The real downside of the SAEC tonearms is the ceramic headshell which must be the absolute worst choice of headshell material ever imagined....
Though they still command outrageous prices (if you can find one).....this work of the 'devil' will make every cartridge sound like fingernails being dragged down a classroom blackboard.
If you have a wood-bodied cartridge like the Clearaudio Virtuoso.....you can just about listen without feeling discomfort.

It's easy to eliminate this problem by simply selling the ceramic shell and using a good after-market headshell like the Yamamoto HS-4 Carbon Fiber.
It's easy to twist the cartridge in the headshell to re-set for any geometry one chooses.

Those beliefs are reasonable Lewm...
@rauliruegas  I wonder why our experienced member and collector of the tonearms posted this:  

The SAEC 506/30 was designed to be used with 10" and singles only. It’s geometry does reflect it. 
-Dertonarm   

As far as i know SAEC 506/30 is a professional tonearm, so what i tried to explain is why in the professional industry (radio broadcast) singles ("7 inch vinyl and "12 inch EPs) are more inportant than LPs. 

 



Dear @chakster : "  so what i tried to explain is why in the professional industry (radio broadcast) singles ("7 inch vinyl and "12 inch EPs) are more inportant than LPs. "

whom said is more important?. It's not, for an audiophile LP are the important subject.

Radio stations needs are way different than a home audio system at our  places.  As audiophiles we are looking always for " the best " the best quality performance levels when in a radio station they are looking to other issues: why the Denon 103 for broadcasting? it's a rugged cartridge spherical  stylus tip because they do not needs more quality level they only need that can sounds at decent level and that's all. Sp-10s were designed for broadcasting: they needed fast star up and fast stop too, speed stability, etc. but they did not needs a special plinth to avoid resonances/vibrations as we need in a home system. Different needs that's all.

Broadcasting is not the reference for we audiophiles as in the same manner recording engineers can't be a reference for audiophiles and only if they are true audiophiles we can take it as reference.

R.
@rauliruegas you’re right, but the SAEC 506/30 is a professional tonearm, audiophiles are not a part of the pro industry, professional used to be meant for broadcast in the 80s. In the broadcast industry nobody cares about LPs, singles are made especially for radio deejays and for promotion of the upcoming LP albums. Making professional tonearms SAEC or any other respected manufacturers must take in count the media format of the PRO industry and no wonder that special geometry applied for this specific format of the records (they are smaller than LPs). I think this is what our member (dertonarm) pointed in his comment many years ago.

Maybe SAEC 506/30 consumers in the 80s were not the hi-fi enthusiasts (private individuals), but the professional broadcast studios (special market) ?

For example here is Technics SL1000 MKII P ("P" = Professional)
There is a build-in balanced preamp Technics SH-10U
professional version of the EPA-100 tonearm (EPA-100P) or even the best EPA-100mkII as an option.

The cabinet is definitely not the best, but the whole concept reminds me EMT turntables, i think they are highly regarded among the audiophiles and price for them reflect it pretty well. Same about Denon broadcast decks.
Dear @chakster : Professional or pro industry works with " tools " according to its needs. Technics, Denon, EMT, etc figthed for that market and that's why appeared the SP10s or the DP100M with built-in phonopreamp/speaker. Before these models and along other names that market was extremely competitive due the grow up of that market all over the world not only in Japan.

The pro-model manufacturers wanted to take as many  costumers as they can with more atractive items for that partuicular kind of customers where they need it  trusty/confident items with the capacity to works 24 hours seven day a week year after year with very low maintenance. All these means high build quality but they were not looking for the penultimate accuracy in the frequency response or cartridge tracking habilities or to be truer to the recording.

No one of them used top cartridge models as : Accuphase AC-2 or  Audio Note IO or Audio Technica AT1000. Tonearms as the own Technics EPA 500 or Audio craft or Micro Seiki.

SAEC tonearms are very good looking tonearms that were builded with very high quality excecution but never been and never be a top tonearm design because that bearing type in the audiophile market where pro-industry does not belongs. Forgeret about but if you want to really know on the 506 then buy one and finish your " story " where you made a no-sense conclusions.

Better than that please do it a favor and due that you listen mainly to 7" size recordings then take this alignment parameters for your 64FX tonearm that will give you the lower tracking error with the lower distortion levels for a 7" recordings :

 P2S: 238.55mm   ; offset angle: 15.294° ; overhang: 8.45mm

the alignment is Löfgren A ( Stevenson gives no single advantage even with this special alignment. ) dedicated for that size recording and only as an example the tmaximum racking error goes down from: 1.9°-2.1° to only 0.36° that's outstanding and then way lower tracking distortion levels.

I hope your tonearm permits to mount it and mount the cartridge exactly with those parameters.

Good luck,
R.