Is this DIN connector suited for MIDI devices?

While one might expect that the socket's contacts would be a round metal receptacle, there is another design that looks like a fork. The two extensions of the fork make contact with the plug's pins by contacting the pin on either side. This fork-contact has a flat profile, and during manufacture, it is inserted into the slot that you see as a "line". The sides of the fork also flex inside this slot in order to provide a spring-loaded contact with the pin from the plug.

So these "lines" (slots), and the angle they are made at, have nothing to do with the pin arrangement in the socket. Only the round hole where the pin actually enters is a factor in whether the "pins are in the right place".

Something may be adding to the confusion. There are indeed 2 different types of 5-pin DIN connector.

In this image they are called 5-way 180º and 5-way 240º, and yes, there is a difference in angle between them.

• 5-way 180º: centerlines of the holes are across a 180º arc
• 5-way 240º: centerlines of the holes are across a 240º arc

The one you need for MIDI is the 5-way 180º. As the other answers have indicated, the angle of the slit across each pole is not important.

If you look inside the socket you will see that the contact is a fork with two prongs. They are angled to prevent interfering with each other.

The important point is that the circular pin entry points are in the required pattern, 3 o'clock, half-past four, 6, half-past seven and nine o'clock.