Tube mic: t.bone SCT2000 - replacement tube: 12AX7B or 12AX7?

[RockNote]

The t.bone SCT2000 is said to have a 12AX7B tube. Such a tube is on sale from Thomann. However, I wonder if a regular 12AX7 tube would do just as well. What does the B mean anyway? Watford Valves seems to know of no such tube.

 

The mic:

http://www.thomann.de/gb/the_tbone_sct2000.htm

 

The tube:

http://www.thomann.de/gb/the_tbone_12ax7b.htm

[Zooey]

Regular 12AX7 will do fine. The 12AX7B appears to be a slightly higher gain Chinese tube, but still within normal for the 12AX7 type. Other factories use other letters after 12AX7 to distinguish between different models produced by the same factory.

 

Did the tube in your microphone actually fail? I find that's rare in tube mics. Most people swap out the tube just for the sake of fiddling with it.

[Phil O'Keefe]

I've had tubes go out in microphones before - it's fairly uncommon in a mic, but it does happen.

 

Any good 12AX7 should work fine. My only caution would be to make sure it's a low noise 12AX7 - sometimes you'll see 12AX7A, which is fine too. I've never seen a 12AX7B before. The 7025 is basically the same tube - it was the original "low noise" version of the 12AX7, but later builds of the 12AX7 (with the A added) are supposedly just as quiet.

[RockNote]

Thanks very much, Phil.