NOS Tung Sol 6550 VS Tung Sol 6550 New Production

Has anyone had experience with the new Tung Sol 6550 new production power tube. If so how does it compare with the NOS Tung Sol 6550 ones. I want to replace my stock Sovtek 6550 in my ARC Ref 6 . But from what im seeing the NOS Tung Sol 6550 is way up in price of about $ 350. And the new Tung Sol 6550 new production power tube is about $ 35 from the Tube Depot. 
128x128Ag insider logo xs@2xtattooedtrackman
They are two different tubes.  The NOS tube was made in the US in the 50s and 60s, the current tube is made in Russia and only shares the branding with the old tube.  The factory in Russia pays someone for the use of the Tung Sol name and others like Mullard.  

I think it would be unlikely that you would get an improvement in sound equal to the increase in cost.  Unless any improvement at any cost is worth it to you, I'd stick with the current production Tung Sol.
Never listen to Sylvania 6550's from the 1950's  , you will never be satisfied
with new anything tube !
@tattoedtrackman- Just my take on what Schubert meant: The only current production output tubes, that can compete with the old Sylvanias, GEs, Mullards, Tung-Sols, Genelex, etc, are the EAT KT88s. Once having listened to those old tubes, they spoil some of us for anything else. Of course, everything’s VERY subjective, regarding sound quality, aural acuity, pickiness and how much one’s willing to spend. If my money wasn’t funny, I’d still be using NOS GE 6550As. Alas: eight of them, or anything else in their class, have now exceeded my willingness to spend. I’m listening to an octet of the Russian version of the Genelex KT88s, in my Carys. If I ever win a Lotto, NOS Tung-Sols will be on my agenda.
I think that the 6550 the OP is referring to is used in the power supply of his preamp.  I don't think it would have the same impact that a set of NOS power tubes in an amp would.  If I'm wrong, let me know.
I also have the ARC Ref 6 and thought I would try the NOS Tung-Sol.  I like a rich, sweet midrange, which is what the stock Sovtek has.  I did not like the Tung-Sol.  It has more extended highs, a deeper, tighter bass and is more dynamic.  However, the midrange is sacrificed for these qualities--all in all I did not find it musical.  I much preferred to original Sovtek; it has a very sweet, rich midrange.  I thought there might be an issue with break-in time, so I did put 50 hours on the Tung-Sol with only a slight improvement.

some people who have answered you here seem to have only read your title line, then didn’t read what you actually are asking -- which is these titled tubes used in an ARC Ref 6 linestage...

the 6550 position in the Ref 6 is in the rectifier section, it is NOT used as a power tube in the signal chain at all, so its impact on the sound of the unit will be somewhere between minimal and none...

so I would not worry so much about using these ungodly expensive NOS USA 6550’s from the 1950's and 1960's and stick to what ARC suggests to use in terms of modern day produced 6550’s for the specific purpose in your unit

you may want to direct this query to greg christensen at arc (technical / service manager) -- ask him whether they have done usage and listening tests using old stock american 6550s in the Ref 6 rectifier circuit and what they have found

this is one of the hazards of posting a question like this on a forum like this... you give people license to wax lyrical on stuff they have feelings about, but they are not answering you on your specific application -- details matter!

good luck

you may want to consider the Shuguang KT88-T nature sound series. among the best sounding 6550/KT88 I have heard, in a power amp, but do not know what it would sound like as a rectifier.
@jjss49 -     "schubert ....what do u mean .....Never listen to Sylvania 6550s from the 1950s?"      As for myself; that was the question I answered and (as stated), simply with my take on Schubert’s post.        Just a guess; I’ll bet the OP found his tube replacement, long before this dead thread was resurrected.        Not that anything you posted was incorrect, but, at times; dates are also relevant details.

thx for pointing that out

i mistakenly addressed my comment to tattoo, i meant persephone, who commented just previously 0n 10-28-20 to which my comment was meant to be directed to
Regardless of whether the 6550 is a rectifier tube or a power tube, it has a significant difference in the sonic quality of the Ref 6.  The NOS Tung Sol totally changed the sound--for the worse.  I am sticking with the original Sovtek.
Have numerous KT88s, 6550s. The Mac tube amps from the 60s used either Genelex KT88S or Tung Sol 6550s. To me, and I just recently retired my MC60s, the TS 6550s gave these amps which had tube rectifiers, the most convincing reproduction. 
The new Tung Sols have great dynamics but there is definitely a haze that obscures the voices, but all in all the NOS 6550s caused the least listener fatigue. While running the MC60s, after hearing the NOS Tung Sols I rarely swapped them out.