tube question for ARC Ref 3 users

Mkilpi, what do you think of the Tung-Sol 6550? Is it a Tung-Sol original (50-60's version) or a recent version?
I've heard some say that a original Tung-Sol 6550 from the 60's is the way to go, though I haven't experimented yet on my own.

Cheers,
John

I agree with Guido

Stick with the 6550C

Interesting subject. Any thought on Frank's question on the 6H30 tube regarding the audible sonic differences of manufacturer/dating of the tubes? Also applicable to the 6550C?

I need to replace tubes later this year. Would be very interesting to know if a potential audible improvement on the already great (glorious) performance of the ref3 is possible!

I replaced the stock 6550C tube with a NOS Tung-Sol
black plate (1950's) with wonderful results. Have not
replaced stock 6H30 tubes. NOS tube did take alittle
break-in to sound it's best. Nice improvement to an
already great line stage.

VMK, I'm glad you had wonderful result. . . could you please elaborate with some comparative findings? Thanks, Guido