Does anybody have an impedance vs frequency graph of the Fusion 12 Tempest? I can find an impedance measurement of the Delta Pro 12A woofer used in the design and the stated T/S Re of that woofer's voice coil is 5.71 ohms but that is not helping me calculate the reflected impedance across the primary of my output transformer.
Hi Brinkman. I was holding off to see if Jeff Bagby would answer this for you as this info really should come from him. He hangs out at TechTalk if you did want to get the info directly from him. Not sure he makes it over this way often. I do happen to have measurements of 3 Tempests that used prebuilt XO'ers and Jeff and I emailed about them and he confirmed they looked correct. So I'll offer these plots for you.
Thank you so much! I actually just registered with techtalk the other day to ask him directly. Interesting that the Tempest impedance drops to about 7 ohms around 160Hz and is so bumpy between 300 - 5KHz. On the four ohm tap of my tube amp there was a marked improvement in the bass (compared to the eight ohm tap) but the midrange presence took a hit. Overall I think I prefer the eight ohm tap. It might be a good idea to switch to an output transformer with a different winding ratio when I get some active subs in the mix.
Sorry for the late reply. I actually never bothered asking because I was satisfied by your data, which I appreciate.