Tube swap report: Electro-Harmonix 12AY7 in V2
I wanted to tame the low end on my SL900. Like others, I initially ran the bass at 9 oclock, mids at 3:00 (600Hz), and treble to taste. Lately, Ive been further taming the low mid bump by cutting the mids at 200Hz instead, and cutting the bass even further. Cool for grindy tones, but such extreme settings are a bit of a balancing act, and the tubbyness returns the moment I turn up the bass.
The 12AY7 has about half as much gain as a 12AX7. As I had hoped, putting it in V2 lowers the bass and treble relative to the mids, effectively extending the range of mid-boost available.
Here are the pros (all IMO): My top string sounds thicker and more balanced, the treble is less zingy, and the bass is tighter. There's still an ample amount of midrange cut available if you want it, and boosted mids at either 600Hz or 2.7KHz sound better than ever. Best of all, cutting them to 9:00 at 200Hz gives the smooth, natural tone I wanted all along (imagine a Shuttle 9.0 with the controls at noon, but smoother and rounder-sounding). Despite the reduction in overall gain, the range of volume control is more than adequate with even the quietest basses. I'm not a distortion geek, but the 12AY7 seems to make the amp more touch-sensitive and controllable at the edge of breakup.
And the cons: The gain is lowered on the treble as well, so slappers looking for glassy highs might find the treble control a little underpowered. Also, the gain and volume controls have to be cranked quite a bit higher in order to get distortion. That's not an issue when playing loud, but I found that at lower levels, going for maximum breakup meant turning the master almost off. This made the control so abrupt, that I could no longer get fuzz tones at bedroom levels. YMMV, depending on the cabs youre using.
Previously, I made a couple of experiments with vintage 12AX7s, and wasnt blown away. In fact, I had chosen to stick with the stock tubes until now. However, the AY achieves exactly what I was looking for. I highly recommend this swap.