The Reference 6J5 Thread (L63, 6C5, 12J5, 6P5, etc.)

[L0rdGwyn]

I should probably add that the sellers probably don't understand themselves that the mesh parts are screens and not plates.

 

[triod750]

I should probably add that the sellers probably don't understand themselves that the mesh parts are screens and not plates.

'Educated' buyers often know much more than average sellers do, absolutely.

 

[pravous]

One more unique thing I noticed about the type 37 is that both pairs have a getter that looks like a button battery held in place by a wire.

Anyone know what this particular type of getter is called? Any other tube types that use this type?

 

[gibosi]

Anyone know what this particular type of getter is called? Any other tube types that use this type?

It's called "old".

 

[gibosi]

Anyone know what this particular type of getter is called? Any other tube types that use this type?

More seriously, I don't know anything about the names of the different styles of getter holders in these early 1930's tubes. I can say that what I would call the "inverted cup" style is very common in 27's and early 37's. However, by the mid 1930's globe-style bottles had been replaced by shoulderd bottles and the getters were small pieces of sheet metal with a small dimple.

 

[Xcalibur255]

I believe the dimple sheets are usually called foil getters.

 

[mordy]

I believe the dimple sheets are usually called foil getters.

Here is a picture of a foil getter:

In this article it says that foil getters are better, but I am not convinced that this is the case. After all, isn't the purpose of a getter to hold the reactive substance (usually Barium) that is fired up to remove impurities in the tube to achieve a better vacuum? What difference does it make if the getter is a band, a cup, a ring or D-shaped, as long as it does it's job?
https://tubemaze.info/what-is-foil-getter/

 

[bcowen]

Here is a picture of a foil getter:

In this article it says that foil getters are better, but I am not convinced that this is the case. After all, isn't the purpose of a getter to hold the reactive substance (usually Barium) that is fired up to remove impurities in the tube to achieve a better vacuum? What difference does it make if the getter is a band, a cup, a ring or D-shaped, as long as it does it's job?
https://tubemaze.info/what-is-foil-getter/

From what I've seen, the shape/configuration itself is not important -- it's an indication of when the tubes were made. Foil getters preceded horseshoe, D, O, and UFO getters, so the foil indicates an earlier manufacture. And IME, earlier is better when it comes to sonics. Perhaps overgeneralizing to some degree, but it follows along the progression pretty well.

 

[whirlwind]

It's called "old".

Ha

 

[Slade01]

From what I've seen, the shape/configuration itself is not important -- it's an indication of when the tubes were made. Foil getters preceded horseshoe, D, O, and UFO getters, so the foil indicates an earlier manufacture. And IME, earlier is better when it comes to sonics. Perhaps overgeneralizing to some degree, but it follows along the progression pretty well.

So, is the exception to the rule insofar to what you've said in the past that "Double Ds" are VERY important?

 

[mordy]

So, is the exception to the rule insofar to what you've said in the past that "Double Ds" are VERY important?

As mentioned above, the shape of the getters can serve in identifying certain production runs of the same tube and can help in finding the most desirable version.
It was not uncommon for the manufacturers to use different shaped/sized getters in the same tube. As an example, I have three different pairs of the Cetron 6336B tube, and each pair has a different getter.

 

[bcowen]

So, is the exception to the rule insofar to what you've said in the past that "Double Ds" are VERY important?

LOL! IMO, any tube with double D's is worth having even if it sucks.

 

[jonathan c]

Ken-Rad VT-65s start the parade…

 

[Xcalibur255]

From what I've seen, the shape/configuration itself is not important -- it's an indication of when the tubes were made. Foil getters preceded horseshoe, D, O, and UFO getters, so the foil indicates an earlier manufacture. And IME, earlier is better when it comes to sonics. Perhaps overgeneralizing to some degree, but it follows along the progression pretty well.

I agree with you. If two tubes with different getters sound different, it isn't going to be because of the getter, it's because one is older than the other and may have been made on different equipment and have other construction differences that explain the sonic changes. Getters are just one part of the puzzle in figuring out when tubes were made.

One exception I would note is that in the case of tubes whose *quantity* of getters varies I would suspect that more = better. Such as a 5998 tube where you will see ones that have only a top getter and some that have both a top and a side getter, I would be willing to bet the tube with the triple getter setup may have a longer usable lifespan. Possibly the reason for this variation was that some of these tubes were meant to be "long life" variants, but that's just me theory crafting..... I haven't read anything to confirm that.

 

[gibosi]

More seriously, I don't know anything about the names of the different styles of getter holders in these early 1930's tubes. I can say that what I would call the "inverted cup" style is very common in 27's and early 37's. However, by the mid 1930's globe-style bottles had been replaced by shoulderd bottles and the getters were small pieces of sheet metal with a small dimple.

Here's an example. This is an RCA Type 37 manufactured in 1934. The 37 was first introduced in 1931 and early 37's had a globe bottle and an inverted cup getter. By 1934, the globe bottles had been discontinued and replaced with shouldered bottles. And the "inverted cup" getter had been replaced with a small piece of sheet metal with a small dimple. But again, I don't know the precise name for these early getters so I just describe them.