lowering impedance on a class D amplifier

[amplifierfreak]

I was just kinda curious on how to lower impedance on class D amplifiers. I would like to know how to lower the output impedance. The load I'd like to put onto it is 1hm: and the amplifier is only 2hm: capable. Any info or links on how to accomplish this would be nice.

Thanks
Chris

 

[Nigel Goodwin]

I was just kinda curious on how to lower impedance on class D amplifiers. I would like to know how to lower the output impedance. The load I'd like to put onto it is 1hm: and the amplifier is only 2hm: capable. Any info or links on how to accomplish this would be nice.

As with any other amplifier, simply double the output devices (bearing in mind correct current sharing and drive requirements), you will also need to double the power supply capability. For class D you may well have to uprate the output filtering as well.

 

[mneary]

Or, you could split the load into two, 2-ohm pieces and use two amplifiers.

 

[Blatman Bond]

1 ohm is hard to design, and so far from normal speakers (8/4ohm).
If you can't split it, try with audio transformer, but 1 ohm was really hard.

 

[Hero999]

Unlike class AB aren't class D amplifiers designed to power a specific load that needs to be matched to the output filter's impedance?

To reduce the impedance you need to both redesing and up-rate the output filter as well as up-rate the swithing transistors.

 

[Nigel Goodwin]

Unlike class AB aren't class D amplifiers designed to power a specific load that needs to be matched to the output filter's impedance?

No, class D amps, like most others, can feed their minimum load and upwards quite happily. I've never used my class D amp in to 4 ohms (400W+400W), only ever used 8 ohms on it (200W+200W) - like all such amps the specs even list it.