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At our cottage, we have a stereo in the living room, on the deck and out by the covered firepit. Way too many stereos, cables, remotes, etc. What I want to do is have one stereo (living room), a rocker switch panel, and then wires out to speakers to all these locations. I feel I need rocker switches with 4 pins, but can only find 3 pins. Rocker switched with 4 pins would be for the stereo wires (pos/neg) going into the switch, then stereo wires (pos/neg) going out to speakers.
So, I guess my question is, am I doing this correctly? Is there an easier way?
Thanks for any help.
Cheers
 

pc1966

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Some stereos have the '-' of the speakers as common, but not all do! Some have the speakers +/- driven in opposition to get more power from a given supply voltages.

So a 4-pole changeover switch is going to be the best/safest option for you (or even a rotary switch with 4 poles and 3 or more ways for 3 or more speaker sets).

These days many folk use bluetooth speakers, etc, but that introduces all sort of other issues (radio range, need for power to the speakers which may be an issue outside for safety, etc).

If you can solder then this would do:

If you can't then crimp push-on terminals are simpler to use (but get a ratchet crimp, not the horrible pliers type) then this is another options (but out of stock for a month it seems):

The toggle types are easier to mount on a blank plate for a box, switch outlet, etc, and seem easier to get in 4PDT or similar configuration.
 
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Some stereos have the '-' of the speakers as common, but not all do! Some have the speakers +/- driven in opposition to get more power from a given supply voltages.

So a 4-pole changeover switch is going to be the best/safest option for you (or even a rotary switch with 4 poles and 3 or more ways for 3 or more speaker sets).

These days many folk use bluetooth speakers, etc, but that introduces all sort of other issues (radio range, need for power to the speakers which may be an issue outside for safety, etc).

If you can solder then this would do:

If you can't then crimp push-on terminals are simpler to use (but get a ratchet crimp, not the horrible pliers type) then this is another options (but out of stock for a month it seems):

The toggle types are easier to mount on a blank plate for a box, switch outlet, etc, and seem easier to get in 4PDT or similar configuration.
Hi and thanks for responding.
Those were exactly what I was thinking about - solder or crimping. Its good to see that there are some 4 pin ones out there. It was confusing to me because I can't be the first one to think of doing this. And our stereo has a Bluetooth with a remote and it works well.
Thanks a bunch
 

Lucien Nunes

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Beware that you cannot simply connect extra speakers in parallel to an amplifier output channel without checking the total impedance that will result. For maximum power and minimum distortion, the speaker impedance should be within the range specified on the amplifier, typically 4-8Ω. Too low an impedance is where the problem lies; for example, connecting two 4Ω speakers in parallel will present a load of 2Ω which would overload a 4Ω output. With the volume turned up, at best the amplifier would distort and/or shut down or blow some internal fuses, at worst might be damaged and damage the speakers too. If you only want one set of speakers in use at a time, that is not a problem, but take care that your stereo doesn't get fried at the flip of a switch.

Traditional multi-speaker selector switches often worked by switching the speakers into series, and then series-parallel, when more than one set were selected at a time. Nowadays, the usual solution is to use a receiver or multi-zone amplifier with independent power amplifier channels for each set of speakers, with the switching being done at the signal stage.
 

Megawatt

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At our cottage, we have a stereo in the living room, on the deck and out by the covered firepit. Way too many stereos, cables, remotes, etc. What I want to do is have one stereo (living room), a rocker switch panel, and then wires out to speakers to all these locations. I feel I need rocker switches with 4 pins, but can only find 3 pins. Rocker switched with 4 pins would be for the stereo wires (pos/neg) going into the switch, then stereo wires (pos/neg) going out to speakers.
So, I guess my question is, am I doing this correctly? Is there an easier way?
Thanks for any help.
Cheers
They make a 4 way switch
 

davesparks

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You don't need to switch both poles to the speakers, just switching the +ve will break the circuit, the - ve can be joined straight through.

But as Lucien has pointed out, don't connect too many speakers in parallel!
 

pc1966

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You don't need to switch both poles to the speakers, just switching the +ve will break the circuit, the - ve can be joined straight through.
Not always! Bridge-tied load style amplifiers have both + and - driven in opposite phase, though that style is more common for cars to make the most of a lower DC supply voltage without stepping up.
 

Lucien Nunes

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But even with a BTL ouput, you could leave one side of the speaker connected, it's only functional switching. It would leave the speaker flapping around on the end of one PA but unless the cable is miles long and creating too much stray capacitance, it should work.
 

pc1966

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But even with a BTL output, you could leave one side of the speaker connected, it's only functional switching. It would leave the speaker flapping around on the end of one PA but unless the cable is miles long and creating too much stray capacitance, it should work.
Yes, that is true.

I always get a bit paranoid about things getting cross-connected, oscillating, and blowing up drivers!
 

Lucien Nunes

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OT, the first amp I saw go into oscillation was one I had built aged 15. It was my first effort at a valve 100V line public address amp closely following the Brimar application note using two 807s giving 75W in AB2 but modified a little to account for my salvaged transformers not quite matching the specs. It actually has enough iron to give 100W if you can stand 7% THD and a dull red glow from the 807s.

I was standing nearby when, without warning, the 5W carbon film 47R anode stoppers lit up like sparklers on bonfire night, rapidly going O/C. One of my mentors, a seasoned PA contractor and designer, didn't see it happen but heard me react to it. I described the firework display and said I thought the bias supply must have gone off but he immediately recognised it as oscillation. After I changed the resistors and got it working again, we had a look with the scope and it turned out that with whatever load was connected, it was just barely stable, because I had modified the NFB network based on some wrong assumptions about the transformer. Thankfully the tranny survived, as I would likely never have found an identical replacement.

Once I got the NFB right it served me well for many years and I still have it. 15 years ago I was going to rewire the power supply chassis as that was a bit hacked about underneath, but something interrupted me and it's still all packed up in pieces in a box.
 

davesparks

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Not always! Bridge-tied load style amplifiers have both + and - driven in opposite phase, though that style is more common for cars to make the most of a lower DC supply voltage without stepping up.
But there are still only 2 wires going to the speaker so breaking one of them with a switch will interrupt the curcuit and current will cease to flow.
 

pc1966

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First effort going for 807s: a brave/foolish person!

Stability is hard to achieve, the obvious issue is the overall NFB loop, but with the likes of the ultra-linear configuration you have screen grid feedback and that can require some RC damping screen/anode to make things behave.

Then we have exhibit B m'laud, where you forgot the grid/anode stopper and it whistles in the MHz region...
 

DPG

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Nice that you've still got it Lucien. I could live with 7%. Ultra low THD is over rated!
 

pc1966

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But there are still only 2 wires going to the speaker so breaking one of them with a switch will interrupt the circuit and current will cease to flow.
Yes, so long as you don't common the '-' of the speakers between L/R, as they can't be assumed to be at 0V.
 

Lucien Nunes

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It's tetrode output, with a separate rectifier and HT rail for the screens, fixed bias nearly -80V and a 6SN7 as cathode-follower driver. The grid current is pretty horrendous at full welly.

I should fish it out and fix it. I have 197 other projects and 0 time, but it would be fun. I'm also about to move my bench into a different room and it will come to light in the process.

OP, sorry, drifting a bit here!
Post automatically merged:

Ha, found a pic of the PSU before I took it apart, sans lampes. They would be an 83 mercury vapour rec for the main HT (note ceramic UX4 socket), a 5U4 for the G2 / driver supply and a 6X5 for the bias. Main HT transformer came from a WW2 submarine.

The 7-pin O-Z socket connects to the amplifier, with 550V, 350V and whatnot accessible on those uninsulated contacts. I didn't then know that there was supposed to be another paxolin insulator that's missing from this socket. It didn't worry me at the time because I was going to include a pilot circuit with a relay that only grounded the HT secy CT once the neg bias was proven at the far chassis. but that bit never got finished. I got worried about the ground pin going O/C sending the amp chassis up to HT, and doubled up with what was going to be the pilot pin.
 

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DPG

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Jeez that transformer looks huge.
 
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