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Bridging Amp+ Output for Mono?

knowledgebass

June 12, 2015 17:15

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Is it possible to bridge the Amp+ output? If so I assume it would require a speaker with a nominal 8 ohm impedence (rather than the 4 ohm in stereo). Thinking about using it in a mono configuration for a speaker yet to be identified. I realize some ALSA configuration would be required on the RPi side as well.

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3 comments

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  HiFiBerry team June 13, 2015 05:27

  Hi,
  
  bridging won't give you more power. Therefore you don't need to bridge the Amp, simply use only one channel.
  
  Best regards
  Daniel
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  nettings February 16, 2019 10:56

  Does this comment still apply to the AMP2?

  Also, I don't quite understand. By bridging, I guess the OP and me mean to feed one channel with a polarity-inverted signal (to be handled in software), to connect the (-)-Ports of the loudspeaker terminals (usually that's done internally, with a low-impedance link to ground to avoid crosstalk), and to wire a speaker across Left-(+) and Right-(+). This should give twice the output voltage on many output stage designs. Usually, the allowable load is halved as the OP says. But the power of both channels is combined, so total output power bridged is roughly (Ueff * 2)² / (R * 2), a factor of two compared to the single channel case Ueff² / R, off the top of my head. 3dB sure isn't much to write home about, but hey...

  Does your comment apply to this scenario? Are you saying that the output stage is designed such that each channel can use the entire total power budget as long as the other is idle? Many modern amps like the current LAB Gruppen ones behave like that (which makes them very versatile in live PA work). But it would also imply the AMP2 is bounded by the power regulator, not the output stages.

  Edited by nettings February 16, 2019 12:14
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  HiFiBerry team February 18, 2019 09:34

  Bridging won't work as there output is already bridged internally.

  Best regards,
  Daniel