Actually, the purpose of the getter flashing isn't just to absorb leftover air/oxygen that wasn't removed by the evacuation pumps, but also to remove gaseous contaminants that cook out of the metal parts over time as they are heated (in particular, malfunctioning circuits that cause tubes to red-plate can also cause the tubes to become "gassy", whereby the imperfect vacuum becomes an emitter of electrons). Tube-manufacturing processes in the old days included baking the plates and other metal parts *in Hydrogen*! to drive out contaminants (especially water vapor, as well as solvents and oils). I don't know if they still go to such lengths with vacuum tube manufacturing nowadays. (Would you want to live next door to a manufacturing plant that bakes hydrogen in an oven?). PS, the getter flashing, usually a barium/magnesium material (sometimes called misch metal) is splattered onto the inside of the glass with a high energy magnetic or RF field, almost like a microwave burst, and doesn't require any direct electrical connection to the tube pins. The pins are said to be made of Monel, a nickel alloy with the same expansion coefficient as the glass.
Wow! I've seen so many diagrams of the guts of a valve, but this beats them all. Amazing how sparsely wound the suppressor grid is. A big thank-you for this.
Watching you pull the control, screen and suppressor grid structures off of the tube made me think of the lyrics from "Emerson Lake and Palmer: "every day a little madder, a little sadder/ *someone get me a ladder* 😁. The song concludes "still, you turn me on" ---- which would not be a good thing to do to a tube that no longer exists in a vacuum! 💥🔥
Perhaps JJ is sourcing their glass from the same place that made the giant aquarium tank in Berlin that cracked and let all the water and fish out 😳....
I would love to see a comparison between American-made beam-power-tubes and their British pseudo equivalents, such as a 6CA7 cut open and compared to an EL34; and a 6BQ5, and a 7189, compared to an EL84. The American-made tubes supposedly or presumedly aren't true pentodes because of the Phillips patent.....and besides the lack of a suppressor grid, there may also be other differences, such as dual pin-connections for grids and/or screens on some examples of the 6BQ5/EL84/7189 family of tubes.
Thanks Brad, for some interesting insight, on the inner workings of a Valve ! 👍 What's your take, on what causes Microphonics ? 🤔 4 out of 5 of the last EF86 NOS Valves I've tracked down, have been Microphonic . They worked & sounded Ok . Cheers ✌️ P.S. Looking forward to the Bad Cat repair Video ! 😉 #bradsguitargarage #knowyouramp #el34 #knowyourguitar #badcatamps
G'day Curtis, thanks for the Canuckistanian dollars! While I know nothing about what's involved in designing a valve, it seems to be a combination the diameter of the grid forming posts, the tightness of the mica washers, whether the mica washer edges have been comressed due to shock in shipping or vibration in a combo cabinet, the length of the elements, you name it. EF86's are particularly difficult to find with low microphonics, despite what the marketing dickheads say in the product description on the vendor's websites. They are also usually positioned in the first gain stage, making them more sensitive in general to such issues.
Thank You Brad, this is very interesting, i wonder if all power tubes are build the same but they just have different materials and sizes/proportions. Also if preamp tubes are the same in construction since they do a kinda different job (i think?) like 12AX7..
Actually, the purpose of the getter flashing isn't just to absorb leftover air/oxygen that wasn't removed by the evacuation pumps, but also to remove gaseous contaminants that cook out of the metal parts over time as they are heated (in particular, malfunctioning circuits that cause tubes to red-plate can also cause the tubes to become "gassy", whereby the imperfect vacuum becomes an emitter of electrons). Tube-manufacturing processes in the old days included baking the plates and other metal parts *in Hydrogen*! to drive out contaminants (especially water vapor, as well as solvents and oils). I don't know if they still go to such lengths with vacuum tube manufacturing nowadays. (Would you want to live next door to a manufacturing plant that bakes hydrogen in an oven?). PS, the getter flashing, usually a barium/magnesium material (sometimes called misch metal) is splattered onto the inside of the glass with a high energy magnetic or RF field, almost like a microwave burst, and doesn't require any direct electrical connection to the tube pins. The pins are said to be made of Monel, a nickel alloy with the same expansion coefficient as the glass.
Wow! I've seen so many diagrams of the guts of a valve, but this beats them all. Amazing how sparsely wound the suppressor grid is. A big thank-you for this.
Here's a Mullard film showing tube parts and internals. ua-cam.com/video/5WCWejeRR_s/v-deo.html
Super cool! Definitely demystifies what we see in the schematics!
Watching you pull the control, screen and suppressor grid structures off of the tube made me think of the lyrics from "Emerson Lake and Palmer: "every day a little madder, a little sadder/ *someone get me a ladder* 😁. The song concludes "still, you turn me on" ---- which would not be a good thing to do to a tube that no longer exists in a vacuum! 💥🔥
It would have woken me up with those non-insulated pliers, however!
Perhaps JJ is sourcing their glass from the same place that made the giant aquarium tank in Berlin that cracked and let all the water and fish out 😳....
Cool, thanks for showing this!
Great video, much appreciated! if its milky, you know you've blown it!
That was cool.
1st look at the makeins! I have arrived ✝️
Cool beans. Dissect a beam power tube next?
I would love to see a comparison between American-made beam-power-tubes and their British pseudo equivalents, such as a 6CA7 cut open and compared to an EL34; and a 6BQ5, and a 7189, compared to an EL84. The American-made tubes supposedly or presumedly aren't true pentodes because of the Phillips patent.....and besides the lack of a suppressor grid, there may also be other differences, such as dual pin-connections for grids and/or screens on some examples of the 6BQ5/EL84/7189 family of tubes.
Two similar failures at the same time. Last time I saw that was after someone chucked a vodka and coke inside 😅
Thanks for posting this; fascinating and demystifying.
Aren't those angry pixies toxic AF? - Don't do this at home kids.....
Yeah, defo don't lick it.
Thanks Brad, for some interesting insight, on the inner workings of a Valve ! 👍
What's your take, on what causes Microphonics ? 🤔
4 out of 5 of the last EF86 NOS Valves I've tracked down, have been Microphonic . They worked & sounded Ok .
Cheers ✌️
P.S. Looking forward to the Bad Cat repair Video ! 😉
#bradsguitargarage
#knowyouramp
#el34
#knowyourguitar
#badcatamps
G'day Curtis, thanks for the Canuckistanian dollars!
While I know nothing about what's involved in designing a valve, it seems to be a combination the diameter of the grid forming posts, the tightness of the mica washers, whether the mica washer edges have been comressed due to shock in shipping or vibration in a combo cabinet, the length of the elements, you name it.
EF86's are particularly difficult to find with low microphonics, despite what the marketing dickheads say in the product description on the vendor's websites. They are also usually positioned in the first gain stage, making them more sensitive in general to such issues.
Thank You Brad, this is very interesting, i wonder if all power tubes are build the same but they just have different materials and sizes/proportions.
Also if preamp tubes are the same in construction since they do a kinda different job (i think?) like 12AX7..
Here is a 1943 instructional film showing the construction details of early triode tubes. Enjoy! ua-cam.com/video/acGXBJv6AT4/v-deo.html