Preamp Tubes Review

Introduction
Preamp tubes come in different models, types and brands. The most popular for nowadays guitar amps is the 12AX7/ECC83. I've collected and tried a few preamp tubes, and noticed that different types and different brands do sound different. Different enough to write the umpteenth 12AX7 shootout, something nobody wants to read. So why did I write this story anyway? Simply because I needed a reference for myself, and my homepage seemed more organized than my desk.
I'm not striving for the ultimate sound. I've just made an inventory and tried some possibilities, not determined to go in a particular direction, but also trying out not so obvious combinations of tubes. Furthermore, I didn't care about measuring the tubes. Measurements can't tell a thing about the musical capability of tubes. It's all about what you hear, not about the characteristics that you see on an oscilloscope.
The guitar used was a Gibson The Paul SL with standard humbuckers. The neck pickup (490R) was used for the clean sounds (by turning down the guitar volume), the bridge pickup (498T) for the overdriven sounds. Both humbuckers are difficult to amplify, they have very compressed mids. Especially an overdriven rhythm sound - which doesn't sound mushy - is hard to accomplish. Lead and clean are a lot easier. The amp was a standard Rivera R100-212, it has two different sounding channels (Marshall and Fender). Lead, rhythm and clean were tested on both channels. So far only the gain hole (it uses five preamp tubes) was used for testing the tubes. The reference tubes used were one Sovtek 12AX7WA in the gain hole, four Chinese 12AX7s, and four Sovtek EL34WXT power tubes. These were also the tubes the amp came with.
Now before you read my results and start complaining about the low scientific value of this review: testing tubes by listening to them, as opposed to measuring, is prone to becoming highly subjective. Feel free to disagree with me. Please e-mail me if you decide to write your own review. Let your ears be the judge.

- Sovtek 12AX7WA
- Sovtek 12AX7LPS
- Audio-Voice 12AX7A
- Audio-Voice 12AT7A
- Philips Miniwatt ECC83
- Valvo ECC83
- Brimar ECC83
- Brimar CV4004
- National ECC82
- Tungsram ECC83/12AX7
- Tesla (Teslovak) 12AX7A
- EI ECC83

Information from http://www.fbk.eur.nl/BIT/MHM/gear/preamptubes.html