Just finished a quick hack and I figured I'd share. I had a couple pairs of Apple Pro Speakers laying around, but with no computer to use them on. So I decided to hack a pair and see if I could turn them into normal stereo speakers.
Apple did some weird stuff with these speakers, but underneath the weirdness is traditional speaker technology. My first idea was to simply replace the proprietary connector with a standard 3.5mm TRS minijack, but that section of cable is quite short and you'd need to make an interesting breakout connector for the other end. Also, you're limited to the cables already wired onto the speakers--you can't spread them more than a few feet apart.
So I decided to chop out the Y-connector in its entirety. The cabling that the Pro Speakers use is two-conductor shielded plus an outer braid. Carefully strip off the outer sheath and unbraid and cut away the braid. Unpeel the foil and cut away the two strain-relief strings. You're left with two thin wires, yellow and brown for one speaker and white and blue for the other. The wires are about 30AWG, so normal wire strippers won't work well.
At this point, you can just connect the speakers to a normal stereo receiver (AFAIK, the brown and blue wires are the - terminals, and the yellow and white are + ) I wanted to take it one step further, because the speaker's wires are such thin gauge.
So I wired on a 3.5mm TRS minijack onto each speaker lead, connecting the yellow/white wires to tip and the brown/blue wires to sleeve. Normal TS jacks would be optimal for this, but I didn't have any on hand.
I then wired up a simple breakout for the other end. I took a short (about a foot or so) of standard 16AWG speaker wire and soldered a female 3.5mm TRS jack onto one end, then crimped quick-release terminals onto the other end. That way, I can use normal, thicker-gauge wires on the run to the receiver and not worry about the ridiculously thin wires inside the Pro Speakers.
For testing, I hooked both speakers up to the stereo minisystem in my office. Normally my setup consists of 2-way bookshelf speakers and a 50-watt powered subwoofer, and I get great sound from it. I disconnected the bookshelf speakers and connected the Pro Speakers in their place.
Here's what I found:
1. The Pro Speakers work just fine as stereo speakers. They're not incredibly sensitive--you need to throw a bit more power at them than normal speakers--but nothing blew up, started glowing, or began smoking.
2. Equalization is necessary. The Pro Speakers, when used as standard speakers, are incredibly bright and, expectedly, very lackluster in the low end. They sound a bit different than when connected to a Mac, and that's probably because Apple has tuned the Pro Speaker output specifically for these drivers.
3. A subwoofer is recommended. The Pro Speakers produce such limited low-end--I'd estimate the low end of their response at only 400Hz--that even with EQ you'll still have an overly bright sound. If anyone has an iSub laying around, I'd be interested in seeing if there's some way to hack that to work as a normal powered subwoofer.
So what's the point of all this? Mostly just experimentation, but there is some use for the Pro Speakers on their own. I'm planning on using them as surrounds in my home theater (as soon as I get a digital receiver, anyone wanna buy me one?) until I can scratch up the cash for a matched system.
This also shows that, with some work, the Pro Speakers can make some interesting portable speakers. Sure, you could just buy an iFire, but that requires external power to work. For a few bucks in parts at Radio Shack, you could build a battery-powered amp (and if you're really adventurous, wire in the necessary EQ) to plug into an iPod etc. while on the road.
As soon as I get around to taking pictures, I'll make a Hacks page on this, and probably include audio samples as well for comparison.