I’ve done a ton of tube Rolling over the years on the Ares Magnum. The 12ax7 slots make a huge difference. My 3 favorites, from most favorite to less favorite:
1. Mazda silver plates - These have a little extra energy on top, so maybe not the best fit for systems already leaning bright, but they far exceed the next 2 choices in all other respects. Almost as good as a component upgrade. 2. Telefunken - Ribbed plates if you want a little extra zing up top, smooth plates if you want warmer or smoother. Smooth plates are more neutral overall, ribbed can be a little more exciting. Both great tubes, and plentiful if willing to buy used, so don’t overpay for supposed NOS from a dealer.
3. RCA tall black plates. Good overall tube, close to neutral with a touch of warmth and sweetness.
The 12au7 slots, eh I never liked 12au7. You can sub 12ay7 or 12at7 in here. I’ve also subbed 12bh7, which is what I ended up suing the most - MUCH better sounding than typical 12au7’s. The best 12bh7 are 1950s Sylvania black oval plates with D or square getters. RCA of any kind are also good (warm) and Tung-Sol are decent (leaning a bit bright). The real problem with 12bh7 is their noise and microphonics in this application. But the Ares isn’t really the quietest phono stage anyways, so I just went through a bunch until I found a pair "quiet enough" and went with that. For a strict 12au7 sub, the GE 5814 gray plate triple mica were decent enough sounding (warm), easy to find quiet ones of, and affordable.
Rogue OK’d the 12bh7 sub for me, several years ago. These tubes draw 0.3mA more current on their heaters. I’m not sure if Rogue would say they OK it today (they seem to be getting more conservative in their recommendations over time), but I never had any problems.
In all 12ax7-based tube phono stages I’ve had (Hagerman Trumpet, VAC, Herron), those lead 12ax7 make a huge sonic difference. The follower tubes also make a notable difference, though not as much as the 12ax7 until you start trying type substitutes (e.g. 12au7 to 12bh7 / 12ay7 / 12at7) - then the difference can get almost as big.
1. Mazda silver plates - These have a little extra energy on top, so maybe not the best fit for systems already leaning bright, but they far exceed the next 2 choices in all other respects. Almost as good as a component upgrade. 2. Telefunken - Ribbed plates if you want a little extra zing up top, smooth plates if you want warmer or smoother. Smooth plates are more neutral overall, ribbed can be a little more exciting. Both great tubes, and plentiful if willing to buy used, so don’t overpay for supposed NOS from a dealer.
3. RCA tall black plates. Good overall tube, close to neutral with a touch of warmth and sweetness.
The 12au7 slots, eh I never liked 12au7. You can sub 12ay7 or 12at7 in here. I’ve also subbed 12bh7, which is what I ended up suing the most - MUCH better sounding than typical 12au7’s. The best 12bh7 are 1950s Sylvania black oval plates with D or square getters. RCA of any kind are also good (warm) and Tung-Sol are decent (leaning a bit bright). The real problem with 12bh7 is their noise and microphonics in this application. But the Ares isn’t really the quietest phono stage anyways, so I just went through a bunch until I found a pair "quiet enough" and went with that. For a strict 12au7 sub, the GE 5814 gray plate triple mica were decent enough sounding (warm), easy to find quiet ones of, and affordable.
Rogue OK’d the 12bh7 sub for me, several years ago. These tubes draw 0.3mA more current on their heaters. I’m not sure if Rogue would say they OK it today (they seem to be getting more conservative in their recommendations over time), but I never had any problems.
In all 12ax7-based tube phono stages I’ve had (Hagerman Trumpet, VAC, Herron), those lead 12ax7 make a huge sonic difference. The follower tubes also make a notable difference, though not as much as the 12ax7 until you start trying type substitutes (e.g. 12au7 to 12bh7 / 12ay7 / 12at7) - then the difference can get almost as big.