Ideally, every 12AX7 should yield the same gain when placed in the same circuit. However, in reality there are comparative gain differences among 12AX7s. 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.
The purpose of this comparison is simply to provide guitar players with a frame of reference to help in finding the best current production 12AX7 for their needs. The 12AX7 is a 9-pin miniature, high-mu, twin triode. What does that mean? The 9-pin miniature part tells us what kind of socket the tube plugs into. It has nine thin pins arranged along the circumference of a circle with a diameter of just under half of an inch. There is a large gap between pins 1 and 9 to ensure that the tube can only be plugged in one way.
This gives us a general category of amplification that the tube was designed for as compared to other preamp tube types like the "medium-mu" 12AU7. The twin triode part tells us that there are two identical and independent triodes contained within the one tube. A triode is the most basic tube structure that allows for signal amplification and it has three electrodes: plate, grid and cathode.
Each tube sample was tested in the same Fender black face style preamp circuit as shown in the schematic below with bass and treble set to their maximum. A frequency generator was used to measure voltage gain and plot the frequency response from 10 Hz to 18, Hz.
From the frequency plot it could be seen that there are three extrema at about 50 Hz, Hz and 4, Hz. These three frequencies were then used to quickly measure the low, mid and high frequency voltage gain on the same number of samples for each tube in our comparison. The average from each tube's samples was then calculated and used for comparison. The smallest average low frequency gain tube was used as the reference for a gain of "1" and the largest average low frequency gain tube was used as the reference for a gain of "10".
This gain reference method was then repeated for both the mid and high frequency averages. Each tube sample was again tested in the same preamp circuit and an oscilloscope was connected to the amplifier output to monitor the amplitude of the voltage spike produced by tapping on the tube's glass envelope. The average voltage spike from each tube's samples was then calculated and used for comparison. A custom 12AX7 switching box was constructed to allow for a quick switch comparison of six tubes at a time while plugged into the V1 socket of a Marshall JCM guitar amplifier.
A separate filament transformer was used on the switching box to simultaneously heat all six comparison tube filaments without overheating the amplifier's power transformer. A shielded cable was constructed to plug into the amplifier's V1 socket and transfer its pin 1, 2, 3, 6, 7 and 8 connections to one tube socket at a time in the switching box. Listening tests were then conducted while playing guitar and switching between the tubes at various amplifier control settings to come up with tonal descriptions for each tube.
Kurt began playing guitar at the age of nine in Kalamazoo, Michigan. He is a guitar DIY'er and tube amplifier designer who enjoys helping other musicians along in the endless pursuit of tone. Skip to main content. This graph is based on the average gain and noise measured from different tube brands using the same number of samples for each brand.
It should not be assumed that every single 12AX7 from a specific brand will match its place on this graph. The gain rating is only a relative reference e. Gain rated at 7. Gain rated at 5. Gain rated at 4. Gain rated at 3.
Gain rated at 2. Schematic of the preamp circuit used for 12AX7 comparison tests. Note that the information presented in this article is for reference purposes only.
Amplified Parts makes no claims, promises, or guarantees about the accuracy, completeness, or adequacy of the contents of this article, and expressly disclaims liability for errors or omissions on the part of the author.
In English called "Frame Grid". How little understanding there is about this, can be seen under tube manufacturers who today sell you a ECCS with normal grids. By itself a ridiculous situation, but who cares, people need lower cost ECCS, so they just stamp it on the glass for you. SO it is part number faking. Well who cares All others are imitations.
So they are "balanced" per definition. You must be interested reading this, otherwise you would have clicked this boring text page away. Let me explain here what a frame grid is, and what's so nice about it. Perhaps you have opened up an old radio tube, and removed the grids one by one. When you touched them with your thick fingers they were damaged. Specially the very fine ones.
Well not so with a frame grid! With a normal none-frame grid, the grid wires are used to keep the grid bars in position, right? This may seem kind of natural, but there are other ways to do it. If they get too thin, the grid would get too sloppy.
However for miniature high gain tubes, you need thinner than thin wires, and for high transconductance you need them closest to the cathode. Here is where frame grids come in.
The frame stays inside the mica.Since All rights reserved. Copyright note. If you were looking for that, I have to disappoint you. It is better to recognize there is a lot of emotion behind tubes, as well as a lot of rationality from the engineering point of view.
Things get a little difficult when an rational hardliner wants to make emotional users look silly for not understanding the physics behind it. Whereas for other people a discussion becomes closed, when some tubes sound better than others, even though they do not know how electronics work.
Though myself I try to understand some part of both worlds, I am somewhere in the middle.
All user reviews for the JJ / Tesla ECC803 S Gold Pins
So, what is a valid argument for one person, is invalid for another. So yes, we all know JJ makes low cost copies of all popular tubes, and some prefer those for that reason. Whereas others avoid them, simply for the same reason.
Myself, I had several bad experiences with JJ tubes, and that triggered a factor inside myself, saying JJ is only good to save money. I have an RFT ECC82 tube at a particular position in the amplifier of my Hammond organ, and only with that tube, the percussion of the organ sounds so fresh the way it does. Though this tube costs only 20 Euro or so, I would pay a lot more if had to, just to get back that sound. I have similar feedback from a person with a guitar amplifier.
He bought a quad of the expensive TESLA E83CC, and after finding out the amplifier sounded better as ever before, he bought another quad, so to have enough spare tubes.Graylog alert plugin
To make it even more complex, many people today just buy NOS tubes, because they see prices go up and up, and regard it a safe and good investment. I have no numbers available, but I know first hand from an ex TFK employee living in Ulm, they were never made in large quantities.
So you can stop searching for those sleeping lots in old warehouses. Those never existed. For them this tube was constructed, for their test equipment. I know this company, I have visited them several times, for other reasons in All Rights Reserved. All text and images on this website may not be used without express permission.
All prices and product information subject to change without notice. We are asked this question multiple times everyday. Since he started Eurotubes in we have had the unique opportunity to listen to and play hundreds of different amps. During the first few years we worked with local players here in the studio one-on-one to achieve the best results for each. This gave us the opportunity to play, and more importantly listen, to hundreds of different amps. Thousands of hours were spent trying different combinations of preamp tubes and power tubes to better understand their characteristics and tonal differences, and we continue to do this today.
Before we get into methods, reviews and brands we would like to answer some of you who have asked us about the new production Telefunken tubes. Most players who know us understand that we have a very tight relationship with JJ Electronic.
In fact JJ verified that Telefunken is not even a customer of JJ Electronic and said they must be getting them from another dealer!
So, you will not find reference on this page to the new Telefunken tubes because they are in fact JJ Electronic tubes. Continuing on, we quickly learned that the method most people used to compare tubes, which is to set the tone controls to one place and leave them for the entire test was inadequate.
This procedure does not allow you to get acquainted with the capabilities of the tubes. Some tubes get sweet when treble is dialed in and some get very piercing.
The following opinions reflect our opinions and the opinions of the vast majority of our customers, you can find well over a thousand customer reviews here. Below is a list of the most common power and pre-amp tubes. A good way to describe the tone in one word would be to call it "cardboard".
They make your amp sound like a big Wheaties box. The low end is flabby and only gets worse as more lows are dialed in. The highs are piercing and brittle.
These tubes are just flat and lifeless sounding without much harmonic content. When over driven they get real grainy and the breakup transition is quick and not smooth. Sovtek EL84M: This tube has the same tonal characteristics as the standard Sovtek EL84 and is even more lifeless and less touch responsive.
Electro Harmonix EL These are sovtek tubes and all the above applies. It should be against the law to muddy a good name like this The problem is finding good ones that are matched.
They have nice harmonics and breakup pretty evenly. The upper mid and highs are this tubes strong points. Nice detail even when distorted. These are nice, warm sounding tubes with good dynamics, nice harmonics. This tube has good definition but is hard to drive into distortion.
Vacuum Tube - 12AX7, Tung-Sol Reissue
A nice tube overall but we would use the EI before spending the money on these. They work pretty good for Hi-Fi.Your question may be answered by sellers, manufacturers, or customers who purchased this item, who are all part of the Amazon community.
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The jj ECC is a long-plate version of the standard 12AX7, the longer plates give the tube higher gain, it has a rich and full tone with creamy distortion that does well in any 12AX7 application. Spiral Filament for reduced microphonics.
Jj tubes are known for known for their high quality, durability, and their excellence in tone, formerly produced by Tesla, jj tubes are still made to exacting standards, they work well in all applications. Skip to main content. In Stock. Add to Cart. Secure transaction. Your transaction is secure. We work hard to protect your security and privacy. Our payment security system encrypts your information during transmission.
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JJ ECC803S / 12AX7
Image Unavailable Image not available for Color:. The jj ECC is a long-plate version of the standard 12AX7, The longer plates give the tube higher gain It has a rich and full tone with creamy distortion that does well in any 12AX7 application.
Spiral Filament Formerly produced by tesla, jj tubes are still made to exacting standards, They work well in all applications. Have a question? There was a problem completing your request. Please try your search again later. Product information Item Weight 0. International Shipping This item is not eligible for international shipping. Learn More Shipping Advisory This item must be shipped separately from other items in your order. Additional shipping charges will not apply.Twrp mount
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Top Reviews Most recent Top Reviews. There was a problem filtering reviews right now.Location: Birmingham Posts: 5, I'm James. Cheers James I will take a look at that supplier. NOS Tesla's hard to come buy. VPI Scout 1. Not necessarily. Valves that meet minimum manufacturers standard were sold as new. That is why this spec, now often taken as a litmus for NOS condition, is really not. However I do agree that a valve that measures poorly cannot be to minimum manufacturers standard and so cannot be NOS in any rational sense unless new old reject stock and should definitely be avoided Originally Posted by Jazid Not necessarily.
I hope this helps some who find the world of valves confusing Good point James.Lesson 2 homework practice function rules answers
It's a minefield when considering the number of valves advertised as NOS and worse than this is that generalisations get heaped on one particular brand or other, elevating prices or the reverse when quite often there may be less sonically between various brands than meets the eye, given two different valves with the same specs and measurements.
The other point is that many valve designations were more performance specs than blueprints for a specific construction and various manufacturers followed their own designs for their own reasoning, giving some very specific performance specifications for similar valve designations.Electro Harmonix EL34EH VS JJ EL34 - Tube Shootout
The ECC83 has long been used for the gain stage in preamps etc and is a very popular valve with a fair few differing constructions, meeting the same electrical output values give or take. It's when one examines the construction for things like microphonics and consistency of batches for tolerance, that one can start to generalise more accurately.
This involves a fair bit of research and testing and I wonder if any one resource as yet has all of that info clearly displayed? There are a few sites I know of which get close.
I've largely given up trying to get any warranted tolerance matching for NOS bought valves and to a greater extent dont bother these days as they're so ridiculously over-priced Telefunken s in particular but also some of the ladder plate Mullards.
I look for low microphonic new issue valves, and in particular recommend the gold pin JJs for ECC83 positions over just about any new valve it's based on the Tele s construction. A cleaner sounding 83 type I've yet to find. Originally Posted by Jimbo You are certainly right there Marco. Might have to invest in some more so have enough NOS valves to see me out.
Can,t go back to some of those new production valves as the difference is simply too great. One small thing that troubles me is getting hold of NOS valves that have never been used.
There are too many circulating that have had many hours on them. The best, I thought, were the RCA black plates by the boxes on the far right. The plates are a very gloss black, maybe made around ? In that circuit Worth checking out sometime maybe. Attached Images tubes.Read here what is a real ECCS or not.
First we start with this standard data, from the Muiderkirng book.Bolero vietnam 2018
This datasheet shows the way an ideal tube would bias. The complete book you find on www. Next we show the curves, these are from the General Electric datasheet, and most other datasheets you'll find are the same. So the following critics is not for GE only, it is for all of those faked datasheets, these are most of them. Here is a detail from the same datasheet. Look at those nice, parallel lines, with their well defined cut off points. So the lines do not point all to some vanishing point, as with real life tubes.
The distance between each line is the same, regardless where you look. This means the tube has no distortion. Now with amplifying devices, distortion and gain go hand in hand. However, not so when looking at those GE datasheets here. How did they do that?
Well for drawing such curves they used a flexible ruler. That is a plastic bar, with lead inside, and you can nicely bend it in any desired shape to draw curves. Anyway, these curves show how an ideal tube must look like, but how ideal are they in real life?
The average is always around 1. Also for new tubes, and 1. The dictionary definition of "normal" is: "occurring most often". So this somewhat lower current must accepted as normal, and in a good auto bias circuit, such tubes bias completely normal, at the correct values. The test data was taken with the Amplitrex AT This digital unit has 10 bit resolution at full scale, which is 0.
The low scale is 10mA, so digital steps are 0. No problem at 10mA, but it gets visible below 0. Also the transconductance is always ending on "00". So steps are like,etc, and a tube with on both systems is in reality for instance No problem, as long as we know it. When you compare the graph with the test data, of course you will find the test data from the table in the curves, since it's from the same tube. The curves are made from System1not System2.
Look just above the number at the blue line. The measured value is right above that number So not at the left or the right. Look at the test data. The tube is set for -2Volt grid, and then at V plate the tube is tested So the plate current is exactly 1. Also Tesla can have some deviation. The transconductance is exactly right 1. Next thing is something O observed more often: Gain is a bit lower at around I don't know what that is, but I seldom find an ECC83 with a gain if x and when I do, it's a bit funny testing tube anyway.
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