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Power supply voltage: Does it matter?

martin3

March 22, 2015 18:58

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So far I used a 12V supply with the Hifiberry Amp+, which worked fine.

Over the weekend, the Raspberry/Hifiberry replaced a Zeppelin Mini in my home office, because it sounds a lot better. Now I have an extra 16V power supply that I can use. It works fine, and seems to produce the exact same volume level than the 12V supply.

Is there any reason to prefer one over the other? E.g. is 12V more power efficient than 16V? Does the 16V burn off more heat?

The 16V can deliver 3.2A on 16V, and the 12V 3A, so the 16V is roughly 40% stronger.

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7 comments

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  martin3 March 22, 2015 19:26

  Actually I have one more power related question: How much power does the Hifiberry Amp+ on a Raspberry Pi Model 2 B use, if there is no audio playback at all?
• 0
  
  martin3 March 22, 2015 19:48

  I found part of the answer to the 2nd question: The Amp alone uses 30mA on 12V.
  
  A Raspberry Pi Model 2 draws on 5V about 230mA when idle. In addition there is the WLAN stick, which by definition must be under 100mA, since it is USB connected. So Pi and WLAN would be max. 1.65 Watt, plus the 0.36 of the Amp would be a total of roughly 2 Watts. In Switzerland this is about 3 CHF per year, so I guess I'll just leave the device running ;)
  
  Does my calculation look ok?
• 0
  
  HiFiBerry team March 22, 2015 20:19

  Hi Martin,
  
  12V work fine and will create less heat on the voltage regulators.
  The power consumption of the Amp will be a bit higher as the power supply itself is often not very effective on a very low load. Therefor I would guess 4-5W is more realistic. This largely depends on the performance of the external power supply.
  
  Best regards
  Daniel
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  cpg April 23, 2015 09:42

  Hi, I have a Thinkpad 20 volt power supply. Does that extra 2 volts over the recommended 18 volt maximum mean that this should not be used?
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  HiFiBerry team April 23, 2015 12:14

  Hi,
  
  you should not use this. The extra 2V might damage the Amp. If you can't get a good 18V power supply (we have one in our shop), use 12V. You won't notice a big difference in sound volume between 12 and 18V even if the output power on 12V looks much smaller.
  
  Best regards
  Daniel
• 0
  
  martin3 May 22, 2015 11:25

  Because I have a lab power unit by now, I could do some measurements. These values don't change much between idle or playback.
  

  
  
  • 12 Volts: 220mA (2.64W)
  
  
  • 16 Volts: 190mA (3.04W)
  
  

  
  
  Very good values, IMO.
  
  Edit: Of course this is what the Pi/Hifiberry consumes. The electric bill will show more, because the power adapter itself doesn't work at 100% efficiency.
• 0
  
  HiFiBerry team May 22, 2015 13:42

  Hi Martin,
  
  most of the power consumption in an idle scenario comes from the Raspberry Pi itself. Even when playing music quite loud, the power consumption is usually not much higher when the speakers are not very inefficient.
  
  Best regards
  Daniel