Question for knowledgeable Sovtek 12AX7 experts!

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Over the years I have accumulated hundreds of tubes, enough to fill a large red Craftsman toolbox. It was a mess in there.
Recently I decided to sort through the tubes and discard the used, stray and unmarked ones. Many had to be put back in their boxes and that kind of thing.
I came across four different Sovtek 12AX7 variants:
12AX7WA
12AX7WB
12AX7WXT
12AX7LPS
I seem to recall that the A and B were almost identical, except for slight tonal differences preferred by certain guitar amp manufacturers. I think they were intended for guitar amp replacement applications and are not ideal for high end audio apps.
The WXT differs from the other three in that it has three mica spacers, like a GE 5751. I believe it was selected for low noise and had more gain than a "standard" 12AX7.
The LPS is their latest version and is a very high performance variation with a larger grid and low hum and noise. It is said to have a "spiral filament", but I thought all filaments were spirals. Go figure!
Can anyone add to this? I'm mostly interested in the 12AX7WXT as it differs from the others with its triple mica construction.
Thanks!

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Topic - Question for knowledgeable Sovtek 12AX7 experts! - nightdoggy 10:40:09 03/16/07 (4)

Re: Question for knowledgeable Sovtek 12AX7 experts! - Rivieraranch 06:45:37 03/17/07 (3)

Yeah - nightdoggy 08:01:04 03/17/07 (2)

Re: Yeah - Jim McShane 10:31:06 03/17/07 (1)

Sorry-my mistake (nt) - nightdoggy 13:16:42 03/17/07 (0)

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