Is it acceptable to 'jumper' speaker wire through a switch?

[ChrizK]

Firstly, I hope it is ok to discuss the wiring of speakers here. TBH my ignorance in all things electrical knows no bounds, and I am guessing it is a discussion about ohms, of which I have less idea about than watts.
To that end, I would appreciate any responses in the simplest of terms. Once again, I apologise if this is the wrong forum, as I suspect it is attended by many large brains that would rather speak in 'scientific' terms. However, my question is more 'theory' rather than 'straight electrical'.

The question relates to using a sound system with a TV on one wall which is perpendicular to a projector screen on another. The TV has Front Left and Front Right speakers located above it ...the idea is to 'switch' the Front Right to becoming Front Left (the projector), and Front Left to a separate speaker.
I bought a two-way speaker switch box from Amazon. I guess it is obvious to say that this is normally used to switch the input to two pairs of output.
In my case, I have speaker cable running to a single speaker on Pair(1) Right BUT ALSO 'jumpering' to Pair(2) Left.
As you may surmise, Pair(1) Left goes to a speaker, and Pair(2) Right goes to a speaker ...so three speakers in total.

If I think of this as 'direction of flow' when I select Pair(1), the Input(amp) is directed to Pair(1) Right speaker, and is 'dead ended' to Pair(2).
I turn off Pair(1) and select Pair(2), in which case, Input(amp) is directed to Pair(2) Left speaker, and Pair(2) Right jumpered to the twisted/join in Pair(1) speaker.

Hopefully I have explained that well enough (don't think a picture would actually provide any clarity)

This works ...but, sometimes my speakers just 'cut out'. Strangely (and please don't shout at me), if I increase the volume on the TV, it suddenly comes on and I deafened until I quickly turn the volume down. My initial theory was that it was the amp cutting out, but I considered that turning the volume up shouldn't resolve the problem, and so I believe it to be the switch.

So, my question is 'could this be considered a legitimate use of the switch, or am I doing something so stupid that I should expect it to cut-out?'

Thanks for your time.

 

[James]

i think a diagram would be helpful here.

 

[DPG]

i think a diagram would be helpful here.

Not just me then!

 

[davesparks]

If turning the volume up cures it then I'd hazard a guess at a loose connection somewhere.

 

[ChrizK]

If turning the volume up cures it then I'd hazard a guess at a loose connection somewhere.

In my ignorance, I was thinking along the same lines. Given that the speaker wire is just terminated into standard 'grips', I was thinking that it is possibly an internal fault with the switch. However, I was concerned that I was causing my own problem by attempting to do something that was fundamentally 'silly'.

The switch does allow Pair(1) and Pair(2) to be selected, ie both on. I suspect this might cause issues and so I have put a note on it to say switch both off first, before selecting the required pair. Not wishing to blow a speaker ...or even the amp(?), I have never tried having them both on.
Theoretically (appreciating that you have to visualise what I am attempting), could I damage the speaker or amp by having both pairs 'on'?

 

[DPG]

The main way any damage could be done when combining speakers is if you have multiple speakers wired in parallel and it reduces the impedance (resistance to all intents and purposes in this case) to a value lower than the amplifier can handle. This could damage the amplifier.

 

[ChrizK]

i think a diagram would be helpful here.

 

[ChrizK]

i think a diagram would be helpful here.

I hope you are not requesting a switch diagram, as I am afraid I am not competent. Hopefully the above is adequate.

 

[DPG]

View attachment 105656I hope you are not requesting a switch diagram, as I am afraid I am not competent. Hopefully the above is adequate.

Ah I see. No, don't connect the two speaker switch outputs together. That is what will be causing your problem.

 

[ChrizK]

The main way any damage could be done when combining speakers is if you have multiple speakers wired in parallel and it reduces the impedance (resistance to all intents and purposes in this case) to a value lower than the amplifier can handle. This could damage the amplifier.

If my diagram is sufficient, is that effectively what I am doing?
Given the switch allows both pairs to be 'on', would it also result in the reduction in impedance you mention?
Or, could it actually enhance it and negate the problem?
If so, given my 'misuse' of the switch, could it make things better or worse?

TBH This is where Ohms start to lose me ...why the reduction can cause damage ... although your wording perhaps has given me a clue. Is it that having more and more speakers reduces the resistance, so 'more gets through'? Again, I am not totally sure 'of what' ...is it equivalent to more 'power' getting through, and therefore the much spoken about 'blowing up the amp'?

 

[DPG]

I still can't quite picture what exactly you are trying to achieve with the whole left/right/crossing/whatever. But you don't want to connect the left speaker output of the TV with the right speaker output.

I'm pretty certain you won't need a speaker switch box either, as you are wanting it set up permanently - you don't need any switching. The worse you may need is a couple of dummy load resistors I reckon.

 

[ChrizK]

Ah I see. No, don't connect the two speaker switch outputs together. That is what will be causing your problem.

Oh ...
I know I asked not to have a technical explanation, but would you mind explaining a bit more?
ie, why does the sound cut out, and am I potentially damaging the amp or speaker?
Also, is there a reason why increasing the volume makes it come back (and does that too increase the risk of damage)?

Is it the case that there is no possible way to achieve what I want, other than having two pairs of speakers (resulting in two speakers right next to each other, which is what I wanted to avoid)?

 

[ChrizK]

...as you are wanting it set up permanently ...

Perhaps this is where the confusion is ...it isn't permanent. Either I will be watching TV with one pair, or the Projector with one 'switched' speaker + the additional speaker on the right of the projector. Hopefully that makes sense.

 

[DPG]

Perhaps this is where the confusion is ...it isn't permanent. Either I will be watching TV with one pair, or the Projector with one 'switched' speaker + the additional speaker on the right of the projector. Hopefully that makes sense.

Ah sorry, I didn't quite grasp that bit.

However you do this, you can't cross connect the left output with the right output. That will be why you have the cutting our problem.

I would reconsider to be honest - for the best sound results you want a matching pair of speakers in use and positioned properly, especially when you are using the projector. Also then you could use your switch box as it is intended.

The 'technical' reason is that you are interconnecting the outputs of two separate amplifier circuits. They designed to feed two separate speaker loads.

 

[davesparks]

However you do this, you can't cross connect the left output with the right output. That will be why you have the cutting our problem.

Unless ive misunderstood that switch box selects between pair 1 or pair 2. So as its drawn a cross connection doesn't happen because only on of the linked sets of terminals will ever be connected to the amp.

If it was a cross connection it shouldn't work at all, not just cut out after a while.

 

[DPG]

Unless ive misunderstood that switch box selects between pair 1 or pair 2. So as its drawn a cross connection doesn't happen because only on of the linked sets of terminals will ever be connected to the amp.

If it was a cross connection it shouldn't work at all, not just cut out after a while.

Yes that's a fair point. To be honest it has confused me this thread.

I think some phase reversal might occur though - I need to draw it out but I'm going to have a beer instead!

 

[ChrizK]

Unless ive misunderstood that switch box selects between pair 1 or pair 2. So as its drawn a cross connection doesn't happen because only on of the linked sets of terminals will ever be connected to the amp.

If it was a cross connection it shouldn't work at all, not just cut out after a while.

Appreciate the input ...almost a pun there.
It is unfortunate that I can switch both Pair(1) and Pair(2) into the on position at the same time. Although I don't fully understand resistance, I had a feeling this would be a bad thing to do ... so always ensure both are off before selecting one or the other. Again, I don't fully appreciate the technicalities of cross-connection, but my 'theory' was that having one or the other would effectively be 'straight through' and not a problem (accepting the risk that I may inadvertently select both and blow something!). Wasn't Scotty always warning Kirk about Phase Reversal
It is interesting reading the comments in the linked Amazon listing for the switch, as I note that the negative reviews mention things like "When switching a speaker output on, one channel can occasionally (often) not switch on. Rocking the switch back and forth can then convince it to come on, but that's far from ideal".
Given your comment and the information from @DPG , I am thinking that, although there is a significant risk having both 'on', the theory is ok, and it is very likely to be poor manufacturing. It is a great shame we allow Chinese manufacturers to sell items with little to no quality control, invariably producing unsustainable waste

And I do appreciate @DPG advice to reconsider, although I am no 'audiophile', and only had a practical solution in mind. TBH I don't use the projector screen that much, and would rather has less kit (and the middle speaker is by the TV, which would send said audiophile to an early grave).

Really appreciate everyone's time to help explain. Thank you.

Being really cheeky, would you guys know anything about RF interference?

 

[Lucien Nunes]

OK, I can guess what is going on here, disconnect it in case you damage the amp. I suspect the speaker switch does not work the way you have assumed, i.e. that it routes the signal to either output 1, or 2, or both in parallel.

Instead, a normal 2-way speaker selector connects both sets of speakers in series all the time, but short-circuits (i.e. bypasses) the speakers that are not in use. If both are selected, it does not short anything, and if neither, it open-circuits the amp. There is a reason that it works this way: With both speakers active they are connected in series so the impedance seen by the amp is higher than either speaker alone, rather than lower as it would be if they were in parallel. Also, with only one set active, the speakers that are not in use are shorted to damp the cones against sympathetic resonance.

This being the case, your problem is not about impedance but about the series configuration of the switching, in which all speakers are always connected to the amplifier even when bypassed. In this non-standard application, the cross-connection for the 'middle' speaker is tying the two amplifier channels together which can damage it, and could cause the cutting in and out that you describe as one or both amp channels go into protect mode and stop fighting each other, or all sorts of unsavoury effects could be going on. What you want to achieve is perfectly feasible, but we will either have to start with a different switch, or modify this one. Please post some pics of the innards and if it is possible to make the necessary modification I will guide you how to do that.

If for any reason your switch does not work the way I describe, we can pursue alternative explanations, but I thought I would jump on that bandwagon in a hurry because of the potential for damage. Possibly, the switch is configured for parallel switching, which is unusual but not impossible. Then a likely explanation for the sound to cut-in at high volume is that the product is substandard, using switch contacts that are unsuitable for audio, which are maintaining a high resistance until a certain minimum 'wetting voltage' is placed across them by increasing the output.

 

[ChrizK]

What you want to achieve is perfectly feasible, but we will either have to start with a different switch, or modify this one. Please post some pics of the innards and if it is possible to make the necessary modification I will guide you how to do that.

What a fabulous offer. Hopefully I can provide what is needed at the weekend ...TBH 'when' it gets to the point of soldering in components, I may get cold feet, but I find the discussion very informative.

 

[ChrizK]

If for any reason your switch does not work the way I describe, we can pursue alternative explanations, but I thought I would jump on that bandwagon in a hurry because of the potential for damage. Possibly, the switch is configured for parallel switching, which is unusual but not impossible. Then a likely explanation for the sound to cut-in at high volume is that the product is substandard, using switch contacts that are unsuitable for audio, which are maintaining a high resistance until a certain minimum 'wetting voltage' is placed across them by increasing the output.

Hi, I cannot apologise enough given your good intentions. I totally appreciate that this was raised in January, and my interest appears to have been lost. Life issues keep getting in the way of my 'projects'. In this case, the switch has not been used for the fear of breaking things, but I would still like to reach the solution. To that end, I have included some photographs. Funnily enough, since taking the unit to pieces, it seems to have stopped cutting out, but that is a limited observation due to lack of use.
NB Stupidly or not, I did actually try switching 1 and 2 on at the same time, and it seems to result in 'all' speakers working (I didn't have the confidence to play with this, as it is not intended use, so no idea if reduced performance, or even if it causes a problem, as I switched back to 'position 1' quickly).
As you will see, the wiring is incredibly simple. As it looks 'secure', I guess the actual rocker switch is not good quality, hence causing the cutting out and my concerns. I would however appreciate your expert point of view, if you can forgive me.

NB You will see I took the pictures in April, and still didn't have time to get back here ... really sorry
Furthermore, the casing is horrible and I didn't manage to align it properly when putting back together (as feared).

 

[DPG]

Hi, I cannot apologise enough given your good intentions. I totally appreciate that this was raised in January, and my interest appears to have been lost. Life issues keep getting in the way of my 'projects'. In this case, the switch has not been used for the fear of breaking things, but I would still like to reach the solution. To that end, I have included some photographs. Funnily enough, since taking the unit to pieces, it seems to have stopped cutting out, but that is a limited observation due to lack of use.
NB Stupidly or not, I did actually try switching 1 and 2 on at the same time, and it seems to result in 'all' speakers working (I didn't have the confidence to play with this, as it is not intended use, so no idea if reduced performance, or even if it causes a problem, as I switched back to 'position 1' quickly).
As you will see, the wiring is incredibly simple. As it looks 'secure', I guess the actual rocker switch is not good quality, hence causing the cutting out and my concerns. I would however appreciate your expert point of view, if you can forgive me.

NB You will see I took the pictures in April, and still didn't have time to get back here ... really sorry
Furthermore, the casing is horrible and I didn't manage to align it properly when putting back together (as feared).

Sadly Lucien has recently passed away. He is greatly missed on the forum.

Hopefully someone will be able to assist with your issue though.

 

[ChrizK]

Sadly Lucien has recently passed away. He is greatly missed on the forum.

Hopefully someone will be able to assist with your issue though.

Oh my goodness, I am so sorry for everyone's loss. That certainly puts life's issues into perspective.

 

[Avo Mk8]

Like everyone here, I'm missing Lucien's perceptive insights on this and other forums.
I do hope his vision of the Museum of Electricity and Electronic Technology will come to fruition in some form or other.

ChrizK - I'll contribute to the limited extent I can, making some assumptions as to what is in your switch box!
I can see it uses small printed circuits as "bus bars" across the input contacts and also across some of the rocker switch pins.
One can see the tracks on the nearer pcb but not on the rear connectors, so I'm making some possibly incorrect assumptions in drawing the scrappy circuit below (with a leaking biro!)
I don't think it is as sophisticated as Lucien initially suggested, but his closing comments are pertinent. I can't really add anything about the behaviour you experience, save to say the following:

By cross-linking the left and right speaker outputs you seem to have created the situation where the 'negative' right and left channel speaker outputs are permanently connected together. Depending on the design of your amp, this may create an immediate problem with its performance and overload protection. If your amplifier -ve speaker output is ground anyway, then it's not a problem.
And then, if you operate both switches simultaneously (which you have generally tried to avoid!) you will connect the amplifier left and right speaker outputs together, which is probably not a good thing. For a stereo signal it will be feeding one amplifier output back into the other channel, so 'fighting' with each other.

Assuming you continue to avoid the above, I think the switch you have ought to do what you want, but I fear Lucien's comments about the quality of the switch contacts is perhaps the answer.

My suggestion of what's in the box:

In my younger day you used to be able to buy, cheaply for a shilling or so, an ex-military Cutler-Hammer 4-pole, double throw, (centre off if you want) toggle switch, with which you could wire up the necessary configuration, without any danger of connecting outputs together etc. I was going to suggest that would be a better approach, but I see the prices have gone up !!

If your amplifier has the -ve speaker output connected to ground you can use a double pole double throw switch rather than the above!

 

[ChrizK]

In my younger day you used to be able to buy, cheaply for a shilling or so, an ex-military Cutler-Hammer 4-pole, double throw, (centre off if you want) toggle switch, with which you could wire up the necessary configuration, without any danger of connecting outputs together etc. I was going to suggest that would be a better approach, but I see the prices have gone up !!

Not fully appreciating the poles, I absolutely love your anecdote
Thank you for the reply. It gives me some confidence, and underlines that I should never switch 1 and 2 to on.

 

[Avo Mk8]

Not fully appreciating the poles

4 poles meaning 4 switches in one!
This sort of thing:

12 PIN 2 POSITION 4 WAY 2 POLE ON-ON 4PDT 240v 10A HEAVY DUTY LATCHING SWITCH | eBay

Find many great new & used options and get the best deals for 12 PIN 2 POSITION 4 WAY 2 POLE ON-ON 4PDT 240v 10A HEAVY DUTY LATCHING SWITCH at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

eg if the amplifier speaker outputs are connected to the middle row of 4 terminals, then the speakers to the outer rows, you can arrange the connections as needed

 

[ChrizK]

4 poles meaning 4 switches in one!
This sort of thing:

12 PIN 2 POSITION 4 WAY 2 POLE ON-ON 4PDT 240v 10A HEAVY DUTY LATCHING SWITCH | eBay

Find many great new & used options and get the best deals for 12 PIN 2 POSITION 4 WAY 2 POLE ON-ON 4PDT 240v 10A HEAVY DUTY LATCHING SWITCH at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

eg if the amplifier speaker outputs are connected to the middle row of 4 terminals, then the speakers to the outer rows, you can arrange the connections as needed

I must admit, I have been staring at the picture of terminals (screw down) for a few minutes, and can't picture how on earth I would wire it up in a similar manner. Please don't feel obliged to answer, but it is interesting that you consider it a solution!

 

[Avo Mk8]

I must admit, I have been staring at the picture of terminals (screw down) for a few minutes, and can't picture how on earth I would wire it up in a similar manner. Please don't feel obliged to answer, but it is interesting that you consider it a solution!

Will get back to you when I've recovered from the grandchildren's birthday party tomorrow, which may take a while!

 

[Avo Mk8]

Just about recovered from yesterday

ChrizK - if I have correctly understood what you were doing with the speakers, the scrappy diagram below shows the connections to the type of switch I was speaking about.
There may be other ways of doing this, but not knowing whether your amp has common -ve speaker connections for example, this is probably the safest way!

 

[BenCos18]

Sadly Lucien has recently passed away. He is greatly missed on the forum.

Hopefully someone will be able to assist with your issue though.

R.I.P
sorry for everyones loss.
never knew that till now and that's auctully sad to hear as I used to read his comments and posts a good bit

 

[ChrizK]

Just about recovered from yesterday

ChrizK - if I have correctly understood what you were doing with the speakers, the scrappy diagram below shows the connections to the type of switch I was speaking about.
There may be other ways of doing this, but not knowing whether your amp has common -ve speaker connections for example, this is probably the safest way!

View attachment 109415

Fabulous, that makes sense. Just to be completely sure ... from the diagram, I jumper the left 'bottom' pair onto the terminals of the right 'top' pair. The terminals of the right 'top' pair also wire into the 'switched left/right' speaker.

NB Your diagram is great, but I am not familiar with diagrams 'strictly portraying' the physical reality! It kinda looks like the positive is spliced into the wire going to the speaker, but I am fairly surely this is just for clarity. Sorry, I am almost embarrassed to ask the question, but just making sure there isn't a reason to do so (again, underlining my ignorance!).

 

[Avo Mk8]

Fabulous, that makes sense. Just to be completely sure ... from the diagram, I jumper the left 'bottom' pair onto the terminals of the right 'top' pair. The terminals of the right 'top' pair also wire into the 'switched left/right' speaker.

correct

NB Your diagram is great, but I am not familiar with diagrams 'strictly portraying' the physical reality! It kinda looks like the positive is spliced into the wire going to the speaker, but I am fairly surely this is just for clarity.

Yes it was just my way of trying to make it 'neat'. Sorry - a bit 'old-school'. If you build it, you take the wire to the terminal, not splice it into the other wire.

Sorry, I am almost embarrassed to ask the question, but just making sure there isn't a reason to do so (again, underlining my ignorance!).

Not a problem. A 'circuit diagram' is to show the concept of the circuit, not the physical implementation. Once you see what is connected to what, you are free to wire it however is most convenient.
(actually this may not be true for radio and high frequency circuits, where it can matter where things go!! - but that is not the case here)

 

[ChrizK]

Firstly, I hope it is ok to discuss the wiring of speakers here...

Thanks for your time.

Just want to close this question with a HUGE THANK YOU to everyone. You have been really patient with me, especially as I have been supplying bits of information over the course of the conversation (and have no idea how my amp works, so can't answer some important questions, making the overall question a bit sketchy).