Switching speaker channel positions

jonnyapps

Member
Hi,

I have a bit of an interesting setup involving a 42" plasma and then a 120" projector, perpendicular to one another. Position 1 is the sofa, position 2 is a pair of salvaged cinema seats.

Screen_Shot_2014_08_18_at_14_40_36.png

(There is no flexibility regarding the living room layout, as has been decreed by the better half)

I built a quick and dirty switch box to change the channels around for 'film night' and it works although I'm sure it'll make a lot of people cringe. What I'm wondering is if there's another, more elegant, solution? The TV/projector are driven by either a PC via HDMI or Chromecast. I'd be interested in a PC-based software solution but would rather install a more functional hardware switch.

1450096_510968490610_953010494_n.jpg

The speakers wire in to the underside of the phono box and then the phono plugs are swapped positions as needed and route into the AV Receiver.

The next problem is going to be the centre speaker which arrives tomorrow. God knows what I'm going to do with that. Might have to buy 2!

Would welcome any and all suggestions on a more usable switch solution to this setup!
 

PSM1

Distinguished Member
I know of no off the shelf hardware (or software) solution to your issue hence what ever you do is going to be some form of home DIY job I believe. What you have may not look pretty but if it works and did not cost you much then it may be better to stick with it.
You can buy source selection switches for speakers so you could use a couple of these and then run 2 speaker wires from each of the outputs from the amps to the relative switches. Source 1 could then be for TV use and Source 2 for the projector.
2 of these would do the job:
Beresford TC-7220 MKII
 

PSM1

Distinguished Member
Do not use a cheaper speaker switch in reverse because these often allow both outputs to be selected at the same time. This would ineffect cross wire your amp and more than likely damage it. A source selection switch may cost more but it will not allow the 2 amps to be fed to the one speaker at the same time so prevents this costly error from occuring.
 

Steroc

Well-known Member
I'm looking to do the exact same set up you have there but with the two centre speakers.
I managed to get one of these off eBay for under a tenner, Xantech CC12.
And hope to wire this to a few relays to do the switching.
The CC12 is designed to be used with a Xantech IR system to do the switching but it also has a DC current sensing input to manage switching. My plan is to connect the current input to the USB port on the projector (or TV). So that when the projector is turned on the speakers will automatically be switched over due to the 5v supplied by USB then switch back when the projector is off for normal TV viewing.

Also worth noting that most amp speaker negatives are all connected directly together inside the amp so you may only need to switch the positives and connect all the negatives together inside the DIY switch box. Probably not a recommended way to do it but I don't see what difference it can make.
 
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BlueWizard

Distinguished Member
I'm confused about the actual equipment. The Photo shows what appear to be RCA connections. In this case, what is connecting to what?

If this is between Pre-Amp and amp, the you can use a simple RCA Line Level Switch box, but you would need one box for every two channels. So, depending on where the switch is set, depends on where the channels are routed.

So, you would need one switch to reconfigure the front speakers and one switch to reconfigure the Surround channels. And if you have two Center speaker, then you would need on switch to switch between the center channels. Though the Center confuses things a bit.

If we use speaker switches, it would be similar, one source path can be switched to one of two destination paths. Again needing up to three switch boxes.

To do this, you have have to make sure that the box had exclusive control of the channels of the speakers. That is, the same channel could not be wired to two switch boxes.

However, I confess that this is extremely confusing, especially when I don't really understand the equipment. Why does the photo show RCA cables for the various channels? Are we talking about switching speaker or are we talking about switching the channels that drive those speakers. Again, the existing equipment is to gray in my mind to offer a real solution.

I think the best solutions is simply a amp and stereo speakers for the TV, and an AV Receiver and 5.1 speakers for the projection screen. I suspect it is easier to get a Stereo and a AV Receiver to share a common source than it is to switch all these channels around.

Steve/bluewizard
 

Steroc

Well-known Member
I'm confused about the actual equipment. The Photo shows what appear to be RCA connections. In this case, what is connecting to what?

If this is between Pre-Amp and amp, the you can use a simple RCA Line Level Switch box, but you would need one box for every two channels. So, depending on where the switch is set, depends on where the channels are routed.

So, you would need one switch to reconfigure the front speakers and one switch to reconfigure the Surround channels. And if you have two Center speaker, then you would need on switch to switch between the center channels. Though the Center confuses things a bit.

If we use speaker switches, it would be similar, one source path can be switched to one of two destination paths. Again needing up to three switch boxes.

To do this, you have have to make sure that the box had exclusive control of the channels of the speakers. That is, the same channel could not be wired to two switch boxes.

However, I confess that this is extremely confusing, especially when I don't really understand the equipment. Why does the photo show RCA cables for the various channels? Are we talking about switching speaker or are we talking about switching the channels that drive those speakers. Again, the existing equipment is to gray in my mind to offer a real solution.

I think the best solutions is simply a amp and stereo speakers for the TV, and an AV Receiver and 5.1 speakers for the projection screen. I suspect it is easier to get a Stereo and a AV Receiver to share a common source than it is to switch all these channels around.

Steve/bluewizard
I assume it's just to switch the speaker layout between the amps speaker terminals the and speakers, to rotate the listening field by 90 degrees. If you look closely at the picture you can see he has joined and taped the phono plugs on to the speaker wires from the receiver and he states that the speakers are connected to the underside of the phono socket panel. It's not ideal but it enables them to be quickly swapped over. Although it could've been done using just 4 phono plugs instead of 8 if I'm understanding it right.
The only problem I can see with manual switches is that all speaker channels would ideally need to be switched at the same time as each speaker (except centres) would need to be wired to two switches (to NC of one and NO of another). One way would be to use a set of 3 position switches (centre off) and switch all switches to off before switching fully over.
 
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jonnyapps

Member
I assume it's just to switch the speaker layout between the amps speaker terminals the and speakers, to rotate the listening field by 90 degrees. If you look closely at the picture you can see he has joined and taped the phono plugs on to the speaker wires from the receiver and he states that the speakers are connected to the underside of the phono socket panel. It's not ideal but it enables them to be quickly swapped over. Although it could've been done using just 4 phono plugs instead of 8 if I'm understanding it right.
The only problem I can see with manual switches is that all speaker channels would ideally need to be switched at the same time as each speaker (except centres) would need to be wired to two switches (to NC of one and NO of another). One way would be to use a set of 3 position switches (centre off) and switch all switches to off before switching fully over.

Hi, yes it's as you described. How could I do this with just 4 cables, out of interest?

I've recently discovered that MPC-HC has an audio switching option which would be ideal except it doesn't seem to work for me. It's possible (probable) I'm misinterpreting its functionality. Does anyone have experience with this? (it's in options>internal filters>audio switcher)

With regards to the centre speaker, I bought some banana plugs and wired 2 speaker positions up. Now I just plug/unplug and move the centre speaker between 2 shelves.

Photo of the underside of the switch box
speaker_wiring.jpg
 

Steroc

Well-known Member
Hi, yes it's as you described. How could I do this with just 4 cables, out of interest?
You would still have same amount of wires, it's the RCA/phono plugs/sockets that can be halved. Each of the phono sockets on the faceplate should have two connections (the centre pin and the outer sleeve). You appear to have the positive to one phono plug and the negative to another for each speaker. If you'd have connected the positive to the centre pin and the negative to the outer sleeve on the phono plugs and sockets then you would only require one plug for each speaker instead of two as you have it.
 

jonnyapps

Member
You would still have same amount of wires, it's the RCA/phono plugs/sockets that can be halved. Each of the phono sockets on the faceplate should have two connections (the centre pin and the outer sleeve). You appear to have the positive to one phono plug and the negative to another for each speaker. If you'd have connected the positive to the centre pin and the negative to the outer sleeve on the phono plugs and sockets then you would only require one plug for each speaker instead of two as you have it.

Doh! Thanks. It does work and I'm awful at soldering so I'll probably just leave it as it is!
 

spyder viewer

Distinguished Member
Hi and welcome to AVForums.
I can clearly see that you have put a great deal of thought and effort into your project. It might be more helpful if you give some explanation of what it does, how in practice one uses it. Also, do you use any special components or cabling for the internals (plenty of scope there for argument ;) ). Also, your schematics might be a bit clearer if your watermark didn't go through the middle!

Very interesting!
 

kiwimack

Novice Member
Thanks Spyder for the input,
Dropbox - 90 DIGREE SPEAKER SWITCH 2.pdf
I have a difficult layout due to the shape of our extention with a vaulted ceiling and patio doors out to the garden with couches and TV on the side walls.
Dropbox - IMAG0179.jpg
I've searched for the last couple of years for a simple input-output switch that I could change the 5.1 speakers from the TV 90 degrees to the projector screen, we pull the couch around into the middle of the room to watch films.
The Pro-wire IW-101 switch caught my eye on ebay recently, I looking up the wiring diagram and the quality of the switches and found there was no feed back or crossing when switching from the A to B setting also liked the fact that it was screw in connectors so that I could swop cables around if it wasn't right when first tested with a multimeter. These switches are from the USA and I haven't been able to find anything similar in the UK. I removed the plastic front from the switch that is held on with 4 small screws, there is a L shapes metal bracket that holds the circuit board that the switch is on. I had to drill two holes in the top of the bracket to screw it to the box top. Due to the height of the button and the top of the box I had to redrill the mounting holes in the circuit board to get the height correct. The terminal boards where a great find with the input side requiring 5 pairs of inputs and the output requiring 6 pairs due to the second center speaker these were fitted to either end of the box. Before fitting the Terminal blocks to the box I first soldered speaker wire to each of the solder points on the input terminal board the output required two cables to each apart from center speaker connections. I laid out the box top with the switches on it with the terminal boards at either end of the switches. The wires for my box required for them to be long enough to lift out the top and switches from the box to work on them. Once wired up I checked the connections and cross switching with a multimeter.
The inputs terminal of the box is wired to the outputs from the receiver. The output from the box goes to the speakers plus the extra center speaker.
Dropbox - IMAG0178.jpg
I've explained it the best I can so hope this is of some help to everyone. The only thing I would change is the box shape so that it could sit on top of blue-ray player with switches to the front and terminals to back. Otherwise works great..
 
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kiwimack

Novice Member
Does your projector have a USB socket? If so you could use a series of 5v relays to do the switching powered from the projectors USB socket. That way the speakers would automatically switch over when the projector is powered on and back when powered off. Just a thought.
Not sure how I would get a cable to projector on the roof as cables are built into the walls and I haven't worked with relays before and don't know if I could make up a powered circuit.
 

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