[xecluded]

Greetings,

Can I use 12AY7 tubes in the linestage board instead of 12AT7 (just want to try some tube rolling on my Van Alstine Transcendence 7.)  Also, if i don't use phono, can I pull the 2 12AX7s off the phono board.  Thanks.

[avahifi]

I have no information regarding a 12AY7 tube type.  Perhaps someone else does.

You should leave the phono tubes in place because some B+ voltages may go higher than the rated values of some parts if they are left out and cause damage.

We used the 12AT7 tube in the line stage of that unit because it had good current drive.  If you change to a tube with different biasing requirements, your results will be random.  Not a good thing to do unless you understand the tube electrical requirements and the circuit design.

Regards,

Frank Van Alstine

[Listens2tubes]

http://www.nj7p.org/Tube4.php?tube=12AY7

[rlee8394]

xecluded,

Like Frank says, the 12AT7 has greater current drive. The 12AY7 has a lower amplification factor, 40 vs 60 for the 12AT7; it's plate resistance is double that of the 12AT7; it's transconductance is one third that of a 12AT7; the plate current is 3 ma vs 10 ma for the 12AT7. I can appreciate your desire to roll tubes, but your choice of 12AY7 is "going the wrong way." You could substitute a similar type such as a 6201, ECC81, ECC801, or CV4024. Go here for more choices.

http://tdsl.duncanamps.com/show.php?des=12AT7WC

If I were you, I'd call Jim McShane and get a matched pair of Mullard CV4024's or RFT ECC81's. Jim's site:

http://pages.prodigy.net/jimmcshane/tubes.htm

Just my $0.02 worth,

Ron

[Lefty052347]

FYI:

The gain of the 12AY7 is rated at less than 75% of the 12AT7.  The 12AY7 probably does not have the gain required by the T7 line stage.

Regards,
Dean

[xecluded]

Thank you all for your suggestion.  I guess I will stick with the variant for 12AT7's family.  I have one telefunken 12at7 so i will just need to get one more to try.  Thanks again everyone.

[rajacat]

xecluded,

In my system Mullard CV4024 sounded better than the stock tubes. They just seemed to have an overall more refined presentation... smoother with a larger sound stage and less strident top end. The detail was still there too. The difference wasn't subtle. I'd also be interested in trying some Telefunkens and Siemens.

-Roy

[xecluded]

Thanks Roy for your insight on the CV4024.  I will have to try them.

[martyo]

xecluded,

There are many NOS AT7's to choose from, but if the Telefunken "sound" is your cup of tea, the Seimens E81CC's are 2nd to the Telefunkens IMO(which are hard to come by). They are very linear like the Tele's. Many NOS are rolled off at both frequency extremes and often the bass isn't as defined as the Tele's or Seimens. Valvos are my 3rd choice. Tubes with that more lush midrange, like the Mullards, would be Brimars. I like the Brimars midrange a lot, you just have to give up too much in the lowend for me. If you want to, PM "mark funk", my brother, he has tried so many, he can give you characteristics of the sound of most, through his AVA gear.