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In Reply to: RE: Music Reference RM9mkII Driver Tubes posted by Berrell88 on August 21, 2020 at 14:09:41
Put the old tubes back in and try again. Despite the mystique of NOS tubes, your chances of getting crap are pretty high. Even if they were tested on a tube tester, once in circuit, with the higher voltages and currents a lot of tubes don't run properly.
If it runs with the old tubes, you've bought some clunkers. Also make sure they are the right tubes.
Re the NOS or more correctly old stock in most application, I share your skepticism.A matched pair of Sylvania chrome top 6sn7's acquired from Tube guru Brent Jessee in 10/2016 and not overused in my Cary preamp, are now unpleasantly noisy with gobs of tube rush. And this is going through a Class D stereo amp which is nearly dead quiet.
Thanks for getting back. Wasn't clear in my note. I did reinstall the original driver tubes from Ram Labs and flipped them to see if that would make a difference. Nada. You get tired of fooling with the trim pots after a while. Something happened to upset the amp by inserting those NOS tubes--but what?
If comfortable doing so, just use a soldering iron to reflow the existing socket pins where they contact the pcb board. Just smear a titch of flux using a toothpick on each contact should give you good results. Don't add more solder unless you really need to. Remove flux with flux remover if you have any on hand. Not too critical if you use it sparingly.
Doing a solder reflow should fix any broken connections.
Soldering done with amp off if course.
Clean and tighten the tube socket insert contacts too if you can.
Barring all the work above, you could always try wiggling the tubes in their sockets to see if the sound sputters back. But if it does, you'll end up doing the repair anyways. And sometimes wiggling isn't the best thing unless you've felt with situations like this before.
"I know just enough to get into trouble. But not enough to get out of it."
As mentioned above, those boards are a bit flimsy. Probably a broken board trace or two.
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