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Old 1st April 2006, 03:35 AM   #1
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Default 6L6, 12L6 not same tube!

The industry was pretty good about standardization. If you take a 6SN7 and a 12SN7 you know that except for the filament ratings the tubes are identical.

My questiion is why is the 6L6 family not the same family as the 12L6, 25L6, 50L6? These higher filament voltage derivatives sharing the same name are wimpy 10 watt PD tubes which match the 6W6, whereas the 6L6 is a serious PD output tube, in any of it's incarnations. 6L6, 6L6G, 6L6 GB = 19 watts PD. 6L6GC=30 watts PD.

Comments on why? In a world gone mad with inconsistencies, this example baffles me.
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Old 1st April 2006, 02:38 PM   #2
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I am not sure, but the 6L6G is designed from the 807 tube family that is actually a transmitting tube. The 12L6, 25L6, etc should have been a new number such as 12J6GT.
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Old 2nd April 2006, 03:06 AM   #3
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Default Re: 6L6, 12L6 not same tube!

Quote:
Originally posted by rcavictim
The industry was pretty good about standardization.
Well, no, not really.

Quote:
If you take a 6SN7 and a 12SN7 you know that except for the filament ratings the tubes are identical.
You can't count on it, however.

Quote:
My questiion is why is the 6L6 family not the same family as the 12L6, 25L6, 50L6? These higher filament voltage derivatives sharing the same name are wimpy 10 watt PD tubes which match the 6W6, whereas the 6L6 is a serious PD output tube, in any of it's incarnations. 6L6, 6L6G, 6L6 GB = 19 watts PD. 6L6GC=30 watts PD.

Comments on why? In a world gone mad with inconsistencies, this example baffles me.
You can find lots of examples just like this. The 50C5, 25C5, 17C5, and 12C5 are all, like the 6SN7/12SN7, identical except for heater voltage/current ratings. You also have a 35C5 which is a different tube with different ratings.

Also take a lookitdis (see attached). The 50C5 has a 50V heater, and the 25C5 has a 25V heater, so far, so good. The 17C5 has a 16.8V heater, so they rounded up. But the 12C5 has a 12.6V heater, so shouldn't this be called a 13C5? Or shouldn't the 17C5 be called a 16C5 instead? There is no consistancy here at all.

Reusing type designators like **C5 or **L6 should not have been allowed, and they should have decided: round heater voltages up or use the whole number part as the leading type number.

But that's not how things worked out.
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Old 2nd April 2006, 12:31 PM   #4
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Default Re: Re: 6L6, 12L6 not same tube!

Quote:
Originally posted by Miles Prower
But the 12C5 has a 12.6V heater, so shouldn't this be called a 13C5?
12.6 volts (or 6.3 volts for that matter) is so it will run properly from a fully charged car battery. And those batteries are generally referred to as a 6 volt or 12 volt, (courtesy of each cell being nominally 2 volts) so it sounds reasonable to call it a 12C5 because of the association with a "12" volt battery.
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Old 4th April 2006, 01:48 AM   #5
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Ye-e-e-e-s!

Just to echo. At the time (from someone who was there then - but I also still have all my hair, rcavictim), the logic (sic) seemed to have been that beam power tubes were ...L6s, that is the octal types. "6" for the number of electrodes - but then 117L7 or 70L7 had 2 extra electrodes by way of a built-in rectifier, so should have been ...L8s. As far as I know "L" seemed to have come from the German for "power tube", i.e. Leistungsrohre (dots on the "o") - but they again had a totally different numbering system.

Logic, such as it was, seemed to have been limited to 6V types - well, in a way. Welcome to the well-defined world of electronics.

Regards.
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Old 4th April 2006, 08:07 AM   #6
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Heh, forgot to add 50L6, different again
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Old 4th April 2006, 08:30 AM   #7
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Quote:
Originally posted by Geek
Heh, forgot to add 50L6, different again
What do you mean, forgot? I covered 50L6 in my starting post. It is identical to 25L6, and the other 10 watt PD xxL6's.
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Old 4th April 2006, 12:37 PM   #8
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Quote:
Originally posted by rcavictim


What do you mean, forgot? I covered 50L6 in my starting post. It is identical to 25L6, and the other 10 watt PD xxL6's.
Oooops, you did too
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Old 4th April 2006, 03:12 PM   #9
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Obviously the 1L6 must be related to the 6L6 and 50L6 as well

6BY7 is not like 12BY7
6AB5 is not like 12AB5
6K5 is NOTHING like 12K5
6A7 and 12A7 are not even close.
How close is a 6B4 to a 12B4?
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Old 11th April 2006, 05:16 AM   #10
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Originally posted by Tom Bavis


Obviously the 1L6 must be...

```````````````````````````````````
was only for/used in one thing...

http://antiqueradio.org/art/zen18.jpg
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