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Hi,
I've got a couple of questions concerning 6C33C used in Joule OTL applications.
1) Are they reliable? People tell me the 6C33C is notoriously unreliable, but Joule, BAT, and Lamm owners say they have no problems with this tube. Circuit-related issues, perhaps?
2) Are there any particular makes/models that are sonically superior?
Follow Ups:
There's a coupe of problems with transporting such tubes, the often broke being bulk-packed.Just need to make good individual package.
Or better bulk-package.See original package on the photo.
--
Best regards,
Anton Zverev
http://www.gstube.com
What JLH says is true, according to most users. However, I have not cleaned my tube pins or sockets in 5 years and have had no problems. I think the need for maintenance is related to the provenance of the sockets. The older sockets were apparently made differently and don't tend to corrode with age, or have less of such a tendency anyway.
As for the tubes themselves, I have heard scuttlebutt (defined as unreliable gossip) to the effect that tubes made prior to 1992 or thereabouts are more reliable than later production. Victor Khomenko of BAT knows a great deal about the various sources for 6C33Cs in Russia, and you might consult him for advice on how and where to purchase the best that are available. My amplifiers use twelve 6C33Cs (six per monoblock), and I have had no failures after 5 years on the original set of 12.
The biggest, or only problem I have seen is due to the high heater current consumption of the 6C33. What happens over a period of ~6 months or so, is the socket contacts start to discolor and create a high resistance contact point. However, if you clean your sockets and tube pins every 6 months or so, you will not have problems. Even the fancy Teflon tube sockets have this issue. Its not the socket material, its the metal contacts that cause the problem. There is just a lot of heat generated by the heaters on the 6C33. Although, I think it is worth putting up with. I have never seen another tube with the specs the 6C33 brings to the table.
Would the SST enhancer prevent a discolor / resistance issue from occuring?.
6C33C-B's give off a lot of heat, which could cause a so-called contact enhancer to form a varnish and become an insulator, which in turn would make things worse and cause tube failure.
Your point about contact enhancers is certainly relevant, but so far no one has reported this phenomenon with the Walker SST. For whatever it's worth, Lloyd Walker states that one of the best uses of this product is on tube pins in power amplifiers. And some tweaker on another website reported that he heated SST with a torch and it did not either liquefy or turn into a varnish. OTOH, I confess that I have so far refrained from using SST on the pins of tubes in my amplifiers, although I use it elsewhere in my system (where heating is insignificant) to great advantage. Anyway, I doubt that SST would prevent corrosion/erosion of the tube sockets. The heat is still there regardless. (Remember that the problem seems to be mainly with the socket, not with the pins on the tubes, as I understand what others have reported.)
FWIW, I've applied SST to the pins of the 6AS7 output tubes on my Atma-Sphere MA-2s. It's now going on 6-weeks of pretty heavy use since application, and no problems yet. Lloyd Walker has been using SST on the output tubes on his Viva Auroras (35w, pure class A) with no apparent problems there.I plan to pull the tubes on the MA-2 in a couple of weeks and can make an visual inspection of the tube sockets then. If I see anything unusual, I'll post a follow-up.
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Unless you have some kind of unusual fiber optic probe, you won't be able to see anything with respect to the tube sockets just by removing the tubes. You would have to invert the amplifiers and remove the bottom panel to get a decent look. Since my own MA240s use the MA2 chassis' and power transformers, I know how humongously heavy and awkward they are to manipulate, so I predict you will not want to do that. However, do take a good look at the tube pins and let us know what you see. Try scraping the pins to see if there is a filmy gunk on them, i.e., varnish. Also, see whether the filament pins look any different from the other pins, i.e., corroded or otherwise deteriorated.
Lew, just reporting the results as I promised... I finished pulling all of the output tubes and examining the pins and the sockets for any sign of problem with the Walker SST application. After 7 weeks of very active use, I could see no corrosion, no film, no unusual residue, on either the pins or in the sockets. The SST was dry on the pins, and still removed easily with a bit of isopropyl alcholol on a Q-tip.
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I am reading so much here about problems with the filament connections of 6C33Cs that I am beginning to think I must have a problem with mine that I don't want to know about. In 6 years I have never removed any of the twelve 6C33Cs (in my Atma MA240 monoblocks) from its socket. The amps sound wonderful and there is no indication of any malfunction (which I could detect if present, since my amps were built to allow me to bias each power tube separately). Thus I am predisposed to leave well enough alone. If I pull the tubes to put SST on them and then they later fail, I will never know who or what to blame. Meantime, the SST on all the OTHER connections in my system (including preamp tube pins) continues to work wonders.
Glad to hear of your positive experience with SST in your system, Lew. Matches my experience, too.
Thanks for the suggestions, Lew. Actually, I will be removing the bottom panel from one of the amps, so I'll make a point of looking from below.
Gents,When I purchased my VZN 100 I called Jud to inquire about SST on the tubes in the amps. He suggested once I "settled in" with my new babies that I only treat the input tubes and not the output tubes. He had no expereince with the SST on his Outputs at that time. (July 04)
Treating the outputs was on my list of CES discussions with Jud but it looks like the 12-15" of snow on the way it may effect my travel plans to LAS for more than a few days!
If someone sees Jud at CES, would they please inquire about this issue and leave his reply here.
Thanks,
It has been suggested to me to try Wright Silver Polish on the tube pins, but I never have. I did try CAIG ProGold once but it was a big mistake. Too much heat cause the CPG to polymerize and created a coating that I had to scrape off with a knife. Do that one time to each tube pin on a dozen tubes, and it will cure you of putting anything on them.I have bought extra tubes from Jud but have used only one replacement tube (knock on wood) after five years of almost daily use. I love these amps. (VZN 100.) skip
skip clemmons
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