No budget. I'm just kicking tires and slamming doors here, or looking for the range of people's comments on this topic. I generally don't set budget parameters on post like these as I like to read the full gamut of experiences. From that I end up having to figure out how deep I'm willing to go into my pockets.
I gave a Hafler DH 110 to a buddy of mine years ago. I also gave him the matching tuner and equalizer. He never got around to using any of the stuff. Maybe I should ask for the preamp back!
6SN7's are a good choice for the Aikido. If prices weren't so insane, I would get some NOS 6SN7's for mine.
How does the Van Alstine ST 70 compare to the original unit? I first stumbled into tubes back in the 1980s and, like a lot of folks, the ST 70 was my "gateway drug" into tube electronics. Actually, my introduction was a Mcintosh 240 and matching preamp a college room mate of mine came into at a base auction on Vandenberg AFB for a stupid low price. As Mcintosh prices have always been astronomical, Dynaco units became my substitute amp and preamp because back then you could go into the Soundwell in Berkeley and get a good ST 70 for 85-bucks (or about 250-bucks today) or a MC 240 for 800 (or about 2400-bucks today). I soon thereafter learned about Van Alstine's modification of the ST 70. However, I never jumped into that end of the hifi pool and have been curious ever since.
The Ultravalve is a fantastic amp. It is a product of Mr VanAlstine's years of tweaks to the original circuit. From what I understand the plates of the driver tubes are regulated (6GH8A) along with a few other tweaks. The basic circuit is the same as the original. The amp utilized the same circuit mods as his U70 retrofit board but is built as a new amp on a slightly different chassis than the original. It has deep powerful base and beautiful highs. I can listen for hours with no fatigue. I also have an ST 70 Series 2 which is closer to the original circuit, while my series 2 is a very nice and dependable amp the Ultravalve is steps above. I get as much enjoyment from my Ultravalve as I get with my kit built (Cary) SE-1. When examining the parts used they are standard components, some dale resistors but no boutique capacitors. The build quality is excellent, it's an amp I will never sell. I just retubed it with a set of JJ EL34's after a stock EH 6CA7 began to get noisy after 5 years of use.
Yep. I used a few PAS preamps in stock and modified form and prefer the Chinese M7 clone. It’s a significant upgrade.
You can go crazy with the M-7 board kit and replace the coupling caps, other film caps, and electrolytics with fancier ones, but it does sound pretty darn good with what's suppied in the kit, or the various finished M-7 preamps.
"While possible effects can be modeled, and measured, how likely is it that conducive conditions would ever be encountered in actual use? In the PAS 2/3 test case, where the line stage was already driven, undistorted, to the point where most power amplifiers would be severely be overloaded, it took an additional subsonic "peak" input level nearly twice as great to induce distortion. Furthermore, the conditions required to induce distortion occurred with the volume control set to maximum, something that would rarely occur with any regularity in the real world. At more realistic volume settings, subsonic input levels would be attenuated significantly, further reducing the likelihood of overload induced distortion. In reality, the subsonic anomaly is likely more of a curiosity rather than a concern."
So did Holger sell the PAS part of his business?
