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Building an open embedded audio applicance.

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francolargo

francolargo

Member
Joined 2007
Paid Member
Russ White said:
Also make sure you are using a battery with built in protection - including under-voltage.
Click to expand...
I assumed one needed 5v, so when I happened upon a small LiPO interface board that runs at 5v, I ordered. Two for 6 dollars! It has uUSB or pad 5v input (1A), std USB or pad 5v output (1.6A), over/under charge protection, and function LEDs. Two drawbacks: mounting is not simple, and ripple is 50mV @ 100Hz. This raises the question: For BBB power, how 'dirty' is 'too dirty'? Specs on lots of 5V switching power supplies are up around 100mV...
 
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Duffy Moon

Duffy Moon

Member
Joined 2008
I'm a little perplexed. My dual - mono Buffalo II/Ivy III/BBB/Hermes/Cronus setup is only playing the left channel. That's to say that both DACs are playing the left channel. My first thought was that I'd set the DIP switches incorrectly, but having double - checked them, they're correct.
Could it be the firmware chip on the Volumite? When turning the rotary encoder, I only get sound on one channel until it's almost all the way up and then the other channel cuts in (although as I now realise, it's just the left channel in both speakers).

Sent from my GT-I9505 using Tapatalk
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
Kindhornman said:
Why not an analog volume control after all the digital is converted to analog? From my understanding digital volume control it only causes a loss of S/N ratio for anything below full scale.
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All volume controls cause a loss of S/N. Digital volume, when properly implemented (as in the ES9018) is actually about the best you can do. It is possible to best it with an analog control, but not easily.
 
Kindhornman

Kindhornman

Member
Joined 2012
I didn't intend to start argument about volume control. There was a long discussion about volume control at one time on the oh so long Blowtorch thread and some very intelligent minds pointed out the problems that were directly related to doing volume control in the digital realm. There was a definite degradation of the S/N ratio when done in digital by any means, the only solution and it also had problems was a very expensive analog solution and there were also real issues caused by any type of switching so I guess there really is no perfect solution. The only real advantage of the digital solution was no contact resistance and oxidation problems in digital. From what I understand as you lower volume in digital you are cutting the bit rate, as you do that the noise is fixed so it becomes a higher percentage the lower you set the volume. I'll leave it to smarter minds to have that discussion.
 
S

siao

Member
Joined 2012
miero said:
siao, I'm not able to see the picture. What are you using and how is it configured?
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Sorry.
26738399026_3b46687db7_h.jpg

I found there is a PCM/DSD switch noise in ES9018K2M, but not in ES9018S.
 
A

adeveza

Member
Joined 2013
Raspberry Pi 3 i2s

Russ White said:
For quite some time I have been interested in streaming direct from an embedded system to an Asynchronous DAC.

I did this many moons ago using a beaglebone, and later beaglebone black, but while the results were great - I was not entirely happy with the complexity. I basically had a custom kernel and ALSA modules. In short more than I was happy to share, and it took far more effort than the average Joe would care to undertake.

Recently however the folks behind Raspbian and especially Florian Meier with his contributions to I2S modules have made me take a much closer look at the raspberry pi - particularly "model B - revision 2". The addition of P5 and the newest Raspbian and Volumio builds make it possible to have an incredibly good I2S based music appliance by simply adding a great DAC - such as the Buffalo III-SE - which works perfectly - but you could just as well use any asynchronous I2S input DAC.

Using the raspberry pi with the B3SE is very simple. I have tested two scenarios - each with distinct advantages.

First pi -> DAC direct.

This is really simple:

just wire P5 to the DAC appropriately - as show in the attached picture. Pin 1 is indicated on the rpi by the square pin. And P5 is located right next to P1 (directly below with P1 oriented at the top).

The best news is once configured you can use the pi as an airplay receiver (with a mac) for audio (at 44.1khz) and as a direct audio appliance at up to 192/32bit sample rate (the limit of ALSA at the moment).

I have mine streaming directly from NAS (an ASUS RT-AC66U with a USB SSD drive) at up to 192Khz sounding superb! No complaints. The sound is incredible.

The second method I will introduce if there is enough interest.

Here is detail you will want if setting up Raspbian, or Volumio for B3SE.

make your /etc/modules file looks like this:

Code: 
snd_soc_bcm2708
snd_soc_bcm2708_i2s
bcm2708_dmaengine
snd-soc-pcm1794a
snd_soc_rpi_dac

I am happy to help anyone who has any further questions on how to make it work.

You won't be disappointed with the results.

I have developed two different USB -> I2S modules, and I have yet to find any reason to use one of those over this much more direct approach. Especially for the Buffalo III-SE.

Cheers!
Russ
Click to expand...

I just got a Raspberry pi 3. Russ method above does not work with RP3. I think I got the wiring correct, from GPIO. However, I could not figure out the code to get the i2s to work. Have anyone done this on a Raspberry Pi 3? Can anyone help me get this thing to work? Russ, anyone? Please

Alex
 
francolargo

francolargo

Member
Joined 2007
Paid Member
adeveza said:
I just got a Raspberry pi 3. Russ method above does not work with RP3. I think I got the wiring correct, from GPIO. However, I could not figure out the code to get the i2s to work. Have anyone done this on a Raspberry Pi 3? Can anyone help me get this thing to work? Russ, anyone? Please

Alex
Click to expand...

It seems there may have been an issue in early Pi3 kernels. The following is all I've seen:

https://github.com/raspberrypi/linux/issues/1321

Good luck...
 
A

adeveza

Member
Joined 2013
RP3 Model B

francolargo said:
It seems there may have been an issue in early Pi3 kernels. The following is all I've seen:

https://github.com/raspberrypi/linux/issues/1321

Good luck...
Click to expand...

I got my RP3 Model B running Runeaudio thru USB(Amanero-Hermes-Cronus). It may not be as good as the I2S approach, but the sound is quite impressive already. I do have also a Beaglebone Black and just found out about the Hermes-BBB and Cronus combination by Twisted Pair. This may be the ultimate solution. As I understand it correctly, this is the most direct. It takes care of isolation, timing issues and no more conversion to pwm then back to dsd which the Amanero does. I am just waiting as they are Out of Stock of Cronus.

Alex
 
francolargo

francolargo

Member
Joined 2007
Paid Member
adeveza said:
I do have also a Beaglebone Black and just found out about the Hermes-BBB and Cronus combination by Twisted Pair. This may be the ultimate solution. As I understand it correctly, this is the most direct. It takes care of isolation, timing issues and no more conversion to pwm then back to dsd which the Amanero does. I am just waiting as they are Out of Stock of Cronus.
Click to expand...

I think you will be pleased with the Hermes/Cronus setup for the BBB. The user base is generous and collaborative, and folks are continuing to refine their BBB-based appliances. My system is down for moving right now, but when I get back to it I'll be working on testing the possibilities for simple FIR filters using the BBB's CPU. If those prove insufficient, I'll mess with running complex versions at the server level. The objective is to incorporate and evaluate the advantages of rePhase.

Cheers,

Frank
 
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