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Author Topic: Speaker distortion vs drive level question  (Read 1077 times)

Steve M Smith

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Re: Speaker distortion vs drive level question
« Reply #10 on: March 08, 2019, 03:16:10 am »

So EVERY loudspeaker changes the input signal, so therefore is creating distortion.

Something I have thought about before but never really investigated. How much does a speaker suffer from some sort of mechanical compression?  My thinking is that as a driver approaches the limits of its excursion, the springiness of the surround is greater than when it is near its centre position.

Would it be correct to assume that a difference in voltage from a near centre position causes a greater movement than when the cone is near its limits?


Steve.
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Chris Grimshaw

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Re: Speaker distortion vs drive level question
« Reply #11 on: March 08, 2019, 04:06:49 am »

Something I have thought about before but never really investigated. How much does a speaker suffer from some sort of mechanical compression?  My thinking is that as a driver approaches the limits of its excursion, the springiness of the surround is greater than when it is near its centre position.

Would it be correct to assume that a difference in voltage from a near centre position causes a greater movement than when the cone is near its limits?


Steve.

Yep, that's reasonable.

Other factors do come in, though - the motor itself might not be linear over it's travel, either.

Look up Klippel testing for more info - there's a lot to digest there, but it's very informative. Sometimes a manufacturer will claim 20mm one-way excursion, but testing will reveal that everything is grossly non-linear at that point, and it'll start rounding stressed at half of that.

Chris
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Dave Garoutte

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Re: Speaker distortion vs drive level question
« Reply #12 on: March 08, 2019, 02:06:38 pm »

If the voice coil has fewer and fewer coils inside the 'magnet', it will lose power as the surround gets more resistant.
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Frank Koenig

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Re: Speaker distortion vs drive level question
« Reply #13 on: March 08, 2019, 03:58:40 pm »

It's interesting that, while it's been tried a few times, closing the loop around the speaker motor with position feedback never caught on in a big way. It would put an end to this source of nonlinearity, just as it did for amplifiers around 1940. --Frank
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John Roberts {JR}

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Re: Speaker distortion vs drive level question
« Reply #14 on: March 08, 2019, 08:25:31 pm »

It's interesting that, while it's been tried a few times, closing the loop around the speaker motor with position feedback never caught on in a big way. It would put an end to this source of nonlinearity, just as it did for amplifiers around 1940. --Frank
More than tried, IIRC Phillips patented closing the loop back in the 60s (70s?). The servo drive by tom danley was by definition closed loop.

JR
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Re: Speaker distortion vs drive level question
« Reply #14 on: March 08, 2019, 08:25:31 pm »


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