Philips, if you please.
I'm not aware of any Eindhoven production either. Philips had their major research labs in Eindhoven, though. It is quite possible, even probable, that the research production lines of those reseach labs made some. Some of the Eindhoven "numbers" point to actual research labs. I'm not sure about number 4, though.
And of course, Oskari is absolutely correct. :)
Amperex Electronic Corporation was a well-established American vacuum tube company, located in Brooklyn, NY, until it was purchased and incorporated as a wholly-owned subsidiary under Philips around 1955. The ECC88 was likely developed in the Philips' research complex located in Eindhoven, but once in production, ECC88s were often marketed under the newly acquired Amperex brand name, especially those manufactured in the Heerlen, Holland factory.
So it is important to realize that by the late 1950's, "Amperex" was nothing more than a brand name painted on the outside of the tube. And many of you who have rolled a few of these "Amperex" tubes know that it is not at all uncommon to see the "Amperex" label on tubes manufactured in other factories as well. And the same goes for Mullard, Valvo, Dario and all the other brands that were part of the Philips conglomerate. This is why it is advisable to find out the Philips tube codes before you buy. It is the only way to confidently determine when and where these tubes were manufactured.