Buy 12ax7 tube

I prefer vintage GE circa 60’s and 70’s. You can pick them up at real good prices. The Sylvania Baldwin green label is another one of my favorite 12AX7 type tube!

It seems that one of the tubes is the driver and the other two are the left and right channels (the gain stage).

The driver can be a different brand, but the L & R must be matched tubes.

Can i use 2 brand or 3 in my amplifier in same time?
For example rca svetlana and chinese tube in same time?
Isnt harmful?

Joe of Joe's Tube Lore did not favor the 12AX7 Telefunkens.  I still consider his opinions the gold standard.  That said, I have been purchasing the matched pairs of  Psvane 12AX7-TII from Grant Fidelity.  You pay a little more for Grant Fidelity supposedly picking the best pairs.

Oh, OK. SED made the "Winged C."

^^^
Svetlana 12AX7 - For several years the original Svetlana 12AX7 tube from St. Petersburg (Winged "C"/SED) tried to develop a good 12AX7 and mostly failed. The current production Svetlana is a New Sensor product and is a member of 12AX7-EH and Tung-Sol 12AX7 family. All three of these tubes is virtually identical. The biggest difference seems to be in plate coating, gain and sound quality. I find the tube to sound a bit smoother than the EH and it has less gain than the Tung Sol. If you are not inspired by the Electro Harmonix and also find the Tungsol too grainy then this is the tube you want to give a chance. It has everything you want in a good pre-amp. Low noise, no Microphonics issues and very clear and open without being too bright. The construction is on par with the more expensive Tungsol. The price point on this 12AX7 tube is great because it will hold its own with more expensive options. Samples seem very reliable. If you like the JJ ECC83S but want something with a litter more glimmer this is where you should put your money.

lowrider, I think that the company that made the the SED Winged C El34 (the old Svetlana in St Petersberg) is not the company that took on the Svetlana name and now markets the 12AX7 and other tubes labeled Svetlana. I don't think that the St Petersberg Svetlana ever made a 12AX7. If they did I missed it. :-)

That's interesting about the Svetlana 12AX7. They are famous for making the highly rated  Winged C EL34.

Most of the tubes I get are from Brent Jessee; have also bought from Tubeworld. I think the guy is Brandon. Good products from both.

Don't discount these for new production. They have bested a lot of NOS in my phono pre
SVETLANA 12AX7 

First of all, I must say that it's preferable to buy tubes from a reputable dealer who's stock will be high quality and guaranteed. Tubes from a Chinese website may not be genuine or may not test as new or NOS. There are plenty of good, inexpensive dealers on Ebay.

Regarding your tubes, I see the Vincent uses 3 12AX7s (ECC83) in the preamp stage. I assume you are  replacing all 3. 
Telefunken are the most neutral and linear, but expensive. RCA Blackplates are affordable and offer a sweet midrange with good dynamics, $40 to $50 each. Raytheon is a low noise tube with open sonics. I would choose these NOS tubes over Genalex.

You'll want these tubes to be matched since they're in the preamp stage.

A reference for the 12AX7...
https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#12AX7

On Ebay, Viva Tubes is a reputable dealer with good prices.
Brent Jessee has everything.

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I own both the Raytheon & RCA black plate 12AX7’s and both (IMHO) are better than any new production 12AX7 tubes. For what it’s worth the RCA’s black plates are my favorite 12AX7’s. The RCA’s are on the mellow side but plenty of detail. I also own Mallards and Telefunken and to my ears the RCA’s are somewhere in the middle. Another great low distortion tube especially in the phono section is the RFT 12AX7.

I found these tube for 40$ in taobao
I cant afford more expensive stuff than 40$

Apart from the primary consideration that must be made, i.e. any tube's potential to synergize with your other components, speakers, room acoustics, etc, assuming you want a neutal tube, ala the Telefunken, which I consider one of the best, you might consider the not so old NOS EI12ax7a which was made with the Telefunken machinery which was purchased by EI. I just saw someone selling an unused octet of these tubes  (labeled ARC) for slightly under $200. A deal(!) if you can justify getting the octet. If you are interested in the Tele's you might do some research first. I haven't heard the other tubes you mentioned so I can't compare. 

The Genelax 12AX7 tubes worked wonders in my McIntosh C2500 preamp. Much more fully fleshed sound.  

I wold take the Raytheon or RCA over the Russian Genalex. I don't know where you'll get any of them for $40 though. I use Telefunken medical grade AX7 in my phono stage and original Tesla ECC803S for the AX7's in my amp. Telefunken is generally recognized as the most accurate and tonally neutral 12AX7 ever made.