Raspberry Pi vs USB vs Mac Audio
The audio hardware of Raspberry Pi is known to produce relatively poor sound quality. I bought a cheap USB sound card to try as an alternative. Here is what I found.
This is how the USB card was identified by the Raspberry Pi kernel.
usb 1-1.4: new full-speed USB device number 21 using dwc_otg usb 1-1.4: New USB device found, idVendor=0d8c, idProduct=013a usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0 usb 1-1.4: Product: USB PnP Sound Device usb 1-1.4: Manufacturer: C-Media Electronics Inc. input: C-Media Electronics Inc. USB PnP Sound Device as /devices/platform/bcm2708_usb/ usb1/1-1/1-1.4/1-1.4:1.3/0003:0D8C:013A.0007/input/input6 hid-generic 0003:0D8C:013A.0007: input,hidraw0: USB HID v1.00 Device [C-Media Electronics Inc. USB PnP Sound Device] on usb-bcm2708_usb-1.4/input3
I listened to some music pieces both with the Raspberry Pi audio output and with the USB device, but I could not discern a big difference. I therefore recruited a volunteer to conduct a series of simple a/b tests. Again, the test results were inconclusive, so we decided to look at produced waveforms with an oscilloscope.
The first measurement was of an A440 tone (440 Hz, musical note A above middle C). I produced that on the Pi with the following commands.
speaker-test -t sine -f 14080 -Ddefault:CARD=ALSA
speaker-test -t sine -c 2 -f 14080 -Dfront:CARD=Device,DEV=0
Raspberry Pi | USB device | MacBook Pro |
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After more careful reading, I found that the problem with the Raspberry Pi PWM output was apparent at higher frequencies. Therefore, I moved five octaves higher, and looked at the output at 14080 Hz. Here are the results.
Raspberry Pi | USB device | MacBook Pro |
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The moral of the story is that the Raspberry Pi output isn't great, but it's not worse than what you get from a cheap USB audio card. Will this affect my use of the Raspberry Pi as a media player? I'm not sure. While reading on the topic I found the following great quote.
A music lover listens to music with his sound system.Read and post comments
An audiophile listens to his sound system with music.