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Philips/ECG tubes

Maxxarcade

Maxxarcade

Active Member
Just found a set of NOS Philips/ECG 12AX7 tubes at work, and they have that odd issue of doing the incandescent white flash on power up, both in my tester and on my Magnavox 175 amp.

Did Philips really make these, or are they some other OEM?

They do sound great though, despite the flash. Will they do that all the time, or just until they are broken in?
 
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sloober said:
12AX7 will often flash at startup. 12AX7A will not. Don't sweat it. Just dig the music.
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They are marked as 12AX7A/ECC83/7025. That's why I was curious. The original 12AX7's from the amp don't flash at all. I thought it might have been because they sat for so long, but it's probably just the way they are made.
 
It is odd they are marked with the "A" suffix. That is supposed to be reserved for tubes with a "controlled filament warmup", which means they shouldn't flash on startup. Regardless, yours seems to flash. It'll do it every time you power up the tube cold. If you turn it off, then turn it back on again before it has a chance to cool off it won't flash. I wouldn't recommend doing this though - it's unnecessary wear on the tube.

The Eico labeled 12AT7 seen in the photo below flashes brightly every time I turn on the amp. It's completely normal, and the tube sounds very good.

 
Maxxarcade said:
Just found a set of NOS Philips/ECG 12AX7 tubes at work, and they have that odd issue of doing the incandescent white flash on power up, both in my tester and on my Magnavox 175 amp.

Did Philips really make these, or are they some other OEM?

They do sound great though, despite the flash. Will they do that all the time, or just until they are broken in?
Click to expand...

Mullard and Amperex became part of Philips in the late 50's and very early 60's (depending on WHICH plant was producing WHICH tubes). They produced tubes for more than 35 other companies that bought from them, and placed their own brand label on them. They were HUGE in the rectifier and signal tube industry.

Depending on the type of tube and the year it was manufactured, you may (or, may not) have the original Mullard codes that were etched on the tube's glass envelope.

. . Falcon
 
ECG's were some of the last commercial tubes made. As Falcon Eddy stated, Philips bought out several companies Including Sylvania's tube manufacturing in the US.
Those tubes could be actually a design from any one of those. Heres where code # reading comes in handy if there are any codes to read.

Alot of ECG's are JAN tubes (military contract) and were bought up as surplus.
Ive seen a few non military ones that had yellow print but all four types I have are blue print JAN tubes.

1980's ECG JAN/5751's are highly regarded tubes. The ones I have are medium plates with a disc getter and are very clean with moderate gain. Probably between a 12au7 and a 12ax7 I have one handy and the only numbers are a date code of 1986 and 34167 whch I didnt find as meaning anything to my notes. I would say Sylvania by the looks of it though.
 
Here's some pictures. I couldn't read the silver codes near the bottom of either tube though.

They do seem to have a smoother, less gritty sound than the original 1958 Magnavox tubes in my amp.

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Appears to have the "X-seam" on the top of the tube... which is another way to confirm it's a "real" Philips/Amperex/Mullard type tube.

Is there any tiny writing anywhere near the base of the tube? Like two rows of three to four characters each?

Regards,
Gordon.
 
GordonW said:
Appears to have the "X-seam" on the top of the tube... which is another way to confirm it's a "real" Philips/Amperex/Mullard type tube.

Is there any tiny writing anywhere near the base of the tube? Like two rows of three to four characters each?

Regards,
Gordon.
Click to expand...

There is writing near the bottom, but it is too smudged to read. Is there a known code I can look for that might make it easy to spot through the smudge?
 
Those silver #'s there on your pics are the codes. Should be 6 numbers and they are read in a column, top to bottom. First is IEC manufacturer and second is usually location or date code.

About the top having the seams. Does it have an X patern or 2 that are on either side of the point?

2 seams instead of 4 means Matsushita (Japanese)

Also, try looking thru it against a light bulb or breath on it closely to fog it and try to read the numbers.
 
Maxxarcade,

What is the first symbol in the second row? A semi-circle with a dot means Nis, Yugoslavia, but this one seems to be turned on it's side.

These markings look like the "old" Philips code.
 
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