Does it matter if you touch the tubes with bare fingers? Will the oils etc. from our hands overheat on the glass? I always use either a white glove or tissue to grasp the tube to avoid any contaminants.
I use RFT EL34 power tubes in a AudioNote Kit Amp that I have and find them to be excellent tubes. RFT make some nice vintage tubes that are still very affordable as NOS. I buy them from eBay sellers in Germany also.
Most people from the beginning of time have handled tubes with their bare hands. I think this is more an "audiophile" thing than anything else. Small signal tubes are made from very thick glass, compared to the larger power tubes, which have much thinner glass. You are not going to have any effect on the smaller tubes, short of smashing them into the floor, by handling them with your bare hands. Larger power tubes I handle with a small dishcloth or washcloth more to protect my hand from and possible glass breakage than anything else. I think this is particularly important when removing tubes that have been used in the amp for a while and the glass envelope has been subjected to a lot of heat related stress being turned and off over a period of time. Also, sometimes the tubes may be hot, when I have powered down an amp and I am removing them shortly thereafter.
Doesn't matter. If you have some 'valuable' tubes, I might suggest gripping the tube by avoiding the labels so as to keep the, maybe fragile, lettering from coming off. I like to give the tube ample time to cool down before removing. They get very, very hot inside. Using a glove or towel so you can get them out in a hurry is not what I would do. The outside of the tube will cool faster than the insides so give it some time.
Thanks for the helpful replies, SandAndGlass and onemug. I just have two sarcastic responses. "From the beginning of time..."? Does that include Neanderthals? Oh, I'm very adept at dropping and smashing things!
What about 6SN7 tubes? Do you take them from the glass bottle or the plastic (is it really plastic?) base? For those interested, here are some inexpensive RFT ECC82/12AU7 : ECC82 PHILIPS VALVE/TUBE NOS | eBay I sometimes use these (it depends on the mood) as V3 which is a tube buffer on a cathode follower configuration to keep impedance low and reduce distorsion. These are nice and inexpensive tubes, and its small plates makes them almost inmune to microphonics.
You do not have to worry about touching the glass, even with the tubes that get quite hot. But, as a matter of good practice, you would not have much reason to be handling the glass. You should never remove the tube from the socket by pulling on the glass envelope, which can become separated from the base, you always pull and rock the tube from the base. The notion that you should not touch the glass comes from the high intensity bulbs used in some projectors (e.g., metal halide bulbs) and the high intensity bulbs used for headlights. The reason that causes bulb failure in these applications is interesting. If you deposit oils from your hands on the bulb, the high temperature of the bulb envelop results in that oil becoming carbonized. That leaves a black spot on the glass envelop. That black spot will absorb light energy at a much higher rate than the surrounding glass and that uneven heating causes stress in the glass leading to the bulb exploding. There are no tubes used in audio that get that hot, nor do they emit enough light for this failure mode to ever occur.
Are you talking about 6SN7 tubes? I've always removed these from the socket by pulling from the glass. Do 6SN7 tubes last as long, as an average, as small signal tubes like 12AX7 or 12AU7?
Any tube that has a base is best pulled by grasping the base. The top and base are glued together. Particularly with older tubes, and tubes that get hot, the glue will eventually dry out and lose strength. I have not seen the glue in 6sn7's fail, but, I have seen it with other tubes, such as 300b's. It doesn't hurt to be more careful, particularly with older tubes. As for the life of 6sn7's, as with all tube types, a lot depends on the design of the gear and hard hard the tube is pushed. In the amp that I own that uses 6sn7's (Audio Note Kageki), they can run for quite a long time before they have to be replaced; the tube can test pretty bad and they will still work well in this amp. But, I've also seen gear that push small tubes hard enough that they don't last more than a year or two when used a few hours each day. The particular tube/brand also matters. There are some older types that seem particularly long lasting compared to currently manufactured tubes. The Telefunken variant of the the 12AX7, marked ECC 803S, is notable for its longevity. I run that tube in my phonostage.
Good question, but as has already been advised, tubes with a bass are best removed by grasping the base. Plus, larger tubes with a base tend to have thicker glass envelopes than the smaller signal tubes. I have a tube preamp that uses 6SN7 tubes. I bought it back in 2013 and it is only on its second pair of modern tubes. After the first year or so, I have usually left the preamp on 24/7. It has been in storage since December of last year. The appear to last a rather long time. Long enough anyway.
New member and Vincent SV 237MK owner for 1 year. Signed up after reading this thread. First off, I LOVE this integrated amp, and so do my Klipsch Cornwall lll's. I recently replaced my OEM 12AX7 with a Gold Lion and was also very pleased with the sound change. BTW, when I tried to put the original tube that came with mine back in for a quick comparison, it shattered as I was very gently re inserting it! Keep in mind that I am old enough to remember going to the local drug store with a pocket full of vacuum tubes to test them on the drug store's tester, so I actually have some experience removing and replacing them! As for the 6n1P-EV, everything I've read seems to corroborate that the Russian tubes are well suited for this amp. As for equivilant replacements, in an excellent review of the SV 237MK on i-fidelity.net, designer Frank Blöhbaum said this: "Instead of the 6N1P, we will use the American 6BQ7A in a special series of the SV-237 as a JAN (qualified for Joint Army Navy) valve, which is a heavy-duty military-grade valve with a lifetime of over 10,000 hours – at no extra charge. The JAN 6BQ7A and the 6N1P can be used on par with no modification in the SV-237. The JAN 6BQ7A are original »made in U.S.A.« valves. All valves are run far below their limit values and on a regulated operating voltage, so that a very long life of typically more than 20,000 hours may be expected – most SV 237 owners will never need to change the valves. And if they did, Sintron has a well-stocked inventory of valves for the SV-237". (Vincent SV-237: Vincent SV-237 - i-fidelity.net ) I may try those in the near future, as well as some NOS American made 12ax7's, but as it stands right now, I'm pleased with the current sound.
Follow up on my "bad". Article is on the SV 237, the previous version of the newer MK. That being said, the 6BQ7A tubes are still a viable substitution in the 237MK as the 6n1pEV are just ruggedized versions of the 6n1P.
The 6N1P Wiki page states that the 6BQ7A is the closes American equivalent to the 6N1P. From Wikipedia, the free encyclopedia Jump to navigation Jump to search Current production 6N1P-EV tube (1999) branded with the original factory logo (right) and Svetlana brand name (left) The 6N1P (Russian: 6Н1П) is a Russian-made miniature 9-pin medium gain double triode vacuum tube intended for use as a line audio amplifier and cathode driver. Basic data: Uf = 6.3 V, If = 600 mA µ = 35 Ia = 7.5 mA S = 4.35 mA/V Pa = 2.2 W The 6N1P has similar ratings to the 6DJ8 and in the past was sometimes rebranded as such, however differences between the two types (the 6N1P requires almost twice the filament current and has only one third the S value) mean they are not directly interchangeable. The S is about 4.35 ma/V, the 6DJ8/ECC88 has a S of 12.5 ma/V and a gain of 33 and a lower internal resistance. However, the 6N1P is typically more linear for a given load. It is therefore inaccurate to say that these two tubes are identical. The correct Russian equivalent to the 6DJ8/ECC88 is the 6N23P, the latter has a S of 12.5 mA/V and a gain of 33. The closest western equivalent to the 6N1P is the well known 6BQ7A. A ruggedized/extended ratings version of the tube is designated 6N1P-EV (Russian: 6Н1П-ЕВ). It has currently found a use as a driver tube in hi-fi tube amplifiers (such as Audio Research models VS55 and VS110) because of its excellent low distortion and low noise characteristics. The tube is manufactured by the "Voskhod" plant in Kaluga, Russia (see [1]) and is distributed in the West under the Sovtek and Svetlana brand names.
I stand humbly corrected. As per a post on Audio Karma by AΩmega, Sep 25, 2017; FYI. Just received this from Vincent so posting it here. This relates to the new SV-237MK You can't replace the tube by 6922 or 7308 tube. You always have to use 6N1P tube. This was a limited edition in the past. On the current SV-237MK you can't use the 6BQ7 tube. The plate is 139V Please note, our engineer has chosen the tubes very carefully. The circuit is especially designed for the tubes we use. We really recommend not to change the tubes of the SV-237MK
I posted that on Audio Karma. The limited-edition with 6BQ7 tubes were Sylvania Military Tubes, which are hard to find. I tried many brands of 6BQ7 tubes and they all sucked - majorly - in comparison to the 6n1P, just keep those and roll the 12ax7. I did put Gold Pins and Gold Grid 6n1p-ev's in but noticed no sonic difference from the stock tubes. So just recommend rolling the 12ax7. 6N1P is a good tube you don't need a NOS tube there. No one has reported any other tube to replace the 6n1p in this amp that sounds good and didn't break their amp. lol As for 12ax7's, most NOS tubes sound great and the typical characteristics can be heard. I recently picked up a Red-Tipped Telefunken 12ax7 Smooth Plate and another Tele with a Leeds & Northrop (L & N) label and both sounded amazing. My generic Tele Smooth Plate did not sound so good. The L & N and red-tipped tele's are probably the best sound I've had to date. These match well with the vincent, a node 2i, and my Focal Speakers.
Another little tweak performed on the 237MK- Herbies Audio Labs Ultrasonix tube dampers on the valves ( not the window position as the damper would not fit. Anyhoo got a very nice jump in sound quality.
I just installed and 1950's RCA Long Plate 12AX7 from Brent Jessee and the difference is phenomenal. I previously had an Electro-Harmonix new production 12AX7 in the amp.
Yep, that's what I started to notice. Whenever anyone said they were having problems with their 237-MK, there seemed a good chance that they had also taken out the 6n1p-EV and replaced it with another tube that was supposed to be an equivalent, but wasn't. Best to just leave it as it seems it's used in that position for a reason. Why risk it, especially when the amps designers say don't do it ? And like you said, if you have the desire to try different tubes, just stick with rolling the 12AX7.
Sounds wonderful, prior to this I did not like Teles in the vincent. This one sounds amazing and looks cool too! 1960's I believe.
