The midi range, not the tweeter, is the most important driver in a speaker.

@ MikeLavigne Great post, summing things up ~~w/o bias, no distortion~~~
I was not aware of the fq range numbers for voice/cello/piano/other important instrumentation, particular to classical muisc. 
For light classical (- nota  orch in full bloom) most speakers can handle the fq's voicing. Again , some may  prefer speaker A's warmer sound, = B&W othersa  sharper more clinical sound = SEAS especially their top design The Excel series. 
You pinned down the critical fq phase, for all my classical, especially voice, 40-250,,and i guess this is why SEAS designed the MTM, which offers 2 midwoofers ddoing the job in this range = offering a  fuller soundstage. 
I always wondered how to incorporate the 20-40 hz's, now with a  new pre amps avaliable  having to pre outs, i can employ a sub amp/woofer. 
So ideally the Thor is the best speaker for voicing a  full orchestra. 
The  1 thing to keep in mind with the Thor, is one needs a amp taht can handle the low sensitivty. @ 87db. ,,no wait, its 89db, yet 4 ohms, = requiring/demanding a  Class A amplifier, Specs say 50-400 watts, You obviously do not need 400 watss, as that high wattage will shed the surrounds. 
Yet 50 watts, will have to be Class A 50, not Class A/B, as my cayin MT35, rated A/B/32 watts ultralinear proved no match for the Thors and the trans quicjkly over heated. 
My guess the cayin MT45/50/55 might just barely make the grade to drive the Thor. The Jadis orch Refer had no issues at all. and the speaker responded with full bloom,,,I never tried other tubes, than the stock EI's, which have a  good reputation, but as  trejla has mentioned, the EI's may bea  bit over rtaed, and in this i agree. They hada   top end *steely* harshness at times,,but the voice/soundsatge was likea  real live show in your living room with jazz. I wish I had rolled the KT90's to KT88's and others, before i sold it. 
Truly a  Class A/b amp, The trans very  high quality. 
The 2 bias controls/treble/bass, near worthless. 
Best amp for the thors ona  budget is the Cayin KT88. Or Muzishare or Line magnetic, all 3 offering powerful trans, all near Class A energy. 
The thors need a  class A power, A/B  power is sacrificing /debilitating the quality of the speakers complex components. 
Years ago, there were few class A push pull amps that were afforadble, Now with the 3 main chinese lines of amps, its all within  reach of a reasonable budget. 
This is how i arrived at  the term, Class A speaker. 
Class A cd player. If you want Class A sound, you can not have a  Class A amp and the other components less than.
A
A/B
A/b
B
C
D 
F
 You need to figure out where each of your components fall. 
You can takea  Class \A/b component and make it pure Class A, but employing mods, which i am in the process of doing. 

My Thors with 2001 xover parts is really a  class A drivers with class A xover design, but parts, are now Class A/b or even B rated, since latest tech developmernts have been offered, = Silver, even Gold/Oil. 
Thus the excel drivers are pure Class A, but with xover parts being Class B, lowers , debilitates the Excel drivers to a  Class A/b performance. By updating the xover parts, the Excel drivers can now become true Class A voicing. 

Hope some of this clarifies the issues we are all facing in our quest to acheive pure true, no fake Class A fidelity in our systems performance/muisc reproduction. 


http://www.seas.no/index.php?option=com_content&view=article&id=382:thor-seas-diy-kits&catid=66&Itemid=365

Here is a Q for the board, 
The SEAS Trym is a 2 way, 87 db, yet rated a  better 8 ohms. 
Here is my Q.
Will a  845 amp work under the load of a  low sensitive speaker ~~rated 87 db~~~ yet 8 ohms...IOW will the tube have issues with the impedance of 87 db?  Maybe not full  orch, but as in  chamber, which i have a  good collection of. 
I may be interested in a  2nd system and want to hear the magic of the 845. 
My guess is the voicing of the 40-250 fq's will be anemic/weak. 

I just cked the specs,,says highly recommended 50 pure class A watts, = 845 is not recommended. ....
I want the Trym, but which tube amp to deliver the goods?


http://www.seas.no/index.php?option=com_content&view=article&id=384:trym-seas-diy-kits&catid=66:seas-diy-kits&Itemid=365

 

As for the mention of the Thor, I do have a bit of a soft spot for the Seas Magnesium drivers. They have a unique warmness on the mid and lower mid but very natural, and at the same time, very detail like a hard cone. It took a bit of time to break in and probably may be the longest of any drivers I’ve had. At first they sound a bit cold and clinical, but once fully broken in, it’s all fine. They have a bit of a break up so just be mindful of the xover.

I currently have a pair of speakers that use the Seas Nextel 5.5in driver and the magnesium has the exact the same dimension so it’s a one to one swap. Hm... I have might an itch to get a pair.

But is the mid more important?  Probably but it needs the right tweeter to make a perfect dance partner.  

Hey Andy, I do not see a  listing for the Nextel 5.5 mid,,I do see a  listing fora  SEAS Nextel midtweet, does have the neo magnet of its bigger brother, the Millenium,,the Nextel tweet hasa  higher 92db efficeny,,the Millenium is very low at 89 or 87, can't recall. 
SEAS hasa   new  nano cone W22, which is built on new dewsign materials,,,Its quite expensive , but if you could have Madisound build youa  2 way with the SEAS W22 Graphene + Millenium with Mundorf Silver Oil caps (or whatever cap you can afford, IMHO, that might bea  superior way to go vs the Thors. 
This way, you might not needa  sub, as the W22 will pick up the low fq's very nicely and the Millenium will meet the W22 effectively. 
Basically you are getting the Trym , but witha  superior W22.
Instead of rebuilding my Thor xovers,,I may put that cash in the W22 Graphene+ Millenium. Have to chat with madisound's tech guys, see what their opinion is ,,they havea  great friendly straightup crew ready to assist. 
If you geta  quote on the design, please pass it on.
paul
huge SEAS fan down here in new orleans

Just cking Madisounds web,,no listing for the W22 Graphene,,,so had to google,,now i know why, the W22 Graphene was just released last month, 
Price will be $600+ I am sure, as the W19 Grap is $529. 
She looks a  dandy,,, 


https://audioxpress.com/news/seas-announces-excel-graphene-w22-8-inch-woofer-launch