speaker on off switch

henrylrjr · 2013-09-26 2:08 pm

Hi all,

I am planning to make an on/off switch for a pair of remote speaker. The remote speakers are connected to my main amp, that also powers speakers, in my main listening room. My plan is to use one dpst toggle switch, rated for 20 amps and 125 volts ac. I thought I could connect + wires from the amp and + wires to the speakers to the dpst, mount the switch on a box cover, attaching it to an electrical in wall box, where I had a volume control for the remote speakers. All thoughts and recommendations will be greatly appreciated.

Thanks,
henrylrjr

Osvaldo de Banfield · 2013-09-26 2:39 pm

It appears to be reasonable and sufficient the idea you have. No comments nor suggestion from me. Only be sure that the amp is capable of supporting both loudspeakers load at the same time.If it can, no problem at simple view.

henrylrjr · 2013-09-26 2:42 pm

The amp is an aragon 8008bb...plenty of power.

Osvaldo de Banfield · 2013-09-26 2:48 pm

It isn't a problem of power, the problem may arrise if the amp cannot sustain both speakers in parallel with a lower impedance than with only one, some can oscillate, other simple explode.

Osvaldo de Banfield · 2013-09-26 3:33 pm

I was thinking to suggest that t will better if you operate the switch with the amplifier shut down, or almost with no too strong output power to avoid sparks in the switch and in the amplifier's output.

henrylrjr · 2013-09-26 5:48 pm

I have been using the amp, for about 10 years, driving up to 3 sets of speakers at the same time. One speaker set was wired to one pair of the amp outputs and the other pair of amp outputs were connected to a Nakamichi RS-730 speaker selector, with options for off, set a, set b or a+b, and never had a problem.

Frank Berry · 2013-09-26 5:55 pm

Many amplifiers and speaker selectors put the 'A' and 'B' speakers in series when feeding both. Be careful feeding multiple speakers in parallel. You can cause damage to the amplifier.

weltersys · 2013-09-26 6:08 pm

henrylrjr said:
I have been using the amp, for about 10 years, driving up to 3 sets of speakers at the same time. One speaker set was wired to one pair of the amp outputs and the other pair of amp outputs were connected to a Nakamichi RS-730 speaker selector, with options for off, set a, set b or a+b, and never had a problem.

Then your 20 amp SPDT will not be a problem now.
I use a 20 amp SPDT on my deck speakers to turn on when outside, the Technics receiver has no problem with three sets of mains and subs, though my kitchen and deck speakers are 16 ohms, so the amp sees a 4 ohm load.

That said, most decent amps have no problem with 2.7 ohms, as long as they are not passing more than their rated power.

henrylrjr · 2013-09-26 7:08 pm

How do you do it with an spdt? I thought, because there are two + wires for a pair of speakers, one would have to use a dpst.

wolf_teeth · 2013-09-26 7:11 pm

Frank Berry said:
Many amplifiers and speaker selectors put the 'A' and 'B' speakers in series when feeding both. Be careful feeding multiple speakers in parallel. You can cause damage to the amplifier.

Depends on the amp. Some place in series, some in parallel. A+B is series. A and B is parallel. My old Technics was paralleled.

Later,
Wolf

Frank Berry · 2013-09-26 7:35 pm

Many consumer amplifiers are not rated for less than 6 ohms (especially the newer ones). A friend connected a pair of 4 ohm speakers to his Sony amplifier which was rated for 6 ohm load. It was a big mistake. The first time he cranked it up to a good listening level, the power amplifier modules 'smoked.'
Before connecting multiple pairs of loudspeakers to your amplifier, perhaps you should get the amplifier specifications.
Better safe than sorry.

Cal Weldon · 2013-09-26 7:42 pm

If you want to be safe use a DPDT and have only one set running at a time.

weltersys · 2013-09-26 8:58 pm

henrylrjr said:
How do you do it with an spdt? I thought, because there are two + wires for a pair of speakers, one would have to use a dpst.

You are correct, my post was dyslexic, tish happens

.
I am using a DPST on the deck main speakers, a SPST on the deck subwoofer.

henrylrjr · 2013-09-26 9:07 pm

Cal,
Thanks for the reply but I hate to add anything to my system. The switch in the remote speaker path will be a mil spec dpst with silver contacts which, combined with the mil spec silver plated ofc teflon coated wire, should minimize any effect to the sound. I don't want to put anything in the path to the main speakers.

weltersys · 2013-09-26 9:08 pm

Cal Weldon said:
If you want to be safe use a DPDT and have only one set running at a time.

Oh my, my shop with four sets of speakers and home with 3 sets is unsafe

!

Frank's suggestion to get the amplifier specifications is a good one, his example of a six ohm rated amp smoking with a four ohm load points to the sad state of some designs, or perhaps some crossed wires

.

Since the OP already knows his amp is safe with three sets of speakers, two sets won't be a problem.

cT equals piD · 2013-09-27 2:59 am

If the negative speaker output terminals (black) on the amp are common to both channels, you could use a SPST switch making/ breaking the common connection to the remote speakers. Also then you could have a three wire (rather than 4 wires) run to the location of the remote speakers.

bentoronto · 2013-09-28 6:07 pm

Generally, it isn't that an amp instantly catches on fire when load is low, but that the power it can output is diminished (before it catches on fire). Likely we have here (and in many systems) oooodles of power (possibly enough to worry more about the noise floor rather than the max power), so somewhat lower loading not an issue.... not that the published speakers impedance specs are any good guide to load in the first place.

The different sets of speakers (and their listeners) all happy at the same amp output level simultaneously? No quaint L- or T-pads in there?

Teflon wires and MIL-spec switches are nice, maybe, but I'd sooner favour getting cinderblocks to rest on my speaker boxes instead.

Ben

weltersys · 2013-09-28 7:42 pm

cT equals piD said:
If the negative speaker output terminals (black) on the amp are common to both channels, you could use a SPST switch making/ breaking the common connection to the remote speakers. Also then you could have a three wire (rather than 4 wires) run to the location of the remote speakers.

To maintain the same damping factor on the remote speakers, better to double up the common (-) connection.
Using three wires for stereo is about the same as dropping down a wire gauge or so, and on a long distance remote run the difference can be audible.

Edit:Frank's #19 points out a double-pole switch (on the two +) is needed even if one only used three wires.

Frank Berry · 2013-09-28 7:46 pm

If you break only the black (common) to both speakers, You will leave the red (+) connected to both channels. The speakers will still operate. They will deliver L-R audio.
You must use a double-pole switch.

weltersys · 2013-09-28 7:59 pm

Frank Berry said:
If you break only the black (common) to both speakers, You will leave the red (+) connected to both channels. The speakers will still operate. They will deliver L-R audio.
You must use a double-pole switch.

You are right, cT equals piD's suggestion would turn the remote speakers in to a "Phantom" stereo, any stereo difference signal would be heard through the remote speakers when the switch is open.

Fun effect, but not the OP's intended result.

speaker on off switch

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