I just bought two 2-way in-ceiling speakers (Yamaha NS-IC800). Each of them is rated at 8 ohms. I wired them in parallel (so it's 4 ohms in total):

enter image description here

The amplifier I will be using is Nobsound NS-20G which supports 4-8 ohms:

enter image description here

However, here comes the confusion. Since I only have a set of wire (1 red 1 black) due to parallel wiring, am I supposed to wire both of them to just the right channel or to just the left channel, or am I supposed to wire 1 red to right channel and 1 black to left channel?

The latter seems to be sensible given that I need stereo audio (not mono.)

However, I then discovered that doing this means that it's bridged and hence it is mono.

Not to mention the issue with the increased watts due to bridging (the amplifier has 100W x2 ratings) while the speaker only need 50W RMS per side so this setting could potentially damage the speaker.

I must have gotten or understood something wrong here.

  • \$\begingroup\$ It should be pretty obvious that you need a separate pair of cables for each channel to connect to each speaker. \$\endgroup\$
    – Transistor
    Jun 25, 2020 at 9:35
  • \$\begingroup\$ Also, the outputs on the amplifier are outputs, that means you should never connect them in parallel as that might damage the amplifier. Only use the amplifier as suggested in its manual. If you want stereo, 2 channels are needed meaning 2 pairs of wire and each speaker needs its own wire. \$\endgroup\$ Jun 25, 2020 at 10:05
  • \$\begingroup\$ If they are wired in parallel then you do not have stereo audio. Stereo audio is where the left speaker plays a different sound from the right speaker. But if they are wired in parallel, they play the same sound. Therefore, you must not wire them in parallel. \$\endgroup\$
    – user253751
    Jun 25, 2020 at 10:11
  • \$\begingroup\$ So OP bought consumer electronics and wants to connect it with other consumer electronics and people still answer this question? \$\endgroup\$
    – pipe
    Jun 25, 2020 at 13:45

2 Answers 2


Here's how you would need to wire them.

enter image description here


The amp uses a single TPA3116 chip for each output. So it has a D-class output stage where a single output channel is already driven in bridge mode. I do not recommend to do a stereo mix down to mono by using + and - from separate channels as they come from separate amp chips.

You really do need to wire both speakers separately to get stereo.

Because each output channels is already bridged, even if bridging between different channels is done (which I don't recommend), it's still 100W.

Two 50 watt speakers are a 100 watt load. If single channel of amplifier is rated at 100 watts, there is no problem. The speaker can handle 140W peaks.

And, obviously, with a 60W power supply powering the device, you will only get less than 60W to the speaker. Basically, based on power rating, neither your amp or power supply has the capability to damage the speaker under normal use.

Note that a single speaker has a sensitivity of 90dB, which means it produces 90 dB SPL with 1 Watt, measured at 1 meter distance. At two meter distance, it's 84 dB SPL. At 4 meter distance, it's 78 dB SPL. For reference, typical lawnmower is approximated to be 80-90 dB SPL.

So in light of this, you won't need much power really, 1 or 2 Watts is plenty for normal listening, so the range of 10W to 100W is completely unnecessary.


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