dread pierat wrote:bajaman wrote:I will NOT use ANY Russian tubes for any of my amplifiers or customer's repairs
Did you try SED Winged C tubes from St. Petersburg, or is this opinion based on the Reflector Corp. products made in Saratov?
All the St. Petersburg tubes I've tried have been excellent, and I've also had good experience with certain Reflector Corp. products. These include Sovtek branded 12AX7WB, 6V6 and EL84M, and Tung-Sol 5881 and 12AX7.
I got a pair of SED 6L6's about a year and a half ago, and they are as excellent (so far) as when they were simply referred to as the Svetlana types about a decade+ ago.
At some point about 5 years ago, I started experiencing issues with Sovtek pre tubes that I previously never had issue with - the 12AX7LPS and its 70% gain counterpart, the 5751. My last two 5751's in particular developed hum and other issues shortly after using them. I haven't purchased any EHX 12AX7's in quite a few years, and don't typically prefer them anyway. I've gone thru two of their 12AY7's, with both starting to hum within months of usage. OTOH, I have a Sovtek or EHX 12AT7 that seems to be fine (knock on wood).
...These Sovtek/EHX pre tubes that are failing all tend to get that silvery look to over the top 1/3 of the glass. I forget what this is indicative of, or if it is an issue, but it is something I have visually noticed. While I've had other UOS/NOS/JAN/older stuff also develop hum or performance issues when used in the same amp(s) as the failing Sovtek/EHX stuff, I don't recall seeing this "silvering" going on with them.
I can say that the Chinese WA's and WB's that people tend to pull from their newer amps from the get-go have actually been okay in some of my amps. I also have a TAD EL84 in a little SE amp that has worked without issue for probably two years now.
I have no Chinese power tubes in my possession to comment on (other than the TAD EL84 and a 6V6 that's sitting in a box), but was going to try some Shuguang stuff, but was primarily only interested in their KT66, and only two of my amps will support the filament draw for those.
I *will not* deviate from using the JJ 6V6S in my Deluxe Reverb, despite it being more like a mini-6L6. They are simply bomb proof in all the time I've used them. I had a Sovtek recto in the DR that failed miserably, so I built a 4X1N4007 SS recto in an old octal base and popped that in, and rebiased the JJ's appropriately. Nice tight bass, no blow fuses, and the ability to up the mains filter caps should I want (the Deluxe Reverb is plugged into a 2X12 cab quite frequently).
...Which brings me to the Tung Sol 5881's. I had to try a pair after all of these guys just raved about them. I dropped in a pair and biased to maybe 65%, and had one redplate on me within maybe 12 hours of usage. Before pulling the amp apart to double check the bias circuitry (which I had overhauled/bolstered some time ago), I powered the amp down, swapped the pair of 5881's in their locations, powered up, and the redplating has been absent ever since. Needless to say, it has me a bit worried, and I find myself checking the rear of the amp probably more than just playing thru it. The amp in question has a max B+ of about 390VDC...
The funny thing is I have a scratchbuilt amp that I've put a bunch of different 6L6 and 6V6 types in, and I settled on a pair of those non-5881's that are the old Sovtek 5881WXT military surplus aberrations. That amp has cathode bias and a B+ of 360VDC. Most users seem to reject that tube outright, but this pair was free from a friend. They actually sound better than any other pair of tubes I've put in the amp, with a pair of Mesa-rebranded 6L6's at a close second. Since I picked up the Mesa's used and those tubes are "graded," I have no idea on the specifics.
I don't mind a shorter lifespan and "less grail sound" from the new production stuff, but it would be good to at least get a nominal period of decent usage without excessive noise problems, or worse yet - something that could lead to catastrophic failure. While I don't mind replacing a cheap (but decent sounding) Hammond Deluxe Reverb replacement transformer, I don't want the oldies in my non-scratchbuilt amps failing under any circumstances.
