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HELP advise PLEASE - Focal Sopra 2 Speakers - I want a tube amp but " Min 2.6ohm @ 104Hz "

HELP PLEASE advise bought a pair of Focal Sopra 2 Speakers that I absolutely love.

I want to use an integrated tube amp with them but the measurements worry me even though many Sopra owners say they happily use tubes with these speakers.  


HERE IS THE ISSUE:

  From HiFi News September 2015, lists Minimum impedance is around 2.6 ohms at 104Hz. Combined
with high impedance phase angles at low frequencies this results in a minimum EPDR (equivalent peak dissipation
resistance) of 1.1ohm at 85Hz – challenging to the partnering amplifier.

Can I used an integrated tube amp and hope for success? 


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From HiFi News September 2015, minimum impedance is around 2.6 ohms at 104Hz. So the amplifier should be capable of approximately doubling its 8 ohm output power into at least 4 ohms and preferably again into 2 ohms.
Min 2.6ohm @ 104Hz. Focal claims 91dB sensitivity for the Sopra No 2 but our measured pink noise figure of 88.2dB falls almost 3dB short of this. Low impedance is a factor in achieving this figure: Focal specifies a minimum impedance of 3.1ohm (which would indicate a 4ohm nominal rating rather than the specified 8ohm) but we measured a dip to 2.6ohm at 104Hz. Combined with high impedance phase angles at low frequencies this
results in a minimum EPDR (equivalent peak dissipation resistance) of 1.1ohm at 85Hz – challenging to the partnering amplifier. The forward frequency response [Graph 1, below], measured on the tweeter axis, is essentially flat in trend with just a mild presence band dip.




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fsmithjack OP
712 posts
 
Good stuff - I thought I might be overthinking it. 
Also, I didn’t know the dip could make a tube amp sound louder. Glad I asked. Appreciate the info. I read these measurement can be tough on an amp but didn’t know what that meant in real world use.
Do you guys think a reasonably priced used integrated tube amp like Like a VAC 160i or Octave Audio V110SE or even a value one like Ayon Spirit III will work ok? These are all in my used price range of around $4kish. 
I don’t want to tube Pre end SS amp for no other reason then cost of 2 boxes and another IC’s and PC’s is more then I have to spend. Just downsized my speakers and love the Sopra’s so hoping I get lucky with a $4k ish used Integrated amp. These are all around that rough $4k range. 
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fsmithjack OP
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Thank you for the excellent responses. I downsized my system cost wise (Magico S5 MKII to Focal Sopra 2) and Soulution amp to now wanting tubes in the chain. I should have provided a price range which is around $6k. I am buying used for the reason listed above. I was thinking GamuT / Alnic because they fit roughly in my price range and SS amp wise have the power and have a Pass like tubish sound and the Alnic because it has great Output impedance to match with SS amps. Has anyone heard the Mac 352? It also fits the price range? Any other recommendations? I agree a tube integrated might not match well. Some folks says Octave Audio Integrated amps do well with low impedance dips like the Focal present but I’ve never heard them? 
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fsmithjack OP
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Been thinking about SS and tube preamp. I wasn’t but a few of you guys mentioned the idea and it has started to stick with me. I want the Linear power and control from SS but now need that tubes sound. The hybrid integrated I’m now borrowing is so good it’s tough. Wish I could afford it but I can’t. What do you think of GamuT D-200 MKIII and a Alnic L4000 combo. The transformer coupled output on the Alnic provide nice lower output impedance and Gamut is a little tuby on its own so was thinking good match for Focal Sopra 2? Think this would be better then a hybrid like a Mac 352?
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fsmithjack OP
712 posts
 
What do you think or know about LAMM 1.2 mono’s. Do they have enough tubeness in them. I know they have one 6922 in them. I’m strongly considering them. 
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