Is connecting two Amps to one set of speakers for A/B testing safe?

[Astojab]

Hi everyone!
I am soon going to receive the Topping PA5 and would like to do a A/B test with my other Amp (Hegel H90) in order to see how big the differences are (if there are any) and maybe a more proper Blindtest later.

I have a multimeter for level matching and could either switch between inputs with the E50 DAC or use the internal DAC and use an optical switch I bought. Since I would rather not invest in an speaker switch but still do want to switch fast I wanted to ask if it is possible to connect both amps simultaneously to the speakers via banaplugs and bare speaker wires and only feed one Amp at a time the signal?

Or is that a sure way to blow up the amps or speakers?

 

[Zek]

Since I would rather not invest in an speaker switch but still do want to switch fast I wanted to ask if it is possible to connect both amps simultaneously to the speakers via banaplugs and bare speaker wires

NO, because you can fry power stages in amplifiers.

 

[Astojab]

And that is even the case if there is only ever a signal on one of them?

 

[MakeMineVinyl]

NO!

 

[MakeMineVinyl]

And that even the case if there is only ever a signal on one of them?

NO!

 

[egellings]

NO! The amplifiers act as hard voltage sources, and when connected together, they will fight each other to establish a voltage across the speaker terminals. Heavy circulating currents between the amplifiers will flow, and one or the other or both will be damaged. Best way is to just pop for a switch to toggle back & forth between the test speakers, or just manually toggle the speakers' connections. Be certain that this switch has break-before-make contacts in both directions of the switch. Voltage amplifiers do not like having their outputs connected together, not even momentarily.

 

[Astojab]

NO! The amplifiers act as hard voltage sources, and when connected together, they will fight each other to establish a voltage across the speaker terminals. Heavy circulating currents between the amplifiers will flow, and one or the other or both will be damaged. Best way is to just pop for a switch to toggle back & forth between the test speakers, or just manually toggle the speakers' connections. Be certain that this switch has break-before-make contacts in both directions of the switch. Voltage amplifiers do not like having their outputs connected together, not even momentarily.

Thank you for the explanation. Is there a switch you can recommend?

 

[MakeMineVinyl]

Thank you for the explanation. Is there a switch you can recommend?

That speaker switch you didn't want to spend money on might be a good start.

 

[egellings]

You could use a DPDT toggle switch, found in the electrical departments of hardware stores as a possibility. That would let you select one or the other speaker, or neither if the switch has a center position. Be careful if you are using a tube amplifier. They do not like having no speaker connected while playing. In all cases, have the volume at zero when operating the switch.

 

[Astojab]

That speaker switch you didn't want to spend money on might be a good start.

Ok that would be this one (description in english), but no clue if thats decent.

 

[MakeMineVinyl]

Ok that would be this one (description in english), but no clue if thats decent.

That seems like a good one.

 

[Astojab]

You could use a DPDT toggle switch, found in the electrical departments of hardware stores as a possibility. That would let you select one or the other speaker, or neither if the switch has a center position. Be careful if you are using a tube amplifier. They do not like having no speaker connected while playing. In all cases, have the volume at zero when operating the switch.

After a quick google search I am not sure I wouldn't fry my amps with one of these.

 

[egellings]

Toggle switch would likely be better and certainly less expensive. I don't know what quality and ampacity (current carrying ability) the switches in that product have. It could be good or not very good. If you don't do audio-oriented DIY, then opt for the switchbox.

 

[mhardy6647]

 

[egellings]

That baby will do it for sure!

 

[pjug]

You might ask @RichB what he used do do similar. I think he got a device with remote control which would be convenient. Whatever you do make sure it switches out both + and - , doesn't connect - in common since one of your amps is bridged.

 

[Kal Rubinson]

4 poles might be necessary, depending on the amps.

 

[Zek]

Two such switches, one for each channel.

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[brimble]

 

[mhardy6647]

4 poles might be necessary, depending on the amps.

Yeah, I know -- I was going to put a 4PDT switch image, but I saw that one, reflected upon it for a moment, and thought -- meh, good enough!