Warm Audio WA-47 Large-Diaphragm Tube Condenser Microphone

The WA-47 utilizes a custom reproduction of the vintage K47-style capsule that was used in the classic U47 microphone—designed with the same hole pattern and frequency response. Warm Audio’s version of this capsule (model WA-47-B-80v) is carefully manufactured by an Australian capsule manufacturer whose precision and consistency allows sonic replication of the most important piece of this classic style of microphone.

The JJ 5751 vacuum tube from the Slovak Republic is a lower gain, low-noise tube that forces much of the sonics of the capsule and transformer to be heard more significantly than some higher-gain tubes might allow. After auditioning four different tube brands, the folks at Warm Audio fell in love with the JJ 5751. Its frequency response and tonal contributions are smooth and vintage in nature.

The WA-47 utilizes an American-made TAB-Funkenwerk (AMI) USA transformer with imported large-core German laminations. This transformer helps provide the creamy smooth top end and the larger-than-life bottom end one would expect from a U47-style condenser microphone.

One component of a tube microphone often overlooked is the 7-pin cable that connects the microphone to its power supply. When auditioning the WA-47 and other tube microphones, Warm Audio learned a lot about 7-pin cables and how the shielding and wire gauge can drastically change the sonic characteristics of a tube microphone. Warm Audio partnered with Gotham Audio in Switzerland to use their carefully built, premium 7-pin GAC-7 cable. Using this cable increases top-end presence and the overall size of the recorded image in the stereo field by reducing phase shift and the parasitic effect often found in poorly built cables.

The WA-47 uses a polystyrene coupling capacitor for uncompressed top-end response from the capsule. WIMA film capacitors are present throughout and an imported Solen capacitor drives the TAB-Funkenwerk (AMI) USA output transformer.