Question about speaker wire hookup

[suttondesign]

Hi all. Is there any reason I cannot hook up two speakers to one set of +/- terminals on an amplifier IF I leave one speaker disconnected at the speaker location?

The reason is that I'm about to test out multiple speakers running from the same amp, and the amp is located in a hard-to-reach spot. I use Speakon connectors at the speakers, so no bare wire will be lying around if one pair is disconnected.

 

[Deleted member 89782]

Go ahead. But you should unconnect one pair before hooking up on pair two. So you might just as well use the same cables.

 

[kyuu]

Shouldn't hurt anything AFAIK. However, I agree with Rider: why not just swap the same speaker cables between the sets of speakers?

 

[suttondesign]

Because they are not the same kinds of speaker designs, and each has outboard crossovers, and one is three-way, where the other is 2-way. Thus, the new run to the 2-way has a different signal than the two that go to each 3-way.

 

[Davey]

I don't think I would do that. The unconnected speaker cable could act as an antenna and couple RFI back into your amplifier output.
(Devils advocate here.)

 

[suttondesign]

Hmmm. Its termination is inside a Speakon connector. Doesn't that help? Or could I terminate it in some other way at the speaker end?

 

[Davey]

Hmmm. Its termination is inside a Speakon connector. Doesn't that help? Or could I terminate it in some other way at the speaker end?

There's no termination inside a Speakon connector.

I'm talking about an electrical termination between the +/- legs (that's not an actual speaker.) This could be a small RC network connected across the leads that would terminate the line, for RF purposes.
Are you following?

 

[suttondesign]

Yup. I wonder if speaker selector switches have these built-in? I will research it.

 

[DVDdoug]

I don't think I would do that. The unconnected speaker cable could act as an antenna and couple RFI back into your amplifier output.
(Devils advocate here.)

That's a super-rare problem and the wires that are unconnected at one end are still connected to the other amplifier and to the other speaker so any EMI radiation is seeing a low impedance load and it will be greatly attenuated.

And if it happens it will likely also happen with one regular speaker connection.

 

[suttondesign]

I will be using in-wall-rated, twisted pair speaker wire, so that may help.

 

[Davey]

That's a super-rare problem and the wires that are unconnected at one end are still connected to the other amplifier and to the other speaker so any EMI radiation is seeing a low impedance load and it will be greatly attenuated.

And if it happens it will likely also happen with one regular speaker connection.

Well, I've seen it before. So not super-rare.
This would be highly amplifier and environment dependent, obviously.

The OP is free to do as he likes. I was just highlighting a 'potential' issue.

 

[Speedskater]

About a half century ago, in the age of vacuum tube amps and CB & taxi radios.
Speaker wires could act as interference antennas. But now days not so much.
In the rare case, twisted pair cables are more interference resistant than widely spaced wires.

 

[Heinrich]

Well, I've seen it before. So not super-rare.

Don't class A/B amps have a Zobel network (lol, cap plus resistor) at the output? If not, one could just add some. I mean, a speaker box ain't a clean termination anyway.

 

[Davey]

About a half century ago, in the age of vacuum tube amps and CB & taxi radios.
Speaker wires could act as interference antennas. But now days not so much.
In the rare case, twisted pair cables are more interference resistant than widely spaced wires.

Well, a half century hence the spectrum is full of many things that didn't exist back then.
More than likely there will not be an issue here. But, I've encountered situations where people tell me "it shouldn't be a problem" right up until the time it becomes a problem.
I'm more conservative than most EE's, and I don't think it's good practice to leave wires open-ended.

A snubber is just a simple suggestion. I won't have any deleterious effect.