Edge-terminated vs Centre-terminated Capsules

What does “termination” mean in a microphone capsule?

A condenser microphone capsule contains a very thin, electrically conductive diaphragm positioned close to a backplate. Together, they form a variable capacitor. When sound moves the diaphragm, the capacitance changes, and the microphone electronics convert those changes into an audio signal.

The word termination describes where the diaphragm’s electrical connection is made. It does not refer to where sound enters the capsule, and it does not mean that one design is automatically better than the other

What is an edge-terminated capsule?

In an edge-terminated capsule, the electrical connection is made at the outer edge of the diaphragm. The central area of the diaphragm is therefore free to move without a centre connection or attachment interrupting its movement.

Edge termination is strongly associated with the historic AKG CK12 family. The original CK12 combined edge-terminated diaphragms with a dual-diaphragm construction and a complex multi-chamber acoustic design. That complete combination, not edge termination by itself—helped create the capsule’s distinctive performance.

How can edge termination affect the sound?

Edge termination can contribute to a diaphragm behaving differently from a centre-terminated design, particularly at higher frequencies. In practice, edge-terminated capsules are often chosen when the designer wants an open, detailed or airy presentation.

The result still depends on the whole capsule. Diaphragm thickness and tension, the backplate hole pattern, the diaphragm-to-backplate spacing and the acoustic chambers can all change the frequency response and transient behaviour. A different microphone circuit or headbasket can also change the result.

What is a centre-terminated capsule?

In a centre-terminated capsule, the electrical connection is made at the centre of the diaphragm. This creates a different mechanical and electrical arrangement from an edge-terminated capsule.

How can centre termination affect the sound?

Centre-terminated capsules are often associated with a strong centre image, rich low-mid body and a smoother or more controlled high-frequency character. These descriptions are common design tendencies rather than rules. The exact sound depends on how the capsule is tuned and how it is matched to the transformer, headbasket and other parts of the microphone.

Does edge termination always sound brighter?

No. Edge termination is often linked with an open or extended high-frequency character, but it does not guarantee a bright capsule. A designer can alter the result through diaphragm tension, backplate geometry, acoustic chamber design, headbasket design and circuit voicing.

Likewise, centre termination does not automatically mean that a capsule will sound dark or warm. A centre-terminated capsule can be voiced for clarity, presence or extended high frequencies. It is more accurate to treat termination as one part of a capsule’s design identity rather than as a simple “bright versus warm” switch.

Common misunderstanding: the capsule does not work in isolation

It is tempting to say that an edge-terminated capsule “sounds like a CK12” or that a centre-terminated capsule “sounds like a K47.” Those comparisons can be helpful, but they are incomplete.

A microphone’s result is shaped by the interaction between:

• diaphragm material and thickness;
• diaphragm tension and tuning;
• edge or centre termination;
• backplate profile and hole pattern;
• diaphragm-to-backplate spacing;
• capsule size and acoustic chambers;
• single- or dual-diaphragm construction;
• headbasket design;
• amplifier, transformer and other circuit voicing.

This is why two capsules with the same general termination style can sound noticeably different, and why a capsule swap may not produce the expected result in every microphone.

Summary

The main difference is the location of the diaphragm’s electrical connection: an edge-terminated capsule connects at the outer edge, while a centre-terminated capsule connects at the middle.

An example of an edge terminated capsule is Beesneez BN2 the Beesneez Ck12

An example of a Centre terminated capsule is the Beesneez K67 and the Beesneez K47