joessportster Posted November 1, 2015 Share Posted November 1, 2015 So I started using the power conditioner, which puts out a few volts more than my outlets Listening to my setup the Havana Dac and the right channel was not playing, I pecked on the tubes and when I pecked on the Havana I got a loud painful pop and then the right channel started to play............A couple minutes later and the right channel stops again at this point I shut Havana down and swap the tube. It plays fine now on both channels Looking at the tube I pulled the top discoloration around the getter is deformed compared to the others I have, This is a 1948 WE 396a tube any thoughts could the higher voltage coming in affect the tubes ? Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted November 1, 2015 Share Posted November 1, 2015 So I started using the power conditioner, which puts out a few volts more than my outlets Listening to my setup the Havana Dac and the right channel was not playing, I pecked on the tubes and when I pecked on the Havana I got a loud painful pop and then the right channel started to play............A couple minutes later and the right channel stops again at this point I shut Havana down and swap the tube. It plays fine now on both channels Looking at the tube I pulled the top discoloration around the getter is deformed compared to the others I have, This is a 1948 WE 396a tube any thoughts could the higher voltage coming in affect the tubes ? I'm thinking no way unless your outlet power is way over 120VAC. If it was a power tube on an old 1960's era amp maybe but not on a modern piece of tube equipment. That said, the WE 396a tube is a long lasting tube. Have you got an idea of how many hours on this particular tube or the date code off of it? Quote Link to comment Share on other sites More sharing options...
muel Posted November 1, 2015 Share Posted November 1, 2015 Who knows how many hours that WE tube had on it before you installed it. I had one in my Havana that went bad after a couple of years. I know it had seen some use before it got to me but I have no way of knowing how much. Quote Link to comment Share on other sites More sharing options...
joessportster Posted November 1, 2015 Author Share Posted November 1, 2015 No I dont know what the tubes use was prior to me getting it, it was from 1948 I got it used and tested however there were no numbers posted for the test, simply stated tested strong.........Had good feedback so ?? I cant complain I got 4 of them for low $$$ so I am still looking good if I dont loose more.................I need to get a tester but those damn things are expensive If anyone has a tester and would like to test the tube I will send it along free.................if its still good you have a good tube, if its not at least I have confirmation Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 1, 2015 Share Posted November 1, 2015 Hi Joe, I have a couple of theories. Since that tube is an output buffer it is probably a cathode follower configuration. That particular tube has a heater to cathode max voltage rating of 90v. When the tube's heater is not warmed up it can't conduct current but there is still high voltage present on the cathode unless there is a diode from grid to cathode or a time delay circuit, most likely the latter. Those tubes are dual triodes so each channel has it's own triode. Possibly the right channel's cathode didn't have a good ground connection and when the time delay circuit lifted there was over 90 volts at the cathode, tapping the tube caused the connection to come back but the tube might have been damaged due to an arc from cathode to heater. Another theory is that the tube had a small crack and lost it's vacuum, the slight tap ended it's life completely, if the getter is now white this is most likely the situation. I doubt it was the slightly higher voltage, if it was it would most likely effect both channels. Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted November 1, 2015 Share Posted November 1, 2015 If anyone has a tester and would like to test the tube I will send it along free.................if its still good you have a good tube, if its not at least I have confirmation If the getter flashing is all white it's probably toast and not worth mailing out. But if you want I have a nice calibrated Hickok 539b that I would be happy to fire up for you. PM me if interested. Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted November 1, 2015 Share Posted November 1, 2015 No I dont know what the tubes use was prior to me getting it, it was from 1948 I got it used and tested however there were no numbers posted for the test, simply stated tested strong.........Had good feedback so ?? I cant complain I got 4 of them for low $$$ so I am still looking good if I dont loose more.................I need to get a tester but those damn things are expensive If anyone has a tester and would like to test the tube I will send it along free.................if its still good you have a good tube, if its not at least I have confirmation I've got a tube tester or two that were resident in a couple of tube manufacturing plants in their heyday's of the mid 1950's to mid 1960's but I'm up on the moon from where you are. I suspect that you can find someone closer and cheaper to ship too. As to hours on tubes, I keep detailed records on every power tube and every expensive non-power tube I've owned in an Excel Spreadsheet except for one tube amplifier at a 2nd residence. The WE396 is a long lasting tube but if yours is dated 1948 I suspect it was most likely a pull from some WE telephone or signal equipment. That tube was optimized for voiced communication. Quote Link to comment Share on other sites More sharing options...
joessportster Posted November 1, 2015 Author Share Posted November 1, 2015 (edited) JPM Getter does not look white, I think I would like to mail it out if you dont object PM me an address and I will send it out tomorrow Thanks for the offer Joe Edited November 1, 2015 by joessportster Quote Link to comment Share on other sites More sharing options...
Fjd Posted November 1, 2015 Share Posted November 1, 2015 This is just a general observation and I have not done any accumulation of empirical data to study; however, I have noticed that in many instances regarding the life of a tube that is testing as "new" really doesn’t mean a tube has a long life left. It seems to me in relation to the tubes that I’ve bought new, the tube will continue to test new for maybe 70% to 80% or so of its life (keeping in mind the +/- 7% to 9% deviation of accuracy on my Roger Kennedy upgraded Hickok 539b tester). In general, in many instances the test scores would drop when the tube was in the last 20% to 30% of its life. I think as a hobbyist without noticing this trend, I would have thought the tube would just gradually wear down similar to a tire, but they don't. 2 Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted November 1, 2015 Share Posted November 1, 2015 This is just a general observation and I have not done any accumulation of empirical data to study; however, I have noticed that in many instances regarding the life of a tube that is testing as "new" really doesn’t mean a tube has a long life left. It seems to me in relation to the tubes that I’ve bought new, the tube will continue to test new for maybe 70% to 80% or so of its life (keeping in mind the +/- 7% to 9% deviation of accuracy on my Roger Kennedy upgraded Hickok 539b tester). In general, in many instances the test scores would drop when the tube was in the last 20% to 30% of its life. I think as a hobbyist without noticing this trend, I would have thought the tube would just gradually wear down similar to a tire, but they don't. In my experience, once a power tube test's 70% or less its on it's way to tube heaven. Some tubes, like 7189's tend to not go quietly in the good night when they finally go. Quote Link to comment Share on other sites More sharing options...
Fjd Posted November 1, 2015 Share Posted November 1, 2015 This is just a general observation and I have not done any accumulation of empirical data to study; however, I have noticed that in many instances regarding the life of a tube that is testing as "new" really doesn’t mean a tube has a long life left. It seems to me in relation to the tubes that I’ve bought new, the tube will continue to test new for maybe 70% to 80% or so of its life (keeping in mind the +/- 7% to 9% deviation of accuracy on my Roger Kennedy upgraded Hickok 539b tester). In general, in many instances the test scores would drop when the tube was in the last 20% to 30% of its life. I think as a hobbyist without noticing this trend, I would have thought the tube would just gradually wear down similar to a tire, but they don't. In my experience, once a power tube test's 70% or less its on it's way to tube heaven. Some tubes, like 7189's tend to not go quietly in the good night when they finally go. That makes sense. In trying to contrast the life of a tube with tire wear, I was actually describing the life span in percentages and not the testing results. For example, if a tube had a 10 month life span, it seems the tube tests as 'new' for about 7 of those months and when it moves from new, I may have about 3 months left. Of course, not in all instances, but it seems to work this way more often than not. Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted November 2, 2015 Share Posted November 2, 2015 This is just a general observation and I have not done any accumulation of empirical data to study; however, I have noticed that in many instances regarding the life of a tube that is testing as "new" really doesn’t mean a tube has a long life left. It seems to me in relation to the tubes that I’ve bought new, the tube will continue to test new for maybe 70% to 80% or so of its life (keeping in mind the +/- 7% to 9% deviation of accuracy on my Roger Kennedy upgraded Hickok 539b tester). In general, in many instances the test scores would drop when the tube was in the last 20% to 30% of its life. I think as a hobbyist without noticing this trend, I would have thought the tube would just gradually wear down similar to a tire, but they don't. In my experience, once a power tube test's 70% or less its on it's way to tube heaven. Some tubes, like 7189's tend to not go quietly in the good night when they finally go. That makes sense. In trying to contrast the life of a tube with tire wear, I was actually describing the life span in percentages and not the testing results. For example, if a tube had a 10 month life span, it seems the tube tests as 'new' for about 7 of those months and when it moves from new, I may have about 3 months left. Of course, not in all instances, but it seems to work this way more often than not. Many older NOS power tubes with maker's like RCA, GE, Western Electric were built to last for tens of thousands of hours. For example I run a modern set of mono-block amps that use 211 power tubes. I have several pairs of pre-WWII GE VT-4C tubes that I acquired along with a single pair of VT-4B tubes made by RCA in the 1920's. These tubes were initially made to be used by the 2 way radios in B-17, B24, etc. US Bombers, they were also used in the British/Canadian made Lancaster Bomber radios (this is the bomber that my father served with during the war). These radio's were both huge and out-dated by the 1940's. One reason they probably weren't replaced with smaller units was the VT-4C tubes they used never seemed to quit working unless they were damaged by enemy fire. That and there were hundreds of thousands of VT-4C tubes made and sold to the air force as spares. Quote Link to comment Share on other sites More sharing options...
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