12AT7 tubes

I am using Sylvania Gold Brand 6201 in the phono section of my VTL TL 5.5 with excellent results. I also tried Mullard CV4024 with very good results. I currently use the Mullards in my VTL ST150. Between the these two tubes I liked the Sylvania just a little better. The Sylvaias have a more pronounced but at the same time better controlled bass than the Mullards. Other than that I like them equally well.
Both were much better than the stock tubes.

Cheers,
Jim

Easytune: You wrote that you need to replace "one tube" in the phonostage. Do you mean by that literally a single tube? I mention this only because most phonostage circuits use L/R pairs of matched tubes, and you wouldn't replace one without replacing the pair with the same choice, tested and matched for gain. As for your question about the Mullards, the wisdom I've received is that in general, the earlier you go in manufacture date, the darker they will sound, whereas the Tele's are said to be pretty consistent throughout. I've tried versions of the Mullards, Teles, RCAs and Sylvanias, and they all sound different, but my best advice to you, with a phonostage (where quietness is at an absolute premium), is to make sure you're dealing with someone who can really test and vouch for his tubes' freedom from incipient noise and microphony issues, and will stand behind them if an audible problem develops within a reasonable period of time.

For a detailed (read exhaustive) description of the various 12AT7s, try Joes Tube Lore over at the Asylum.

Hi everyone,
First , thanks everyone for all inputs,advice and recommendations. I have bought siemens tube,and planned to get amperex one. I would love to get Telefunken ,mullard ,RCA tubes when opportunities come. I would post my impressions from tubes i bought.
To:Zaikesman,
My VTL tp2.5 phono stage uses 1 single 12at7 and 3 12ax7 tubes.I broke 12at1 one when i clamped mapleshade tube anchor with it. Do I need to match my new single 12at7 tube with old 12ax7 ones for the gain? Thanks for your advice.KB

The gain factor is constant for a 12AT7. The age of the tube can be a factor in dissipation but it's only noticible if you have a brand new or near dead tube. Is that what you meant about matching it to the 12AX7s. Go to the Tubestore.com and use their gain factor chart. Or did you mean matching channels in that case both should be very closely matched and the same tubes. I don't get it? You don't need to match the the 12AX7s.