| #53 Wurlitzer GE Long Plate Halo Getter 12AX7 Tests Strong/Very Good Balance There are 11 photos of the item below TESTER USED: Vacuum Tube Valley Dual Triode Characterizer (VTV) I borrowed this from a friend that used to be a Groove Tube Dealer, It is the same tester used by the tube retailer Doug's Tubes to evaluate preamp tubes (they comment on how they use the tester and why in their FAQ, see those comments below). While I am not a;regular tube vendor, having access to this tester (and having instruction from someone with years of professional experience) has I believe allowed me to present the tubes honestly (the tubes I'm selling are all of my preamp tubes I've accumualted over the years, I just have way more than I will ever need). Plese take the time to read the notes about the tester TESTER SUMMARY: This is not a well known tester (I read less than 500 were made, my friend that loaned me the tester said the person that made and sold this has since passed away), it is a modern era tester designed to test dual triode preamp tubes, with an emphasis on a very precise balance test (that does not rely on gain results, Doug's Tubes mentions this as does the manual, there are photos of the manual pages below, so with this tester the gain numbers may not match but the tube might be perfectly balanced), the balance test according to the manual was developed to measure precise balance to a standard that would identify true NOS "super premium" tubes. It also measures gain and has a built in speaker to test microphonics and noise. TEST RESULT TERMS (please see the additional notes further down): GAIN is pretty standard, a number pair based on a range, BALANCE, the terms I use are my own and are defined further down below, each term such as EX, GOOD, OUT, etc is based on the location of the balance meter needle during the test (you can see the meter in the photo of the tester below). My friend said any result between the two ends of the meter range can be read as a tube with good or acceptable balance, and that the closer to center the more perfect the balance. He also said most tubes (especially modern tubes) do not land near the center of the balance meter and that many tubes that measured as balanced on his calibrated triplett or hickok can measure as unbalanced on this tester, The meter needle goes past the UNBAL ends of the range so tubes out of balance are identified as well. MICROPHONICS is either a result of YES or NO (and sometimes with notes to accompany the results). The manual notes that tubes measured as microphonic should not be used in a sensistive positition such as a phono preamp or the 1st position in a combo amp. I did put some of the tubes that measured microphonic in a small combo amp and they sounded fine (but that's not to say they all would, I'll just guarantee that the microphonic tubes are guaranteed as useable or they can be returned) . NOISE (the noise test is too subjective for me to use accurately), this is a subtle listening test where the tester makes subjective evaluations of white noise played through the tube and determining how noisy the "white noise" sounds, this test would require alot of experience with the noise test to claim meaningful results, because of this I didn't attempt to test or grade noise, but of course tubes that are defective due to excessive noise can be returned (my friend told me the noise test is really only a guidline, that the only real way to test for noise is to put them in a circuit like a higher end phono preamp) PLEASE SEE PHOTOS Tube may be dirty (I didn’t want to risk wiping off the lettering), Pins may not be clean, and or have small bends or not be perfectly aligned or straight. I do multiple views so you can see any date codes and getter shape; Tubes do not include a box unless shown in the photo RETURNS: If you feel the tube you receive has been misrepresented or is defective in some way (excessive noise/microphonics) then it can be returned. My recommendation if you need a low noise tube, pick only those with strong gain, excellent balance and no microphonics INTERNATIONAL BUYERS RETURN POLICY For International buyers, tubes are sold strictly as-is. I only use the ebay global shipping program, I know it is expensive (sorry). It is not practical to accept returns from international buyers. International buyers should only choose tubes with the best test results to reduce risk of disappointment, buyers should avoid microphonic tubes in the event it does not work for it’s intended use or is unusable due to microphonics/noise,international buyers accepts the risk of making the purchase and understands returns are not accepted and that the tube is sold as-is. COMBINED shipping for multiple tubes (wait for me to send an invoice after purchases) #53 Wurlitzer Branded GE Long Plate Halo Getter 12AX7 Tests Strong/Very Good Balance
BALANCE TEST RESULT TERMS USED Meter is a half arc, at each end is UNBAL and in a small center section is OK (see photo of tester to see meter), EX+ (meter directly in middle of OK section) EX (meter within OK section) VERY GOOD (meter needle close to edge of OK section) GOOD (meter approx midway between OK and UNBAL) ACCEPTABLE (meter in area between GOOD and close to UNBAL label) OUT (meter on or past UNBAL, but meter needle not pegged, manual indicates in this case the two triodes have an imbalance from anode to anode greater than approx .5V) OUT/PEG (meter pegs past UNBAL, very unbalanced) COMBINATION such as , VERY GOOD/EX (would be right on the edge of OK section) GOOD/ACCEPTABLE (between GOOD and UNBAL) MICROPHONICS TEST RESULTS TERMS USED YES (tube produces feedback/howls) NO (does not howl or produce feedback. If tapped, a glass tap may or may not be heard, but it does not start to ring or feedback) YES/NO (tube shows some microphonic behavior that is described in the notes of the grade given) ADDITIONAL COMMENTS On the Vacuum Tube Valley Dual Triode Characterizer Tube Tester GAIN Measured gain is not to be seen as a balance test, this is a paragraph from the Doug’s Tube FAQ on the meaning of gain numbers on this tester: "The gain numbers for your preamp tube represents the gain of each triode as measured on our Vacuum Tube Valley dual triode characterizers(VTV). The gain scale is not to be construed as the actual Mu of the tube, but is an arbitrary scale used by VTV that helps us grade each preamp tube and compare them to each other. Since many of the preamp tubes we sell have dual triodes, you'll find two numbers on the side of the tube. The higher the number, the higher the gain. We consider 110/110 or more per side to be HIGH GAIN tubes." BALANCE: The meter has a highly accurate balance test that is not based on the gain results of each triode, so you may see un-matched gain numbers on a balanced tube, or vice versa (the comments from doug’s tubes also mentions that and why).The manual indicates that the designers of the tester found that true NOS tubes of a "super premium" or instrument grade always had a closely matched DC offset between triodes and mention this test is solid to verify claims of NOS, you can read this passage in a photo of a manual page below. This is a comment from the Doug's Tubes FAQ on Balance and this tester "What do balanced triodes mean? Do I need them? Dual triode preamp tubes like the 12AX7 really have two separate tubes inside one glass envelope. 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. These may or may not also have the same gain on each triode but are still considered balanced. Chances are that these are not required for your particular circuit. What we have observed after testing 1000's of preamp tubes using the Vacuum Tube Valley dual triode characterizer is that tubes with balanced triodes seem to be more consistent with a standard specification tube as to gain and low noise and microphonics." MICROPHONICS Tester AMPLIFIES conditions to produce microphonic noise, it runs a white noise audio signal through the tube and plays it back on the built in speaker. Test is designed to produce feedback/howling/ringing/rattling in a clear audible way. As mentioned above, I’ve tried some of the microphonic tested tubes and so far they have all been useable in my combo amp, and I know some have been used in a George Wright AG phono preamp in the past. So a microphonic result does not mean the tube is bad, however I haven’t listened to each tube in a normal audio circuit so it is possible a microphonic tube will not work for your application, tubes listed as microphonic are guaranteed useable but not necessarily in critical conditions. If your tube is unusable because of microphonics or noise it can be returned NOISE: The NOISE test on the tester is not quantifiable in terms of a numeric value. As mentioned above the tester runs white noise through the tube and the user is supposed to listen to the noise to listen for differences from a known low noise reference tube, My friend that loaned the tester can listen to the white noise and detect subtle differences, but even with his experience he considers the NOISE test a general guidline. He is always trying to find very quiet tubes for phono preamps and said the only way to really know the noise level is to listen to it in a sensitive circuit or to use the scope output on the tester to look at the signal, neither being practical for me. This is a comment from the Doug’s Tubes FAQ regarding the tester which references "noise" "....tubes with balanced triodes seem to be more consistent with a standard specification tube as to gain and low noise and microphonics I don't know if that is the case for all tubes or even a guidline for noise levels, but it is something to note --- See photos for condition details --- Will be well packed --- Buyer pre-pays endprice + Shipping -- USPS 1st Class or Padded Flat Rate Priority Envelope --- Payment must be received within 7 days of purchase. --- The item description is guaranteed to be accurate but all items are sold as-is unless otherwise stated. --- Washington State Residents add Sales Tax. --- I don't have a way to arrange for a local pick-up of this item, I'm sorry for the inconvienence 
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