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Logitech Speaker Technical Question

Last response: in Components
December 5, 2008 8:40:59 PM

First off, I want to apologize for posting this here. I wasn't sure where else to post it, but the fact that there was another speaker related question here seemed like a good place to start. I owned a set of the klipsch promedia ultra 5.1 speakers for three or four years, and recently it died (amp failure). Rather than paying Klipsch $150 to fix it, and having no idea how long it would last after that, I bought a set of logitech z-5500s. I'm moving soon and will only have a macbook to hook these speakers up to: the fact that the logitechs have a TOSLINK is essential. Anyways, I've heard pretty good things about the logitech (unfortunately, not as good as the Klipsch) but I've also heard the sats leave something to be desired. I still have the (fully functioning) sats from the klipsch setup, which are dual-driver (compared to the Logitech single driver). They also have a total harmonic distortion ten times lower than the logitech sats, if you believe the numbers. Basically, my question is this: can I use the old klipsch sats with the new logitech system without worrying about blowing something out? The tech specs are this:
Klipsch: FTC Rated per Satellite: 60 w/channel @ ≤ 1% THD, 100Hz - 1KHz (Note: all channels driven). FTC Rated Sub-woofer: 170 w @ ≤ 3% THD, 40 - 100Hz. Maximum Burst Power*: 500 w. crossover frequency HF: 3000Hz LF: 120Hz

Logitech: Total FTC power: 505 watts RMS. Sub-woofer: 188 watts RMS (into 8 ohms, @ 100Hz, @ 10% THD). Satellites:Left/Right: 62 watts RMS x 2 (into 8 ohms, @ 1khz, @ 10% THD). Center: 69 watts RMS (into 8 ohms, @ 1kHz, @ 10% THD). Rear Left & Right: 62 watts RMS x 2 (into 8 ohms, @ 1kHz, @ 10% THD).

So the klipsch sats only draw 60 watts, but the logitech draw variously 62 or 69. The amp is built into the sub of each respective system. If I were to hook the Klipsch to the Logitech, would I be frying the speakers (ergo the sub is sending the full 62/69 watts)? Would I be frying the sub (speakers only drawing 60 even though the amp was designed for 62/69)? Would issues arise from the crossover? Or would I essentially be fine?
December 5, 2008 8:53:25 PM

it's a forum bug. There were originally line breaks where those
were, put there by hitting the enter key.
December 5, 2008 9:02:00 PM

It should work, and they are better than the logitech setup. The two things to watch out for are the impedence of the satellites (it looks like the Logitech setup is expecting 8 ohms), and the crossover frequency. If the logitech's crossover frequency is about the same, it'll work fine, and if it is significantly higher, it'll also work. If the Logitech uses a lower crossover though (than 120Hz - the LF crossover is the one that matters), it could cause problems.
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December 5, 2008 10:44:05 PM

I've read that the impedance of the ultra sats are "6-8" ohms, and heard both 6 and 8 individually. Is this a problem, and if so, how could I get around it?
December 5, 2008 11:27:04 PM

It shouldn't be a problem, though don't crank the volume all the way up. Lower impedence than the amp was designed for means that it will be easier to overload the amp with the speakers than it was in the logitech setup.