Philips had factories all over the world, so you cannot assume that a particular subsidiary like Dario in France or Mullard in Britain produced its own valves. The only way of determining the source of a particular valve is in the code letters and figures etched into the glass (not the same as the printed designations, EL84, ECC83, etc). These can be read with aid of a magnifying glass and compared with the "Philips Factory Valve Codes" document which can be found at various locations by googling the title.
I expect to have them in a few days.All I know now is the production date which is 1963.I will have a look when they arrive.Actually what I am trying to learn is,if European made Philips tubes have a diferent sound than JAN US made Philips,and if all European Philips have a consistent sound between them despite the (European) country of manufacture.
Ah, the ECC83/12AX7! I suppose most valve factories in the world have made these. Mullard in the UK made at least two very different versions. I suspect the Dutch factories would make special quality versions too. I remember that the Vacuum Tube Valley magazine in the USA devoted an issue to this valve but they couldn't agree which was best. There were different outcomes for use in audio and in guitar amplifiers. You would need a lot of money and time to compare only the Philips variants. Military valves (such as JAN) are not necessarily better than the normal commercial variants for audio : they have different priorities.
Yes,the ECC83/12AX7 
Mullard would be my choice but with such high prices for NOS one doesn't dare easily to risk.But since you mentioned about two very diferent Mullard 12AX7's can you tell me which are they and how they compare?Who knows maybe next X-mas Santa may surprise me.Till then,I have to know a few things and write him what I want.I would go for the warmer smoother one.Any advice?It seems that the same -various versions-is true for other manufacturers,including Philips.I hope the mimiwatt is at least better-to my taste-than the JJ Gold pin I'm using now.
Mullard would be my choice but with such high prices for NOS one doesn't dare easily to risk.But since you mentioned about two very diferent Mullard 12AX7's can you tell me which are they and how they compare?Who knows maybe next X-mas Santa may surprise me.Till then,I have to know a few things and write him what I want.I would go for the warmer smoother one.Any advice?It seems that the same -various versions-is true for other manufacturers,including Philips.I hope the mimiwatt is at least better-to my taste-than the JJ Gold pin I'm using now.I was thinking of the difference between the "box" anodes of the M8137/CV4004s, special quality ECC83s and the classic thinner "ribbed" anodes of the ordinary ECC83. I have no idea about "warmer, smoother " sound. To me that implies loss of detail, as live music is a lot spikier than people think. I woud look for accuracy of reproduction. Generally speaking the "special quality" valves conform more closely to published specifications or over fulfill them (usually in anode current). It's conceivable that the ordinary valves could be "warmer" and "smoother".
The Philips ECG 12AX7A and JAN 12AX7WA were artifacts of the Philips acquisition of GTE Sylvania's ECG component division in the very early 1980s. (I was working at GTE LABS at the time) The European Philips produced tubes were made on entirely different (and unrelated) tooling than the US made version which was really unchanged from the old Sylvania types - Philips continued production here in the USA until around 1989 so this is a time frame of about 7 or 8 yrs IIRC. (Unfortunately I don't remember the exact date of the change over. Philips and GTE had very cordial relations and the GTE company store had a lot of Philips products in it.)
IMHO Just about any of the European made Philips versions sound somewhat to significantly better than the old Sylvania/Philips ECG type which I used extensively because it was readily available to me in those days. The ECG type seemed to have a lot more 1/f noise than the European made types which was particularly noticeable in the passively eq'd phono stages I was designing at the time. I measured it at the time and IIRC the difference was a not trivial - something like 6 - 10dB worse in very late production - I suspect this was due to poor processing practices in the last few years of operation.
IMHO Just about any of the European made Philips versions sound somewhat to significantly better than the old Sylvania/Philips ECG type which I used extensively because it was readily available to me in those days. The ECG type seemed to have a lot more 1/f noise than the European made types which was particularly noticeable in the passively eq'd phono stages I was designing at the time. I measured it at the time and IIRC the difference was a not trivial - something like 6 - 10dB worse in very late production - I suspect this was due to poor processing practices in the last few years of operation.
barretter said:
For me,"accuracy of reproduction"is the most dangerous words to use in hi-fi.What sounds nice and "accurate" with an EMI record,suddenly collapses with the next Deutsche Grammophon record.I believe that all have an "accurate" ideal,or,better still,taste.Also,we all receive music in a diferent way and sensitivities,and this is one reason why we have diferent perception of what "accuracy" is.For me at least live music is one thing and recorded music is another.Recorded music is not so "spikey" as live music as you rightfully said.And in the end,what we listen through our hi-fi systems is recorded music,so we can "tune" it to our taste/perception,one way or another.
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