Not tried the 5881 in a Leben. However the plate voltage in EL34 and 6L6 modes are 414Vdc and 450Vdc respectively. This is more than the spec sheet max of 400Vdc for original Tung Sol tubes. Other manufacturer’s 5881 which claim higher plate voltage may not be 5881 but rebranded 6L6GB etc. I have tried NOS TS 5881 in my 6L6GC vintage monos and I couldn't bias them down from slight red plating so I didn't push it and took them out.
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The 6L6GC is a 30W valve. The 5881 is a 23W valve. So that’s quite a big difference. <<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>> Your unit is designed for (2) 6L6GC (32 WPC) or (2) EL34s (28 WPC) 4 valves total 2 per channel. The 5881 will work because of the 32 watt output per channel TOTAL. 5881 is a very rugged valve but lower wattage 23 watts per valve or 46 watts total vs 60 watts total. I see plenty of overhead in either valves. The bias is respectively low via the information I read, BUT I didn’t look at the bias or how it was set up. If it has a bottom to top bias pot, you could bias up KT66 too. I’m pretty sure you’ll be ok.. BUT once again it is designed with 6L6GCs or EL34s. Plenty of great valves in either. KT77s/EL34 or 6L6GC/KT66s 6L6W is military, literally for a Russian Mig It’s VERY tough and the G rating is HIGH (G force). 30-32 watts per valves. Very thick black plate valves. Sonically, they are NOT my favorite, BUT the longer you play them the better they sound.. It’s one of THOSE valves.. :-) Hope this helps. Regards |
Here is a handy chart for Leben CS600/CS600X valve switch settings for various power tubes posted by Jeff Day. The 5881 is exceptional in the Leben. In fact, Leben ships with the 5881 if you ask for them. Good luck. https://jeffsplace.positive-feedback.com/tube-rolling-in-the-new-leben-cs-600x-integrated-amplifier-... |