Series parallel

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Series parallel

If you have a look at this video of the Infinity IRSV's new home, some might be wondering how in the world those 132 drivers are all connected together.

It's a question I get asked a lot.

Take, for example, the 12 midrange panaler ribbons. How can you arrive at a 4Ω impedance for the amplifier powering them when each of those drivers is 4Ω?

The answer lies in a technique we often employ called series parallel.

Two 4Ω drivers in parallel half their impedance to 2Ω. Two 4Ω drivers in series double their impedance, to 8Ω.

Now, imagine the Infinity designers placed those 12 midrange drivers in 4 groups of 3, seriesed together. Each group's series impedance would be about 12Ω (4Ω+4Ω+4Ω). Now, place the 3 groups of 12Ω in parallel, and bingo! You're just about 4Ω.

The woofers are a different matter. In the original IRSV configuration, all six 4Ω woofers were in parallel and amp designer, Greg Shug, built a beast of an amp that could reliably drive 1/2Ω load.

When we rebuilt the system, PS engineer Bob Stadtherr made us a customer amplifier chassis for each woofer tower featuring six 1000 watt amps, one for each woofer.

And still, even after all that, the FR30s now gracing Music Room Three best these ancient beasts in many respects.


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Paul McGowan

Founder & CEO

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