Hi all, it's been forever since I've posted here. Lots of life stuff since then. Sorry for the long post.
I'm having difficulty testing GE JAN 5670W tubes I ordered from a reputable tube vendor, along with the 6922 adapter they sell. I bought 38 tubes and 18 adapters so that I'd have two full sets to populate the 6922 locations in my Sonic Frontiers Line 3 preamp (10x) and two Power 3 monoblock amps (4x each=8). The vendor is willing to replace the tubes I'm having issues with. I do, though, want to get to the bottom of why I'm getting the results to make sure the tubes are dodgy and that it's not just a weird quirk with testing this particular tube model, etc. Or an issue with my tester. I'd also like know of any tips to reliably test them if there's something else I can try.
I received the tubes just about two weeks ago. I went to test them on Sunday and I got a lot of troubling test results. Odd behavior. My tube tester is a B&K 747. It was professionally restored and calibrated by Doutt Electronics in 2002 ("Cap & Semi & Res Kit" + new sensitivity pot).
Note: Most of the testing I did was with the tubes as 5670's without the adapter. That is because they all test Bad when tested as 6922's using the adapter (testing from 25 to 39 in the Bad range). I've asked the vendor about why that is but have not received an answer back yet. (I do see that the 5670 sensitivity test setting on my B&K is 60 whereas it's only 24 for 6922 tubes. It might be that that alone causes all of the 5670 tubes to test bad as 6922's using the adapter. I'm waiting to hear the vendor's explanation on that. I would hate to think they would be "weak" in a 6922 application but don't know enough about tube/testing "physics" and what the test results mean to know one way or the other.)
Some tubes test fine. Allow a little warm up and the needle moves steadily to the Good range and its value. This is the type of test result that I've always gotten with this tester. I took some of my known good 6922 tubes and tested them to compare and they all followed this pattern (all tested Good, too). Some of the 5670 tubes tested consistently Bad (really low in at least one section) and those are definite rejects. However, about half of the 5670 tubes are giving me Bad or ? results, but also odd and inconsistent results. To make it easier, I'll separate points into numbered headings.
1. In contrast to normal test behavior (of moving steadily to their value), a lot of the tubes have a distinctively different test result pattern. Upon pressing the test button, the needle will quickly "Pop" with a jolt to a higher value then immediately drop to a worse value, often in the ? or Bad range. For instance Tube 35 jolts to 65 (? range) the immediately drops and sags to 47 (Bad). Tube 7 Pops to 65 then Drops to 41 or 42.
2. After getting a lot of weird results like this, I retested a few of the earlier ones that tested normally and they continued to test normally.
3. On tubes that Pop and Drop as described in #1 above, I will sometimes get worsening performance over immediate retests. (Varied wait times, maybe 5s, maybe 10s, maybe 30s.) For instance, Tube 24 1st Section: Pop to 80 Drop to 70, repeat test and Drop to 75. Retested the next day, the results were Pop 70 Drop to 59, then subsequent tests settled at drop values of 61, 63, and 65.
The next tube I tested (Tube 25) tested in the normal manner by steadily rising to 97 on the first section and 98 on the second. No Pop, no Drop.
4. On many tubes that Pop and Drop, if I hold the test button in for a long time the value very slowly rises, dramatically. By "long time", I mean like 20-30 seconds or more. For instance, Tube 30 Popped high, Dropped to 70 but with a very long press of the Test button (30s or more) the needle rose to 85 where it topped out and sat until I released the button.
Tube 35 was sometimes similar but also odd. 1st Section: Pop to 80, Drop to 65, extra long hold and it slowly rose to 82. I waited 30s and retested without a super long hold and it settled at 70. 2nd Section: Pop into the 90s, Drop to 82, Hold rise to 97. Wait 1 minute, retest, Pop to 92, Drop to 83, long Hold to 95. However, I then retested it right away without long holds and it settled at 60, then 60 again, then 60 again. What the heck?
5. I have only gotten "Good" test results on slightly less than half of the tube order. That is surprising because I thought NOS JAN military spec tubes from 1984 should be decent quality. The vendor said they were unaware of big problems with these tubes but who knows if people test them right away.
I can just return the ones that are giving me weird test results and the vendor will replace them. However, I don't want to be caught in a never ending loop of testing weirdness on the next batch. Getting odd results and retesting over and over again is very time consuming. So I'm trying to see if anyone here has any insight one way or the other on what might be going on or other steps I could take to figure this out. Like I said above, my B&K 747 has been working fine and gives me consistent results other than these tubes. I've used it to test 12AX7s, 6550C's, 6L6s, 6SN7s, 5U4GBs, 6922s and more without any problems. I would also like to be able to get a consistent testing regime so that I can sort the tubes for use as pairs in the sections of my preamp.
Thanks.
p.s. I am in Orange County, CA if anyone else lives nearby and has a reliable tube tester that I could cross-check some tubes on. I looked at the sticky for other OC people and didn't see anyone current. One was from 2005 and the other hasn't visited since 2012. I even searched the sticky for "California" and the remainder were in NorCal hundreds of miles away.
I'm having difficulty testing GE JAN 5670W tubes I ordered from a reputable tube vendor, along with the 6922 adapter they sell. I bought 38 tubes and 18 adapters so that I'd have two full sets to populate the 6922 locations in my Sonic Frontiers Line 3 preamp (10x) and two Power 3 monoblock amps (4x each=8). The vendor is willing to replace the tubes I'm having issues with. I do, though, want to get to the bottom of why I'm getting the results to make sure the tubes are dodgy and that it's not just a weird quirk with testing this particular tube model, etc. Or an issue with my tester. I'd also like know of any tips to reliably test them if there's something else I can try.
I received the tubes just about two weeks ago. I went to test them on Sunday and I got a lot of troubling test results. Odd behavior. My tube tester is a B&K 747. It was professionally restored and calibrated by Doutt Electronics in 2002 ("Cap & Semi & Res Kit" + new sensitivity pot).
Note: Most of the testing I did was with the tubes as 5670's without the adapter. That is because they all test Bad when tested as 6922's using the adapter (testing from 25 to 39 in the Bad range). I've asked the vendor about why that is but have not received an answer back yet. (I do see that the 5670 sensitivity test setting on my B&K is 60 whereas it's only 24 for 6922 tubes. It might be that that alone causes all of the 5670 tubes to test bad as 6922's using the adapter. I'm waiting to hear the vendor's explanation on that. I would hate to think they would be "weak" in a 6922 application but don't know enough about tube/testing "physics" and what the test results mean to know one way or the other.)
Some tubes test fine. Allow a little warm up and the needle moves steadily to the Good range and its value. This is the type of test result that I've always gotten with this tester. I took some of my known good 6922 tubes and tested them to compare and they all followed this pattern (all tested Good, too). Some of the 5670 tubes tested consistently Bad (really low in at least one section) and those are definite rejects. However, about half of the 5670 tubes are giving me Bad or ? results, but also odd and inconsistent results. To make it easier, I'll separate points into numbered headings.
1. In contrast to normal test behavior (of moving steadily to their value), a lot of the tubes have a distinctively different test result pattern. Upon pressing the test button, the needle will quickly "Pop" with a jolt to a higher value then immediately drop to a worse value, often in the ? or Bad range. For instance Tube 35 jolts to 65 (? range) the immediately drops and sags to 47 (Bad). Tube 7 Pops to 65 then Drops to 41 or 42.
2. After getting a lot of weird results like this, I retested a few of the earlier ones that tested normally and they continued to test normally.
3. On tubes that Pop and Drop as described in #1 above, I will sometimes get worsening performance over immediate retests. (Varied wait times, maybe 5s, maybe 10s, maybe 30s.) For instance, Tube 24 1st Section: Pop to 80 Drop to 70, repeat test and Drop to 75. Retested the next day, the results were Pop 70 Drop to 59, then subsequent tests settled at drop values of 61, 63, and 65.
The next tube I tested (Tube 25) tested in the normal manner by steadily rising to 97 on the first section and 98 on the second. No Pop, no Drop.
4. On many tubes that Pop and Drop, if I hold the test button in for a long time the value very slowly rises, dramatically. By "long time", I mean like 20-30 seconds or more. For instance, Tube 30 Popped high, Dropped to 70 but with a very long press of the Test button (30s or more) the needle rose to 85 where it topped out and sat until I released the button.
Tube 35 was sometimes similar but also odd. 1st Section: Pop to 80, Drop to 65, extra long hold and it slowly rose to 82. I waited 30s and retested without a super long hold and it settled at 70. 2nd Section: Pop into the 90s, Drop to 82, Hold rise to 97. Wait 1 minute, retest, Pop to 92, Drop to 83, long Hold to 95. However, I then retested it right away without long holds and it settled at 60, then 60 again, then 60 again. What the heck?
5. I have only gotten "Good" test results on slightly less than half of the tube order. That is surprising because I thought NOS JAN military spec tubes from 1984 should be decent quality. The vendor said they were unaware of big problems with these tubes but who knows if people test them right away.
I can just return the ones that are giving me weird test results and the vendor will replace them. However, I don't want to be caught in a never ending loop of testing weirdness on the next batch. Getting odd results and retesting over and over again is very time consuming. So I'm trying to see if anyone here has any insight one way or the other on what might be going on or other steps I could take to figure this out. Like I said above, my B&K 747 has been working fine and gives me consistent results other than these tubes. I've used it to test 12AX7s, 6550C's, 6L6s, 6SN7s, 5U4GBs, 6922s and more without any problems. I would also like to be able to get a consistent testing regime so that I can sort the tubes for use as pairs in the sections of my preamp.
Thanks.
p.s. I am in Orange County, CA if anyone else lives nearby and has a reliable tube tester that I could cross-check some tubes on. I looked at the sticky for other OC people and didn't see anyone current. One was from 2005 and the other hasn't visited since 2012. I even searched the sticky for "California" and the remainder were in NorCal hundreds of miles away.
