Two speakers in parallel, sonos amp, maximum volume?

  • 15 September 2021
  • 2 replies
  • 39 views

I wired a sonos amp to two speakers per channel in parallel.  The amp is 8 ohm stable to 4 ohms, and the speakers are 8 ohms each. So total impedance reduces to 4 ohms. The amp outputs 125 watts per channel and the speakers are 120 watts EACH. This is permitted by the sonos manual.

The amp blew the speakers after a few hours of use. The customer was running the amp at 80% to 100% volume.

If two speakers are connected in parallel like this, what is the safe maximum volume?

According to the sonos manual, if two speakers are connected in parallel, the amplifier output doubles to 250 Watts per channel as the impedance reduces by half from 8 ohms to 4 ohms.

Does this mean that the amp will output 125 watts per channel at 50% volume if two 8 ohm speakers are connected in parallel to each 125 W channel?

We replaced the speakers and the second set also blew out very soon.

if this calculation is correct, the amplifier will output 96 watts per channel when set to 38.4% volume. (38.4 % of 250 = 96). Which is safe for a 120 Watt speaker.

Why has a warning about the volume level, when connecting two speakers in parallel, not been included in the sonos manual

Thanks


2 replies

i found the answer:

https://support.sonos.com/s/article/4730?language=en_US

if two 8 ohm speakers are connected in parallel to one sonos amp channel, each speaker must be rated at 250 Watts.

our supplier gave us 90W and 120 Watt speakers, so they blew out!

Userlevel 7
Badge +21

Even with matched Amp power output and speaker power ratings you can damage a speaker by over-driving an amp into clipping. Folks focusing only on volume and not the quality or the sound may ignore the warning signs and experience problems.

I’m not an Amp owner so I haven’t looked into it but Sonos may have some design tweaks to lessen that danger.

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