother with reclocking. I also note on the other thread link you posted about the twisted pair DAC, that Russ White didn't seem to be worrying about jitter. So I was wondering what your thoughts are?

I do strongly recommend trying the Pi with I2S as soon as you can for the money its amazing.

Cheers
Ian

Paul Barker · Post by **Paul Barker** » Sat Mar 15, 2014 3:32 pm

Well now that you have succeeded, I shall do. I have to order a new rPi though with the P5 connector first. Will probably just put Raspian on the old one and turn the television into a smart tv with it. I already have a wireless keyboard that works with it. So that one won't be wasted. When I can't get to use my laptop (the only household computer) I will have something a little better than an android phone to surf the net on.

So many websites are crippled to the mobile browser by taking away the only useful functions when working in mobile. We have a long way to go before we won't need a conventional browser to get full functionality everywhere.

Am I off topic again?

Forgot to mention about fitness in this thread.

ed · Post by ed » Fri Apr 25, 2014 4:05 pm

for those experiencing problems with their raspberry pis and i2s I just stumbled across this:

http://iqaudio.com/?page_id=28

It uses the same dac that I'm fiddling with for the beaglebone, but if I'd seen this first I might have been tempted to save all that soldering and wiring....they are selling for £20 which I think might be a bargain.....the dac chip is £8 on it's own, and it's 32/384 capable, although I havn't heard mine yet so I can't comment on the sound quality.

izzy wizzy · Post by **izzy wizzy** » Fri Apr 25, 2014 9:22 pm

I'm going for that DAC once it's back in stock. I have the HiFiBerry I2S DAC going on the Pi with picoreplayer. Works a treat and super easy to set up. I hope the UK product is better than the HiFiBerry.

cheers,

Stephen

Ray P · Post by **Ray P** » Fri Apr 25, 2014 11:35 pm

I now have a HiFi Berry DAC and will be installing it on my RPi shortly but this is the route I'm now going to adopt for the main hifi system;

http://www.diyaudio.com/forums/twisted- ... ost3905098

The last few pages of the thread should give you a flavour of this planned BeagleBone Black audio cape and driver/kernel updates.

Ray

Ray P · Post by **Ray P** » Sat May 03, 2014 2:00 pm

Unfortunately my RPi renderer has been delayed because I was a total dunce and accidentally sent part of it to India with some boards I sold to a guy there

Waiting to get the bit back.

Ray

pre65 · Post by **pre65** » Sat May 03, 2014 2:13 pm

Ray P wrote:Unfortunately my RPi renderer has been delayed because I was a total dunce and accidentally sent part of it to India with some boards I sold to a guy there Waiting to get the bit back.

Ray

It'll come back with a suntan, or covered in curry.

nic · Post by **nic** » Fri Nov 14, 2014 10:49 am

I have tried USB xmos soundcards with ES9023 DAC , Hifiberry and the Pidac . The Pidac is the best of the lot , I think I2S audio is the way to go . Hifiberry is ok but no hardware volume control , XMOS has the occasional clicks and pops . Fine with Hifiberry and hardware volume control works . Unfortunately if you fit headers for a Hifiberry and buy a Pidac , you're screwed as these have different genders , I just went out and bought another Pi . Out of the software (Raspyfi/Volumio/Rune) I'm enjoying Rune 1.3 beta very much , it's much more powerful than previous versions , has internet radio and gitpull update facility

Nic

IDM · Post by **IDM** » Fri Nov 14, 2014 11:43 am

Hi Nic,

I was looking at the Rune Audio website the other day and was tempted to download and flash to an SD card to see how it performed. Previously when I had checked there was no I2S, it seems that provision of I2S is now pretty standard which is good.

Cheers
Ian

nic · Post by **nic** » Fri Nov 14, 2014 1:53 pm

Volumio just seems like Raspyfi with I2S DAC support . Early versions of Rune (for me) seemed a bit buggy , for example I could not see some files . Rune now seems to be a lot more polished and responsive offering a lot more features than Volumio . Their forum is excellent . I would strongly recommend flashing an SD card with Rune and giving it a try

Nic

Ray P · Post by **Ray P** » Fri Dec 05, 2014 7:50 am

Well, a little progress at last...

I've moved away from the RPi and bought a BeagleBone Black and I've also taken delivery of an AckoDAC AKL-SO3 Digital Isolator/Re-clocker.

https://sites.google.com/site/ackodac/home

The SO3 does essentially the same job as the FIFO product I started this thread about, but on a single integrated board. Apart from being integrated, the SO3 is also available whereas the original FIFO solution still hasn't progressed as a group buy after getting on for a year!

My SO3 is equipped with 90MHz family NKD clocks because I'll be using it for full sync mode from Beaglebone to Sabre9018 DAC (Buffalo 3SE) but you can specify other frequencies for other situations.

The Beaglebone is loaded with the Botic Linux distribution, which works with the SO3 to achieve some good stuff - depending on native sampling rate of the incoming data the BeagleBone/Botic sends a clock select signal to the SO3 which then sends back the correct master clock signal to the Beaglebone/Botic so the Beaglebone's iffy quality, single frequency onboard clock is avoided and thus your audio doesn't get resampled (with it's single clock the Beaglebone resamples 44.1KHz to 48KHz, which might be audible)

http://www.diyaudio.com/forums/twisted- ... river.html

Because I use UPnP to control my playback I've installed a suitable front end onto the Botic distribution;

http://www.lesbonscomptes.com/upmpdcli/

Anyway, I've just started to assemble the hardware and will report back when I get it up and running.

Ray

audio-talk

Raspberry Pi - Addressing a Weakness?

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