# Answer me this: 5881/6L6WGB vs 6L6GC...



## StevieMac (Mar 4, 2006)

Seems every bias calculator/chart I've encountered on the web (except for Weber's) lumps 5881s & 6L6GCs together. Now, aren't 6L6GCs rated @ 30 watts max dissipation and 5881/6L6WGBs @ 23-26 watts? Shouldn't those 4-7 watts matter when setting your bias? Depending on your plate voltage for instance, that difference could be 10 mA or more correct? Finally, are the ratings for 5881s and 6L6WGBs in fact identical i.e. are they the same tube. Just curious...


----------



## Wild Bill (May 3, 2006)

Yeah, you're quite right!

However, nowadays a lot of tube manufacturers aren't as true to the data book specs for 5881s. Basically, they just put a regular 6L6GC inside the glass.

The only way to tell if you have a true 25watt Pd 5881 is to check the manufacturer's site. 

thetubestore.com is really good at labelling which brands are 25watt or 30watt.


----------



## DavidP (Mar 7, 2006)

*Well, if you're talking about NOS JAN stuff...*

like the Phillips JAN 6L6WGB, then good luck. I did some major searching a year ago and never found an actual manufacturer's data sheet but a LOT of different interpretations, ranging from 'true 6L6 guts in a small bottle' to statements like 'never put them in an amp like a super reverb calling for robust 6l6s', so go figure... I have a few of these, my Canadian GEs look identical to TungSol 5881s, while the Philips look like small bottle 6L6s -- what I do is bias them for 70% of an assumed maximum dissipitation target of 25 watts on my part--they sound pretty good there and nothing has blown up (yet).


----------



## StevieMac (Mar 4, 2006)

Thanks guys. I think for future then, I'll assume 25 watts and set my 50-70% based on that. It's not much of an issue for me as I'm rarely biased as hot as 70%. Still, for others, that 5 watt difference could matter...


----------



## nonreverb (Sep 19, 2006)

Don't be too worried...the original 5881's were a robust tube. I once found one in a Leslie 122 paired up with the stock 6550 and, judging by the look of it, had been there for years! It was still working when I finally replaced it. An excellent and desirable tube which will work in pretty much any 6L6 amp. IMO


----------

