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As for 12AT7, most tube equipment designers think this tube is not a great audio tube due to its non-linearity compared to other more popular tubes. Famous NOS versions are easily available. AC member "SY" tested a bunch of brands of 12AT7 very thoroughly, and found the new JJ 12AT7 superior to all others in THD and harmonic distribution. He said alot of them, even the famous NOS versions have excessive 5th order harmonics, which is much lower in JJ. I bought a pair to replace the EH splitter inputs that came with my amps and heard a very noticable improvement in smoothness and a lighter, more glistening approach (damn words!) I assume it got even a little better with break in, but didn't really notice that. I got the gold pins, matched and triode balanced, from tube depot, FWIW. You might think they suck in your amp, but that's my .02 Rich
Seriously has anyone ever heard these things? Also for the NOS gang, I know squat. Are there any reasonable 25. per tube NOS or other 12ax7, 12at7 that would offer me a pretty serious sound improvement over Swetlanas of the same model #?thanks in advance,
Quote from: Response Audio on 20 May 2007, 09:56 pmI have to agree with you on this one Josh. This is why you see so many designs using the 12AT7 as a driver/phase splitter. I have also found that the 12AT7 usually provides better results when it is used in substitution for a 12AX7 as an input tube. The only other tube I would prefer (depending of course on the circuit requirements) is the 6SN7 or 12SN7. This is only a personal preference based on my experience with this tube.
I have to agree with you on this one Josh. This is why you see so many designs using the 12AT7 as a driver/phase splitter. I have also found that the 12AT7 usually provides better results when it is used in substitution for a 12AX7 as an input tube. The only other tube I would prefer (depending of course on the circuit requirements) is the 6SN7 or 12SN7. This is only a personal preference based on my experience with this tube.
There has been some welcome technical progress in the EL34 type in the last few years, due to the huge demand for them in guitar amps. John Lennon used them and made the sound famous, as did many many other guitar heros on famous solos. It can be a rich ballsy sound, but hifi demands are quite different than guitars which want as much distortion as possible, which stereos want the least. My amps require 8 of them, so I spent a whole week reading the opinions and researching them, and contacting a lot of the distributors for their recommendations. Among the best quality EL34s in new production:SED winged C EL-34Groove Tubes E34LS (made by JJ, not same as JJ EL34)JJ KT-77 EH There were some other tubes called "the best I ever heard..." but these listed were consistently mentioned above any others. Some have suggested that the KT77 are better than NOS Mullards, but in my amp, the GT tubes were better than the KT77. The GT tube designer also designed my amps, so no wonder they are preferred, so I am sticking with the OEM tubes. Like Bill said, you just gotta bite the bullet and try a few different ones to see what you like. If you want some quality brands to consider, the above might be a good starting place. Often the OEM tubes are best, since they were selected by the designer for a number of reasons. Rolling is fun, and occasionally you hit the jackpot, but it can be expensive and feels like gambling. Thrilling, maybe addictive for some people. Uh-oh! Flames coming!As for 12AT7, most tube equipment designers think this tube is not a great audio tube due to its non-linearity compared to other more popular tubes. Famous NOS versions are easily available. AC member "SY" tested a bunch of brands of 12AT7 very thoroughly, and found the new JJ 12AT7 superior to all others in THD and harmonic distribution. He said alot of them, even the famous NOS versions have excessive 5th order harmonics, which is much lower in JJ. I bought a pair to replace the EH splitter inputs that came with my amps and heard a very noticable improvement in smoothness and a lighter, more glistening approach (damn words!) I assume it got even a little better with break in, but didn't really notice that. I got the gold pins, matched and triode balanced, from tube depot, FWIW. You might think they suck in your amp, but that's my .02 Rich
In the Jolida 1000a stock form can I use 12AT7s in place of the (2) 12AX7s?
I have read the gain is lower on them vs the 12AX7?
If so I would be replacing the (2) driver tubes and the (2) pre-amp tubes all at the same time.
Are the 6SN7 or 12SN7 another option I can try with this amp? Thanks in advance,
normal confiquration is:(2) 12at7s for pre amp(2) 12ax7s for power drivers.