Dumb Question - Same Speakers/Multiple Sources

1

147JK

Active Member
They say there is no dumb question, but I'm about to prove them wrong.:D

Is it OK to wire a single pair of speakers directly to 2 different sources (receivers in this case) without damaging the source components? Of course, both sources would not be used simultaneously.. only one or the other.

I don't know of this is OK, or instead I should use some kind of isolation switch.

Thanks
 
They make special equipment switches for what you want to do. Some are good, some are not so good.

check parts express they have some.

Some people just buy another set of speakers to avoid the switching requirement.
 
Yes, you need a switch. There are switches intended for using one amp with two pair of speakers that you can use backwards - i.e. one speaker for two amps. They're inexpensive.

Happy trails,
Larry B.
 
Never connect a pair of speakers to two amplifiers at the same time. It will cause, at the very least, major oscillation in your amplifier and possibly blow up outputs of both.
 
dewdude said:
Never connect a pair of speakers to two amplifiers at the same time. It will cause, at the very least, major oscillation in your amplifier and possibly blow up outputs of both.
Click to expand...

I was not intending to operate both amps at the same time. Concern is "backfeed" to the amp not operating, if there even is such a thing.

Anyway, it seems I could use a single 4-pole dual throw switch to do this.. it's a dirt-simple circuit. The "store-bought" switches I see are ridiculously expensive for such a simple job.
 
Last edited:
I was going to ask a similar question in the future, but now is as good a time as any. Would a switch like this work.

knifeswitch_zpsab46b84e.jpg


Middle to speaker, each end to a an amp. One on the back of each speaker?
 
147JK said:
Anyway, it seems I could use a single 4-pole dual throw switch to do this.. it's a dirt-simple circuit. The "store-bought" switches I see are ridiculously expensive for such a simple job.
Click to expand...

Quite a few online sellers have them as low as $12.50. A homemade switchbox would cost you pretty close to that, counting the switch and a box to put it in.

Happy trails,
Larry B.
 
Makes no difference...

147JK said:
I was not intending to operate both amps at the same time...
Click to expand...

Just remember there is "signal" flowing, and anything hooked up will receive that signal. The power switch (for the idle receiver) only cuts live juice getting to the rest of the circuitry. But by sending signal directly to the terminals is like going in the backdoor, so to speak. Definitely WILL cause damage. For some it isn't picked up right away. I've read of people testing their amp/receiver after such an incident, thinking all was OK, then days or weeks later the output stage failed.

I use an RS speaker selector switch. The one I use has internal load balancing that can be overridden, though I would not advise doing so. I would agree that some switches are likely better than others, but your personal tastes will dictate how important that is.
 
Several years ago I ran a system with dual amplifiers -- one for my 2-channel music, and another receiver for the TV. Same speakers, using a home-made switchbox. One day at work I got a call from my wife saying my amp blew up, and she was REALLY sorry! After I got home I realized it was the HTR that blew up because one amp was switched in before the other one was switched out. It literally blew apart the output transistors of the receiver!

So yeah, you can do it. But yeah, there are inherent risks. :yes:
 
dobyman said:
I was going to ask a similar question in the future, but now is as good a time as any. Would a switch like this work.

knifeswitch_zpsab46b84e.jpg


Middle to speaker, each end to a an amp. One on the back of each speaker?
Click to expand...

Looks perfect to me - I had a similar idea - I think you can do the entire circuit for both amps using one, 4 pole dual throw switch. Either way, these switches completely isolate each amp->speaker circuit, so I don't see the danger.
 
Cool. I figured that if you use one on the back of each speaker, there's only 2 tiny screw holes to attach, or Velcro, double sided tape, etc. This way, up for tubes, down for SS, or up for Pioneer, down for McIntosh, etc. Both up or both down, Easy.
 
Here's an example single switch. This should handle 2 amps going to 2 speakers. It's $5.
 

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The only problem I see with that is if you are using Monster Wire, or better, it will be pretty tough getting them on those small lugs.
 
A friend of mine purchased a switching system that does a myriad of sources and speaks instantly. Cost him around $50.00 and quality w/8 switchable throughputs'. We configured more (using other boxes too) but have simplified back to basic since.

I'll get the model # but can only say it was a major game changer in comparing serviced/non-serviced equipment and learning pairing marriages.
 
dobyman said:
I was going to ask a similar question in the future, but now is as good a time as any. Would a switch like this work.

knifeswitch_zpsab46b84e.jpg


Middle to speaker, each end to a an amp. One on the back of each speaker?
Click to expand...

This would work fine for your purpose. The main reason these aren't used in some electrical connections is that they build up carbon and oxidation very fast when switching with high power sent through them at the time... one of many reasons that relays are used with switches. You should be able to avoid this by flipping the switch while both amps are off.
 
dobyman said:
The only problem I see with that is if you are using Monster Wire, or better, it will be pretty tough getting them on those small lugs.
Click to expand...

Oh yes, not for monster cable for sure. I use 22 GA wire for my speakers, so this ought to be OK. How much current is going out to speakers anyway (typical)? I always thought it was only a very small amount of power.:scratch2:
 
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