Add 6 speakers to 8 amplifier

Discussion in 'General Electronics Chat' started by drkblog, Dec 20, 2012.

  1. drkblog

    Thread Starter Member

    Oct 4, 2012
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    0
    I have a small jukebox with two 8Ω speakers and I have to add two 6Ω speakers. The jukebox has no additional speaker output, and there is no line output either. I have come with a couple of ideas:

    1. Putting the additional speakers in series mode. That would let me with a 14Ω speaker to each channel. I know I'm going to lower the maximum output power. But that won't be a problem as long as the music can be heard, since it's at a doctor's office.
    2. Using an audio amplifier for each channel (a TDA2030 or something simple) using the speaker output as the TDA's input. Here I'm making the assumption that TDA's high-impedance input will allow me to connect it in parallel with the 8Ω speaker without burning the jukebox amplifier nor damaging the TDA.
    A third option would be connecting a TDA amplifier to a proper signal source, but I would have to open the jukebox and find a connection point. And I would rather leave that as the last resort.


    Is it possible to implement one of the options I presented here?
    Is there a simpler solution?
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Connecting the additional speakers in series with the existing speakers is the simplest way.

    Connecting an additional amplifier to the existing amplifier's speaker outputs must use an attenuator (two resistors) for each channel since the additional amplifier has a certain minimum voltage gain far higher than 1.
     
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  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
    745
    Sounds ok to me connecting extra speaker in seies, if you want to connect the TDA amp to the internal source, connect the signal across the volume control of the jukebox, there is usually three terminals use the outer two, then you can have a separate volume for the tda amp.
     
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  4. drkblog

    Thread Starter Member

    Oct 4, 2012
    109
    0
    Thank you! I'm going to try series speakers first. If the sound level goes too low, I'm going to open the jukebox and add the TDAs amps.
     
  5. Audioguru

    New Member

    Dec 20, 2007
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    If the amplifier produces 10W per channel into 8 ohms then the output in the existing 8 ohm speakers drops only a little when 6 ohm speakers are in series.

    The output voltage swing is the root of 10W x 8 ohms= 8.94V RMS.
    8.94V squared /14 ohms= 5.7W. The 8 ohm speaker gets 3.25W (1/3rd of the power sounds only a little less loud) and the added 6 ohm speaker gets 2.45W. To make the sound at the same volume as before, simply turn up the volume control a little.
     
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    You can probably just hang the 6 Ohm speakers on in parallel to the existing 8 Ohm speakers. Most output stages can drive 4 Ohm loads. If it sounds distorted, maybe not but it's worth a try.
     
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