Maxicut

The birth of Maxicut
Maxicut was the name given in 1978 by Studios 301—the recently renamed and re-equipped EMI Studios, Sydney—to a series of modifications made to its Neumann VMS-70 disc-cutting lathe.

The modifications were contained on two printed circuit boards that replaced the standard Neumann SV-66-V2 and TE-66 cards. Together, they allowed engineers to cut lacquers at significantly higher levels—typically 6 to 8 dB louder—without causing the tracking problems that less-expensive turntables and cartridges commonly experienced when attempting to reproduce heavily modulated grooves.

Crucially, Maxicut achieved this without removing any part of the recorded signal or significantly reducing the available playing time.

The problem Maxicut solved
The Neumann disc-cutting system had been designed principally around the natural level and phase relationships found in stereo classical recordings. As an orchestra grew louder, there was generally a corresponding increase in ambient, out-of-phase information. The Neumann system could detect this and automatically adjust the depth and spacing of the groove to accommodate the increased modulation.

Loud rock and pop recordings presented a different problem. Their low-frequency information was often largely mono, meaning that it appeared in the groove as lateral rather than vertical movement. The standard Neumann system did not respond to this material in the same way, potentially producing a groove that was too shallow to be tracked reliably by inexpensive playback equipment.

Former Studios 301 mastering engineer Don Bartley explained the problem—and EMI (Australia)’s solution:

"As most mastering engineers at the time knew, the Neumann cutting system was designed around stereo classical music and its natural phase/level relationship. In other words, as the stereo orchestra played louder, there was an equal increase in the ambient out-of-phase information.

"The Neumann lathe would see this increase in level and phase—particularly at the bottom end—and adjust the depth and pitch of the groove to accommodate the modulation of the signal, avoiding “light” grooves and “groove jumping” on playback.

"However, the Neumann system was not user-friendly to loud rock and pop music, whose bottom-end signal was practically mono. This resulted in the lathe maintaining a constant-depth groove regardless of the level of the signal. The pressing plants classified the result as a “dangerous” cut that could groove-jump on cheaper playback systems. Most engineers therefore did something to overcome the problem.

"Before my days at EMI, I was mastering records for RCA Sydney and developed a system whereby a phase shift was introduced to the bottom end of the lathe control signal. This produced a level-to-depth relationship and resulted in a “safer” cut.

"The clever people at EMI decided to redesign the control circuitry of the Neumann lathe and replace one of the printed circuit boards with their own Maxicut board. This created a sensation, and engineers around the world were peering into their microscopes to see what was going on.

"By the time I joined EMI in 1980, Maxicut II had been introduced. It was a more refined version and the one we used throughout the 1980s and into the 1990s.

"Maxicut was definitely the best and most transparent solution to what was an annoying problem with the Neumann cutting system. I believe there was a patent on the design, although I am not sure whether Maxicut was adopted by any other users."

How Maxicut worked
Studios 301 described the process in greater technical detail in its March 1980 Report on Technical Developments.

Method
The standard Neumann disc-cutting chain—the VMS-70, its associated rack, pre-listen tape machines and electronics—is designed to cut a groove of typically 25 microns depth. This depth will vary with stereo programme material, and this is aptly known as vertical information.

To control the minimum and maximum depth of the groove, Neumann takes the pre-listen programme and derives a control signal that is delayed in time to correspond with the programme chain. This control voltage limits the depth range of the cutter head. However, the Neumann system of depth control works only on vertical information.

Our investigations have shown that high-level mono signals, or lateral information, need additional groove depth under certain frequency and amplitude conditions to ensure optimum tracking.

The Maxicut system is a dynamic control system that increases the groove depth only during those portions of the lateral information that require additional depth for optimum tracking.

Maxicut also includes a method of improving cutter-head suspension control through the use of a “negative output impedance” amplifier. This allows more accurate control over the mechanical movements of the cutter head, as well as improved low-frequency response. The heavy fluid normally used to damp the natural mechanical resonance of the cutter head can consequently be reduced or removed.

Other than this negative-output-impedance cutter-head control amplifier, Maxicut does not alter the standard vertical cutter-head control.

We are currently investigating the use of a 20-micron groove depth with Maxicut to improve programme length without reducing operating levels or, for a given playing time, to increase levels on disc still further. However, our current levels are probably already as high as most modern replay equipment can handle.

System
From the stereo pre-listen chain, a left-plus-right lateral signal and a left-minus-right vertical signal are derived.

Maxicut takes the lateral signal and equalises it to provide a signal representing constant amplitude-to-frequency in relation to the lateral deviations of the groove. The signal is then delayed to correspond in time with the signal from the programme chain of the disc-cutting system.

This signal is fed to a threshold and shaping network. The network has a signal threshold level and pre-emphasis curve that correspond directly in amplitude and frequency to the trackability overload point of a reference turntable.

The signal is then rectified and combined with the output of the Neumann vertical-information depth control. From these signals, a control voltage for the cutter-head suspension is derived. Whichever of the lateral or vertical depth requirements is greater determines the depth of the cutter head.

Results
Our results have been very encouraging. We have seldom encountered a disc cut elsewhere that—given the same tapes—we could not match or better in terms of level and low-frequency response, while maintaining trackability on our reference “groove-jumper” turntable: an HMV three-in-one system.

John Schell remembers
John Schell, the EMI (Australia) engineer who developed Maxicut, later recalled how the system evolved—and the decidedly modest playback equipment against which it was tested:

"I began working on it [Maxicut] in 1977 and had a functioning system in 1978. It was used on the VMS-70 in Mastering Room 3—MR3.

"Mastering Room 1 never had the Maxicut boards fitted, as it had the old VG66 rack and later the SX68 cutter head. MR1 was used only for older or lesser-quality releases.

"Once I had proved that the system worked, it was used for cutting discs almost all the time—even 7-inch singles and 12-inch 45s. EMI applied for a patent on Maxicut and did not release information about it until 1980, once the patent had been granted.

"Basically, the system allowed the cutting engineer to begin with a small groove—40 microns—and increase its depth when heavy bass was present in the music. It helped dramatically with dynamic music.

"I recall making a test cut of heavy-metal music and finding that I could increase the level of the cut by less than 1 dB. This was to be expected, as the VU meters hardly moved from 0 VU.

"The required deepening of the grooves was determined using an old record player with a crystal cartridge, as these were the machines that would groove-jump if the groove was too small. I checked it using other similar record players as well.

"It is a pity that we had to accommodate such “lousy” record players at the time."

From Maxicut to Maxicut II
The original Maxicut system was not without its problems. Under certain conditions it could produce extremely deep grooves, potentially causing areas of non-fill during pressing if the problem was not detected.

Mastering engineer Richard Mott reportedly cut through the lacquer and struck the aluminium substrate on a couple of occasions, breaking the cutting stylus in the process.

The problem was rectified with the introduction of the more refined Maxicut II system around 1981. This became the version routinely used at Studios 301 throughout the 1980s and into the following decade.

Maxicut and Direct Metal Mastering
Maxicut’s use continued after Direct Metal Mastering was introduced at Homebush. The Neumann VMS-82 DMM lathe was also fitted with Maxicut, allowing the system to operate when masters were cut directly into copper rather than lacquer.

Which records used Maxicut?
Maxicut was used for almost every master cut on the suitably equipped lathes at Studios 301, including 7-inch singles and 12-inch releases. Its use extended from conventional lacquer mastering through to the later DMM era.

For Beatles collectors, this means that virtually all Australian Beatles releases and recuts produced from 1978 were cut using Maxicut.

Earlier Maxicut lacquers may carry a "MAXICUT" inscription in the run-out groove. Studios 301 discontinued this practice at some point during the early 1980s because the lacquer could occasionally be damaged while the inscription was being applied.

The absence of a Maxicut inscription therefore does not mean that the process was not used. Indeed, many records cut using Maxicut carry no identifying mark at all.

The system was generally switched off only when cutting an unusually long classical side. In those cases, the priority was to conserve the available playing surface during very quiet passages and accommodate the required programme length.

The Maxicut sound
Maxicut pressings remain highly regarded by collectors, audiophiles and members of the Australian music industry for their high cutting levels, powerful low-frequency response, dynamic presentation and reliable tracking.

Rather than altering the recorded programme, Maxicut enabled the cutting system to respond more intelligently to loud, bass-rich material. It allowed EMI (Australia)’s mastering engineers to produce records with greater impact while remaining playable on the modest domestic equipment found in many Australian homes.

More than a technical workaround, Maxicut was an ingenious Australian contribution to the art of analogue record mastering—and one whose benefits can still be heard on surviving pressings decades later.

A curious footnote
Phonogram—later PolyGram—once sent EMI (Australia) a memo insisting that at least 80 per cent of a record’s playing surface be used, regardless of the length of the programme.

It argued that customers might otherwise believe they were not receiving “value for money” if too much of the vinyl remained unused!