I thought it worth the time De-Mystifying Sovtek 12AX7 WA WB WC Variants. Why are there three versions of the Sovtek 12AX7 and what use one versus the other?
One common characteristic of all three types is that they are very low in microphonics. The “W” in the part number is there to tell us its a ruggedised valve. Ruggedised valves are made to withstand more vibration than a standard type. SO this makes them ideal for amp combos where the vibration in the cabinet is higher than an amp head.
Lets look at the three types:
The WA version has lower gain than the WC- to be more correct the right term is the amplification factor Fender use the WA in amps such as the Blues Jr, Hot Rod Deluxe. OK so it is branded Groove Tubes, but, it is still a Sovtek 12AX7WA The lower gain makes for an amp with smoother break up of the amp. It also helps make the Hot Rod Deluxe volume much more controllable. Some folks report the volume of the Hot Rod Deluxe is all or nothing. Usually generic ( high gain) 12AX7’s have been fitted, and this magnifies the sensitivity of the volume control
This valve is very similar to the WC version. It has the same gain. The big difference is that has a “darker” tone than the other two. This therefore makes it an ideal valve to tame a very bright sounding amp. and the WB has the same gain as the WC
The WC version has the higher gain then the WA. It is also brighter than the WB or WC. It can be used to brighten up what is a dark sounding amp
Usually there are multiple pre-amp stages in heavy rock/ metal amps. The Laney VH 100 is a great example.
The high gain of the Sovtek 12AX7WC pushes the later pre-amp stages into distortion ( “break up”). The chain of 12AX7’s start to break up . As a result the El34’s in the Laney example get a big final push from the pre-amp stages. The lovely hard rock tone magically appears!
We need a mention the fourth member of the Sovtek 12AX7 family. It is the Sovtek 12AX7LPS . . This is a long plate valve so has a very rich tone. Longer plates result in being more prone to microphonics so it is not a good choice in combo guitar amps. It has a lot of headroom and combined with the rich bottom end and this makes it a superb choice for HiFi amps.
We have all the above valves in stock!
We are always available to give advice.