I'm not the genius behind the rebuild on these (Thespeakerdude8
, who started the thread over a year ago is) only the end user that gets to take them home and enjoy 'em.
Sadly I haven't gotten alot of time to play them but I can say these are some of the best sounding amps I've heard. The detailing in the mids & highs is absurd, right down to the decay of a piano note or pluck of a guitar string. I was surprised by the bass that these can produce, not something I'd expect from tubes. My preamp doesn't have tone controls nor needs them. In fact, my speakers (some home built towers) sound much brighter and almost too bright to the point I may go in and changed out resistors on the tweeters to pull them down some.
I have an old set of early '80's Klipsch Heresy's I've recapped I hooked up to my Denon solid state system and almost pulled immediately as I couldn't stand how they sounded (that's another thread)... no bass, mids & highs sounded ok but not stellar, almost muted. On the tubes its a different story. Highs & mids are very detailed almost too much (not sure if I'm hitting the limits of the drivers, they're showing the limits of the recordings probably a little of both). In fact on the tubes, the Heresys even hint that they do have a set of balls and hint at some deep bass. They have detailed & solid bass, much more so than the solid state stuff but still have the usualy Heresy complaint of lack of low end. It was enough to impress me and decide to keep the Heresys around.
My only complaint (and that's not saying much as its not really a complaint) on these other than the fact they're space heaters is the input sensitivity. These replace an older set of '20 watters' that utilize the older input Thespeakerdude8 references. I had to find a preamp with a hot enough output that you could almost run an arc welder off of (30v @ 10db gain). I think I fried the input of an EQ I was using. I had hoped with the newer preamp circuit & doubling the output tubes I'd have more useable power. There is more power and a bit more output but I still need to use the high gain output on my preamp (one is the 30v, the other is a 10v 0db gain I believe.) The nice part about these is unlike the less power amps these replace, these have a good power reserve and don't run out of power like the other ones did occasionally. I had them driving some fairly inefficient speakers and they'd top out on some loud crescendos in some music passages, but not very often.
Overall I'm happy with them. Bobby had A-B'd these with some other tube amps he had and while some of the lower powered ones played as loud as these, they didn't have near the rich sound or detailing the Baldwins do.