Stereo wiring question

Factual Questions
1

We’ve got our stereo connected up to speakers in two different rooms.

When one of us is in the second room, and doesn’t want to hear the stereo that’s being enjoyed in the first room, we untwist the wires that connect the speakers to the stereo (and retwist them together again to reconnect them, when required). Needless to say this is a highly imperfect solution, partly because it’s annoying, partly because it causes the wires to weaken (and thus they are getting ever so slowly shorter), and partly because there’s got to be some inexpensive gadget (perhaps a switch of some sort?) that has been designed for the purpose.

It’s not attached to a wall or anything, the speaker wire just runs along the floor by the wall (and the speakers get moved around sometimes), so any gadget would have to be lightweight enough to accommodate that.

Any ideas?

2

Since your stereo apparently doesn’t have switchable A and B speaker circuits you might just add a switch to the speaker cords themselves. Seriously, a little rotary lamp switch that is made to install inline in the cord. You’ll need to use two as AFAIK there is no DPST version of those switches but it’s cheap and unobtrusive.

3

You can go with a speaker switch to control the two sets of speakers. You can also go with a set of bullet connectors to make the connecting/disconnecting easier. Be VERY careful to not let the powered ends of the speaker wires touch, that kind of short can damage your amplifier.

The speaker switch would the preferred method, though you might need a higher powered version for your purposes.

4

What’s “DPST”?

And, exactly which are the ‘powered ends’? Perhaps we’ve been lucky so far.

Those bullet connector things: we would need two, yes? (If not then I don’t understand how they’d work.)

5

The wires that come from the amplifier have a voltage across the two ends, that’s what powers the speakers. Sort of like how the two wires from an electrical socket have voltage across them, only a much lower voltage. If those ends touch while there is a voltage across them (when music is playing in Room #1), the circuit shorts, and draws far more current from the amplifier than it should, and can damage the circuits. Disconnect the wires at the speaker end, and you have two bare wire ends in close proximity to each other, risky.

You would need one pair of bullet connectors for each wire, so you would need 4 male and 4 female to wire up your 2 speakers. Radio Shack has a wide variety of similar connectors, there might be another type of connector that would be better and can give you less risk of a short.

6

You don’t want the bullet connectors; get a switch. It’s cheap, and it’ll do exactly what you want. Also, don’t worry about DPST (or DPDT, which is really what you want). Just walk into your local Radio Shack or Frys or whatever, and tell them you want to hook your stereo to two sets of speakers and switch between them. They’ll know what you need. The link from Cheesesteak is exactly it if you want to order online.

And as Cheesesteak mentioned above: DO NOT accidentally connect the outputs from your stereo together. You’ll fry your amp.

7

Are you sure your amp doesn’t have an A/B speaker switch? I can’t remember the last time I saw an amp or receiver that didn’t.

How expensive is your equipment? If it’s really cheap, and doesn’t have an A/B switch, perhaps now is the time to upgrade?

If not, get the external switch. Don’t mess around with twisting and untwisting your wires.

8

For the record:

DPST = double pole single throw
DPDT = double pole double throw (these come in two varieties, on-on, and on-off-on)

These are types of switches. Your basic light switch is a single pole single throw switch - it is either closing the circuit, or it isn’t. What you need is to do this on two circuits, so you need either two SPST switches, or a DPST switch, which is functionally equivalent to two SPST switches operated by a single toggle. I have no idea why Bill H thinks you really want a DPDT switch.

If I were in your shoes, I’d probably raid work for some inline SpeakOn jacks rather than going with a switch, but that may just be me.

9

Here are some diagrams of common switch types, along with pictures, and definitions.

10

Ah, lovely. I started typing out a description of a double throw switch several times, but ditched all of them because they were just confusing the issue and ultimately not terribly relevant. But with pictures! it all becomes clear, and this is a good thing.

11

Oh, and I keep forgetting to mention - if you decide on getting a switch, be sure to ask about its current rating. If it’s not rated to carry enough current, you could fry the switch in short order. Just ask if the switch can handle the current in a speaker line.

12

Wow ! This is all very educational.

The thing is, I need to be able to switch the speakers off from the room that the stereo is not in - ie if I’m in bed, and my husband puts on the stereo, I want to be able to switch it off without having to get up and go into the living room.

But it does look like I will have to figure out a way to mount something on the wall.

13

Gorsnak wrote

The typical solution to cowgirl’s problem is to use a DPDT switch at the amplifier. the left output from the amplifier goes to the center of one of the switches, and the two “destinations” of that switch go to the left connectors on each of the speakers. Same setup for the right.

Using a DPST would allow you to turn on and off a single set of speakers, but not switch between them.

However, new information from cowgirl:

In this case, you do want a DPST switch in the second room, and possibly in the primary room as well, if you want to hear things only in the second room.

14

I had considered that you might be thinking of this arrangement, but rejected it since it doesn’t allow you to play to both sets of speakers at once, which was something I took the OP to be wanting to be able to do.

Yup, this is exactly right. The switch controlling the speakers in the second room can be located anywhere along the speaker line, and hence can be in the second room. That switch could be, as was suggested by Padeye, one of the little rotary switches you sometimes see on lampcords, which you should be able to get at a Home Depot. You’d need one for each of the two speakers in the second room if you go this route since those switches are single pole, not double pole. You don’t necessarily have to have anything mounted to the wall.

15

The one issue that I didn’t see addressed in any post thusfar is impedance. Depending on the impedance of the primary and secondary speaker set, and the levels at which they are driven by the amplifier, the audio output stage may not be happy. Any switching arrangement must take this into account. Failure to do so may cause amp damage.

16

The remote switch will work, but it’s a lousy solution. Unless the speakers are matched very well in terms of efficiency with the ones in the other room, what you really want is individual volume controls.

Here are your options:

First (and cheapest), is an L-pad. This is like a volume control, except the impedence that the amp sees does not change.

Something like this..

This allows you to not just switch the speakers off, but individually control the volume of the second set of speakers. You can also get them with an on-off switch, although I don’t know if it’s necessary. I have a couple of these pads, and when they are turned all the way down no sound comes out of the speakers at all.

However, these switches require that you run the speaker cables for both speaker to the switch, and from the switch to the stereo. Can you do that? Or are your wires in the wall and not accessible?

A more elegant solution is to go with an infra-red extender, and control the volume at the source. You can get speaker switches/volume controls that sit with your stereo gear and can be controlled with an infra-red remote. Then you can get a powermid IR extender to control it from your other room. But this solution will cost you at least $300.

The best solution for you might be to replace your receiver with a cheap 2-zone receiver. A 2-zone receiver will not only allow you to control your second speakers from the other room (again, with a $49 powermid remote extender), but you can actually play different sources at the same time, so one person can be listening to a CD while the person in the other room listens to the radio.

You should be able to find a receiver with a second zone starting around $300. This will give you the most flexibility, ease of installation (you don’t have to change anything about the way stuff is wired up now), etc.

There are other ways to go as well. There are multi-zone amplifiers, whole-house audio systems, etc. Mostly, big bux.

One other thing - you say that right now you are twisting and untwisting the wires. If you can’t switch from A to B speakers, then wiring all four up at once is going to cause your speaker impedence to drop. If you have 2 8 ohm speakers, putting two more in parallel with them will drop the load to 4 ohms, which will make the amplifier work harder (if it’s a cheap amp, it may not handle it). If your speakers are 4 ohms already, you’d be better off wiring them in series, but that might be very hard to do with your setup.

I think your best solution is upgrading to a 2-zone receiver, if you can afford it.