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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Showing 7 responses by artemus_5

@tuberist

I read 2 threads about these tubes and most everyone  said something similar to what you have said. And I am overall satisfied because I think it is the dynamics which are causing  what appears as brightness. And its just that one part in the song,  not the whole song. Actually, I'm surprised at how much change these tubes have gone through. I've never had any tubes which changed sound as much as these, But  I also see all the good qualities you spoke of about the tubes as well. 
@wolf_garcia 

I had been switching back & forth from Gold Lion KT-66 to the Russian 6p3se/6n3ce. The 6p3se sounded similar to the KT-66. Great bargain IMO. Yeah, gotta love that blue glow.
@wolf_garcia 


No blue glow but very musical. And cheap...if you can find them. eBay is the only place I've found them now. I bought my last set from Cryoset which is not in business anymore
One week of break in. I've played 2-3 hrs every night. Some nights 4 or more. I'd guess I have at least 15 hrs on these tubes....probably 20. I still question these tubes. Everything is good except vocal placement is recessed but not all the time. Its like these tubes are hit & miss. Maybe I still don't have them burned in. I don't know. I'm not a tube guru with 50 yrs experience but I've never experienced the changes I've seen with these tubes. I think I'll put a CD on continuous play and let the amp play all day. I can see the promise of very good sound from these tubes though. So maybe I'll get a treat.
OK, so I let the amp run several hours yesterday before listening last night. Bottom line, no strange noises last night. Everything come together nicely. I do believe these tubes are burnt in now. Sounds good.
OK, I'm here to cap off this mini review of the Tung-Sol 7581A. Though a roller coaster ride prior to being run in, these are  well balanced tubes. If there is a frequency range which dominates the other, it may be the midrange though both high & low frequencies are well represented. They are smooth top to bottom. However,my system is very revealing . My speakers are well known for their midrange clarity. And so, I wonder if this hot midrange is as a product of tubes & speakers which display midrange better than most? Also I am a drummer who cherishes bass and eschews midrange. So I may be more midrange sensitive than others. Whatever the case, everything has settled in now and I find no offense. I would recommend these tubes with one caveat...Patience will be rewarded with a good balance of music
I think I learned of my midrange "disdain"(?) in the 70’s when Graphic equalizers were the "in" thing. I always made a nice smiley with the 5 band. I couldn’t imagine the mid above the 0 (neutral).   I really like a good bass line and then too, playing so tight and closely with the bass may have something to do with my lack of mids. I hear midrange fine. and play off it too. 

I also remember having to change it when I had the band practice house. We’d play a recording of the song we wanted to do and the guitarist would most often point out the midrange lack. Sounded fine to me. 

I have heard very good things about the GL KT77. I had the 66’s and was very happy with them. I might have to give the 77’s a try. It is nice to have an amp where so many different tubes can be used