Scan Speak vs. Seas - Page 2

Bricolo · 4th January 2004, 09:31 PM

Quote:

Originally posted by Pan
The distortion at 1.5 k is not affected by a notchfilter.

Are you telling that when you "flaten" the FR curve with a notch filter to "damp" the breakup, the distortion isn't reduced?

Vikash · 4th January 2004, 09:41 PM

The distortion is reduced at the breakup/notch filter, i.e. 5kHz, not 1.5kHz.

capslock · 5th January 2004, 08:19 AM

No, it's not. When you put 1.5 kHz into the driver and the motor has some nonlinearity, it will feed 4.5 kHz to the cone, and there is nothing the notch filter can do about this.

Regards,

Eric

Pan · 5th January 2004, 10:55 AM

Hi Eric

"The distortion is reduced at the breakup/notch filter, i.e. 5kHz, not 1.5kHz.

Vikash,

I believe the distortion is not affected at the ~5k peak either. The amplitude is surpressed but the % of THD is still (probably) roughly about the same. I´m not sure about this but it seems like the magnesium cones has a "lot" of distortion at the point of break up... this is hardly visible at measurements on ceramic cones.

And.... if this distortion products is from the cone itself, then reducing excursion will not give less THD as a function from the motor and suspension non-linearitys.

Possibly, if the cone adds distortion as a direct function of the break up resonances (which I believe but have nothing to back it up) this is something that may be an effect that is or is not, related to excursion. ie. the harder the cone is driven, the more severe the breakup. I would love to see some deep investigation on this subject as it is still open to debate.

SL among others believes the cone/dome breakup resonances does not add distortion. Martin Colloms, Peter Moncrief and I suspect the engineeers at Seas, JM Lab/Focal and Accuton do believe the opposite.

/Peter

4th January 2004, 09:41 PM	#12
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	The distortion is reduced at the breakup/notch filter, i.e. 5kHz, not 1.5kHz. __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

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5th January 2004, 08:19 AM	#13
capslock diyAudio Member Join Date: Feb 2002 Location: Germany	No, it's not. When you put 1.5 kHz into the driver and the motor has some nonlinearity, it will feed 4.5 kHz to the cone, and there is nothing the notch filter can do about this. Regards, Eric

5th January 2004, 10:55 AM	#14
Pan diyAudio Member Join Date: Sep 2002	Hi Eric "The distortion is reduced at the breakup/notch filter, i.e. 5kHz, not 1.5kHz. Vikash, I believe the distortion is not affected at the ~5k peak either. The amplitude is surpressed but the % of THD is still (probably) roughly about the same. I´m not sure about this but it seems like the magnesium cones has a "lot" of distortion at the point of break up... this is hardly visible at measurements on ceramic cones. And.... if this distortion products is from the cone itself, then reducing excursion will not give less THD as a function from the motor and suspension non-linearitys. Possibly, if the cone adds distortion as a direct function of the break up resonances (which I believe but have nothing to back it up) this is something that may be an effect that is or is not, related to excursion. ie. the harder the cone is driven, the more severe the breakup. I would love to see some deep investigation on this subject as it is still open to debate. SL among others believes the cone/dome breakup resonances does not add distortion. Martin Colloms, Peter Moncrief and I suspect the engineeers at Seas, JM Lab/Focal and Accuton do believe the opposite. /Peter

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