[S Clark]

Gary Dodd has rebuilt some of the circuits for a pair of Knight KB-85's for me with results that have made me a very happy listener    , but I have a problem.  The newest of the pair had a 5U4GB rectifier in place of the correct 5AR4 that the older amp had.  After listening politely for about 10 minutes, I cranked the newer amp up just a bit, and the fuse blew with the incorrect tube.  Replacing with the correct tube from the other amp solved the problem.  The older amp had a pair of Sylvania 5AR4's.  Should I match the other with the same ( I plan on running them in mono to power my LS9's), or should I look for another option?  JJ's are cheap, Mullard's are not, and the Sylvania's are in the middle.  I could use the knowledge of the circle 

[Dmason]

It is becoming clear that the newer production Sovteks are pretty damn good overall. They are tough, built with Mullard design and tooling,  which Saratov apparently bought, and are the best value. The old stuff might last longer, but prices are going up and you have to poach them off ePay, or pay ridiculous retail prices. Avoid JJ 5AR4. There are plenty of stories of people arc'ing their way through several in quick succession. The Sovteks can be got for ~12.00 at www.tubedepot.com. But dont take my word for it, many tube luminaries, such as Gordon Rankin of Wavelength wholeheartedly recommends the Sovteks. Screw high prices, these are 16 dollars delivered to your door.

[BossaNova31]

I had a new production Sovtek 5AR4 in my 300b SET amp and went to a NOS Mullard. The improvement was subtle - probably not worth paying $100 for if you are on a budget.

[S Clark]

Well, it sounds like a pair of Sovtek's are in my immediate future with Mullards on my Xmas list.  Thanks for the advice.

[DaveC113]

IDK, many people (including myself) haven't had the greatest of luck with new Sovtecs either. That said, I've compared the new JJs to the Sovtecs in my preamp, and prefer the JJs for my system. They both sound quite different, the JJs being warmer, juicier, and fuller sounding. They are cheap enough that I'd buy both and try them out... the difference isn't all that subtle in my preamp.

[nodiak]

I agree it's a preference with each amp. I have used both the new Sovtek and JJ's. Sovteks sound cleaner and more transparent to me, JJ's more body and rounder. The Sovteks sound better to me in the Scott 222c, a pretty juicey/tubey amp. The JJ's sounded better in a SE EL84 I had. They're both pretty affordable, could get each and try.
Don

[rpf]

New Sovtek tubes have, in general, a good reputation for reliability. That said, I have heard of, and myself have had, problems with their 5AR4s. Instability in a pair of them blew power tubes in a pair of Quad II mono-blocks I have. Mullards are currently overpriced. NOS GE or Japanese (Mullard copies) 5AR4s from the '70s are of good quality (and better sound than the Sovteks) and can be had for $50 from various reputable dealers.

Rob

[enjoythemusic]

Agree, the new Sov's are great. i do have some rare CV1377 brown base Mullards and the good ol' CV378 tubes too. Yes there are differences, but at what costs... i look at tubes like seasoning for food, sometimes i want a bit mor subtle, othee times i might want tobasco. Good thing it is so easy to change tubes

[Listens2tubes]

You could buy the Sovteks and keep your eyes open for a deal on a pair of the Sylvania Big bottles. They are a good choice in most cases.

[ohenry]

The Tube Amp Doctor (TAD) 5AR4 is now imported to the US and for sale at Antique Electronic Supply http://www.tubesandmore.com for $19.95; no more deal-killing shipping costs from Germany.  It's has thick glass, a nice brown base and looks pretty in the dark.   

I highly recommend this one, it works great in my Carina producing tight bass and perfect highs.  In fact, it has displaced my Mullard 5AR4 for now... it's that good.  Maybe it'll work that well in your application too.