PD 1550 Impedance Graph

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   https://www.precision-devices.com/products/archived-products/pd-1550/

Ive got two of the 16ohm versions of these working nicely in a in 75L bass reflex enclosure.  Looking at the impedance graph of these drivers I notice how steep and high the impedance goes (on the 8ohn) version compared to a lot of other drivers like the JBL 2226.  Any reason why this large peak over 250ohms (in a 107L vented enclosure according to the spec sheet) is so high? 

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shaun1264 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 06 September 2013 Location: Surrey Status: Offline Points: 242	Post Options Post Reply Quote shaun1264 Report Post Thanks(0) Quote Reply Topic: PD 1550 Impedance Graph Posted: 12 January 2022 at 11:09am
	https://www.precision-devices.com/products/archived-products/pd-1550/ Ive got two of the 16ohm versions of these working nicely in a in 75L bass reflex enclosure. Looking at the impedance graph of these drivers I notice how steep and high the impedance goes (on the 8ohn) version compared to a lot of other drivers like the JBL 2226. Any reason why this large peak over 250ohms (in a 107L vented enclosure according to the spec sheet) is so high?

smitske96 Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1006	Post Options Post Reply Quote smitske96 Report Post Thanks(0) Quote Reply Posted: 12 January 2022 at 11:26am
	I think its a mistake in the specsheet, impedance graph is probably free air.

shaun1264 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 06 September 2013 Location: Surrey Status: Offline Points: 242	Post Options Post Reply Quote shaun1264 Report Post Thanks(0) Quote Reply Posted: 12 January 2022 at 12:26pm
	On the 'new' version of this driver they have the same Thiele Small Parameters and graphs but this time measured in a 975 litre box! So it seems rather confusing and misleading or clear glaring errors in the measuring or marketing department! But that is still a huge peak on impedance even it's an free air