Tung-Sol 7581A......Wow!!


So, after seeing a few posts about the 7581a I figured I had to try them in my Bob Latino ST-70. Besides, I needed new tubes and I like something different. That's the fun of tubes....well, at least partially.  I installed them and it took some time to run them in. They still may not be run in. I probably only have about 15 hrs on them. The first day was spent hoping they would get better. They did. They are getting there slowly. I'm coming from GL KT-66. These are different. Very promising but the emphasis is completely different than the KT66. I heard some details which I hadn't heard before, yet it was in the lower mids /upper low frequencies. Kind of surprising since the KT66 has great bass. But the 7581 has cleaner bass. I could tell from the beginning that dynamics are a strong suit of the 7581. And the more I play, the more the dynamics expand...and expand. The dynamic range now is stunning....maybe even too much at times. My system is very resolving. I listen mostly to classic rock where the  dynamics
are really emphasized especially by lead guitar.  But the great volume swing makes the  guitar often sound very bright.  I've played in rock bands most of my life (Drummer/vocalist) so I know what live music sounds  like. There is an over emphasis on the dynamics with these 7581a's. I have not heard anything with a wider dynamic range than I experienced last night as I played Molly Hatchet LP. The lead guitarist sounded as if he was playing a hot guitar with a hot amp and an overdrive pedal. I  am amazed at the dynamic range...even though it is over extended IMO. Its kinda like a freak of nature. OTOH, I really like these tubes. Detail and tone are very good but more subtle than the 66's. My wife loves them, though she agrees that they get close to being too bright I can see where these tubes are great for less aggressive music. Not sure about classic rock. Then too, most of it sounds pretty doggone  good........well, until the dynamics grab you and hurl you against the wall (-:. I'm hoping that the dynamics will ease off some. maybe I'll try some classical music and see what the dynamics do. I have the 1812 Overture on Telarc. But that might knock the walls down. Oh well, I just had to tell someone about it. FWIW, I've read nothing by anyone else in pointing out an extended dynamic range. And because everything is so system dependent, I suspect it will ease off with mine.
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@artemus_5 

Yeah, the blue is really nice...very photogenic!

What I call "monoblocks" is essentially one channel of two separate Dyna/VTA 70s with SS rectifiers.  I think they'd be most similar to the Mk IV.

 

@knotscott 

Nice. I have one of the Latino VTA Dyna 70's. great little amp. I liked it so much that I bought Don Sachs Kootenay 120. Do took the design of the ST120 and customized it with the best of parts, auto bias, dual mono Power supplies, It sound great. I often wanted to try the Mk IV's. I'm surprised that VTA didn't offer that amp as a kit or assembled.

I like the VTA mods a lot.  They do have the Mk 3 and M125s in kit.  Not sure how different the Mk IV is.