jaxonmills said:
Would you say changing the preamp tubes resulted in a substantial tonal improvement? What are some of the tonal differences between those tubes and the stock tubes?
I've had very limited experience with NOS tubes. I remain a skeptic. If you're happy with current production tubes, I think that's the way to go.
I would say that just about any tonal improvement is worth pursuing, and this definitely includes preamp tube upgrades. Noticeable, for sure;
substantial, probably.
Differences: logically, it's mostly in the way the preamp handles your attack, especially the breakup style. My impression was that the Mesas were both cold and dark, and didn't produce the kind of texture I like to feel when I play, at least compared to the replacements I tried. After I swapped, everything felt smoother and more alive somehow. Definitely brighter, with some grain that I was more comfortable with, and better dynamic-handling. The Mesas made things feel murky and flat, where the new set seems to respond more readily to whatever I do. I find I can also work with the highs a little better now, they're less pointed and forced-sounding... they seem more like a natural part of the sound, and can be dialed out if I like.
The ECC803s in V2, which is where you'll get the most gain-focused results, was not what I'd hoped; it sounded a little harsh to my ears, whereas the Mullard is much more pleasing and smooth. But I have not had a chance to really give it a good field test, I'll fiddle with it more sometime. I know a lot of people really like this tube, so it's probably worth dropping a few bucks on just to see if you do.
I guess where taste plays in here heavily probably corresponds to which harmonics are emphasized by each tube combination; since these tubes are closest to your hands, it makes sense that what appeals to you is how these tubes translate your own stray harmonics and dynamics. Which is why we like the LS so much in the first place, right? So, yeah, do it.
PS. When swapping, I'd advise marking each of the stock Mesa 12ax7's with their slot # (v1, v2, etc) for future reference.... it comes in handy for troubleshooting later.