strange dip on every woofer of a particular manufacturer

[tech.knockout]

Need your expert opinion here.

there is a large dip at almost exactly 60hz on every woofer by this maufacturer (woofers range from 8" to a great 21"):

http://www.speakerschina.com/products/products_list.php?cate_id=38


Likewise there is a large dip at almost exactly 95hz on every woofer by this manufacturer:

http://www.poshing.com.cn/en/speaker/en/list.htm


Do I presume that these dips are merely because of some sound anomaly caused by the measurement setup and environment, or because of some strange inherent property of every woofer by each manufacturer?

Im leaning on the former.

 

[Paul W]

The impedance and phase plots are also very ragged at nearby frequencies...so maybe a very strange breakup or some other problem in these drivers. I would look for alternatives.

 

[sreten]

Hi,

I'd say definetely measurement setup - which appears crude,
the graphs would look much better with some smoothing.

/sreten.

 

[DeonC]

If that anomoly is in every measurement, and at the same place (for all drivers from 8" - 21"), my suspicion would fall to the measurement place or equipment. I think it must be a room anomoly because there is enough difference between the driver sizes for this not to be driver related (well so I would think, anyway).

Deon

 

[SY]

The double peak near resonance is interesting, almost like what one sees in a damped ported box. I wonder how the speakers were mounted?

 

[infinia]

Yikes
The spec on F0 is 20%. Me thinks you will have to wait to get/measure your driver to find out what you could build.

40-60Hz range on a driver with F0 of 50Hz.
thats china's QC worksmanship i guess.

 

[lndm]

The impedance and phase plots are also very ragged at nearby frequencies...

Room anomalies will be reflected through the impedance.