So, I want to get some NOS tubes for my 63 bandmaster....There's crappy Sovtek GT's in there now. I was told on another forum that I should not use 5881's in it, as the plate voltages are too high...instead go with 6l6GC (guy who owned the same amp)...ANy truth to this....If I get it biased it wont matter anyway right?....There's a set of Tung Sol's in the Emporium that I'd like to pick up...But not if I'd be better off to pick up 6l6's... One more question...Will there be any tonal differences between 6l6's and 5881? and if so...what would they be?
The schematic for your amp shows 448v B+ on the plates of the power tubes. It's probably a little bit higher with today's wall voltages. That's a little high, IMO for true 5881s. If my memory serves me right - real 5881 are only rated at 400v. They'd probably work fine but, you might have shortened tube life. I'd go with a pair of JAN Philips 6L6WGBs. Extremely reasonably priced and they'll handle the 450v. My 2 cents.
I just looked into the Jan Phililps and it said these were great for amps where less headroom was wanted...my question is would it lower the headroom than the GT i have in there now...they were rated at 7....I pretty much love where the amp breaks up at this point....I think i would deal with more headroom better than less ...as it already growls at 6 (where i usually play in a full band setting)
The rating number on Groove Tubes is pretty much marketing crap. The only time that comes into effect is if the amp was properly biased with say a GT 4, the plate current difference in a GT 6 will make the amp distort slightly less. If you bias the amp properly, a rated 1 tube sounds like a rated 10 tube. Biasing does not change the B+ voltage, so regardless of your bias, you can overvolt the tubes. Here's the spec sheet on a 5881. Blue Strat will know better than me about the real world applications, but I don't think I'd jack them with nearly 500vdc of B+ and expect 'em to live long. http://tdsl.duncanamps.com/show.php?des=5881 FWIW though, my buddy has a pair of old Tung Sol 5881's in his Vibrolux and he hasn't popped 'em yet. He said they sound amazing.
I love those old Tung-Sols, but the jan Phillips are great tubes too, and aren't that expensive, so they'd be worth a try. As to the volume when they break up, new tubes are going to increase the volume and thump significantly so that won't be a problem. You really need to experiment with preamp tubes, too, which can often change how the amp sounds more than the power tubes (as does speaker choice).
I have all old stock RCA in the pre-amp besides one...which is an old GE....Im really happy with the overall tonal spectrum honestly and Im running it through a 65 Bassman 2 X 12 with jensen Vibranto's...but I feel like some NOS are in order over the GT
