I came by an old set of RCA 6L6GC tubes and I am not very familiar with the construction of these old ones. They are long bottles , as long as my Sylvania 6L6GC-STR 387 tubes. They have double round top getters. Can anyone tell me what I have here and if they would work well in an 81 pro reverb?
They are 6L6s, why would they not work well in that amp? The amp isn't picky, and it does not ask a lot from them.
As to what you have there. Other than functioning 6L6s, maybe you mean from a collectibility standpoint? I'll defer to the tube fans out there for that.
As to what you have there. Other than functioning 6L6s, maybe you mean from a collectibility standpoint? I'll defer to the tube fans out there for that.
Just looking to gain tone info on them. I have used many RCA's before , but I had never seen this construction before. The amp is in the shop so I can't check them out yet. I'm also a little concerned about how they will stand up to the Ultralinear 70Watt construction of the amp. It is designed to use the STR tubes because of the high plate voltage.
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Just because it says RCA doesn't mean they actually made the tube. Many of the major tube manufacturers rebranded each others tubes, particularly at the end of US vacuum tube manufacturing.
Those look like Sylvania made tubes, and I'm going to guess that they are actually Sylvania 7027A's. True RCA's will have the "stop sign" octagon around the type number. GE's will have the etched dots near the number that was their date and manufacturing code. Sylvania's will have the letters USA under the number without periods after the letters. That is barely visible in one of your pictures. The 7027A has a plate structure that's a bit different that most US made 6L6 types.
Sylvania began some serious glass stuffing in the last days of tube manufacturing. Why make 5 or 6 different types, just stuff the biggest guts that will work in most circuits into the glass and be done with it. The 7027A is a very good 6L6 type and it should work well if that's what it is.
Those look like Sylvania made tubes, and I'm going to guess that they are actually Sylvania 7027A's. True RCA's will have the "stop sign" octagon around the type number. GE's will have the etched dots near the number that was their date and manufacturing code. Sylvania's will have the letters USA under the number without periods after the letters. That is barely visible in one of your pictures. The 7027A has a plate structure that's a bit different that most US made 6L6 types.
Sylvania began some serious glass stuffing in the last days of tube manufacturing. Why make 5 or 6 different types, just stuff the biggest guts that will work in most circuits into the glass and be done with it. The 7027A is a very good 6L6 type and it should work well if that's what it is.
The only other print you can read besides RCA if you see them up close the read...6L6GC and under that is USA and next to the RCA they say AZD and under the RCA it appears to say 1K
I saw that in the picture. The AZD is the date code, but I don't have the info to decode it. I don't know what the IK or 1K means.
Somewhere around here I have a pair of very similar looking tubes with Sylvania branding on them. I'm pretty sure that yours are Sylvania made tubes. Whether they are 7027's, 7027A's or 6L6GC's is debatable, since Sylvania used all three numbers on the same guts in the later years of tube manufacture. They also made tubes with the Philips ECG name on them.
Somewhere around here I have a pair of very similar looking tubes with Sylvania branding on them. I'm pretty sure that yours are Sylvania made tubes. Whether they are 7027's, 7027A's or 6L6GC's is debatable, since Sylvania used all three numbers on the same guts in the later years of tube manufacture. They also made tubes with the Philips ECG name on them.
This looks like a good thread to continue the topic of date coding on Sylvania power tubes. I have a quad of Sylvania tall bottles with single getter disk. They are over-printed as RCA with date code HWU beside RCA, and a batch code HZ under the RCA. They look the same as all photos of identified 6L6GC Sylvania's, and have glass etched:
6L6
GC
USA
They may be original issue of an amp built in July 1969, but equally could be a complete swap out from a later date.
Sometimes the collective noting of valve date codes and equipment build dates can narrow down date coding usage.
6L6
GC
USA
They may be original issue of an amp built in July 1969, but equally could be a complete swap out from a later date.
Sometimes the collective noting of valve date codes and equipment build dates can narrow down date coding usage.