Can it damage a stereo amplifier to connect multiple speakers into a single channel, playing at full or high volume?

As an example, consider the Cambridge A1:

Input Impedance: 47k ohms
Loudspeaker Impedance: 4 to 8 ohms
Power Output: 25 watts into 8 ohms 

And the following speakers are at my disposal:

  • 2× Akai 40-watt speakers with tweeter and woofer (but weak bass)
  • 2× rear satellites, 1× center, and 1× subwoofer from a Panasonic surround set

With the above, one could split them roughly in the middle:

  • Left channel: 1× Akai, 1× satellite, 1× center
  • Right channel: 1× Akai, 1× satellite, 1× subwoofer

The goal is not to achieve surround sound (would need to buy an AV amplifier for that), but to compliment the Akai speakers with the rich bass and low-range of the Panasonic 3.1 set.

Is this possible? If not, how can it be achieved on a limited budget? Good speaker management systems seem expensive even when second-hand.

As you can probably tell, I'm very new to this, but I assume that there's a simple mathematical relationship. What specifications of each speaker do I need to take into account? Voltage, power, resistance/impedance, etc.?

  • Based on the speakers involved, this appears to be about home audio, which is off topic on sound design. Sound design is not about home listening environments, which appear to be what this is about. Studio monitoring would be on topic, but home/personal audio is not. – AJ Henderson Apr 23 '14 at 15:40
  • @AJHenderson, I think that this question is applicable in either scenario – Baumr Apr 23 '14 at 17:34
  • Yes, but answering every home theater/listening environment question that comes along ends up resulting in a large portion of the site being dedicated to the home theater support group. The point of cutting off questions like this that aren't clearly indicated as studio related is to prevent issues. If this is home recording studio oriented, please clarify that in the question. – AJ Henderson Apr 23 '14 at 18:04

It is impossible to tell without the input impedance of the speakers, but generally speaking the answer to your question is yes - you can damage either the speakers or the amp.

Say your speakers are each 8 ohms. If you connect 3 in series, you'll be presenting 24 ohms to the amp (8 + 8 + 8). This means the speakers will easily 'suck' the power off the amp, causing it to heat and possibly blow.

If you connect the 3 speakers in parallel, you'll be presenting around 2.6 ohms to the amp (see resistors in parallel for the calculation). This means that a lot of power will not be delivered and seeking high output level the amp can again to heat up and blow.

In both cases the speakers may blow as well.

So I wouldn't recommend this, especially with a weak amp like the one you share.

  • Thank you for that. Is this a fire hazard? – Baumr Oct 19 '15 at 12:49
  • 1
    Anything that overheats may cause fire. In the case of the speaker, this overheating is of the voice coil itself and should simply melt the wire causing short circuit - little chance of the speaker catching fire. But the amp could potentially catch fire, although this is very very rare as most have a thermal cutoff mechanism and failures elsewhere (the fuze, for example) are likely to break the circuit. So the chances are minute but still there, specifically with old amplifiers or dusty ones. – Izhaki Oct 19 '15 at 13:11

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