Originally posted by: BD2003
http://www.dansdata.com/speakersets.htm
A part that you want to read:
"The second piece of marketese in the Z-560 specifications has to do with the abovementioned power output issue. Logitech make a big deal about the Z-560 system having 400 Absolutely Genuine Federal Trade Commission Authorised Totally Real RMS American Watts Baby. 188 watts for the sub, 53 watts for each satellite.
This is not true.
Well, OK, it could be true. If it is, though, the speakers should all blow up.
Point one - not enough amp power. No way is that a 400VA toroidal in the corner of the box. It'd have to be a bit beefier even than that, of course, because the amp isn't 100 per cent efficient. If it were, it wouldn't need a heat sink.
Point two - insufficiently chunky drivers, with embarrassingly low power ratings printed on them.
Such things as almost-200-watt eight inch drivers exist. If you want to cheat then you can make a zillion watt speaker by putting a crowbar across its input wires; now you can pump vast amounts of power through that speaker (if you define the crowbar as being part of the speaker...), and it won't make any more noise than it would from far less power without the crowbar. In other words, its efficiency is now astoundingly poor.
That's not what Logitech are doing; it's not what any sane speaker builder does. The drivers in these speakers have perfectly OK efficiency for their size. If the eight inch bass driver had an ultra-humungous magnet around a similarly huge voice coil and a unit retail price up around $AUD200, then it'd be plausible for it to have better than 150 watt power handling.
That's not the kind of driver that's in there, though. The back of the sub driver hides behind the huge bent port, but you can peer through the gap to see the mere hundred watt rating.
Similarly, I suppose it's possible to make a three inch mid/treble driver, like the ones in the Z-560 satellites, which can handle 53 watts. I don't know whether any such product actually exists on the retail market, but I'd be happy to learn otherwise.
Once again, though, that's not what Logitech have actually used. 15 watts, people. A Tangband Speakers W3-665SC, to be exact. Which isn't listed on the Tangband site; I just linked to that site out of malice.
Exceed the rated power handling by a significant margin for a significant period and you'll kill the driver. Unless the sticker ratings are very conservative, therefore, one 100 watt sub plus four 15 watt sats is 160 watts. QED.
The driver-peering also revealed that none of the Z-560 speakers contain any resonance-reducing damping material at all.