We just got our first batch of the new Tungsol 7581A tubes. Unlike their standard 7581 vacuum tubes, the “A” version is rated for more power. It takes the typically 6L6GC/7581 30W rating and raises it 5W to 35W plate dissipation! This is the same rating as the vintage USA made 7581A tubes. This tube has a very large plate with four additional fins to help dissipate the extra wattage. As we expect, overall constructions is top notch. All this technical stuff aside, they sound great too. Consider these for any 6L6 based amp if you need a lot of headroom. Check out our review:
“7581A gets an A+. The 7581A was a tube that stood head and shoulders above a standard 6L6GC. There have been a few attempts to recreate this tube but it was never really accomplished. The 7581 that Tung-Sol has been selling is really a high grade 6L6GC and the tube store advertises it as such. That may be changing very soon. Today I got a sample of a new 7581A from Tung-Sol and it looks to be the real deal. If not, it’s the closest thing I’ve seen, with its roots in another personal favourite the 7591A that has been shipping from Russia for many years.
The 7581A does not use the familiar plate stamping that you see in the Tungsol 6L6GC, 7581 and Kt66. This bottle has a plate very similar to the 7591 but is enhanced with large cooling fins, a larger 6L6 size bottle and thick mica’s top and bottom. The bottle is just big enough to hold the plate structure, so you get a lot of power from a pretty compact tube. I think this tube could replace the KT66 that is so hard to fit into a reissue Marshall Blues breaker and probably the 7027 used in Ampeg amplifiers.
Balanced, is the first word that comes to mind when I think about the sound. Other descriptive words would include detailed, rich and responsive. In my single ended amp I was running it class A with about 44 ma of current and it was just great. The bass response, midrange and treble were very balanced and the EQ could essentially be left flat. Very rich sounding with enough shimmer and harmonics to put a smile on my face. Construction quality is high, with nice bottles, a single halo getter, 8 support points for the plate structure and nicely finished pins. The next re-tube of my beloved vintage Harmon Kardon integrated stereo amp will feature these tubes. Based on this small sample I have to say that this will be a best seller.”