The USA made Sylvania 6CA7/EL34, commonly referred to as the 'Big Bottle' or ''Fat Bottle' Sylvania 6CA7, was first produced around 1970 in the company's Emporium, PA and Salem, MA plants. They also ended up being produced in Canada, as well, but unfortunately the production of these tubes stopped in the mid 1980's. PhilipsECG was apparently the holding company for Sylvania at the time production was ceased. Sylvania purchased companies such as GTE in the 70's that allowed them to stay financially strong. On the right, you can see the different labeling that occured on the Sylvania labeled 6CA7's. Some labeling was done on the base of the tube, and some on the glass. The colors varied between green and yellow, and looking at the last three tubes, the font size and style is actually different on all three. There is also a less common white labeled version, but I don't have any at this time to show.
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On the left are the different PhilipsECG labeled tubes. Same exact tube, but with a different label. The tube on the far left is NOS, and shipped without a label. It's not worn off, it simply never had one. It came in a PhilipsECG box such as the middle box, below. The other three tubes are examples of the different labels that occured in yellow, blue, and white, respectively. All Sylvania/PhilipsECG USA made 6CA7's had the standard grey "USA 6CA7 EL34" label on them. These tubes are easy to identify because of their unique welded and three hole plates. GE's version used crimped plates, and had a rectangular punch in the middle position of the plate. Most Sylvania 6CA7's were made with dual getters at approximate 45 degree angles, but you will also find some with just one horizontal getter. There are also some dual getter tubes that actually have a third getter on one side of the plate at the edge of the glass. Another interesting characterisitc is that they all were made with a hole in the middle of the bottom pin guide, just like the Mullards are known for. These tubes are known for their great tone at all frequenices, particularly the bottom end. These are also known to be extremely durable and last a very long time.
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To the right are a few examples of boxes from the 70's and 80's. Notice that the first two are very similar except the top box also has the Sylvania label included. These two boxes are from the 1980's. The bottom box is a very common box from the late 70's, I believe.
On the left are two examples of re-labeled Sylvania 6CA7's. One is labeled Amperex, and the other is Standard. There are many more examples, and I've even seen them re-labeled as Realistic. Unfortunately, most audiophile tube fanatics know these things, it's not as easy to find one of these sleepers for cheap.
Above is a Sylvania 6CA7 waiting to be tested on a Hickok 539B tube tester.
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To the right is an interesting comparison of different tubes. On the left is an NOS USA Sylvania 6L6GC. Of course, the middle tube is the NOS Sylvania 6CA7, and the tube on the right is an NOS USA GE 6CA7. The 6L6GC is a little smaller in size, but the GE is larger. Notice the rectangular middle hole punch on the plate on the GE that I was talking about earlier. You can also see the crimped plates on both the GE 6CA7 and the Sylvania 6L6GC.. The 6L6GC doesn't have welded plates like it's brother, but it does have the dual getters like the other two. Both Sylvania's have the hole in the bottom pin guide like the Mullards do, and the GE does not.
On the left is an example of two different looking matched quads (plus one additional tube!). .
No mention of Eddie Van Halen on this entire page until now. Everybody knows that he used these in his old Marshall for the early Van Halen records. So why beat the poor topic to death? The truth is, that WAS what grabbed my attention to these tubes, but after trying them I'm thankful that I like them even more than the Mullard EL34's in my Plexi. I will continue to update this page as I find more info. regarding the technical aspects of these tubes as well as dating code information.
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