Over the past 40 years Manuel Huber has visited many great mastering engineers and professionals in the vinyl field. A natural curiosity has helped to collect a wealth of information, some of which is presented in the enclosed data sheet.
Vinyl mastering is not a job, it is an art and there are different ways to achieve a desired end result. Confronted with the plight of the record collector who can only find scratched and/or crackling copies of rare LP’s, Alan and Manuel set out to try to ameliorate the problem. That was in 1981…
Now, they have finally achieved what they were aiming at all along: click, pop and crackle reduction circuits that do not negatively influence the audio signal - all done in real time and remaining fully analogue.
Enclosed a link to a simple 11 minute video in which some of the features - including the quite intriguing click and crackle removal of the unique Phono Master - are explained and demonstrated live in real time by Alan and Manuel.
UNIQUE PRECISION IN PHONO LINEARISATION, PREAMPLIFICATION, CLICK AND CRACKLE REMOVAL
When a totally faithful phono reproduction of the original is required -the FM 223PhonoMaster and FM 222 Linearizer/Preamplifier are the ultimate solution. The general characteristics are identical. The FM 223 PhonoMaster additionally provides the extraordinary new click, pop and crackle removal circuits, a treasure for record collectors who own precious works in less than pristine condition.
TRUE BALANCED CARTRIDGE INTERFACE
By design, all phono cartridges are balanced sources. The term “balanced” describes a system in which the audio signal is transferred via two shielded symmetrical conductors, neither of which is connected to ground (see Fig. 1). (For general information on balancing consult Technical Bulletin No. 34).
In an unbalanced system one of the signal paths is carried by the shield or is exposing the signal to the ground carrier. Because of this, interference signals such as hum, RF, noise etc. are picked up by the shield and can thereby enter the audio circuitry.
The lower the signal level and/or the more ambient interference present, the greater is the danger of degradation allowed by an unbalanced (single ended) interface.
To this day the interconnection of phono cartridges has been done “unbalanced” with a few pseudo- balanced phono preamps now available.
Considering the extremely-low signal levels of car- bridges, it becomes obvious that a true balanced signal interface to the preamplifier is a huge improve- meant over presently available designs. Unfortunately, such an elegant system was always faced with a number of technical challenges.
In the FM 223 and FM 222 these limitations have been overcome entirely.
They are the only phono preamplifier which assure true balanced interconnection of cartridges*.
Fig. 1 shows a balanced interface. Such a balanced interconnection of the phono cartridge has major advantages:
- increased dynamics
- higher headroom
- elimination of non-musical signals (interferences) - lower hum and noise
The signal lines from the cartridge are directly con- netted to the true balanced input stages and have no connection to the shield. Thus, the shield can function optimally, conducting all interference signals directly to ground. The ground, of course, must be separate from the electric ground of the circuits (in many other so-called “balanced” products this is not the case).
*True balancing requires more than just XLR connectors on the preamplifier’s inputs and outputs. It is the CMRR (Common Mode Rejection Ratio) that defines the accuracy of balancing and with it the suppression of disturbing non-audio signals. This is one of the characteristics that exemplifies the tremendous difference be- tween the FM 223 and other so-called “balanced” phono stages.