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Two sets of speakers... only one amp
Old 9th September 2012
Two sets of speakers... only one amp

Old 9th September 2012
Lives for gear
Lotus 7's Avatar
Shortest post I've seen in a long time.

Let's see... removing the velvet cover from my crystal ball. It's a fuzzy image but I'm sensing that the OP wants to connect (2) sets of passive speakers to one power amplifier.

If the amplifier is rated for to drive a 4 ohm load (almost all are these days) AND both sets of the speakers have rated impedances of 8 ohms or higher, then a simple parallel speaker switching box will work. It will allow either set or both to be powered.

There are other speaker switches that will connect to more than (2) pairs, but beware of using those for any serious audio application (they are in really intended for background music and PA applications). Those "more than (2) sets" switchers are advertised as "impedance matching". What they actually do is connect the speakers in a series/parallel arrangement to keep the load impedance from going too low. Unless both sets of speakers are exactly the same model, connecting them in series will seriously compromise the audio quality because of the different frequency-dependent impedance changes. Those "impedance matching" switchers should really never be used for any serious music application.

If the OP is asking about using speakers in parallel for a sound reinforcement situation, then it all depends on the speaker impedances, sensitivities and the load impedance the amplifier can drive.

An amplifier that is rated to drive a 4 ohm load can power (2) 8 ohm speakers (in parallel) on each channel, but not (2) 4 ohm speakers, unless they're identical types and then can be connected in series without degrading the sound.

An amplifier that is rated to drive a 2 ohm load (as many current high-power PA amps are) can drive (2) 4 ohm speakers connected in parallel on each channel, or (2) 8 ohm plus (1) 4 ohm, or, of course, (2 to 4) 8 ohm models.

Whoops, the crystal ball is dimming, dimming, dimming. All dark now......
Old 31st October 2014
Lives for gear
Kimotei's Avatar
🎧 10 years
Old thread, but: does it exist a monitor controller for passive speakers so that they can share the same amp?

I just got an amazing amp, and have both nice old passive speakers and new passive ones that would be great to run both from this nice amp, as I cant afford 2.

Old speakers: B&W 603 s3
New speakers: Amphion One18
Amp: Brand new Amphion 100w
Old 31st October 2014
Lives for gear
Lotus 7's Avatar
There are passive speaker switches which can handle the current that a passive speaker needs and can maintain the low output impedance required so that speaker damping is unaffected. However, "Monitor Controller" usually implies something with a level control, or separate level controls for each set of speakers.

Controlling levels at the output of a power amplifier can be done with high-power potentiometers (more often called rheostats when the power ratings are that high). It's not an efficient way to control levels but can work if you must have level control. One such device is the Monoprice speaker switch/controller which is rated for up to 100 watts per channel.

Alternately, if you don't mind controlling levels at the output of your DAW. mixer or amplifier input, a simple high-current passive speaker-switch can be used to switch between the pairs of passive speakers. The basic switch is more efficient and less expensive than the level controller. There are many, similar passive switches that will work, and you should easilly be able to find one in Europe.

Hope this helps.
Old 1st November 2014
Lives for gear
Kimotei's Avatar
🎧 10 years
Thank you very much!
📝 Reply

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