8 Amperex 6922 PQ D Getter Gold Pin Vacuum Tubes - $400 (shipped in USA)Offered on behalf of a third party is a nice group of 8 Amperex 6922 D-Getter gold pin vaccum tubes. While I have these priced as a group of 8, I am open to splitting them up for the right offer. All 8 tubes have an identical internal construction. Seven have date codes from 1960, and the eighth is from 1959. Printing is marginal to very good on most of the tubes. Too many people play the "NOS" game, and I will never call something NOS unless (1) I have the original box (or I know for a fact that tubes were pulled from a bulk pack), (2) the tubes actually look unused as evidenced by the printing and pins (or there is a legitimate excuse for their appearance, such as the tube was stored under damp conditions), and (3) the tubes actually test like new. In the real world, that eliminates the vast (vast) majority of vintage tubes out there from NOS classification. These 6922s are not NOS but, as you will clearly see from the photo and results below, they still are in good condition and seem quite able to continue for a while. I have gone to the extra effort of double testing these tubes on a Weston 981 III and a Kaye Small Signal Tube Checker (just back from a checkup by George Kaye). On the Weston 981 III, min (65%) value is 1350, making about 2075 "theoretical" 100% (Gm = 6X meter). The results are as follows (rounded off to the nearest 50) (date code/meter): Tube #1 *0C 1800/1850 Tube #2 *0C 1900/1750 Tube #3 *9K 1750/1700 Tube #4 *0A 1800/1850 Tube #5 *0E 2050/2000 Tube #6 *0E 2000/1950 Tube #7 *0C 1750/1750 Tube #8 *0E 2000/1850 As indicated above, I went to the added step of testing these on a Kaye Small Signal Tube Checker. For those not familiar with the Kaye Small Signal Tube Checker, this device was sold some time back by Kaye Audio, and provides an INDICATION (see my TERMS AND CONDITIONS below) of noise, microphonics, gain and distortion. I do not use this piece of equipment very often, but it does provide what I believe to be useful information. UNFORTUNATELY, I DO NOT KNOW EXACTLY HOW THIS INFORMATION TRANSLATES INTO REAL WORLD PERFORMANCE. The noise and microphonics tests are totally subjective as they involve actually listening (the unit has a built in headphone jack), and I do not have a lot of experience judging, but here is my view. I define "noise" as the noise a tube inherently makes (after proper warmup). This often exhibits itself as pops, crackles and swooshing sounds. No amount of damping or anything else should affect this parameter, although the conditions under which a tube is run may make a difference (and it may change over time as the tube ages).
I define "microphonics" as the noise a tubes makes with external stimulus that I induce (like tapping), or where the tubes acts like a little microphone. This often exhibits itself as a ringing that can vary from slight that is transient (like a small bell), to excessive that is extended (or does not stop, like a gong). Tube damping, for example, might have an effect on microphonics. In the Kaye, the tube sits out in the open, so is subject to all environmental stimulus (which has a negative impact on noise and microphonics). The Kaye tester instructions actually recommend to keep the tester away from sources of electrical noise, such as transformers and fluorescent lights (how do you do that in the real world), and even shield the tube from light. By the way, I have NEVER tested a tube that was totally immune from some level of microphonic response. To get to the point, I rate the tubes for noise and microphonics on a scale of 0-5, with 0 being worst and 5 being best. The results are as follows (triode 1/triode 2): Noise (T1/T2) Microphonics (T1/T2) Tube #1 5/5 5/5 Tube #2 5/5 5/5 Tube #3 5/4 5/5 Tube #4 5/5 4/5 Tube #5 5/5 4/5 Tube #6 5/5 5/3 Tube #7 5/4 2/5 Tube #8 5/4 4/2 Just as a note, it appears that Triode #1 on the Kaye corresponds to Triode #2 on the Weston, and vice versa. The tubes that exhibit microphonic behavior were not "ringers" but rather were "little microphones" (I think this is better but am not entirely sure). Based on these results, my estimate is that a "tube pro" might sell Tubes #1-5 (or even Tubes #1-6) as phono grade, Tube #6 as line grade (not good enough for phono grade, but better than driver grade), and Tubes #7 and #8 as driver grade. Again, however, I must stress that I have no idea how these tubes might perform under real world conditions in real world equipment. The gain test is supposed to measure the gain of a tube in a class A circuit, cathode bypassed, with a -10 db 500 hz tone applied to the grid (please don't ask me what this signifies), and involves reading a meter (spec for 6DJ8 type is 27db). The results are as follows: Tube #1 27.5/27.5 Tube #2 28/28 Tube #3 26.5/27 Tube #4 27.5/28 Tube #5 27.5/27.5 Tube #6 28/28 Tube #7 27.5/28 Tube #8 28/28 These all appear reasonably balanced for gain. The output/distortion test is supposed to show the maximum output a tube can produce (measured in Volts, with spec being around 50) at 10% distortion. I do not, however, know how this might translate to sound. All tubes were at or above the 50 V mark on all triodes. In any event, this is definitely a nice group and, based on the tests results, you should easily be able to quad and/or pair up all of the tubes. As indicated above, while the listing is for 8, and I would like to sell all 8 as a group, I might be willing to split the group for the right offer. I can provide additional information or pictures upon request. GENERAL TERMS AND CONDITIONS – PLEASE READ CAREFULLY Please note that these tubes are being sold 'AS IS', but I will guarantee against a material misdescription in the listing. In such event, I will refund purchase price less shipping upon return of the tubes in the same condition as sent. PLEASE NOTE THAT I CANNOT GUARANTEE (OR EVEN REMOTELY PREDICT) HOW THESE TUBES WILL SOUND OR PERFORM IN YOUR EQUIPMENT. THE TEST RESULTS ARE ONLY PROVIDED AS AN INDICATION OF TUBE PERFORMANCE IN A VERY LIMITED (AND NON-IDEAL) ENVIRONMENT. OTHER THAN AS SET FORTH ABOVE, I EXPRESSLY DISCLAIM ANY LIABILITY WITH RESPECT TO THESE TUBES OR RESPONSIBILITY FOR YOUR USE OF THEM. Money order/cashiers check/personal check preferred, but all (other than US Postal money orders) must clear my bank first. I also accept Paypal for convenience (but add 3% to the total for USA, and 4% to the total everywhere else). Trade value might be considered, particularly for vintage EL34/6CA7 and 6550 tubes. In any event, feel free to propose something (tubes or audio equipment) and I will at least consider it and respond. Shipping in the USA via US Postal Priority Mail is included. If you are outside the USA, contact me for a shipping quote. Please check my feedback on Audiogon, Videogon and Ebay (ID=baileyler) and buy with confidence.
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