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Cone travel one way more than the other
Cone travel one way more than the other
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Old 7th November 2019, 05:45 AM   #11
JMFahey is offline JMFahey  Argentina
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Speaker manufacturer here, agree with Xoc1, suspect poorly reconed speaker.

Only other possibility is program wave assymmetry, but reversing connections dispels that possibility.

Never heard of port rectification, assume effect if present would not explain such a gross difference, BUT you can mount speaker the other way (even if it requires mounting it from the outside) to test that possibility.
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Old 7th November 2019, 06:44 AM   #12
papasteack is online now papasteack  France
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Hard spider probably help. Low Vas driver. Servo driver do not insure cone is centered. It doesn't track center position. It's only AC feedback. I suspect BCspeakers ipal pressure sensor feedback each side of the cone to limit better than accelerometer DC offset by tracking pressure difference mean of each side on the cone. Pressure can be tracked to DC contrary to Acceleration. So it should gives more headroom.

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Old 7th November 2019, 07:02 AM   #13
whgeiger is offline whgeiger  United States
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Originally Posted by papasteack View Post
Hard spider probably help. Low Vas driver. Servo driver do not insure cone is centered. It doesn't track center position. It's only AC feedback. I suspect BCspeakers ipal pressure sensor feedback each side of the cone to limit better than accelerometer DC offset by tracking pressure difference mean of each side on the cone. Pressure can be tracked to DC contrary to Acceleration. So it should gives more headroom.
I did not specify sensor type that is placed in the feedback loop to implement servo control. As you point out there are superior implementation methods. WHG
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Old 7th November 2019, 07:59 AM   #14
papasteack is online now papasteack  France
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Originally Posted by whgeiger View Post
I did not specify sensor type that is placed in the feedback loop to implement servo control. As you point out there are superior implementation methods. WHG
While about it, do you know any other type of sensor that can somewhat track, even indirectly, DC position ?
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Old 7th November 2019, 09:26 AM   #15
David Morison is offline David Morison  Scotland
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I believe Klippel analysis is done using a laser - so that could be one (admittedly, expensive and perhaps impractical) option?
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Old 7th November 2019, 01:51 PM   #16
freddi is offline freddi  United States
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Cone travel one way more than the other
re:"port rectification" - I've seen offset which think "may" be described as such. Its when the port flow stops having a symmetrical back and forth behavior and to a way of thinking, the cone is offset like a DC component has been introduced.

Jon Risch has a patent for asymmetric flow vents to cool speaker motors and IIRC, help with asymmetries.

I've seen it called "vent rectification" somewhere in the past.

Its mentioned here:

Maximizing Performance from Loudspeaker Ports.pdf - Google Drive


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Old 7th November 2019, 10:38 PM   #17
whgeiger is offline whgeiger  United States
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Originally Posted by tonskulus View Post
Sometimes I have noticed the same, cone is moving more inwards at some frequencies (especially in ported enclosures and some tapped horns etc). This sympton may actually lead to spider/suspension sagging.

Any good solutions for that "port rectification"? could not find any documents..
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While about it, do you know any other type of sensor that can somewhat track, even indirectly, DC position ?
While I have not undertaken design of this particular type of loudspeaker control system, I suspect that the offset can be corrected by evaluation of the difference signal. WHG
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Old 7th November 2019, 10:41 PM   #18
whgeiger is offline whgeiger  United States
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While I have not undertaken design of this particular type of loudspeaker control system, I suspect that the offset can be corrected by evaluation of the difference signal. For certain type of sensor implementation this will be easier to accomplish than others. WHG
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