[/QUOTE]
Let's see how many steps:
1)Admitting: The subject was somewhat reluctant to give information but admitted to a military past as in VT-231. VT is very hard to decipher because it is too simple: It means Vacuum Tube.
Date of birth - T 4. Since Ken-Rad was sold to GE in 1945 it seems logical that 4 means 1944. If you assign a letter to each of the 12 months and want to confuse things you start all over with the letter N as January; in that case T is July. Ken-Rad 6SN7GT/VT-231 from July 1944.
2)Cleanup: The pins showed signs of abrasions. A touch up was done under a magnifying glass scraping the pins with a pen knife of Swiss origin.
3)Initial testing: The tube was tested in the GOTL and immediately started humming loudly. When tapped on top (you are not supposed to this with the tube lit up, but since the tube was made to military specifications it has to be able to take a little abuse) it emitted crackling and howling noises. Tapping on the chassis had the same unpleasant effects.
4)The treating team didn't really know what to do, so they resorted to applying an abdominal band of tightly stretched high temperature silicone tape around the glass envelope of the tube. At least it did not deface the tube since it has a black internal coating.
4b)Upon re-testing the noise and hum seem to have been lowered. Until it came back in full strength. The treating team decided on another treatment modality.
5)Heat treatment. Each tube pin was heat treated with an antique Radio Shack 35W soldering iron for 30 seconds. In order to endure this boring procedure, a pair of 12V triodes were inserted in the amp so that this procedure could be accompanied by music.
6)Shock treatment. After the heating of the tube pins was finished, the tube was re-inserted for further tests. The power button blue light hesitated a little to light up and the tube was glowing very brightly. Due to a glitch in the testing protocol a split second or two of 12V was applied to this 6V tube. ALWAYS CHECK THE VOLTAGE SELECTOR BEFORE PUTTING IN A NEW TUBE!
Did this finish the tube? Kaput? Is it all over Charlie KR?
No.
The tube survived the electric shock treatment. Before it s sounded more dull - now it sounds better. This was done serendipitously; this treatment modality is NOT recommended but c'est la vie.
The tube is still noisy and humming, but less hum.
7)Physical therapy: By tapping on the tube and moving it around a little in the socket and tilting it here and there, it is possible to find a position that is more quiet. This requires the use of sacrificial headphones lest a pop will blow your driver. The ones they give out on airlines are perfect for this but I have a bottom line Sennheiser HD201 the so far is holding up.
The tube runs hot - luckily the silicone tape acts as an insulator.
Maybe the tube is less noisy now but still humming.
As a last resort to tame this tube the treatment team decided on something more drastic.
8)High intensity kinetic acceleration/deceleration Rx: The tube was carefully and securely wrapped in a towel and smacked against my palm 10 times. Why 10 times? Why not?
9)After this final procedure the tube was tested for internal anomalies. By shaking it, it was determined that something is rattling in it. Maybe this accounts for the tube being able to function by jiggling it into certain positions. Due to the military blackout restrictions (tube coated black) the cause of the rattle could not be determined.
At this point the tube is usable. It is still microphonic and crackles if the chassis is tapped; however, when jiggling it into the right position, listening via headphones, I can turn up the volume to max on the GOTL (without music playing) and there is barely any hum or noise and then only at too high levels to listen to. I submit that my hearing isn't the best and I cannot hear very high frequencies (age related) that a younger person might hear.
At normal levels the tube now is fine and humpfrey. As a matter of fact, this is a very good sounding tube and it has the familial great bass that Ken-Rad is famous for.
I wish to give thanks to Chrisdrop who graciously sponsored this experiment.
Explanations as to the pathology and possible cures of the tube are welcome.[/QUOTE]
Well you did everything you could. Surgery under the microscope, chest compression, a tourniquet, you got out the paddles to try to get it back in rhythm... after all that the patient is limping and weary, but alive, and still showing signs of its heritage. The only question now is what's the bill for this emergency department visit? And does Chris have insurance?
Let's see how many steps:
1)Admitting: The subject was somewhat reluctant to give information but admitted to a military past as in VT-231. VT is very hard to decipher because it is too simple: It means Vacuum Tube.
Date of birth - T 4. Since Ken-Rad was sold to GE in 1945 it seems logical that 4 means 1944. If you assign a letter to each of the 12 months and want to confuse things you start all over with the letter N as January; in that case T is July. Ken-Rad 6SN7GT/VT-231 from July 1944.
2)Cleanup: The pins showed signs of abrasions. A touch up was done under a magnifying glass scraping the pins with a pen knife of Swiss origin.
3)Initial testing: The tube was tested in the GOTL and immediately started humming loudly. When tapped on top (you are not supposed to this with the tube lit up, but since the tube was made to military specifications it has to be able to take a little abuse) it emitted crackling and howling noises. Tapping on the chassis had the same unpleasant effects.
4)The treating team didn't really know what to do, so they resorted to applying an abdominal band of tightly stretched high temperature silicone tape around the glass envelope of the tube. At least it did not deface the tube since it has a black internal coating.
4b)Upon re-testing the noise and hum seem to have been lowered. Until it came back in full strength. The treating team decided on another treatment modality.
5)Heat treatment. Each tube pin was heat treated with an antique Radio Shack 35W soldering iron for 30 seconds. In order to endure this boring procedure, a pair of 12V triodes were inserted in the amp so that this procedure could be accompanied by music.
6)Shock treatment. After the heating of the tube pins was finished, the tube was re-inserted for further tests. The power button blue light hesitated a little to light up and the tube was glowing very brightly. Due to a glitch in the testing protocol a split second or two of 12V was applied to this 6V tube. ALWAYS CHECK THE VOLTAGE SELECTOR BEFORE PUTTING IN A NEW TUBE!
Did this finish the tube? Kaput? Is it all over Charlie KR?
No.
The tube survived the electric shock treatment. Before it s sounded more dull - now it sounds better. This was done serendipitously; this treatment modality is NOT recommended but c'est la vie.
The tube is still noisy and humming, but less hum.
7)Physical therapy: By tapping on the tube and moving it around a little in the socket and tilting it here and there, it is possible to find a position that is more quiet. This requires the use of sacrificial headphones lest a pop will blow your driver. The ones they give out on airlines are perfect for this but I have a bottom line Sennheiser HD201 the so far is holding up.
The tube runs hot - luckily the silicone tape acts as an insulator.
Maybe the tube is less noisy now but still humming.
As a last resort to tame this tube the treatment team decided on something more drastic.
8)High intensity kinetic acceleration/deceleration Rx: The tube was carefully and securely wrapped in a towel and smacked against my palm 10 times. Why 10 times? Why not?
9)After this final procedure the tube was tested for internal anomalies. By shaking it, it was determined that something is rattling in it. Maybe this accounts for the tube being able to function by jiggling it into certain positions. Due to the military blackout restrictions (tube coated black) the cause of the rattle could not be determined.
At this point the tube is usable. It is still microphonic and crackles if the chassis is tapped; however, when jiggling it into the right position, listening via headphones, I can turn up the volume to max on the GOTL (without music playing) and there is barely any hum or noise and then only at too high levels to listen to. I submit that my hearing isn't the best and I cannot hear very high frequencies (age related) that a younger person might hear.
At normal levels the tube now is fine and humpfrey. As a matter of fact, this is a very good sounding tube and it has the familial great bass that Ken-Rad is famous for.
I wish to give thanks to Chrisdrop who graciously sponsored this experiment.
Explanations as to the pathology and possible cures of the tube are welcome.[/QUOTE]
Well you did everything you could. Surgery under the microscope, chest compression, a tourniquet, you got out the paddles to try to get it back in rhythm... after all that the patient is limping and weary, but alive, and still showing signs of its heritage. The only question now is what's the bill for this emergency department visit? And does Chris have insurance?
Last edited:
I will be up til 4am again.
