Finding (calculating?) speaker and amp impedance


I'm starting to understand why speakers with high efficiency and perhaps more importantly a flat impedance curve work well with tube amps.

If not published by the vendor/manufacturer, is there a way to determine the impedance curve from the specs that are provided?

Also, I have a pair of Magnepans that need high current amplification.

Is there a way to determine the current of an amplifier from vendor/manufacturer provided specs?

Thanks everyone!

hleeid

Good timing for this topic. Using a pair of Focal Aria 936’s with a PL HP Integrated and all is good. But…I just had my 45 year old Sansui AU-717 fully restored and it’s in transit as I type this. Per Stereophile’s review, these speakers drop to about 2.7 ohms in the mid/bass region, yet publish as 8 ohms nominal. The PL tube amp handles it just fine in either mode (70 wpc in ultralinear, about 40 wpc in triode).

Im eager to try the vintage Sansui in this system upon its arrival. Bad idea?

@chocaholic 

I have a Sansui AU-20000 that will not come out of protection mode.  I've been told it is essentially a boat anchor.  Used it for many years and really liked it, put it in a closet when the ARC amps appeared out of nowhere (wink).

Would you please share the repair shop who did your 717.  Thanks.

Regards,

barts

@barts I was referred to a gentleman on AudioKarma that specializes in vintage Sansui. He stripped boards, removed all old corrosive glue, completely recapped in addition to countless other parts, extensively tested, adjusted bias, burn-in, more measurements, etc…and kept me updated with details and photo’s throughout the process. He’s in a small town in Mississippi and prefers not to ship equipment. So, a 10 hour round trip for drop off and retrieval from here. 
 

Bottom line, it’s more of a hobby for him than a business. I’d want to check with him before passing his name along. 
 

@chocaholic 

Thanks...Mississippi is quite a drive for me, so that is out, but I am slightly confused due to you saying the 717 "it's in transit as I type this".  Does this gentleman sometimes ship and sometimes not?

Regards,

barts 

@barts Sorry…I should have been more clear. My wife went to visit her mom this weekend…about 2 hours from his location. She picked up my amp on her way. I married a good woman!