Grrrr! My NEW wa-5 is now broken! One day, the right rectifier tube, the stock Shuguang 247b, sparked upon startup, but thereafter worked fine, but developed a slight rattle during operation. I think I may have not waited long enough after shut down before rebooting in the speaker selection, from the headphone selection. I pulled both tubes. The offending tube has a rattle when I shake it. I have a pair of compatible 5ar4's, so I popped 'em in. After the soft start, the right 5ar4 sparked and the amp blew a fuse . Well, good thing I did not pack up my ASL mg-head OTL yet. Any of ya'll have this problem? Sent an Email to Woo, I'll let all of you know what he said.
Your best bet is to get a pair of 596 tubes but these are starting to get hard to find.
Next best thing would to get a pair or 5U4GB these are stronger then a 5u4G
I know nobody likes the 5U4GB it is not as pretty but a much better tube the 596 and 5U4GB
are electrically close. If anybody says the 5U4GB don't sound good I say BS.
One thing when you buy new rectifiers they have to be the same brand and vintage
or the filaments won't worm up evenly and one tube will blow up