"Apple Pro Speaker" specs?

[Spasticteapot]

A few years back, Apple made some speakers that used a proprietary connector and a power amplifier built into their iMac and Powermac G4 computers. Their sound was pretty good, and they were portable and pretty durable.
Nowadays, they're useless with modern Macs and anything else unless you buy an expensive external amplifier unit with the correct connector. However, they appear to be standard 4-ohm or 8-ohm speakers, and the drivers might work well in small transmission-line speakers with a subwoofer. (They were made by Harmon-Kardon.) Alternately, with a small portable amplifier, they'd make a spiffy portable stereo. (I would'nt be surprised if they came near in performance to the "iStereo", or whatever the heck it's called, when paired with a smallish well-made amp.)
Does anyone know where I could get the specs on the drivers in these , or how I might measure them?

(Oh, and just in case...anyone have some for sale?)

-Joe.

[planet10]

These ones? Apple"s Crystal Spheres.



with 35mm JBL Odessey drivers (they are the ones with the patent) -- some of the newest ones have Foster drivers instead (as the ones pictured). The odessey's looked like this (pic of a 25mm version)



I've not measured them outside of their enclosure. If you snip the wires they become regular speakers. A friend uses them with a Sonic Impact & an iPod for a little portable system.

Impedance of the Foster based ones.



Fs = 195 Hz
Qt = 1.6

dave

[Spasticteapot]

Holy moly, that was fast.
Thanks for the help!

Now, for yet more questions.
1. If the Fs is 95hz, would'nt a quarter-wave transmission line be 90cm long? I'd probbably shorten this to 75cm to account for stuffing.
2. Is there any benifit in making new enclosures for these speaker drivers? (I.E; is it actually worth my time?)
3. What exactly does Fs mean, in laymans' terms?

[planet10]

Originally posted by Spasticteapot
1. If the Fs is 95hz, would'nt a quarter-wave transmission line be 90cm long? I'd probbably shorten this to 75cm to account for stuffing.

I typoed there. Fs (in the "box") is 195 Hz

2. Is there any benifit in making new enclosures for these speaker drivers? (I.E; is it actually worth my time?)

I'd only go as far as modding the original... perhaps making it aperiodic to lower the Q peak. These won't ever be bass fiends -- they are only 35 mm

3. What exactly does Fs mean, in laymans' terms? [/B]

It is the place where all the mechanical & acoustical properties come together to produce a resonance. Bass falls off below resonance (ie this speaker doesn't go much below 200 Hz. It does have a highesh Q which means it has a bump in the 200 Hz region (standard trick you into thinking it has bass) before it plummets. It really needs a helper woofer below 200-300 Hz. If you are doing that then the 25mm driver is worth looking at too. $10 can usually get you a pair of those in their iBall housings. (i have an untested pair in a salvage graphite iMac downstairs)

http://www.t-linespeakers.org/drivers/iBall/index.html

PS: i think the JBL drivers were a bit better than the Foster.

dave

[Android]

Hey, in this spheres are NOT "JBL Odessey drivers" - little Odysseys are from iMac 15" CRT computer!!! They have only 35 mm diameter, but drivers in spheres, which were bundled with G4 Cube computer (and later with LCD iMac), are much larger - about 55 mm. And, they uses special T-class amplifier with Linkwitz-tramsform circuit (or similar equalization) - that's why they are connected with non-standart connection jack, if you have a version without amplifier. For this reasons, the sound is very different - much more low-middle and upper-bass.

[Jumphog]

Very interesting reading in this thread. I heard some of the apple pro speakers connected to some mac laptop a while ago and was very impressed with their sound given their size. Ive just won some on ebay with a view to building a small amplifier and using them with non apple stuff. Id had a suspision that there was some sort of equalisation going on with them, so reading Androids post makes sense to me.

Does anyone know what kind of equalisation is built in to macs to compensate for these speakers?

I do have access to a mac to try the speakers out when I get them, perhaps I could use this to work out the equalisation. Sample a frequency sweep from the macs speaker output and compare it to the headphone output? Any thoughts?

[Android]

It was possible to buy iFire from Griffin company - external amplifier for this speakers. It's powered by FireWire connector, which provided audio input too. I'm really sure that there is some kind of equalisation, because these small speakers are not ported and still has incredible bass.
iFire: http://www.atpm.com/10.02/ifire.shtml

[Jumphog]

Ive seen those, but id be quite interested in doing it myself. Do you think that it would be possible to work anything out from sampling a mac?

[pinkmouse]

Should be easy enough, but take care that the speaker signal level doesn't blow your soundcard. I'd use a pink noise generator program on the Mac, and a FFT on a PC to test

[planet10]

Originally posted by Android
Hey, in this spheres are NOT "JBL Odessey drivers" - little Odysseys are from iMac 15" CRT computer!!! They have only 35 mm diameter, but drivers in spheres, which were bundled with G4 Cube computer (and later with LCD iMac), are much larger - about 55 mm. And, they uses special T-class amplifier with Linkwitz-tramsform circuit (or similar equalization) - that's why they are connected with non-standart connection jack, if you have a version without amplifier. For this reasons, the sound is very different - much more low-middle and upper-bass.

The earlier (ie shipped with the cube) had JBL odessey drivers, ones with 35 mm cones. The iMac ones are also JBL Odessey but only have a 25 mm cone.

1st thing i did was disconnect the wifes G4 cube spheres from the little T-amp. Driven with a better amp they sound better IMHO. The small T-amp was just not a very good implementation.

dave