Based on the help of many of you who have replied to my questions or posted elsewhere, I have made some changes since originally posting and thought I'd share my experience with current and prospective TAD-60 owners. I replaced my Placette passive pre with a used, unmodded MiniMax preamp. There were significant improvements in harmonics, tonality, dynamics and soundstage. It gave the sound a bit more warmth, which I like. The treble edginess was diminished, but it and the stridency were still there. (The gain on the unmodded MiniMax is quite high; I can't go past 9:00 and usually have it between 7 and 8 o'clock.) Overall, I was getting much closer to the sound I was looking for. The most significant tube effect seemed to be the Tungsol 6x4 rectifier in the pre (I tried a Sylvania and GE 6x4, as well as the CV 4005 that came with it.) It opened up the sound, improving the texutre and separation of instruments. I will play with some other 6x4s. I'm intrigued by how much difference the rectifier tube makes and am interested in trying others.
As for changes in the TAD, once I added the MiniMax my preference quickly shifted to triode mode. I replaced the stock JJ 12au7s with Mullard 12au7s and they made an improvement in relaxing the sound, provided more focus and imaging. However, the change that got me closest to where I wanted to be (and is where I am now) was putting in Brimar 12au7s 13D5s and replacing the stock 12ax7s (first with groove tube, then with Brimar). The biggest difference came with the Brimar 12au7s. Amazing tubes! They tame the sound, giving me a much better perspective of where I was sitting in the audience. They image the instruments beautifully, locking in the instrument placement, giving a realistic focus to instruments. They layer the instrumental sounds, providing a depth to the music without losing any detail. Harmonics are gorgeous, timbral quality seems accurate, with a much better sense of material texture of the instrument (the wood of stringed instruments, the play of metal strings and wood of the piano, etc.). Sustains linger clearly, floating away into silence. The Groove Tubes and Brimar 12ax7s relaxed the sound even more (however, what I'm calling "relaxed" does not mean that the attack of instruments is diminished or muted) - putting me a little more distance from the performance. I generally prefer the Brimar to the GT, mostly harmonics and tonality but also a little more restraint. I have also swapped the Brimar ax with Brimar au and it reduces the gain to make an even less strident sound. I'm not settled on which I prefer.
I also briefly replaced the Svetlana EL34s with the GT KT77s. I haven't given them enough time but after 4 hours the sound was still too pinched. There isn't the transparent layering, separation and depth of sound. The tonal signature seems similar to the EL34s. I've gone back to the Svetlanas but will try the GTs again and give them more time to break in.
I appreciate all the help and information people have given.
Thanks,
Bob
As for changes in the TAD, once I added the MiniMax my preference quickly shifted to triode mode. I replaced the stock JJ 12au7s with Mullard 12au7s and they made an improvement in relaxing the sound, provided more focus and imaging. However, the change that got me closest to where I wanted to be (and is where I am now) was putting in Brimar 12au7s 13D5s and replacing the stock 12ax7s (first with groove tube, then with Brimar). The biggest difference came with the Brimar 12au7s. Amazing tubes! They tame the sound, giving me a much better perspective of where I was sitting in the audience. They image the instruments beautifully, locking in the instrument placement, giving a realistic focus to instruments. They layer the instrumental sounds, providing a depth to the music without losing any detail. Harmonics are gorgeous, timbral quality seems accurate, with a much better sense of material texture of the instrument (the wood of stringed instruments, the play of metal strings and wood of the piano, etc.). Sustains linger clearly, floating away into silence. The Groove Tubes and Brimar 12ax7s relaxed the sound even more (however, what I'm calling "relaxed" does not mean that the attack of instruments is diminished or muted) - putting me a little more distance from the performance. I generally prefer the Brimar to the GT, mostly harmonics and tonality but also a little more restraint. I have also swapped the Brimar ax with Brimar au and it reduces the gain to make an even less strident sound. I'm not settled on which I prefer.
I also briefly replaced the Svetlana EL34s with the GT KT77s. I haven't given them enough time but after 4 hours the sound was still too pinched. There isn't the transparent layering, separation and depth of sound. The tonal signature seems similar to the EL34s. I've gone back to the Svetlanas but will try the GTs again and give them more time to break in.
I appreciate all the help and information people have given.
Thanks,
Bob