What's your favorite 12ax7 and why?

[Bambi B]

Another great Sylvania tube

pilotputz,

The Sylvania triple mica has become quite expensive- hey thanks a lot guitar amp crowd!- but keep in mind you can have one or two of those in the first phono and line stage spots and then the GE or Sylvania two mica grey plates are just fine as well to fill the secondary sockets. Keep in mind too that 5751s have 70% of the 12AX7 gain, which may affect the phono if your cartridge is lower output. In the SP8 that's why I would be using them in the line stage only withj the high gain Siemens E83CCin the phono. Still, as I've used the 5751 for years in the mic pre- and microphones are low output devices - I've still never noticed a gain problem.

I thought to mention too - though it's a digression from the 12AX7 topic- that besides the fantastic Sylvania triple mica 5751, the tube type that Sylvania really got right was the 12AT7. For a real treat, if your gear uses the 12AT7, find some NOS Sylvania triple mica, black plate, square getter 12AT7WAs from the late 50's. This was a military issue and I have some in 1958 USAF issue boxes. This tube is just magic- lush, deep, and full in a way I've never found in another 12AT7. I prefer this tube even to the Sylvania Gold Brand 6201 which is very good as well, but doesn't have that swoony "1939 Bing Crosby" sound of the 12AT7WA. I use this one, alternating with Valvo Hamburg 6201s- another favourite 12AT7, in my microphone preamp. My favourite all round 12AT7 is still the Siemens triple mica E81CC- it has a lot in common with the Siemens E83CC qualities I mentioned, but it is a very neutral tube as compared to the deleriously rich Sylvania WA.

Happy hunting!


Cheers,

Bambi B

 

[AFpay]

I like RCA 12AX7's. Cleartops are even better.

 

[RWFE]

pilotputz,

The Sylvania triple mica has become quite expensive- hey thanks a lot guitar amp crowd!- but keep in mind you can have one or two of those in the first phono and line stage spots and then the GE or Sylvania two mica grey plates are just fine as well to fill the secondary sockets. Keep in mind too that 5751s have 70% of the 12AX7 gain, which may affect the phono if your cartridge is lower output. In the SP8 that's why I would be using them in the line stage only withj the high gain Siemens E83CCin the phono. Still, as I've used the 5751 for years in the mic pre- and microphones are low output devices - I've still never noticed a gain problem.

I thought to mention too - though it's a digression from the 12AX7 topic- that besides the fantastic Sylvania triple mica 5751, the tube type that Sylvania really got right was the 12AT7. For a real treat, if your gear uses the 12AT7, find some NOS Sylvania triple mica, black plate, square getter 12AT7WAs from the late 50's. This was a military issue and I have some in 1958 USAF issue boxes. This tube is just magic- lush, deep, and full in a way I've never found in another 12AT7. I prefer this tube even to the Sylvania Gold Brand 6201 which is very good as well, but doesn't have that swoony "1939 Bing Crosby" sound of the 12AT7WA. I use this one, alternating with Valvo Hamburg 6201s- another favourite 12AT7, in my microphone preamp. My favourite all round 12AT7 is still the Siemens triple mica E81CC- it has a lot in common with the Siemens E83CC qualities I mentioned, but it is a very neutral tube as compared to the deleriously rich Sylvania WA.

Happy hunting!


Cheers,

Bambi B

I have some Sylvania 12at7wa's with a date code of 1960. They have black plates, double mica and they sound pretty darn good too when you figure I got ten of them for 26 bucks. I was not really expecting much but they were a lot better than I expected.

 

[Kegger]

keep in mind anyone afraid of using a 5751 for a 12ax7 for fear of gain loss.

Most if not all 12ax7 circuits don't get the full gain of the tube because of the
load and voltage it would take do so, in most cases you will not notice change
in gain when subbing in a 5751 for a 12ax7.

 

[GordonW]

keep in mind anyone afraid of using a 5751 for a 12ax7 for fear of gain loss.

Most if not all 12ax7 circuits don't get the full gain of the tube because of the
load and voltage it would take do so, in most cases you will not notice change
in gain when subbing in a 5751 for a 12ax7.

This is true, in some respects. I've even modeled a 12AT7 in place of a 12AX7 (gain of 60 vs 100) in some circuit designs and alignments, and had little change in overall gain.

HOWEVER- that said, the VOICING of the circuit can change, due to the two tubes being in different POINTS on their load curves/ load lines. Sometimes, one might have different distortion characteristics, due to this. This is probably one of the MOST important factors in the change in sound people encounter, when rolling different tube types...

Regards,
Gordon.

 

[Kegger]

HOWEVER- that said, the VOICING of the circuit can change, due to the two tubes being in different POINTS on their load curves/ load lines. Sometimes, one might have different distortion characteristics, due to this. This is probably one of the MOST important factors in the change in sound people encounter, when rolling different tube types....

Agreed and 1 reason I tend to build circuits for other tubes instead, that is there
are a ton of tubes between 5k - 10K plate resistance that when a circuit is built
for them opens the tube roll possibilities immensely that the tube has a good bit
of/high percentage chance of working properly, where the characteristic's of the
12ax7 don't have much else really near it.

 

[cableguy]

Excellent thread....:thmbsp:
I have a phono preamp that uses 12AX7's and will soon have a Ming Da MC34A that uses them as well.
Most recently I picked up a matched pair of RCA Long Gray Plate old logo 12AX7 preamp tubes with square angled getters..(what does that mean?) and sprung for a lot of 4 ea. NOS 1985 6N2P-EV....w/the Rocket logo...The Russian tubes are a hell of a value so even if they don't blow me away I have less that a 20 spot invested.



Bill