Valve Condenser Microphone
According to the book Recording The Beatles, the U48 was one of George Martin's favorite microphones when actually 'recording The Beatles'.
Utilising the same M7 capsule, BV8 output transformer and VF14K vacuum tube as TELEFUNKEN's historic reissue of the U47, the U48 features cardioid and bidirectional capsule capabilities (instead of the cardioid and omnidirectional found in the U47). Its authoritative mid-range and extended low-end response have made the TELEFUNKEN U48 an excellent tool for recording vocals and acoustic instruments, both near and far.
10 years after the development of the ubiquitous U47, the U48 was released with one variation to the U47; it had "bidirectional" (figure 8) capability. The bidirectional capability can be very useful in more "ambient" recording environments where the engineer recording the sound does not want to hear as much of the room ambience as might be recorded with an omnidirectional or cardioid pick-up pattern.
Each U48 microphone comes complete with M940 power supply, M840 25' dual-shielded ACX-7 tube microphone cable, M740 elastic shock mount, FC40 locking flight case and WB40 wooden microphone box.
A microphone's capsule is often made of two sides. The front diaphragm will produce a cardioid response, as will the rear. When the two diaphragms are polarized in the same polarity, an "omnidirectional" effect is achieved. When they are polarized in opposite polarity a bidirectional or figure 8 pattern is created. This is not an acoustic pattern creation; it is an electronic pattern creation.
All microphone capsules are omnidirectional in the low frequency regions of their response. As you climb the frequency spectrum the capsule will have a more directional response. When you have two identical diaphragms with identical voltage to those diaphragms you will have a smooth "omnidirectional" response.
When those voltages are reversed, an electronic cancellation of common information is achieved; the result is two "lobes," one on the front of the microphone and one on the rear of the microphone, with full frequency cancellation through the frequency range achieved through electronic cancellation. While the capsule head assembly from a U47 can be fitted to a U48 amplifier, the same does not work in reverse.