hi. my jcm 900 dual reverb requires new power valves. at the moment they have stock marshall 5881s but i was wondering if anybody had good suggestions for an upgrade? type of music i play is mostly classic british rock, nothing too heavy. ive heard of tubes like tung-sol and groove tubes but never tried them myself.
thanks. i dont know much about the biasing side. when changing to a different kind of valve should it always get biased?
I've heard groove tubes are just rejected jjs rebadged with a gt sticker and $10 added to the cost. Jjs aren't the best but theyre the best deal
If you can afford them, SED Winged C are the best out there. JJs aren't far behind and cost a lot less.

Relabeling outfits such as Groove Tubes and Ruby usually test and double-check the tubes they relabel. It's not that those tubes are rejects. In fact they go through additional testing beyond the factory.

Yes, with a JCM you will need to at least check the bias. It's pretty easy to do yourself as long as you're ok with having your hand near some pretty high voltage inside the amp, and if you don't get in a hurry (as I found out myself). Check out 311SOZOVHJH's blog on biasing.
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