Picked up a pair of NOS Tung-Sol 5881 (6L6WGB) tubes for $25.00 at an antique radio swap meet this weekend. They have light brown bases and look to be 1950s vintage. The seller said they tested new, and they looked perfect, so I went for it. I've seen these online for $210.00/pair, and I know they are very popular with the guitar guys, but I figured I'd give them a whirl as regulators for my Chenin.
Verdict: They are an improvement over the stock Sovtek "5881" regulator tubes, providing a fuller midrange and slightly tighter bass, with no noticable ill effects. They are definitely a good match with the 7193 linestage tubes. I don't think I would pay $210 for them, but for $25 they are a nice upgrade. I was thinking of selling them at a profit when I picked them up, but I think they are staying put in my Chenin. My rectifier is a NOS GE 5AR4 (the one with the copper sides).
Verdict: They are an improvement over the stock Sovtek "5881" regulator tubes, providing a fuller midrange and slightly tighter bass, with no noticable ill effects. They are definitely a good match with the 7193 linestage tubes. I don't think I would pay $210 for them, but for $25 they are a nice upgrade. I was thinking of selling them at a profit when I picked them up, but I think they are staying put in my Chenin. My rectifier is a NOS GE 5AR4 (the one with the copper sides).