We have arranged a re-match of 12AX7 today at leehc’s home. It was originally intended to be just a re-match between the top two winners of our last battle of 12AX7 – the Mullard 10M 12AX7 and Telefunken ECC803S. at the buffer stage of single-ended 300B power amp.

We were later joined by a number of new challenger 12AX7’s from various friends as follows :

Mullard 10M Master Series 7025

Amperex Bugle Boy 12AX7 with short plate

Mullard 12AX7 with long plate/small round getter/single support

Raytheon 5751 with black plate/big cross getter/gold pin

Mazda ECC83 with stainless steel plate

The testing platform is buffer stage of Allegro single-ended 300B power amp with metal base Bugle boy EL34 and new WE 300B driving the Klipsch KLF30 horn speaker. Pre-amp is the Matisse Fantasy Line MkI. CD is Proceed CDD + Aragon D2A.

We have divided the 7 tubes into two groups and try to get the winners for each group for a head-on final. We use blind test and the usual Naum Chopin + Café Blue + Chinese volin.

After almost 4 hours of listen, no decision can be made on which one is best although everyone agree each tubes sounds very different from each other and much more than when they are used in the pre-amp. The score varies by a huge degree but it did indicate three top scorers with every two of six judges prefer each one of the following . So we agreed that there should be three winners which are the Best of the Best 12AX7. They are :

Telefunken ECC803S

Mullard 10M 7025

Mullard 12AX7 with long plate small round getter single support

In my opinion, the two Mullard is more relaxed and all-round with the most beautiful mid-range while the 10M 7025 being a bit more refined. The 803S has huge frequency extension at both end and has a very distinctive "Telefunken" sound. Again, it really depend on taste and, like what we found out in the 6DJ8 battle, it is probably better to pick three winners instead of trying to identify one which not everyone agree.

I was very surprised that the winner of the last battle – the 10M 12AX7 was actually pushed out of the match in an early round! I suspect I picked the wrong pair of 10M 12AX7 for the match as I have 3 10M 12AX7 and two of them seem to be more matched. When I powered up the pair of 10M 12AX7 in the match, one of them gave a flash when the other did not. I remember in the last battle, both 10M 12AX7 give a flash when I power them up. But any way, since we used blind test, I accept the superiority of the winner(s) over the 10M12AX7.

One last note on the Mullard long plate. I was very very surprised to find out the best Mullard long plate was actually the "cheapest" and latest production model of all Mullard long plate. We have tried the square getter long plate with double support and the square getter double support with long black plate, which are a lot more expensive and rare, but they all sound inferior to this version. So be careful about what you buy next time.