the AC50 is the ULTIMATE chimey vox clean. It is very low gain but chimes for days and still ha some magic vox mids going. Its very high headroom but gets marshally when pinned. I rather want one. I almost bought a broken one off a riend but chickened out at the last minute. The Beatles sound is from the 1 channel ac50 mk1 or the 2 channel mk2. Mk3 and later are a little less clean. These amps are super sparkly with fabulous mids. Top boost channels only though. Until the Mk4 they are stock with 12au7 low gain, hifi dual triodes in V1 which make them really spanky and dynamic but keep the gain really low. They are vox's best pedal platform. They do get VERY HOT because they use a weird cathode/fixed bias scheme on the EL34 tubes. You will want a robust set of power tubes like JJ teslas. Do not get anything Russian or Chinese even if it sounds better. The amp will devour anything less robust like the GT EL34M, new sensor/EHX stuff, and Svetlana winged Cs. A 1965 is either a Mk2 or Mk3, not sure though. They are a little different but both good in their own way. You may wanna have her modded to have a standby switch eventually. I'll explain more if you buy her....
Check youtube for an ac50 demo. There are a few done by stores that capture the real sound of the amp, though you can't experience the punchy feel without actually trying it for yourself.
The price on this AC50 is very good for an original, working example. In the USA mid 60s ac50s regularly trade for well over a grand. MAKE SURE IT HAS THE ORIGINAL OUTPUT TRANSFORMER, don't tke the dude's word for it. If you need me to get pics of the original trannies for you I will. They do not make transformers up to the snuff of the old british iron by radiospares, haddon, woden and partridge anymore unless you wanna pay top dollar (or pound). An ac50 puts out in excess of 60 watts RMS, so a puny modern 50 watt transformer like the drakes in 90s or later marshalls will not handle it. A 50 watt drake of that type was used in the 90s, Marshall built AC30/6TB reissues to handle the lower wattage of that model safely. Okay?
If everything is legit with this amp you should beg borrow and steal to get it before someone else does. If possible see it and try it in person. This is an investment piece that will not only serve your needs, but will ALSO continually rise in value as long as you take care of her. AC50s sound really good thru a quad of 25 watt G12M celestions or a weber 30 watt blue dog mixed with his 30 watt silver bell (both alnico) for a really vintage tone but with safe power handling (old AC50s regularly blew up their 2xG12 blue w/midax horn setup which is why original AC50 cabs are so rare these days)... do not pair the AC50 with a vintage 30, it willg et harsh. If you must go ceramic in a 2x12 try a G12H30 style speaker, preferably with the 55hz bass cone to smooth the vox chime out a smidge. These amps also love hemp cones in ceramic or alnico...
if you can beg around the family and pawn more gear you should go play this amp with cash in hand ASAP. Someone wills coop her up. They are very desireable. Not as much as a JMI 15 or 30, but more desireable than ANY OTHER VOX, even a JMI AC10 in good condition (except maybe the AC10 super-reverb-twin head, which is its own beast and truly awesome even though JMI reverb sucks a dick).