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Using Apple Pro Speakers with a class-d amplifier

Introduction

The Apple Pro Speakers (made by harman kardon) are a great piece of technology. They were specially designed for the iMac G4 and the Power Mac G4 MDD (mirrored door drives) series. Those computers had a special connector which supplied both – an audio signal and power – to the speakers.

There are some guides which explain how to connect the speakers using a 3.5 mm jack, but this will never be a real solution as these speakers need to be driven by a real amp – and not the line-out of a computer or other audio device.

As Griffin iFire converters are expensive and hard to get, this guide relies on a class-d amp, which means that you can revive the speakers for about 40 US dollars.

What you need

  1. Using Apple Pro Speakers with a class-d amplifier, Using Apple Pro Speakers with a class-d amplifier: step 1, image 1 of 1

    • This image shows the complete setup with which you will end up. With a little bit of work you can soon enjoy the clear sound of true harman kardon speakers.

    • Please note: This guide will destroy the original cable/connector which is used to connect the Apple Pro Speakers to an iMac, Power Mac or the Griffin iFire.

    • Please also note that – as with every electronical repair or modification guide – you alone are responsible for your own health and the health of others. Also be aware that you alone are responsible for any damaged electronic equipment.

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  2. Using Apple Pro Speakers with a class-d amplifier: step 2, image 1 of 1

    • Cut each of the speaker cables. To get the maximum length you can cut the cables near the white "knob" which merges the two cables.

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  3. Using Apple Pro Speakers with a class-d amplifier: step 3, image 1 of 1

    • Remove the outer insulation on each speaker cable. Remove up to two inch of isolation. You can use a scissor or a wire stripper. Be ultra careful not to damage or cut the inner wires.

    • Two wires are inside each speaker cable.

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  4. Using Apple Pro Speakers with a class-d amplifier: step 4, image 1 of 1

    • Now also remove the insulation of the small inner wires. Again be careful not to cut the cables as they are very small.

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  6. Using Apple Pro Speakers with a class-d amplifier: step 5, image 1 of 1

    • You should end up with something like this.

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  7. Using Apple Pro Speakers with a class-d amplifier: step 6, image 1 of 1

    • Now you will need to find out the proper polarity of the speakers, i.e. which cable is negative (-) and which is positive (+).

    • Unfortunately – at the time where I did this conversion – I did not photograph the cable colors. But there is an easy trick to find out the polarity:

    • In this image you see two banana plugs and a AA battery. Just imagine these are two stripped wires from one of the speaker cables.

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  8. Using Apple Pro Speakers with a class-d amplifier: step 7, image 1 of 1

    • Now connect one wire to the negative terminal (-) and the other to the positive terminal (+) of the AA battery.

    • If the speaker cone bulges out (left image), you've got the proper polarity. You now know that the wire on the positive terminal of the AA battery is your "+" wire, i.e. it will connect with the "+" output of your amp.

    • If the speaker cone moves in (right image), the polarity is reversed. You now know that the wire on the negative terminal of the AA battery would be your "+" wire, i.e. it will connect with the "+" output of your amp.

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  9. Using Apple Pro Speakers with a class-d amplifier: step 8, image 1 of 1

    • Now solder an extension cable to each of the stripped wires. If you want you can use a red wire for positive (+) and a black wire for negative (-) so you can easily connect the speakers with the amp later.

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  10. Using Apple Pro Speakers with a class-d amplifier: step 9, image 1 of 1

    • Finally insulate the wires properly. Use shrinking tube and/or electrical tape.

    • If you like you can also use shrinking tube on the previously insulated wires, so you end up with a single cable (per speaker) again.

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  11. Using Apple Pro Speakers with a class-d amplifier: step 10, image 1 of 1

    • Now strip the extension cables of each speaker. You are now ready to connect the speakers to your amp.

    • If you like you can use banana plugs with the stripped cables (like seen in the image).

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  12. Using Apple Pro Speakers with a class-d amplifier: step 11, image 1 of 1

    • You are almost done. Now properly connect the speaker cables/banana plugs with your amp. Connect your Mac or PC or some other audio device with the amp and enjoy your old new Apple Pro Speakers.

    • Please note that the Apple Pro Speakers don't sound too loud, but that's by design. Still, their sound is very clean and detailed (on a class-d amp).

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Finish Line

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rafael

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48 Comments

Amp shown appears to be a Muse Audio M20 EX2 TA2020

dick - Reply

Good guide. I'm doing the same thing with a pair of these speakers, but I think I'll use new cables soldered to the speaker terminals.

One quibble though. I believe the correct term for the wire covering is "insulation", not isolation, and in step 9, you "insulate" the wires, rather than isolate.

Chuck - Reply

Thanks chuck, I have corrected the wire covering term :)

rafael -

Will this amplifier work for my Apple Pro speakers?

http://www.amazon.com/LP-2020A-Lepai-Tri...

Brian Hernandez - Reply

Should work. Not the 'best' amp out there, but same tripath chip as most other class-d amps on the market.

rafael -

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