Power Difference, 5881/6L6/EL34???

[NOVA70]

What is the power differences between the following tubes:
5881 / 6L6's / EL34's and how can you measure output wattage?
Thanks,
Nova70

[Old Tele man]

which POWER rating are you referring to: (A) the tube's plate dissipation wattage; or, (B) the signal power output capability?

The plate dissipation wattages (Ppd) are:

19W = 6L6(metal), 6L6G, 6L6GA, 6L6GB
23W = 5881, 6L6WGB
25W = EL34
30W = 6L6GC
35W = 7581A

note also that the maximum plate voltage (Vp) ratings are different with these tubes, which limits "backward" compatibility between them...ie: regular 6L6(metal case) is 360Vdc, but 6L6GC is 500Vdc.

So, an amp with 450-500V plate voltage cannot use a regular 6L6(metal), 6L6G, 6L6GA or 6L6GB without possible risk of burning up the tube(s), unless output power expectations are reduced...and properly rebiased, of course!

[NOVA70]

I'm trying to determine the best tubes for output since the amp is a low volume amp. It's a 59 bassman clone. I would like to get more headroom. I presently have 5881's in it. I am also curious as to the output wattage since the manufactor says it about 40 watts but it does not sound like 40 watts to me. I want to make sure that there's noting wrong with the amp.
Thanks for your interest.
nova70

[hoochiecoochie]

Try a set of 6L6GC. Try a matched set of TAD (Tube Amp Doctor) 6L6GC STR. MOJO has them at a good price. Lots of head room with those tubes. If the amp has the capability of switching the tube rectifier, try a SS in that position. Rebias it also.