Compared to the AKG P220, the upgraded MXL circuit and headshell have a rise centered at 3 KHz and another at 10 KHz with a more rapid falloff above 12 K. This makes a pretty good vocal mic, and should also be good for basses, giving a bit of extra sparkle. Sound sample here.

The other mic getting a capsule swap is an old AKG C-451 with CK-5 capsule. The CK-1 element inside the CK-5 shell had a split diaphragm and the foam lining of the shell crumbled when handled. The screw mounting for the CK-1 was removed and one of the MXL small capsules left over from upgrading the 990s was installed in the top half of the AKG rubber shock mount.

Some navy blue rayon fabric replaced the foam windscreen in the front half of the headshell and a loose wad of it was placed in the back part. The red wire from the capsule backplate was soldered to the center contact on the AKG shell and the black wire from the AKG shell was tucked under the rubber strap around the capsule. The hardest part was cutting and shaping the fabric lining in the front and then attaching it with small spots of Terrifically Tacky Tape.

New life for an old mic. It’s short on headroom for a “close enough to lick” vocal mic. It wants a working distance of 6 - 12 inches or more, and really should be treated like a pencil instrument mic, or should have an external foam windscreen over it. But then the 451 / CK-5 wasn’t a great vocal mic to start with. It was an instrument mic with a windscreen.