Neumann History

Refinements in

Phonographic Technology

Up until around 1953, Neumann built disk-cutting lathes for phonograph records with a constant groove pitch. Between 1953 and 1955, Neumann developed a method of varying the groove pitch depending on the recorded am- plitude. To this end, an additional playback head was mounted on the tape deck. This additional playback head determined the groove amplitude to be recorded approximately one half-rotation of the turntable in advance and fed this value to the cutting lathe as a control signal via a corresponding drive amplifier. Of course, this also required a separately variable pitch drive. For the first time, this made it possible to extend the playing time of an LP phonograph record to approx. thirty min- utes.

So far the records had been monophonic disks made using lateral recording. In 1956, Neu- mann debuted its first stereo disk-cutting lathe, the ZS 90/45, which supported both lateral and vertical recording. The lathe was set up to cut the two stereo channels into the two flanks of the groove at a 45° angle. Over the years, other disk cutting lathes

were developed, the quality of which improved continually. These were all electrodynamical feedback cutterheads. This model series continued with the SX 45, SX 68, SX 74 and finally the SX 84.

Many companies made a name for themselves with their products on the disk cutting mar- ket. These included, for exam- ple, Ortofon, Westrex, Scully, Fairchild, Dauphine, and others. By the end of the fifties, Neu- mann was the only company left that could deliver complete tape-to-disk transfer equipment. Neumann saw this position as a serious obligation to continue refining phonographic technology. This was reflected in the refinement of the disk cutting lathes and improvement of the cutting procedure.

One interesting phenomenon in this connection is the tracing distortion that results from

the difference in geometric shape between the tool used to cut the grooves and the playback stylus. The cutting stylus is shaped like a

spade, while the playback stylus is spherical. During playback, this results in tracing distor- tion, which mainly contains the 2nd harmon- ic. In 1968, Neumann built the Tracing Simulator that solved this problem.

In the early seventies, Neumann successfully developed, in conjunction with TELDEC, a mechanically recorded video record that was played back via a pressure pickup. The experience gained in this connection led to another significant improvement in the process of cutting phonograph records. In the beginning, phonograph records were cut in bee’s wax and for years thereafter in a phonographic foil coated with nitro-cellulose lacquer. Neumann introduced the DMM technology, in which the phonographic foil was replaced by copper foil, resulting in Direct Metal Mastering, DMM. This resulted in substantially improved pulse fidelity of the recorded signal, which represented another significant improvement in the sound quality of phonographic records.

One Step Ahead Again:

The TLM Technology

At the 1983 AES-Convention in Amsterdam, Neumann unveiled a brand new series of microphones with refined circuitry: the Transfor- merLess Microphones of the “fet 100” series. The first representative of this series was the switchable TLM 170 with five directional patterns from which to choose. It used the same dual-diaphragm capsule as its somewhat older, transformer-equipped brother, the U 89.

Each microphone represented a considerable improvement in the common dynamic range of studio microphones at its respective time of in- troduction. Their electronics evidenced lower residual noise and, simultaneously, higher modulation levels than predecessor models. Further-

more, they were also a novelty in the market because they were the first to provide wide-angle cardioid and hypercardioid directional patterns in addition to the omnidirectional, cardi- oid, and figure-eight patterns common at the time.

The “especially open, free sound” of the TLM technology, which made it possible to transmit fine structures “as if a curtain had been pulled aside”, encouraged Neumann to quickly equip other microphones with this system.

In order to be able to fit the complex circuitry into miniature micro- phones, however, it first took an additional development step: hybrid technology. This technology even made it possible to incorporate

all electronics right in the capsule housing, thus giving rise to the “active capsules” of the KM 100 series.

So Neumann’s miniature microphones not only took another clear step toward improved technical data, but now the capsules could be used with the help of accessories such as goosenecks, stand mounts, various cables, and tilting devices without electro-acoustic loss.

This miniature microphone family now comprises seven different capsules with all customary directional patterns.

These also include stereo mounts for XY, ORTF and MS recording techniques.

The Specialists

Besides the aforementioned dummy head, in 1992 the KFM 100 Spherical Surface Microphone was introduced for an additional stereo recording method.

This microphone had two small, high-quality condenser capsules arrayed on

the diameter of a head-sized wooden sphere. In the GFM 132 Boundary Layer Mi- crophone, these capsules had been optimised for sound received at oblique angles. Thus the KFM 100 was a microphone for especially natural stereo recordings with tremendous acoustic depth, making it ideal for miking highly complex acoustic fields, such as those found in churches and large halls.

10

11