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...what are the differences in these...sound, age, etc.
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Jimmy points out that the white print PQ US-made Amperex 7308 sounds the same as the green print US-made Amperex 7308. I believe them to be the same tube and they should sound the same, though there can always be some unit to unit variation. Interesting, though, people can't seem to get rid of the green print US Amperex 7308. Joe's Tube Lore gave them a poor grade. Could this commentary have effected the opinion of this tube so globally?Distinctions between white, green, or orange print, or even mil contracts and PQ/SQ (and other "premium" brandings like GE's 5-Star, RCA's Command, Sylvania's Gold Brand, etc.) may be simple ways to make identification, but may not represent any differences in construction and chemistry inside the tube. And if a tube has been used then all is up in the air about any original grading.
There're some construction detail, and certainly chemistry, differences that don't make themselves evident through visual inspection. I suggest, though, that if the tube looks the same internally, and is around the same vintage, then you can treat the tubes as essentially the same tube. It can be tough to know exactly how a tube changed over its production lifetime. The tube may have remained unchanged or not.
So, to get to an answer for you. The white print PQs are earlier production, the orange print/globe (and orange print PQs) branding later. But the orange print tubes were in production by the late sixties so I suggest that within a few years plus/minus of the branding change these tubes, if they otherwise look the same internally, are likely the same tube just wearing different ink.
'gave them a poor grade'. Problem is tubes respond differently in different circuits. Obviously, Joe knew what he heard. Another possibility was the tube was different construction than the tube Joe auditioned.I gave the Amperex Holland 6DJ8 Orange Globe 'A' frame a less than stellar grade in my amp. Quite frankly, the 7308 JAN 'green print' way outperformed the mediocre sounding the 'A' frame in my amp. Simply, I just have a match 'made in heaven' in this application to the point I consider future tube swapping unnecessary in this circuit.
As far as I know and have been told by several high-end tube suppliers-ALL 7308's have gold pins.Buyer B ware
aedoc,There were some very late Philips JAN- mid 80's and with the very blue lettering, that were designated E188CC and 7308 and these had steel pins. I don't know if this model was labelled by anyone else, and I think these were US made. I see these on Ebay sometimes.
But, the users of this one say not to bother with it unless it's NOS, very cheap, and to become a cathode follower or have some non-sonic duty. A 7308 to be seen but not heard, an NOS alternative at a Sovtek price. But, will the current Sovtek 6922s be quieter and last as long or longer anyway, plus provide a wider selection for testing?
But, other than that one end of the run model, I belueve you're correct, 7308s are alaways gold pinned.
No "splatter" shield with upside down "space ship" getter disk.These 7308 "sound" quite good in my AN DAC 2.1 balanced but I have not compared them to the PQ version as I don't own any.
Original Amperex E188CC/7308/6922 etc. were made in the US, and in the Philips Holland plants. Just comparing the tubes with the label can me misleading 'cos you can find US, Holland and Russian made tubes with the same Amperex Globe logo.
you think that they were originally 6H23n?(as above) I believe that I bought the pair for $12.00 or $14.00 per tube from a reputable seller (Fair Radio Sales)but had doubts from the beginning once I saw the internal construction.The tubes don't sound bad in the application that I am using them in (AN Dac), but should I inform Fair Radio Sales that the tubes are actually Russian manufacture? Thanks for any advice. wpod
No. Amperex would not have re-labeled these. It is entirely possible that the company (Richardson) that bought the Amperex name, and that has the rights to put the Amperex name on any old POS tube they care to did it. This is not to say the Voskhod 6h23's in the picture are a POS tube. Actually I like them a great deal. Are they equivalent to a Siemens or Amperex 7308 ... not even close. But still a very good tube.
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The Jan 7308 I referred to are different construction.
In my amplifier the Amperex 7308 PQ with white writing & made in USA sounds the same as the Amperex JAN 7308 with green writing & made in USA. Of course, the plate & getter structures are identical.I never heard an Amperex 7308 Orange Globe. I have heard a Amperex 6DJ8 Orange Globe with the 'A' frame and it was notibly of less sonic quality with some smearing in the critical midrange.
All tubes tested were new in boxes thus eliminating any chance of a low emission tube plus I check tubes in a tube tester.
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