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Phase Inverter Bridge

Discussion in 'Audio by Van Alstine' started by BillWojo, Jan 22, 2017.

  1. BillWojo

    BillWojo AK Subscriber Subscriber

    Messages:
    2,750
    Location:
    Burlington, NJ
    I have one of these on the way, picked it up on Barter Town in a trade. If nothing else the two Telefunkin tubes will come in handy.
    I can't find any information on this unit at all. Looks like it goes between the preamp and a set of amps. So how does this thing work and what advantages does it bring to the table? Are there any special considerations or precautions when using this?
    At the moment, both of my systems are running monoblocks so I have nothing to use it on. Maybe down the road......
    Thanks for any info and yes, I did search the website.

    BillWojo
     

     

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  2. whoaru99

    whoaru99 Epic Member

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    A bridging adapter provides a normal and inverted output for each channel. Having the normal and inverted outputs facilitates bridging any amp with common ground inputs/outputs.

    In a nutshell, more or less convert stereo amps to more powerful mono amps.

    The most noteworthy drawback is that each amp channel drives half the load. So, when an amp is bridged, an 8 ohm speaker feels like a 4 ohm speaker to the amp, and a 4 ohm speaker feels like a 2 ohm speaker.
     
  3. BillWojo

    BillWojo AK Subscriber Subscriber

    Messages:
    2,750
    Location:
    Burlington, NJ
    Still don't quite understand. If the outputs are inverted from each other and combined at the output terminals, wouldn't they cancel each other out being 180 degrees out of phase?
    Surely I'm not getting this.

    BillWojo
     
  4. Lesterbest

    Lesterbest Super Member

    Messages:
    1,600
    There's nothing to get. Follow the instructions. Then decide if you prefer it. Some amps can't be bridged.
     
  5. avionic

    avionic " Black Knights " Subscriber

    Messages:
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    Fort Dodge, Iowa
    Amplifiers must be common ground.
     
  6. whoaru99

    whoaru99 Epic Member

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    They are not out of phase, just of opposite polarity with respect to each other.

    For example, the normal channel swings +1, the inverted channel swings -1. The difference between is 2. The voltage swing to the speaker doubles. Maybe this will help.

    Bridged.png
     
    Last edited: Jan 26, 2017

     

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  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,711
    Location:
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    You do have to reverse the speaker connections on one of the speakers as well.
     
  8. whoaru99

    whoaru99 Epic Member

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    The positive terminal of the amplifier channel that's carrying the inverted signal connects to the negative speaker terminal.
     
  9. BillWojo

    BillWojo AK Subscriber Subscriber

    Messages:
    2,750
    Location:
    Burlington, NJ
    Ok, I think I understand now. I need to use both of the positive outputs on the amp to connect to my speaker with the inverted channel going to the negative terminal of the speaker.The amps used MUST have a common ground for this to work.
    At the moment I don't have a matched set of amps to play with this but I'm sure my friend Kevin does. Will have to find time to play with this.
    I opened the unit up to take a good look at it. I must say that it is very well built using top notch parts! Even the metal case is very well constructed.

    BillWojo
     
  10. whoaru99

    whoaru99 Epic Member

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    Yup, that how the bridged connections are hooked up.

    It may also be clear now but, for example, the left normal and left inverted go to one amp, right normal and right inverted go to the other amp.
     
  11. whoaru99

    whoaru99 Epic Member

    Messages:
    40,935
    Location:
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    There is another way to use the bridging adapter even with just one stereo amp. I think that's what Avionic was eluding to in post #7.

    Connect one channel of the amp, for example the right channel, to the bridging adapter right channel normal output. Connect speaker to the right channel of the amp in the normal manner, (+) to (+) and (-) to (-).

    Connect the left channel of the amp to the left channel inverted output of the bridging adapter. Connecting the speaker to the left amp channel (the inverted channel) by reversing the speaker leads. Connect speaker (+) to amp (-) and speaker (-) to amp (+), but only on the left/inverted channel.

    This will, in theory, more evenly distribute the demand across the positive and negative rails of the amp power supply when there is common material in both channels.
     

     

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