Hi 65Mustang,The use of the 6F6gs as regulators may have never been known if it was not for Ecclectique bringing it to our attention here some time ago.I love them. When I first read about it I phoned Andy of Vintage Tube Services.I requested the best out of the bunch, he rounded some up and tested them and set aside acouple of nice pairs for me.Both Sylvanias,one pair 1930s N.O.S. matched to with in 2m.a. A secound pair from the 1940s ,carbinizied glass N.O.S.,matched with in 1 m.a.This is critical for the regulators to be matched to get the very best performance, be it these or any others you choose that will work in your Supra pre... Now here is an old radio /juke box tube that will have a major sonic impact on your pre,for very little money.I have seen the 6F6Gs and gts at a vintage radio show for 5 to 8 bucks each,all brands, some N.I.B.s.There are loads of them out there.Mustang,I know Im not telling you anything you dont know already,this may benifit someone else reading this.The power supply tube/s and the regulators have a major sonic impact on how your pre is going to perform...Just make damn sure the power supply tube test values check out.I have afew pair of rare and sought after 6SN7s .They all had their turns in my Chenin ,they were all good .I really had to listen carfully ,switching 6sN7s was nothing like the impact of changing the power supply tube and regulators,not even close.I ended up sitting back and enjoying what I was listening to.Even the new production E.H.6SN7s gold pins sound great,give them 50 plus hours burn in,another inexpensive tube.The phono section I have a pair of mirror matched R.C.A. 6c4s and a small fortune of ecc88/6922s ,Telefunken ,seimans and Philips Mini watt .cca,gold pins and S.Q.s ,only afew that are dead silent phono grade pairs.Buyers beware,looking for top N.O.S. phono grade? good luck.The Philips Miniwatt early 1960s gold pin S.Q.s are[out standing ]and a lot less money,very close in performance to the seimans and Telefunkens.I am very selective who I buy alot of tubes from,Andy of V.T.S. and a seller here on the Gon. from Holland. His user name is Dioto. Tom and Andy are with out dought straight shooters in this game,some of my very best 6922s came from Dioto.Anyway I hope this helps someone and good listening to all.
