12ax7 tube test results to pas sInterpreting test readings (from a practical sense)1. The MaxiPreamp II – the new standard of tube measurement. Strong Set of 12AX7 Tubes. It happens, but it's RARE. I did decide on Amperex Holland in the end over Telefunken East Germany and Mullard Blackburn UK Jun 5, 2021 · 12AX7 Tubes - My Tests Discussion in ' Audio Hardware ' started by allied333, Jun 5, 2021. Dec 3, 2023 · Hi Guys, Testing some tubes on the 6000. The 12AU7 has an even lower gain output than the aforementioned 12AT7, at 20. com: vacuum tube testerCheck each product page for other buying options. Some testers are more accurate than others and tube testing is an art not a science. I shall do so soon, so as to compare my results to theirs. I thought I’d share my results incase anyone else was interested. On the chart the conductance is 1250. He said Jul 27, 2025 · The JJ 12AX7 / ECC83 Preamp Vacuum Tubes (Three Pack) are a fantastic upgrade for your guitar amp. Jul 5, 2025 · "D" Getters. The most accurate method to test tubes, the curve plots can actually be compared to the printed examples for each tube type that appear in the manufacturer technical data sheets and books. "Tested on a Hickok6000A So for this critical tube, like 12AX7, we use autobias testing. some say 65/75 or 90/100 and claim them to be new or "very strong". Since 1993. Free shipping on many items | Browse your favorite brands | affordable prices. Jun 5, 2021 · 12AX7 Tubes - My Tests Discussion in ' Audio Hardware ' started by allied333, Jun 5, 2021. com. Z Carmen Ghia through a "cheapo" 1x12 cabinet (with alnico speaker) from Ruby Tubes. See full list on killerrig. Copyright note This page was moved here Oct 26, 2009 · I've owned a vacuum tube based pre for about six months and am ready to start experimenting with different 12au7 and 12ax7 tubes. 99 Jul 25, 2019 · Then into a Weston Acoustics Troubador that was specially made to run triode connected PP and I believe optimized for EL34s (using different NOS 5U4G, tube store blue base EL34 tubes and two of the above 12AX7 tubes) into B&W CM8 series one towers. INTRODUCTION: I tested 10 different kinds of 12AX7 pre-amp tubes using a Dr. I used those and same Era 12AU7 in my Zesto preamp and honestly the premium JJ 12ax7 gold and ecc802 gold (12au7) sounded better in that unit. The MaxiPreamp II Digital Tube Tester is a compact, precision measurement station for the test bench or sales counter. Looking for more detail and midrange magic. What We Like: Well-balanced, colorful tone: Enjoy a rich sound with clear lows, mids, and smooth highs. If a seller refers to t For your consideration is a 12ax7 tube. May 1, 2010 · i see a lot of tubes on ebay with test readings listed. PHILCO Tube Lettering & Relabeled Tube Boxes. Short Grey Plates. Sep 10, 2025 · How to test ECC83 - E83CC - 12AX7 - ECC803S Last Update: 09/10/2025 05:54:46 JACMUSIC. Note: SYLVANIA 12AX7 Tubes Generally Test High on the TV-7. The Amazon. The Mar 22, 2013 · The Noise Test Setup 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. Oct 26, 2009 · There are all kinds of testers and they give their readings in a variety of numbers, so you can see these same tubes scored as 90/90, 91/92 for example. Diminished sound quality, microphonic behavior, and visual indications of tube wear are all signs that a 12AX7 tube may need replacing. We want to find the corresponding grid voltage deviations, which are the limiting values for a good tube. com Aug 2, 2023 · Recognizing the signs of a bad 12AX7 tube is crucial for maintaining the optimal performance and sound quality of your tube amplifier. some claim 2000 transconductance reading for 12ax7 as new. Get the best deals on Sylvania 12ax7 Nos when you shop the largest online selection at eBay. Price and other details may vary based on product size and color. These tubes bring a rich and balanced sound to your playing. Let's experiment, learn, test, compare and bust some myths About this listing 12AX7/ECC83 Telefunken Red Tip Smooth Plate MaxiPreamp2/TV7 tested (1) tube lot See photos for test results Show More Jun 5, 2021 · 12AX7 Tubes - My Tests Discussion in ' Audio Hardware ' started by allied333, Jun 5, 2021. SYLVANIA CHS 12AX7 ECC83 USA MILITARY BLACK-PLATE TUBE AMPLITREX TESTED RESULTS! Brand New · SYLVANIA $87. Below are the test results on a calibrated Hickok TV-2 test set. Dec 5, 2014 · Here’s a comparison I’ve just done of various new production 12AX7 valves in a Fender Twin. . " or " tube <1> 1450 / 1450 tube <2> 1400 / 1450" Can anyone explain how to interpret these fig Feb 16, 2024 · Late fifties to early 60"s RCA 12ax7 is what I am using in my Quicksilvers. Oct 22, 2014 · Put a socket saver with test points built in, in between the tester and the tube, so you can check voltages while you're testing tubes. (2) Siemens 12AX7/ECC83 TubesMATCHED PAIR!Up for sale is an extremely rare MATCHED PAIR of Siemens ECC83 tubes. Consistent good sound and easy to get. They offer clear highs and solid lows, making your guitar tone really sing. Relabeled Tube Boxes Provided for Your Convenience. Check your 12AX7 (ECC83) guitar hi-gain preamp tubes without expensive equipment (your own amp only!) Welcome to my small lab. 49 Was: $124. What would be some recommendations? Apr 10, 2016 · We have some tips and tricks to help determine if you have a bad vacuum tube when you do not have access to a tube tester. The stock tubes are rebranded JJ’s with the McIntosh logo. One was from China with the Golden lion logo and other was from Russia with the Golden Lion logo. The Golden Lion from Russia sounded and looked identical inside to the Russian 12AX7LPS. Emission testers were useful back when every household had a Tube TV. At Fuzz Audio, we test lots and lots of tubes, and with Mullard valves it is not uncommon for every tube in a batch to test nearly identical to one another (with balanced triodes as well). Get the best deals on Ge Long Plate 12ax7 when you shop the largest online selection at eBay. The tube that boasted a cyro treatment from China did not sound good. for example "Test results: 80/81 & 80/83, whereas a minimum good on my Hickok Cardmatic tester is 50/50. The pre was voiced with those tubes and George of Zesto said there was a reason he used them. I was plugging into the Vibrato channel (flat EQ) and swapping out the valve for the 1st gain stage of that channel. My questions: 1-On the 3000 shunt setting I disregard the fact that the reading is in the “replace” segment of May 4, 2023 · 12AU7 tubes are also closely related to the 12AX7, but again, despite their shared qualities, these two vacuum tubes produce significantly different results. That, coupled with their legendary tonal complexities, balance, low noise floor, and longevity make the Mullard 12AX7 the best 12AX7 ever made. Jul 20, 2001 · Looking at test results for various used 12ax7s, following are two examples, with explanations offered by sellers in quotes: 1. On a TV7, the minimum Gm for a 12ax7 is 800, which is base for most Hickok-based circuits. Tube manufacturers optimized the design around this actual operating condition. Never used except to verify operation in a preamp and for testing using a calibrated TV-2 tester (see last photo). These are also known as a 12AX7/CV4004/5751 tube type. More clean headroom: Get more volume before your amp May 22, 2014 · I performed a test of two Golden Lion 12AX7 tubes. After you set the line adjust, check the heater voltage, then watch it when you press the test button. It takes some practice to get a tube to give the same reading twice. Vacuum Tube Valley (VTV) did the same in issue #1, Spring 1995, but I have not read their 12AX7 report. This Set is No Exception. All rights reserved. This has resulted in current production 12AX7 often showing as bad on classic Emission testers, even though the tubes are working 100% per spec. Apr 14, 2017 · I've been looking online at some NOS 12AX7 tubes and I see various specs quoted. Sep 14, 2019 · I decided to take the day and roll some 12AX7 pre amp tubes to try to decide what is my best sounding tube and I can't really say that only one brand of tubes would be my choice in every amplifier. From the historical datasheets the good/bad limits can be found, using +/-30% deviation of the plate current. Not cheap but real NOS sound great. 5 days ago · A dynamic mutual conductance test is a method for evaluating a vacuum tube by applying a small AC voltage to the control grid while maintaining the proper DC voltages on the other elements. It’s designed to test dual triodes and other signal tubes for the electrical characteristics of gain (A), transconductance (Gm) and noise (dBm). SYLVANIA Mfg. The amp is 15-16W or so depending on the type of rectifier used. The amp is a Twin Reverb Reissue with Celestion G12-65 creamback speakers and has all the stock Sovtek valves. Of course, putting too much Here I report the results of a 12AX7 vacuum tube comparison, where THD of different tubes was measured, when used with the same Hi-Fi vacuum tube amplifier. "D" Getters. Feb 16, 2024 · I thought I’d be able to squeeze a bit more performance from my McIntosh C22 MK V by doing a little tube swapping. though there's probably wide range of result scale depending on tester used, what's "transconductance" reading Understanding vacuum tube test scores can be the difference between adding an amazing valve to your collection and wasting $100. Aug 23, 2025 · One GE 12AX7 ECC83 Tube NOS NIB Short Grey Plate TV-7 & AMPLITREX Test Results Shining Light Audio (5943) 100% positive Jul 20, 2025 · Two Excellent PHILCO 12AX7 Tubes. Aug 5, 2020 · Which 12ax7/5751 tube won the right to be called the best and the worst? Updated August 5th, 2020 Based on user ratings in the last 8 years, here is the list of winners and losers. Triode 1: 95% Gm / 67 min. Each tube tester manufacturer determines a minimum acceptable Gm score based upon the combination of the test parameters of their own machine. When I set the shunt to the 3000 mark and hit the test button the tube comes in around 1000 microohms. to passTriode 2: 90% Gm / 67 min. So unless you're 3,000 years old and you invented the 12AX7 in between shifts on the Sphinx, I don't think you know whether newly manufactured preamp tubes last longer than the ones made in the 50's. A typical new 12AX7 will test between approx 1100 and 1400, with 1250 being considered “nominal” or average for a new 12AX7. Two Excellent SYLVANIA 12AX7 Tubes. Power tubes are a different story, but this thread is solely about dual-triodes. doewtq 3sp mm yjoko igf txb6z swnsb ir7a0 m1fy m4q6nw1u