Raspberry Pi Model B+

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Re: Raspberry Pi Model B+

Postby ACX » 21 Jul 2014, 10:05

Midnight wrote:
ACX wrote:1) the analog output has finally decent quality

Do they use some other chip/driver here? IIRC the bad sound quality was caused by only 10 bit resolution?

According to Pi Team there's also an improved audio power supply so the audio output sounds nicer - we don't have a schematic from the Pi Foundation yet, so we don't know precisely what changed

The most noticeable thing from my point of view is that I don't hear any electrical hiss/buzz anymore... I had this problem with the old B model and almost any PSU I tried.
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Re: Raspberry Pi Model B+

Postby Midnight » 21 Jul 2014, 10:33

Well, actually I've never tried the analog output because the infos I've found in the web. Examples:
The DAC for the Pi's analog audio out uses pulse width modulation, which is a technique I've actually used before myself to get audio out of an Arduino. It's not really an ideal solution for music, and in the case of the Pi the DAC has an effective resolution of just 11 bits!.

http://www.luke.maurits.id.au/blog/post ... ry-pi.html

Since the Raspberry Pi's analogue audio out port only offers 11-bit of sample resolution and because the sound is generated using PWM, I'm using a cheap chinese USB 1.1 audio card that I had lying around.

https://github.com/Derecho/synthberry

If the sound is good now with the same DAC it proofes that high res audio is useless :mrgreen: ;)
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Re: Raspberry Pi Model B+

Postby gswg » 21 Jul 2014, 12:57

The B+ has better noise suppression on the build in 10bit audio PWM support. It's still miles away from HD audio playback but okay if you are used to listening to FM radio through tiny earbuds :-)

I2S has moved to the 40pin header and is working fine however there are core linux software changes needed to fix i2s on the B+ so don't think that this is a HW issue only.

IQaudIO Pi-DAC "Plus" is well underway - with, we hope, a pleasant additional feature or two.

Gordon@iqaudio.com
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Re: Raspberry Pi Model B+

Postby tjaekel » 24 Jul 2014, 18:40

Raspberry Pi Model B+ works fine with I2S DACs, e.g. RPi-DAC, RPi-DAC-RCA:
http://www.tjaekel.com/T-DAC/raspi_Bplus.html

with:
four jumper wires (different GPIO pins now) AND a Rasbian Linux Kernel Patch.
I did the patch for I2S DACs not needing I2C control connection.
Three bytes to change in a kernel module - all fine.
Without Kernel Patch, even going with most recent image and update - RPi B+ will hang if I2S is used.
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Re: Raspberry Pi Model B+

Postby gswg » 25 Jul 2014, 12:28

The i2s driver change is trivial, someone just needs to make the code change - ensure it works on all board variants (including CM / CMIO), push to kernel-next and issue PR to Dom :-)

i2c is not effected

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Re: Raspberry Pi Model B+

Postby gswg » 07 Aug 2014, 18:52

B+ i2s changes have been integrated, plethora of audio boards will come next.
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Re: Raspberry Pi Model B+

Postby gswg » 13 Aug 2014, 16:54

I may need a special Rune Audio build for the B+ i2s changes soon guys.

Pi-DAC+ with headphone support announced today :-)

http://iqaudio.com

Gordon@ioaudio.com

B+_and_Pi-DAC+.jpg
New B+ compatible Pi-DAC+ HAT with hardware volume control and built in headphone amplifier.
B+_and_Pi-DAC+.jpg (233.07 KiB) Viewed 2987 times
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Re: Raspberry Pi Model B+

Postby gasanders99 » 01 Sep 2014, 04:07

I'd like to say Thanks! to the devs on this project. I absolutely love what you guys have done! I started researching this morning, and by the evening I had purchased the hardware (Raspberry Pi B+ and a USB audio adapter), set up everything and am enjoying my music as I type. Awesome!

I downloaded the 0.3-alpha version of Rune Audio for my Raspberry, burned the .img file to the SD card, hooked up the HDMI monitor, ethernet cable and power and watched it boot flawlessly.

My music files (Apple Lossless .m4a) are located on an old headless Linux machine under the stairs. I had to install the NFS server package on it, and following the instructions provided at https://help.ubuntu.com/community/SettingUpNFSHowTo, I got everything set up in a few minutes.

Once the NFS server was running on the file server, I was able to connect to it using the Rune Audio server’s web interface. Rune’s internal MPD server immediately started indexing the music, and in a few minutes I was up and running.

Thanks again for the wonderful work!
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