As I like to point out whenever people claim that the ECB is controlled by Germany: Germany has a very small minority of the votes in the controlling gremium.
European institutions are largely determined by "every member gets something", not economic size.
In this example, the Governing Council of the ECB has 25 members, two of which are German.
It is "first among equals" in the sense that no country has more members and few have as many, but what you're insinuating is factually wrong.
When it comes to any European organization, just assume that each member country has one vote and you'll always be very close to reality.