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Old 20th July 2013, 12:23 AM   #1
Foxx510 is offline Foxx510  Australia
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Default Tripath amps and varying speaker impedance

I keep reading little snippets of how Tripath amps with a certain filter type don't cope well with varying speaker impedance. Can anyone elaborate on this and the real world implications? My FR125s speaker impedance appears to rise significantly as it gets near ~ 50hz - is this a problem for these amps?

Maybe I've misunderstood the whole thing - I'm still learning! Cheers :-)
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Old 23rd July 2013, 05:21 PM   #2
Bare is offline Bare  Canada
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All drivers have a variable impedance with frequency, not to worry.
Larger issue is that Tripath ceased to exist.. Years! ago.
Current Tripath chips are cheap crappy fakes.. of widely varying 'badness'.
Avoid them, is the short answer.
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Old 25th July 2013, 07:35 AM   #3
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To answer your question in a way that is useful, don't worry about it. It really only matters if the speaker impedance change is near the high frequencies.
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Old 26th July 2013, 11:02 PM   #4
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You may think your speakers change impedance over the frequency spectrum, after you measure ESL's, you'll gain a new appreciation for how easy your cone and dome speaker really is.

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Old 26th July 2013, 11:40 PM   #5
john65b is offline john65b  United States
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Larger issue is that Tripath ceased to exist.. Years! ago.
Current Tripath chips are cheap crappy fakes.. of widely varying 'badness'.
Huh? Cirrus Logic bought out Tripath. Cirrus Logic is quite capable of making the Tripath chips. I, unfortunately, was a Tripath investor ...sigh...but luckily made it all back (and then some) owning Cirrus Logic (CRUS), no thanks to the Ipad/Iphone/Ipod
I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V

Last edited by john65b; 26th July 2013 at 11:49 PM.
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Old 27th July 2013, 12:29 AM   #6
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I was thinking this was the situation when the speaker impedance was designed as part of the output filter for the class-D amplifier; not the impedance vs. frequency of a particular speaker. Or maybe I've misunderstood the whole thing. I haven't run into any problems using the same amp with 4 or 8 ohm speakers, so differences, if any, are subtle.
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
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Old 28th July 2013, 04:45 AM   #7
Foxx510 is offline Foxx510  Australia
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Cheers for the replies. I might try a larger Class D amp instead so if it doesn't work on the mains out I can use it for the subs and the effort won't be wasted. The FR125s impedance appears to hit ~40ohms at the low end, if I'm reading the graph right. Maybe that's normal, though.
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