EL84 - 6BQ5 - 6P14P - 6P15P Curves

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EL84 - 6BQ5 - 6P14P - 6P15P Curves

Postby Shannon Parks » Wed Jul 18, 2012 6:52 am

This is my collection of EL84-types. The non-Russian ones are all used tubes. The Russian ones are mainly NOS. There are 57 tubes, sorted by tabs. Use the arrows in the lower left to see all the tabs, and you can use ctrl-pgup and ctrl-pgdn to scroll through them. Note that sorting function buttons are only on the first tab, 01. At first glance, I think I will spec 2k Rp and 3700 Gm a 100% tube. I haven't tried to import via Google Docs yet, so YMMV.

6P14P: 01-12, 47-53
GE 6BQ5: 13-18, 46
Motorola 6BQ5: 19
Sylvania 6BQ5: 20-27
Tungsol 6BQ5: 28
RCA 6BQ5: 29,30,33-37
RCA 7189: 31,32
6P15P (Svetlana SV83): 54-57
Mullard 6BQ5: 38-40
ARS (EI?) 6BQ5: 41,42
Magnavox 6BQ5: 43
Silvertone 6BQ5: 44,45

I'll try to add pix of the various plate structures eventually.

File is 1.2 megs:
http://www.diytube.com/curves/EL84master.xls

Shannon
Last edited by Shannon Parks on Thu Jul 19, 2012 7:08 am, edited 1 time in total.
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Postby WA4SWJ » Wed Jul 18, 2012 8:33 am

Nice work Shannon! Quite a lot of variation. Would be interested in your comments as to why. Wonder how the variations affect performance in a triode connected ST-35? Distortion, etc.
Ed Long
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Postby Shannon Parks » Wed Jul 18, 2012 9:37 am

Thanks for checking it out, Ed. The worst of the variation is because many of these are used, and well used at that (i.e. my GE tubes). But yes, there's a lot of standard variation and tube matching is pretty important.

I am intrigued by a couple of the Svetlana SV83s having high Gm. I just ordered a lot of the 6P15P tubes to have a higher sample. If they average a slightly higher Gm on average, and the screen current never becomes an issue (TBD), these might be a no-brainer sub tube in my upcoming Budgie SE amp. Certainly I think some people have subbed these without issues for years and I guess I remember using mine in the ST35 for a time. But I'm still not clear on the G3 & K connection - all my SV83s are internally connected.

Working on a linearity metric...

Shannon
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Postby Shannon Parks » Thu Jul 19, 2012 7:05 am

Added a "Sort by Linear" button. Closer to '1' denotes linearity at around a 6K load line from -8V at the grid with a 12Vpp signal. Note that some worn tubes may have have a better number, but they aren't better tubes. Looks like a good tubes will average around 0.7, hence the second harmonics.

I'll add a stock PDF with a dissipation curve for loadlining and stuff. This one lacks the dissipation curve:
PDF of Triode Curves (good for loadline drawing)

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