How Long Do 12ax7 Tubes Last

Short plate 12ax7 tubes were first produced in the early 1960's by the likes of RCA, GE and so on, and then picked up by the European producers such as Philips, Mullard and Amperex. They sounded good in a sovtek mig 60, but every other amp they have sounded like I put a blanket over the cab and been overly grainy and dull. The 12AX7 inverter tube has a measured plate voltage of 416 VDC just like the schematic indicates. Only swapping one of them will decrease the gain, but best results will be if you swap both. This is especially noticeable at the high frequency range of your EQ. There is no part that resembles a Sovtek. I owned a SM-400 and experimented with different preamp tubes, including an expensive NOS Mullard. In most cases, they will sound better, perform better and outlast NEW RUSSIAN/CHINESE garbage made today. You could see the middle of the loop of each of the two heaters glowing red-orange near the top of the tube. 12AX7 has very high plate resistance. Out of stock and discontinued. How long should a CP Tung-sol 12AX7 last[?] Discussion in 'Marshall Amps' started by charveldan, Aug 6, 2011. It was usually a 12AX7/ECC83. Forums » AUDIO FORUMS » Replacement Tubes. If you listen to your system fairly frequently, I suggest spending the extra 10 dollars, as tubes will usually fail around 1000 hours if they do not exhibit immediate defects. However, because it is in a Marshall, being a key part of the overdrive, depending on how hard you use it, it should last quite a while. They generally work just. Power tubes general rule is they will last between 6 months to 1 year depend on how hard and loud you play. As a rule, Long Plates usually fetch higher prices than short plates. Fantastic sounding tubes. In most cases, they will sound better, perform better and outlast NEW RUSSIAN/CHINESE garbage made today. ----- This is a collection of Jr. A Comparison of Current Production 12AX7 Tubes. I was wiping the dust off my tubes just now and noticed that there are 2 different 12ax7's in the reverb amp one of them has just "USA 12ax7" etched into the glass and has a long plate structure, the other has "USA 12ax7A" and a shorter plate structure. I think Tele's last a long time. There is a whole range of tubes, from the high gain 12AX7 high gain, to the 12AU7 low gain. The cheap Chinese tube had the same tonal character, but it was noticeably quieter and more muffled than the better tubes. Watford Valves - Test Reviews of the bite and attack that the EH does have. You want quiet recordings? You want this tube! The Telefunken 12AX7 also has a very long life span and will outlive all cheaper 12ax7's by a. Legendary (for a good reason) Dual Post (aka Goalpost) Getter support with large O Getter. That's a well made tube for that era, which is quite close to the end of the good tubes. The valve did reproduce great clean sounds and worked very well in the Fender pro. Generally pre-amp tubes last longer than power tubes, and could quite possibly last the life of the amp. I busted one apart some 40 years ago to have a look at the "guts". My tube amp tech mentioned last night that the most significant improvement for a Princeton comes with replacing the 12AX7 in the preamp socket with an RCA 12AX7. Your Rivera Venus 3 uses 2 x 6V6 in the power stage and 2 x 12AX7. 11, and it's less compressed and more muscular at the same time. Linear Tube Audio sources the best tubes we can find for use in our production units, tested and curated to provide the best experience for our customers. I am assuming the two tubes are pre amp tubes for warmth. As long as your new tube is the same model as what you're replacing (12AX7, 12AT7, 6SN7, etc. Shuguang 12AX7 A - When the tube stockpiles dried up in the 80’s, and before modern tube production ramped up, there was little available on the market except the Shuguang 12AX7. I can't say enough about the Tung Sol tubes. The question I have, is how do they compare to real NOS 12AX7's? For a couple of hundred dollars a pair, you can have genuine RCA black plate 12AX7's. Brand names mean little, factory and codes are the determinate. It belongs to a large family of dual triode vacuum tubes which share the same pinout (EIA 9A), including in particular the very commonly used low-mu 12AU7 and high-mu 12AX7. I hope the Hitachis are as good as those NECs. These were manufactured in the 1950's and have long grey plates, and 7025 is sandblasted/etched in the glass. For more information about our 12AX7 tubes, see our tech corner article on 12AX7s. About This Electro-Harmonix 12AX7 Preamp Vacuum Tube. Preamp tubes can last and long time unless they start to become Microphonic aka feedback going on especially when they is no guitar plugged in. 00/each ; US$ 129. Loading Unsubscribe from PS Audio? Cancel Unsubscribe. It's basically me publicly taking notes on things I found to be interesting, or just wanted handy for quick reference. Don't be afraid to buy used tubes as long as they test well, premium OS 12ax7 last a long time. I have listening to it since mid June and I have to say that I like it a lot. In an amp you can replace a 12AX7 with a 7025 but not vice versa. The lifespan of a tube can be a bit tough to predict but the following may provide a bit of a guideline. Smaller signal tubes, such as the 6DJ8 are rated to last about 5,000 hours and the more durable versions will last incrementally longer. Everything You Ever Wanted to Know About Preamp Tubes We use cookies to provide you with a better experience. ECC83 Vacuum Tubes at Europe's largest retailer of musical instruments - fast delivery, 30-Day Money-Back Guarantee and 3-year Thomann warranty Thomann uses cookies to give you the best shopping experience. You can also find them relabeled Telefunken with diamond mark on the bottom last few years! Diamond bottom mark is done on laser machine, and if you want to avoid that and to be sure that you are buying genuine Telefunken ECC83 12AX7, just take a look at getter and how staples are faced. The valve did reproduce great clean sounds and worked very well in the Fender pro. They last for a very long time. All the other little tubes are 12AX7's. The tubes were tested on a TV-7 tube tester that was calibrated professionally by Dan Nelson it has a digital meter. 5 on the dial vs. Find helpful customer reviews and review ratings for JJ ECC803 / 12AX7 Long Plate Gold Pin Vacuum Tube at Amazon. Just for fun I put in a pair of Sylvania Gold Label, Gold Pin tubes with low noise testing from the manufacturer. Both of these Tung Sol 12AX7's are ECC803S. But in any case they make a noise I like so are staying where they are. The voltage drop there is too great and this tube will not last long there. Maybe it was the tube computer sound card idea I have seen, or the fact that I have enough junk to fill a dump truck. You could see the middle of the loop of each of the two heaters glowing red-orange near the top of the tube. And no fizz! I was a bit worried that it might sound less dynamic or harmonically rich than other tubes in the JTM45 and JMP settings, but it exels there, too. I have checked numerous sites and some individuals state a preference for 5751 tubes over the 12AX7's. You generally won't see people buying NOS power tubes. Dave Hunter kicks off a two-part primer on tubes with some general history on our glowing glass friends and an in-depth look at preamp tubes. With 30% less amplification than a 12AX7, but 100% interchangeable, an amp using the 5751 preamp tube creates a creamier and smoother tone than with a 12AX7. If you own a tube amp, there is a good chance it has one or more 12Ax7 tubes running the preamp section. Glass internal anode tubes generally have the gettering material coated on anodes, which must be operated a high temperatures to activate the getter. Just understanding the principles of how your amp works is well worth the time and effort. I have listening to it since mid June and I have to say that I like it a lot. This Russian tube is full bodied and well balanced. Just sayin'. A Comparison of Current Production 12AX7 Tubes. They have a black background with a slight warm and dark edge with plenty of detail, air, musicality and good dynamics. 10,2017 s silver quarter 25c ellis proof ngc pf70 early releases 4563423-020,usa state of georgia civil war ps868 50 dollars 1863 * scarce * unc. In other words if your amp is designed for a 7025 you can't go down to a 12AX7. We stock and sell more radio and vacuum tubes than any other company in the world. 12AX7 is the type of tube which happens to be the most popular preamp tube in use and it's really two tubes in one. Mình mới chơi ampli đèn nên nhờ các bác có kinh nghiệm giải thích dùm 2 loại bóng 12ax7 và 12au7 khác nhau thế nào ạ, vì mình thấy có preamp dùng cả 2 loại bóng trên, nhưng co preamp chi dùng 12ax7 và co preamp chỉ cần dùng 12au7. Either I've been very lucky, or they don't go microphonic much. Nice to have a good tester of course. it got me wondering if i should get an extra set. Well, this RFT does everything it was advertised to do. 1x 12AX7 EH, 1x 12AX7 EH Balanced, 2x 12DW7 EH, 4x 6L6GC EH Platinum Matched. The bottom line is that tubes are far more reliable and faithful companions than their reputation would lead us to believe. 87: Gold Lion reissue 12ax7 vs Mullard reissue 12ax7 long plate (9. The normal time for gettering is between one hour and one full day. Or the amplifier may "howl" at high volumes, or buzz on certain notes all the time. * The prices shown exclude VAT. To me it makes perfect sense for a couple of reasons. These tubes are similar in frequency balance and extension to the Genalex ECC83/12AX7/B759 reissues but are a bit more harmonically accurate and have a smoother top end than the latter. Preamp tubes can last and long time unless they start to become Microphonic aka feedback going on especially when they is no guitar plugged in. The "Beauty" is a 12AX7 valve preamp. The second triode is a phase inverter, which creates mirror images of the signal to drive the output tubes. There is no free lunch with a vacuum tube. As a rule, Long Plates usually fetch higher prices than short plates. With the 12AX7, I have never had a tube be microphonic though. The last of the military grade ones. I do not have any of the other makes you listed to compare. 12AX7 MULLARD "LONG RIBBED PLATES" 1958 (f91 series) (the long plate Mullards are one of the best sounding 12AX7 ever made; very sweet, great mids) (excellent for vocals, rich and harmonically textured) - Victoria - Bogner Ecstasy - Bad Cat - Sur SL-68 (hand wired) [ SUHR AMPS) ] TO BUY 12AX7 Mullard Long Plates 1950's. I long ago installed a Celestion Vintage 10 and it sounds good, but the best sound is to use the Pro Jr as a head and run it into an open back 12" speaker. I'm impressed. Last month I just tested 200 new Electro Harmonics tubes and a full 40% of them tested out at 84% or less, so in a case like this a new weak 12ax7 would work to the same degree as a 5751!. Find the top hashtags for #12aX7. It's been a LONG time since I've fooled around with 12AX7 tubes, but I remember the heaters going up inside the cathode in a rather rectangular loop. My amps actually sound pretty good, but I'm just being anal it's that last 2-3% of tweaking I like to do. The long plates seem to have a better sound stage than short plates, but as you stated do have a greater tendancy of suffering from microphonics. Last one from my stash. Maybe I also will try different 6SN7s. The 12Ax7 tube is by far the most popular preamp tube used in guitar amplifiers. I agree with you that tone is not improved with a mere preamp tube swap. You can do it either way. I'll go along with DeanG on V1 being the most likely culprit in producing hiss, and some tube rolling may be what you. And no fizz! I was a bit worried that it might sound less dynamic or harmonically rich than other tubes in the JTM45 and JMP settings, but it exels there, too. While we do screen for noise and microphonics, even the best tube testers are quite bad at finding these faults. I did however read something a long time ago that until recently had forgotten about, I read that too much of a good thing can expose the weakness. Or the amplifier may "howl" at high volumes, or buzz on certain notes all the time. The lifespan of a tube can be a bit tough to predict but the following may provide a bit of a guideline. How do we know when to change them? How long do tubes last? PS Audio. Then you have weird 'tubes' like a traveling wave tube (old high performance RF amplifiers) or things like magnetrons or klystrons that also fit the working principle of a vacuum tube (Tho i don't think you find the last two in test gear). The Ampeg V-4B is a two-channel, all-tube, 100-watt beast of an amp head. Linear Tube Audio sources the best tubes we can find for use in our production units, tested and curated to provide the best experience for our customers. “Tube rolling” with quality vintage valves is a lot of fun and will produce wonderful improvements to the tone of valve driven hi-fi component and valve guitar amplifiers. Audio Tubes NOS Tubes PrimaLuna Brand Tubes. My go-to 12AX7 new production tube for all of my builds, upgrades and repairs. Power Tubes (6L6, etc. Telefunken 12AX7 tubes have been known to last tens of thousands of hours - maybe even 100,000 hours. A few years ago I acquired a pair of Valvo Hamburg first generation NOS, NIB 12AX7 long plate tubes made in the 1950's. That’s a number most of us should be able to live with. Vacuum tubes are a critical element in many high-end audio products. Short and long plate 12ax7's, the best I have heard, I've had hundreds of 12ax7's from all the factories. One of UK's leading suppliers of premium tested Valves Tubes, speaker, guitar & amp accessories to the musician and audio industries. In short, how do I know that it's time to change a tube, and what's a good strategy for figuring out Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Please repost, and rest easy it won't happen again. Some tubes like the TFK ECC803S or WE 300B will last a solid 30,000-50,000 hours. If you can do the sub, try a 5751. For sale is a single 12AX7 Mullard with long plates. This inverter would be found in a cathode biased amplifier or there would be another pair of amplifier tubes between the inverter and the power tubes. If you play at moderate levels, 10-15 hours a week Preamp Tubes are generally at their best 2 - 3 years. My go-to 12AX7 new production tube for all of my builds, upgrades and repairs. Both my 50watt Marshalls are running Telefunken 12AX7's that I pulled out of my dad's old tube stereo from the 60's. We have a large fleet of tube testers, and every single one of them has been calibrated within the last year by industry experts. Then it quiets down. info, and posts from various Z-Talk Members, that I found valuable to me as I was learning about my amp. Need Help with EL84 & 12Ax7 tubes for Bugera V5. Selling off some more of my tube collection of 50 years! Up for sale are very fine well balanced early1960's vintage ECC83 /12AX7 Long + Short plates Baldwin Organ Grade 12AX7 + 12AU7 tubes Really nice vintage tubes All tubes are1960's Lush warm rich sweet sound! Tested on a calibrated B+K with no gas or shorts. You want quiet recordings? You want this tube! The Telefunken 12AX7 also has a very long life span and will outlive all cheaper 12ax7's by a. Examples of the test results can be seen above in the last photos. The long plates seem to have a better sound stage than short plates, but as you stated do have a greater tendancy of suffering from microphonics. Mullard ECC83/12AX7 tubes are known for there amazing smooth, mid-range, that brings out a romantic sound. Section 1: 1. Is this the case with tubes? Also, is there a known science behind whether they need broken in, or is the notion based primarily on anecdotal experience?. One day, in the middle of work time, a colleague entered my office to ask something and from the corner of my eye I glimpsed a man who was staring like hypnotized into an amplifier. Keeping the Mesa 12AX7A (JJ tubes) in all other positions works well too. The only difference is the heater voltage. Probably as long as any other quality NOS tube. RCA and Sylvania first introduced the 12AX7 to the world in the late 1940s. This will save you a lot of trouble when you do need them. 1960 date code. There is a whole range of tubes, from the high gain 12AX7 high gain, to the 12AU7 low gain. Got this tube to replace the stock ECC83 tube in my older Marshall AVT50 guitar amp, and it was a good choice. This tube was made, by Mullard, in Gt. You should keep a couple of good spare 12AX7 preamp tubes around at all times for any tube amplifier. NOS 12AX7 = ECC83 TUBE. My go-to 12AX7 new production tube for all of my builds, upgrades and repairs. It is an Excellent tube for Recording Studio Applications due to its extreme low noise. Be gentle to avoid bending or breaking the pins. I wonder if there is any reason to pay this kind of price for Chinese made signal tubes? While they can produce some nice high end tubes, they don't have long break-in times and don't last for crap. How long do rectifier, input, and output tubes generally last? In particular I use 12AX7/5751 , 5AR4, EL34, and EL84s types. Legendary (for a good reason) Dual Post (aka Goalpost) Getter support with large O Getter. It makes the "see-saw" drive voltages that properly drive the output tubes. I think I still have the original preamp tubes in my B15 from the late 60s. 45 mA & 1640 Gm Tested on a New Digital Tube Imp Mini tube Tester at 200 Volts. To me it makes perfect sense for a couple of reasons. It was developed around 1946 by RCA engineers in Camden, New Jersey, under developmental number A-4522. 12AT7 is in the middle, and there are other less common ones between the two. I've always wanted to do a review of 12AX7 tubes but felt that there were too many variables. from what he read anyway they are there to shield the tube from electronic interference but they hurt tone. Today, it is by far the most common preamp tube used for electric guitar amplification and there is an almost overwhelming supply of current production options to choose from. From the net I've read they have less gain than the 12AX7 but how does this translate as output to the speakers? I've read that the 12AT7 has 60% of the gain of the 12AX7. While we do screen for noise and microphonics, even the best tube testers are quite bad at finding these faults. The later models (after 1976-77) replaced the 12AX7 with a solid-state transistor driver board. RCA and Sylvania first introduced the 12AX7 to the world in the late 1940s. New & NOS tubes from Tung-Sol, Electro-Harmonix, JJ & more!. Tube FAQ High Voltage! Valve amps work with voltages that in places far exceed the "normal" mains voltage. In an amp you can replace a 12AX7 with a 7025 but not vice versa. Everything You Ever Wanted to Know About Preamp Tubes We use cookies to provide you with a better experience. 00/each ; US$ 129. If you listen to your amp for 6 hours every day (without skipping a day), such a tube will last you about 20 years. I guess I will try both old and new tubes, roll then through the various V positions in my Twin Reverb, and see what happens! It'll be kind of fun to do a little experimentation. com, is an audiophile show open to the public and scheduled to be held at the Sheraton Atlanta Hotel from April 14th through 17th. Nixie tubes are different since they are essentially glorified neon bulbs (Much prettier to look at tho). They have a black background with a slight warm and dark edge with plenty of detail, air, musicality and good dynamics. The early "script" versions had a 12AX7 tube in the phase-splitter circuit (the circuit that drives the output tubes in push-pull fashion). The reverb driver 12AX7 is the single tube located by itself towards the front of the amp. If a tube is listed as "tests NOS" but is listed as "not True NOS" please expect the tube to have a small amount of use * All tubes have been tested using only the best tube testers. I am running EH 12AX7s and 12AT7s and they give more gain than I need for my Dynavector DV10x5 high-output MC phono cartridge. Matching is $10 extra per tube. In most cases, they will sound better, perform better and outlast NEW RUSSIAN/CHINESE garbage made today. 45 mA & 1640 Gm Tested on a New Digital Tube Imp Mini tube Tester at 200 Volts. Please check out the new Shuguang Psvane 12AX7-T as replacement. A produced some of the best valves ever made which is why these items have become very sought after in the music industry. Then it quiets down. I am assuming the two tubes are pre amp tubes for warmth. Very rare Hitachi 12ax7 with long black plates and D-getter. This will save you a lot of trouble when you do need them. Mullard 12AX7 is also a long plate design. Yes, some tubes fail much earlier than that, but many indeed last that long. Since there are three 12AX7's in the amp, it would be helpful to know which one you're suspecting. Pre-amp tubes can last a long time,, not like power tubes that wear out with use. Feedback received via email: "Hi Rachel, I received the 12AX7LS super tubes and their performance is super! Put the new tubes in and turn on, first 10 mins, comparing to Psvane 12AX7-TII…the new super tube has lower noise floor, sound is more dense and transparent, bass is deeper and better bass layering. My tube amp tech mentioned last night that the most significant improvement for a Princeton comes with replacing the 12AX7 in the preamp socket with an RCA 12AX7. Like all Gold Lion Tubes, Gold Lion ECC83 is built with meticulous quality. In a closet, the tubes will last forever, of course. All tubes, whether it’s your amp or a pedal, need some time before they reach their potential so don’t freak out if the 12AX7 blows your head off the first time you try it. A Comparison of Current Production 12AX7 Tubes. We carry premium hand selected vacuum tubes for guitar and HiFi amps. Schiit Mani gives you the flexibility you need for both moving-magnet and moving-coil cartridges, together with exceptionally accurate, and low-noise performance. If you listen to your system fairly frequently, I suggest spending the extra 10 dollars, as tubes will usually fail around 1000 hours if they do not exhibit immediate defects. All invoices will be issued in EUR. The last preamp tube before the power tubes is usually the "phase inverter". If a tube is listed as "tests NOS" but is listed as "not True NOS" please expect the tube to have a small amount of use * All tubes have been tested using only the best tube testers. Doesn't matter what piece of tube equipment (that includes guitar amps as well as audio equipment) you have, pretty well everything uses a 12AX7 in some form or fashion. Just understanding the principles of how your amp works is well worth the time and effort. Toggle navigation P in R. 52: Tube rolling - Do I need to turn the amp off in between? (8. 12AX7 1950s long plate D getter Holland made Bugleboy tubes, produced and screened for critical use in high end audio and recording equipment. Loading Unsubscribe from PS Audio? Cancel Unsubscribe. You run a preamp or the effects-send of a guitar amp directly into the single-rack-space box, which uses a single 12AX7 preamp tube (running at 175 volts) to mimic the tonal characteristics of a power amp in varying stages of sweatiness as it interacts with a speaker load. Tube FAQ High Voltage! Valve amps work with voltages that in places far exceed the "normal" mains voltage. Last myth debunked for now: real NOS tubes should be able to be matched to within 1 percent or so of each other. That's a number most of us should be able to live with. Long plate 12AX7 tubes sound great in a lot of applications, but due to simple physics, they will be more prone to microphonics than short plate tubes. I assume this amp design would eat preamp tubes on a regular basis!!. Examples of the test results can be seen above in the last photos. Get a low price and free shipping on thousands of items. You generally won't see people buying NOS power tubes. I am assuming the two tubes are pre amp tubes for warmth. Its the best I have heard so far. Everything You Ever Wanted to Know About Preamp Tubes We use cookies to provide you with a better experience. from what he read anyway they are there to shield the tube from electronic interference but they hurt tone. The ECC83 tubes dissected here are of the long plate variety. While NOS 12AX7s can soar as high as $300 each (for super high-zoot Mullards and Telefunkens), Mullard 12AT7s rarely top $30. Mullard 12AX7 is also a long plate design. We specialize in audio vacuum tubes and accessories. Avoid Mullards, Telefunkens and Amperex if you are on a budget. This is especially noticeable at the high frequency range of your EQ. An ECC83(12AX7) should last a very long time in your amp. Find helpful customer reviews and review ratings for JJ ECC803 / 12AX7 Long Plate Gold Pin Vacuum Tube at Amazon. The only difference is the heater voltage. Check out #12aX7 statistics, images, videos on Instagram: latest posts and popular posts about #12aX7. Short plate 12ax7 tubes were first produced in the early 1960's by the likes of RCA, GE and so on, and then picked up by the European producers such as Philips, Mullard and Amperex. With preamp tubes, you don’t need to worry about things like biasing or using matched pairs as you do with power tubes. 12AX7 1950s long plate D getter Holland made Bugleboy tubes, produced and screened for critical use in high end audio and recording equipment. When the plate current draw of each triode is the same(as evaluated by our VTV testers), we refer to that as having balanced triodes. GE long grey plate 12AX7 matched pairs. At this point they still sound goodbut no longer sound great. How long do tubes last? When should I replace my tubes? It depends heavily on use. I've had the MP-P1 since december and have rolled quite a few combos of tubes over the last couple of months and have recently found my perfect sound in 2 NOS motorola labelled Mullard I63 short plates and 2 NOS RCA long black plates. V1a rail voltage is 394VDC with a 200K plate resistor and a cathode resistor of 1K8 to ground. I have a 12AX7 mic preamp, in fact that I absolutely adore. CV4004 / 12AX7 Mullard The CV4004/12AX7 is a high gain, low noise valve with a short plate structure for reduced microphonics. Preamp tubes control the EQ of your amp. C, Telefunken, Siemens, Philips, General Electric and R. The question I have, is how do they compare to real NOS 12AX7's? For a couple of hundred dollars a pair, you can have genuine RCA black plate 12AX7's. Toggle navigation P in R. Power tubes general rule is they will last between 6 months to 1 year depend on how hard and loud you play. Excellent for use in high gain Marshall pre-amplifier circuits where noise and microphonics can be a problem. It's basically me publicly taking notes on things I found to be interesting, or just wanted handy for quick reference. The Tubes I used a 6AX7 for the first stage of amplification. Sounds like you've had a great run! Jagsound , Jan 12, 2010. I assume this amp design would eat preamp tubes on a regular basis!!. It was released for public sale under the 12AX7 identifier on September 15, 1947. If you can do the sub, try a 5751. Power Tubes are generally at their best 1 - 1. 50+ videos Play all Mix - How to KNOW when a tube fails in your amp and JJ Tube testing review : tonymckenziecom YouTube How long do tubes last? - Duration: 7:35. Spiral filament for reduced microphonics. The last digit which represents the week of the month didn't start until about 1962. Dave Hunter kicks off a two-part primer on tubes with some general history on our glowing glass friends and an in-depth look at preamp tubes. The only real test is with your ears. Get the guaranteed lowest prices on Preamp Tubes instruments at Musician's Friend. I once borrowed a pair of 12AX7 NEC tubes from a friend (late 60's or early 70's) and they sounded amazing on my phono pre. We do not accept liability for typographical errors or inaccurate information of any kind. While we do screen for noise and microphonics, even the best tube testers are quite bad at finding these faults. Telefunken 12AX7 \ ECC83 Vintage Preamp Vacuum Tube #4 NOS condition, 17mm smooth plate Telefunken in original box that tests better than new. From then on the only tubes. I have a 12AX7 mic preamp, in fact that I absolutely adore. How long will tubes last in a pre-amp? My Sonic frontiers Line One seems fine, tho I haven't put anything else in place of it to test. If the replacement tube does the same thing, buy/borrow a different brand of 12AX7, and see what happens. Power Tubes (6L6, etc. Power tubes general rule is they will last between 6 months to 1 year depend on how hard and loud you play. I assume this amp design would eat preamp tubes on a regular basis!!. Recently, I am noticing artifacts and distortion [however slight] in my audio playback. com, is an audiophile show open to the public and scheduled to be held at the Sheraton Atlanta Hotel from April 14th through 17th. Do you know how long that is in guitar amp years? Well, neither do I - but its a long time. Unique box plate design, gold pin, absolute high end 12AX7 tube you can find on the market, compete head-to-head with Telefunken ECC83 and Mullard CV4004. Schiit Mani gives you the flexibility you need for both moving-magnet and moving-coil cartridges, together with exceptionally accurate, and low-noise performance. Britain, in 1958, for high end audio use. The supposed downside of long-plate tubes is that they get beat up in combo amps and fail quickly. The 12AT7 is a high mu multi-purpose double triode in a 9 pin miniature package. That's a number most of us should be able to live with. This Russian tube is full bodied and well balanced. That’s a number most of us should be able to live with. These audio tubes are of unsurpassed quality and reliability. Sound of this little treasure is something between GE 5751 & Tung-Sol 12ax7 black plates. Rectifier Tubes are generally at their best 3 - 5+ years. Equivalent to M8137/CV4004. I think I still have the original preamp tubes in my B15 from the late 60s. 12AT7 is in the middle, and there are other less common ones between the two. We have a large fleet of tube testers, and every single one of them has been calibrated within the last year by industry experts. If a tube is listed as "tests NOS" but is listed as "not True NOS" please expect the tube to have a small amount of use * All tubes have been tested using only the best tube testers. I've noticed that most of the vintage ('50s and '60s) Tung-Sol 12AX7 long plates either have a halo or D getter. If it's the Sovtek 12AX7 LPS (used in PI), then the filament glow is hard to see - and visibly less than the ECC83's in V1 & V2. Groove Tubes and Ruby do the same thing. Preamp tubes do last a long time, but most techs seem to think that after 5 years of regular use you should have some spares handy. Legendary (for a good reason) Dual Post (aka Goalpost) Getter support with large O Getter. Because the 12AX7 is a low power tube this circuit can't drive a pair of tubes having 100 k ohm resistors in their grids. The only difference is the heater voltage. The ECC83 tubes dissected here are of the long plate variety.