Dating amperex tubes 12ax7

12AX7 Tubes in Stock

dating amperex tubes 12ax7

For the most European tubes made after date codes are located on In this case it's B0D (this is for Mullard, Blackburn – – April). Find great deals on eBay for Amperex 12AX7 in Vintage Tubes and Tubes Sockets. Shop with Date Code: (made in 15th week of ). and Short Plate. I think the Heerlen (delta) plant made tubes from the mid 50s to the mid 70s. Tubes from the 50s had a 3 character factory and date code, delta.

bugle boy tubes 12ax7

The results are measured both audibly and on an oscilloscope. This will weed out tubes that may not be suitable for extremely sensitive amplification applications.

See the video above for more details. New Old Stock white box. These are the much sought after "Gold Lion" series made by Genalex, with the gold lion logo on the glass, and the red Genalex decal around the base. One of the 2 or 3 "holy grail" 12AX7 tubes ever made at any time, you have to hear these to understand why they are so rare and costly. Excellent tube, you really do get what you pay for.

The ultimate vintage audiophile tube! New production, original box. A decent reissue of the rare original Genalex UK s made tubes with the gold lion on the glass and gold pins.

Amperex 12AX7 | eBay

The B is a very low noise 12AX7, with matched triode elements. Excellent tube, you really do get what you pay for with these babies. The ultimate current reissue audiophile tube! Click the screen at left. The tube of choice for classical, jazz, male vocals, and choral music.

New Old Stock in white box. Among the rarest tubes in the world! This is a very low noise, special quality frame grid construction 12AX7, made with the old-style Telefunken German precision. These have the ultra wide bandwidth of the Telefunken ECC83, but also have nice matched internal triodes, gold pins, and have been carefully factory screened for low noise. These tubes are currently soaring in value as stocks of them vanish.

The yellow tips indicated the very highest grading, and most still have the original yellow paint on the tips to prove it. The yellow tip and cloth SELECTED TUBE label indicates exhaustive after-market testing for low noise, uniform output, freedom from microphonics or physical defects, long heater life, and even, uniform cathode emission.

Hickok tested, and then ear tested in a preamp! The finest Telefunken diamond mark smoothplates, NOS, is what these rare tubes are based upon.

Critical use in hospital or aerospace test equipment demanded tubes with super low noise, and tightly controlled output, and these beauties deliver! The ultimate tube for tube mics and mic preamps! Very fine, very rare tubes, in great demand, especially this smoothplate version. Excellent labels on these. These are all Tele labeled, and have the "selected tube" cloth label.

All are the real deal, with the diamond mark in the bottom glass. These are rare matched pairs, with transconductance tightly controlled internally and from tube to tube. Incredibly accurate, the amazing sound image emerges out of a dead quiet background. The best of the best!! The finest Telefunken diamond mark smoothplates, NOS, that have been further aftermarket screened for low noise, low microphonics, and balance.

Very fine, very rare tubes, in great demand, especially this selected version. The Ruby tube it replaced in my phono stage was clearly the weak link in my system. With the Telefunken, I immediately got a huge improvement in detail, attack, and overall musicality.

Especially noticeable was the improvement in the sound of percussion instruments, particularly cymbals, where I couldn't previously make out the strike of the sticks or brushes on the instrument - just a blurry ongoing ring. With the new tube, the front edge of every strike is distinct, bringing the sense of pace and rhythm to new heights. The effect on plucked strings and articulation in brass instruments was equally impressive.

All in all, it sounds like a totally different system. Thanks for the great pick!

Best sounding 12AX7A/ECC83 & 12AT7/ECC81 tubes? Telefunken, Amperex, Mullard?

Was chomping at the bit during 'burn in'. Was worth the wait, the equipment was connected to the Snell Eiis'. Top it off with the Beatles, Butcher Album. Thank you for your assistance, you have one happy customer. These are all Telefunken labeled, an all have the blue painted tips indicating extensive screening for use in medical equipment.

Very fine tube, in great demand, especially this smoothplate version. Nearly all excellent labels on these. These do not have the cloth "selected tube" labels but are still medical graded tubes that were Grass Instrument mainly for EEG machines stock. These are rare matched pairs, with transconductance matched to within 2 percent. These pairs have been tested in my amplifier for noise, stereo balance and image, and microphonics, then reconfirmed the match on the tube tester.

These are dead quiet at full volume, not microphonic, and sound great! You can't get rare quality and careful hand selection like this on eBay!! The tips are marked in red enamel showing they were graded for use in critical circuits in medical, aircraft, and test equipment. Fair to very nice Telefunken labels on these.

Originally spare parts for hospital, industrial, and avionics equipment, they sound incredible in audio equipment.

dating amperex tubes 12ax7

A sound very much like the smoothplate, phono-stage or microphone-preamp quiet, with perhaps a bit more warmth in the lower midrange, at a big savings. A few are OEM labeled, but are genuine diamond bottom Telefunken tubes. These are all Telefunken labeled.

They don't make-um like they used to. Both the Telefunken and Mullard are absolutely beautiful in their own way. After burning in for 48hrs, and after hearing each one, including the OEM stock tube, I can say that the sound of the OEM stock is very muddy in it's entire range, and with the NOS's, it's as though a veil has been lifted, and clarity and separation of notes is revealed.

It's hard to describe how beautiful these tubes reproduce sound. Fair to excellent labels on those with labels.

Save big on these as some are made for Dynaco, some for Fisher, some not labeled. All are the real deal, with the diamond mark in the bottom glass, same tube as the Telefunken labeled tubes listed above.

Very fine tube, in great demand. Nice Telefunken, Dynaco, and Fisher labels on these. All are original Telefunken diamond bottom marked tubes, most OEM labeled for various brands of amps as they were replacement stock.

These beauties are hand matched to within 2 percent transconductance. These fine pairs have been tested on an oscilloscope and in my amplifier for noise, stereo balance and image, and microphonics, the the match reconfirmed on the tube tester.

Dead quiet at full volume and no microphonics. A sound very much like the smoothplates, phono-stage or microphone-preamp quiet, with perhaps a bit more warmth in the lower midrange, at a big savings!

The Telefunkens transformed the sound of my amplifier. Wow, what a change from the Sovteks. The Telefunkens have a lighter sound. I noticed that voices seemed to lose some chestiness, but gained a delicacy that makes them float in front of me and seem more realistic.

The soundstage is wider and the presentation holographic with ambiance that wasn't there before. Fair to very nice OEM labels on these. Good to fair labels on these, genuine German Telefunken with diamond mark. Save on these same smoothplates but have other brands on the labels, or blank labels. Good to fair labels on these, genuine German Telefunken with diamond mark, most labelled for Dynaco, Mazda, or Fisher.

Plenty of punch in the upper mids and tight bass make this tube sound at home in guitar amps and the finest hi-fi systems alike. I put them in my preamp section of the MA and I can hear a considerable difference over the regular smooth plate Telefunken. These select Mazda tubes have more detail and are very, very clear. I'm extremely satisfied with these tubes and all the tubes you provided. All the Best, M.

dating amperex tubes 12ax7

This tube has an incredibly clear tone that works well in both hi-fi and guitar amp applications. These have the sonics and punch of the silver plates and the low noise of an S type tube, not to mention the low microphonics of a triple mica! Add to this the quiet background, and incredible 3-D soundstage these tubes create, make these about the best silverplates ever made! Carefully matched, a very rare chance to grab a matched pair of these superb vintage tubes.

This is a very low noise, seldom seen silver plate 12AX7. These are the very rare pinched glass bottom tubes. The glass dips inward at the very bottom of the tube and tightly supports the internal parts of the tube, lowering noise and microphonics.

Electrically matched, labels may vary. Very limited quantities available. These are the very rare French Military stock tube with military markings, and in original military boxes. These have the sonics and punch of the silver plates at a savings! Add to this the quiet background, and incredible 3-D soundstage these tubes create, make these about the best longplates ever made!

These have the sonics and punch of the triple mica silver plates at a savings! Add to this the quiet background, and incredible 3-D soundstage these tubes create, make these about the best 12AX7 tubes ever made! This is a very low noise, seldom seen special quality 12AX7.

The sonics are quite similar to the even-rarer Mazda silver anode, and the "S" suffix insures factory testing for low noise like the famous Telefunken ECCS. More stock just in!

  • Amperex 12AX7
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  • Deciphering European tube date codes

A rare boxplate from France, that has been factory screened for low noise and has the "S" suffix for "special" or "select". These are virtually the same as the s Mullard boxplates, with that incomparable European sweetness. In excellent condition, and very RARE in matching pairs! This is a very low noise, seldom seen 12AX7,from France with the rare s long plates. These greyplates longplates have the sonics and punch of the silver plates at a savings! This is a very low noise, seldom seen 12AX7.

These greyplates have the sonics and punch of the silver plates at a savings! Punchy, quiet, and very detailed with incredible dynamic range. These are not often available, and I don't forsee finding more in the near future.

Silky highs, a liquid midrange, and awesome deep bass give this tube its deserved reputation for warmth and full sonics. Tried them yesterday and my god were you right! Never heard such detail come from that amp I still can't believe it. Then I put the JJs back in to make a last check. It sounded like a broken radio. Fizzy noise, all articulation lost, ear piercing trebles. And I thought I had a perfectly good tone. What have I been doing with that amp all my life?

I am particularly impressed at how you were able to nail the guitar tone I was searching for. They bring exactly what I wanted: I want to thank you for that. It was my first NOS experience and I was kinda skeptic. Now I've really understood how they make a difference you'd have to be deaf not to notice! Time for me to stock up with more of those in the near future, so you'll be hearing more from me! New Old Stock in original box and white box. These have the ultra wide bandwidth of the Telefunken, but with just a touch of midrange warmth.

The labels are somewhat faded from sitting in the crumbling foam rubber liner of the box, which is typical of these that are still in original boxes after 40 plus years. The gold pin 10M version is the most sought after, consistently rated one of the best 12AX7 tubes of all time on many audiophile message boards and websites.

These have the ultra wide bandwidth of the Telefunken, but with just a nice sense of midrange warmth. Excellent original yellow label. All date coded very rare military flying lead type with a large vibration absorbing plastic base around the point where the pins meet the glass. Box plates like the CV but even higher specifications. Mullard made in Great Britain at the Whyteleafe factory, which only made special production military tubes. Identical to the industrial type and a superb low noise 12AX7.

dating amperex tubes 12ax7

These are Mullard with the factory code, in a very tightly matched pair. These have that sweet British sound, and you are getting a vibration damped 12AX7 as well! No one else has these, very limited stock, you snooze you lose! All very rare military flying lead type with a large Bakelite vibration absorbing wafer base around the point where the pins meet the glass, to allow the tube to be plugged into a conventional 9 pin socket. Brimar UK made for the British military, these are among some of the most difficult to find tubes, especially modified to be plug and play!

These are Brimar with the factory code, in a very tightly matched pair. Rare early square getter Mullard, with the famous, elusive longplates. Nearly all in this batch are the super rare mC1 production codes from the early to mid s.

Even more awesome is finding a matched pair of these gems. The first generation of Mullard 12AX7 tubes, s vintage mC1 Blackburn factory date coded, some made for brands of amps. The internal construction is identical to the rare 6L13 above, they were from the same production!

The best is the sound of these jewels, which is unsurpassed. These are carefully matched, and tested for low noise and microphonics. As good or better than the famed Mullard 10M goldpin series, at a lower price! Tested as New Old Stock in whiteboxes. A rare early square getter Mullard, with the famous, elusive longplates and the earliest mC1 production codes.

These have an even Gm match between the internal triode elements, and are tested for low noise and microphonics.

Several are made for Amperex with the Bugleboy logo. If you only need a single 12AX7, this is a rare chance to get one of the best ever made! The elusive, never-been-reproduced long narrow plate Mullard 12AX7!

This can be seen on the following table: Actually, coupled with the unique month codes, you could use the change code to zero in on the year and month of manufacture. Prior toanyway. For example, a month code of A and a change code of A would be unique to Jan.

Afterthe code just became the following numbers and letters that would repeat as required: This new code allowed for 35 tube batches after which, it must have repeated from the start again. The year and month started to be used at this point afterso the change code is not really necessary in newer tubes to pinpoint a manufacture date. The purpose of these codes, indeed all of the change code, is unclear from original Dutch Philips documentation.

The theory that they pertain to individual batches of tubes or "production runs" seems to be the most plausible, and is the purpose I have accepted as to their meaning. The factory or country of origin. List is found elsewhere on this webpage.

dating amperex tubes 12ax7

The last digit of the year of manufacture. This is only present in the code used after The month of manufacture. This gets a little screwy, as before there was a sequence of 36 symbols used which repeated every three years according to the following table: In the code used aftereach month is represented by a single letter in the sequence shown on the next chart.

Remember, the last digit of the year began to be used with this code, and this will help identify post tubes. This is the actual week of manufacture within the listed month. Some documents and other sources I have researched indicate this week code was only added from onwards. It also does not mean that all tubes made since have the week code. Use the charts below to see if the week codes even apply to your tube This can get pretty screwy, too.

For the most part, on tubes commonly found in circulation today, the code is located on the side of the glass in dark grey paint, down low just above the bottom. It follows this convention before Afterthe code changed to the following several formats, with the manufacture year Y kicking in to the mix: TTC Another variation with the addition of the week of manufacture: TTC Another variation with a triple tube type number and the week: TTTC And to completely confuse you, yet another triple type number variation without the week: For the most part, tubes made after are what is commonly found on the vintage market today.

This will reduce the number of code choices you have, and the tube type codes of the tubes you use the most will become committed to memory, as they never change.

Here is an example of a Mullard Blackburn, UK factory date code: The first line is rX2. On the second line is B2J5. Note the code is printed on the tube upside down. Amperex, Philips, Valvo and other Philips owned factories coded their tubes in a similar fashion, but their codes were not upside down like Mullard sometimes is. Here is an example of a Siemens-Halske factory code: Note the code is broken down into 3 lines of 2 characters each. The first is A0 which is a or E88CC.

dating amperex tubes 12ax7

The 1 is the change code. The 5 is and the F is June. Siemens never used a week of the month in their codes.