May 23, 2012
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Amperex JAN 7308 Green Label
Amperex 7308 dual triode tubes come in three basic flavors: white, orange and green. These colors are an indication of when the tubes were made with white label tubes produced between 1959 to 1967 and the orange and green ones made from 1967 to 1975. I’m not sure what, if anything distinguishes the orange and green labeled tubes. It may be just the color of the ink used. The Amperex 7308 was made in the Hicksville, NY and Heerlen, Holland manufacturing plants.
Some tubes of this type bear the “PQ” shield on their labels while others have the Amperex globe logo. They all bear the Amperex four-seam, ridged top and have gold pins. The 7308 was created as an upgraded 6922 with improved resistance to shock, vibration, and was also designed to have lower mcrophonics than the 6922. It’s rated as having a 10,000 hour life expectancy.
The Amperex JAN 7308’s used in this review are all from the Hicksville plant, were produced in 1968, and have the green globe logo. They were intended for military use and that’s why they bear the acronym “JAN” (for Joint Army Navy) in their labels. Two of the tubes in this review were from Vintage Tube Services and bear the distinctive red and green paint on their tips which indicate that they have ultra-low microphonic test scores. These are microphonic scores appropriate for a line level preamplifier but below a moving magnet or the even more stringent moving coil grades used in phono stages.
Upscale Audio carries the Amperex 7308 for $50 to $80 each, depending upon grade, and VacuumTubes.net has them for $80 a piece. They may also be found at other online tube sellers and auction sites.
Even though the tubes in this audition were previously used by me, they did take some time to settle in before sounding their best. Total playing time during the course of the audition was 25 hours.
The dual triode tubes used previously in the Premier 16LS2 were the Amperex USN-CEP 7308 and Telefunken 6DJ8. Some comparisons to those tubes will be made below.
Listening Impressions:
- The green label 7308’s present the typical grainless quality of Amperex but with a bit more bite than the USN-CEP white label variety.
- Drums are resonant and provide a more solid foundation to the music than was the case with the TFK 6DJ8’s.
- Timbre and decay are excellent with music realistically sustained and then fading into the noise floor.
- Clear midrange that makes understanding dialogue no chore.
- Detail is excellent with instruments easy to pick out of the mix and follow.
- Electronic instruments such as synthesizers are exceptionally well rendered.
- Treble is accurate to the limit of my hearing with sharpness when it’s called for by the program material. Although instruments such as massed violins are generally smooth, they are never dull sounding.
- Reference level sound staging that projects solid images well into the listening room.
- Music is enjoyable and permits an emotional connection.
Although some are of the opinion that all Amperex 7308’s sound the same, that hasn’t been my experience. I’ve always felt that the white label version has a slightly more refined sound while the green is more incisive. I don’t believe that I’ve ever assembled a set of the orange label 7308’s and therefore do not have an opinion of them.
This tube has been a long time favorite of mine both in the c-j Premier 16LS2 and Premier 140, where it’s used as the input tube. Although the rankings of my favorite 6DJ8/7DJ8/6922/7308 tubes change position depending upon what power tubes they’re being partnered with and quite honestly, my mood, this particular type has always been in my top five or six. This is due to its ability to play well with just about any output tube I’ve used and in my opinion, none come to mind where the combination was anything other than salutary.
If you’re fortunate enough to be able to purchase these, you will most likely not be disappointed.
Comments (3)
Wow, six of these babies. I love that green ink. It reminds me of the green waters off of Honolulu.
I only have four of the Amperex 7308s. Two were made in Heerlen, Holland. The other two are US-made, and label Hewlett Packard.
@rpghero27 -
I know we're supposed to be influenced by how something sounds and not so much by how it looks, but I find these tubes cool to look at, too.
I have some Hewlett Packard labeled Amperex 6DJ8's but not any 7308's. The 6DJ8's are very nice sounding, even if the labels are white.
@NaranKPatel@twitter -
I think that "fullness of the sound" you're referring to is characteristic of the Amperex "house sound" although it varies to some degree with the type, production plant, and vintage of the Amperex tube you're listening to. I've never been lucky enough to hear any Telefunken E188CC's but the TFK's I do have are consistently among my favorites. The Siemens tubes may be more accurate technically but for whatever reason, they always leave me a little cold and never seem to stay in my system for very long. So much of our preferences come down to the system we have and personal taste.
Thank you for your comments.