Stereo out to a single speaker

[Guitar Fogie]

I have a small stereo amp kit left over from some past projects. I am wondering if/how to wire the output to a single speaker. The amp is 10 watt/side. Assuming that the outputs are 8 ohms, what impedance speaker would be best? By combining the outputs (++, --) what would the result impedance be? What effect would series/parallel wiring of the outputs have?
This would be used as a practice amp for myself or a student musician. Plan B might be to use a pair of speakers in the same cabinet with each speaker wired to a separate channel ( L & R).
Is this possible or am I trying to put a square peg into a round hole. PS; I do not want to start any fires or cause things to go boom or poof. Any thoughts or comments? Tks for listening to an old man rant.

 

[Vincent Kars]

++, --

If you combine you have 2 amps (yes, that is stereo) trying to inject their power into each other. Might create some smoke signals...
So don't do this.
If you have a speaker with dual binding post, you can connect each amp to a pair but do remove the jumpers first.

 

[Zinda]

Invert the input signal on one channel and see if the amp bridges, need to check output on both plus outputs or possibly just 1 channels outputs it also may not bridge but you won't know till you try?

 

[Mr. Swordfish]

The general rule of thumb for analog audio is that you can usually use a Y cable to split an output to drive two inputs, but using one to combine two outputs into one input is a bad idea and will either work poorly or blow up your amp.

If you want to combine a stereo signal into a single (mono) signal, do it prior to the power amp. Lot's of ways to accomplish this. Don't Y the outputs of the amp.

 

[DVDdoug]

If you only have one speaker, only use one amplifier channel and leave the other output unconnected.

For a "practice amp" (guitar?) you should only need one channel. (Normal guitar amps are mono.)

If you want to combine left & right you need a mixer at the amplifier input (and you can still only use one channel with one speaker). This is the cheapest-easiest mixer I know of. (Or it's an easy thing to build with a couple of resistors if you know how to solder.)

Invert the input signal on one channel and see if the amp bridges, need to check output on both plus outputs or possibly just 1 channels outputs it also may not bridge but you won't know till you try?

I would NOT recommend that! Inverting is not generally trivial, you can't need a mono input, and you might fry the amp. Bridging is fine if the amp has a "bridge" switch (with the inversion built-in) or if you are building your own bridged amp (which I have done).

 

[RayDunzl]

You should make or buy a little circuit to sum stereo to mono safely.

Stereo to Mono lead

A technical question . . . . ! I am making a lead, to come out of the Luxsin X9 (headphone amp) RCA stereo out, and into an active mono speaker (Aventone MixCube). I am summing the Left and Right ground wires, and then running each of the Left and Right signal wires through a 4.7kΩ resistor...

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