Difference between 5687, 5687WA and 5687WB tubes?

[reaction]

Does anybody know what is the difference between 5687, 5687WA and 5687WB dual triode tubes? As far as I know WA means rugged military version, but what about WB? I have searched unsuccessfully for more info. Thanks in advance.

[TheGatesOfFate]

Generally these suffixes are for military grade tubes.
We find JAN which means Joint Army Navy and also WA,WB, WTC,W.
These tubes were made to withstand shock, vibration, high temps, and humidity for use in military vehicles, ships, planes etc.

Some people like to use in hi-fi because of their robust construction, and also for their greater electric performances.

I don't like very much these versions. I think normal versions sound better because I "see" in military grade tubes a sort of "roughy" in their robust purposes.

Cheers

[richwalters]

I think normal versions sound better because I "see" in military grade tubes a sort of "roughy" in their robust purposes.

Hi there .....JAN/WA/WB etc...they are the same tubes just with stronger connections within the envelope....otherwise no electrical change.
A JAN 6550A will sound exactly the same as a 6550A both made by the same vendor.

richj

[reaction]

Hello,

I read an article where (Morgan Jones if I remember well) explaines that 5687WB has different distortion curve compared to 5687WA and 5687.

So 5687WB *is* different electrically and has "worst" data compared to the other 5687 types regarding Jones.

[richwalters]

I read an article where (Morgan Jones if I remember well) explaines that 5687WB has different distortion curve compared to 5687WA and 5687.


So 5687WB *is* different electrically and has "worst" data compared to the other 5687 types regarding Jones.

Hi there..........if you claim one is worse than the other....this is rather puzzling that nowhere are these curves published or are there ?........same with recently made tubes...there seems a sparce amount of data. Different amp circuits can drastically effect the thd. The data sheet from EI KT90 claims a swap to the KT88 only to find the thd doubled.
The only"bit of info" example is the Svet 6550C.....otherwise have to rely on NOS specs. Perhaps if the 9001 norm was introduced into tube manufacturers then we would have a little more swept above the carpet...

richj

[TheGatesOfFate]

Originally posted by richwalters



Hi there .....JAN/WA/WB etc...they are the same tubes just with stronger connections within the envelope....otherwise no electrical change.
A JAN 6550A will sound exactly the same as a 6550A both made by the same vendor.

richj

It's false.
For example if u see Sovtek 12AX7 WA, WB and WC you will know that WA has a gain of 80, WB has a gain of 90 and WC has a gain of 100.
Read: http://www.tube-town.de/info/doc/tt-...tubes-engl.pdf

In "Modern" classification we often have different electrical values when a military specs are shown.
For this obvious reason, some tubes(of the same brand, but with different military specs) sound different, and, as I told, I like normal version.

[richwalters]

Originally posted by TheGatesOfFate
Read: http://www.tube-town.de/info/doc/tt-...tubes-engl.pdf

Hi there........okay I agree with the preamp stuff but I'm highly dubious of the commentary for the power ones......OMO...My question is ....If I interchange a Svet 6550C for WB series........nothing changes...i.e the quiescent juice remains the same and also the AC full power current...for sim input voltages....which surely must imply the transconductance is same for both tubes. Jein ? (perhaps I should have done the comparisons with nfb disconnected)

richj

[6h5c]

Hi there,

If you take a good look at some datasheets you will find that the WA/WB versions are not only more rugged in construction. The spec's that often differ are the heater warm-up time, max. plate dissipation and/or voltage.
Compare a 6SN7 to a 6SN7GTA and GTB for example. More or less the same issue. See http://tdsl.duncanamps.com/tubesearch.php for lots of datasheets.

Aside to this there are a few manufacturers that produce different clones of a known type. Svetlana also makes some tubes having the same name as the original one, but with different spec's. Take a look at their 6N1P. They claim that it is a substitute for the 6DJ8/ECC88! The SV83 is also not fully compatible (but they mention that). Both of them are good tubes though, that must be said also.

If you want my opinion: manufacturers should stick to the original spec's of a certain type (and don't mess with the pinout!) If you want to change it, make up a new typenumber. That Sovtek mess with three different gains for a 12AX7 is ridiculous.

Greetings,

Ray.

[reaction]

I spoke with a Svetlana factory representative regarding 6N1P and he told me that the tube is a miniature 9-pin equivalent of the old octal 6SN7GT tube with possible closer specifications.

The rumor that 6N1P is a substitute of 6922 is absolutely wrong and is made by all Svetlana resellers without factory permission.

[6h5c]

They did a strange job then. The gain and transconductance are no where near a 6SN7 clone. So much for the close spec's...

Maybe it's just an excuse for not respecting the 6N1P spec's

I use the JJ ECC99 if I need a noval driver tube, or the good old ECC82 aka. 12AU7.

Greetz,

Ray.