Critical Damping Inductor

Monitor Audio Gold GX200

Monitor Audio began operations nearly forty years ago, but is probably best known for introducing and proselytising metal diaphragm drive units, initially for its tweeter domes and soon afterwards for the cones used in its bass and midrange drivers.

Add in some very classily veneered enclosures that were manufactured in its own cabinet shop and the company established a template that still holds good today.

Twenty years down the line, plenty has changed of course, but the same core values remain at the heart of Monitor Audio's more upmarket ranges. The first Platinum series models appeared some four years ago and have been covered extensively in Hi-Fi Choice in recent times: PL100; PL200 and PL300.

A number of the advanced design techniques that were first introduced in those models have now 'trickled down' into the new and rather less costly Gold GX series tested here and it's these design 'luxuries' that we're most interested in with the GX200, the model that Monitor Audio's representative thought showcased the strengths of the new range best.

New Gold

Not that these £2,300 GX200s can be considered inexpensive by most standards, but they're certainly aimed at a competitive sector of the serious loudspeaker sector.

The complete Gold GX range is very extensive, consisting of four stereo pairs plus several models specifically intended for multichannel home cinema.

This GX200 is the smaller of two floorstanders, and is a genuine three-way design, using twin bass drivers to keep the front view fashionably slim.

Narrow floorstanders like this are potentially physically unstable, all too easily knocked over by unwary passing children, for example. Supplying a proper plinth arrangement to counter this possibility shouldn't be the tricky task that some brands seem to encounter, though fortunately Monitor Audio has thought this through carefully and clearly and come up with a rather clever arrangement, which is not only highly effective but also quite attractive style-wise.

Two substantial cast alloy pieces are bolted to each speaker, each accommodating two feet located well outside the footprint of the loudspeaker itself. Though the arrangement is mostly positive, the actual spike-locking arrangements are not ideal.

The requirements for an ideal cone diaphragm are very complex, inasmuch as they have to achieve a compromise between several conflicting variables. Low mass is one vital ingredient, in order to maximise sensitivity and ensure rapid responsiveness. However, rigidity is important to maintain pistonic behaviour across as wide a bandwidth as possible and it's also important that potential resonances within the cone are well damped.

How a resonator works

There are all sorts of resonances around us, in the world, in our culture, and in our technology. A tidal resonance causes the 55 foot tides in the Bay of Fundy. Mechanical and acoustical resonances and their control are at the center of practically every musical instrument that ever existed. Even our voices and speech are based on controlling the resonances in our throat and mouth. Technology is also a heavy user of resonance. All clocks, radios, televisions, and gps navigating systems use electronic resonators at their very core. Doctors use magnetic resonance imaging or MRI to sense the resonances in atomic nuclei to map the insides of their patients. In spite of the great diversity of resonators, they all share many common properties. In this blog, we will delve into their various aspects. It is hoped that this will serve both the students and professionals who would like to understand more about resonators. I hope all will enjoy the animations. on the figure to start or restart it. Mousing off and on again will stop and restart it. This animation shows the interaction of the force in the direction of motion (red vector) and the momentum (green vector). The meters and graphs indicate the force (red on graph), momentum (green on graph), potential energy (purple), kinetic energy (blue) and total energy (gray). All the scales are in "arbitrary" units. Image of animation in separate window (or tab) . 2.4 How a resonator works

How a pendulum works

To better understand how resonators work, let's examine one simple resonator, the pendulum, as being typical of all resonators. Examine the animation in Figure 1, the graphs in Figure 2, and the captions. The resonator uses the interplay of force and momentum in its operation. Whenever the pendulum is left or right of the center position, there is a restoring force (shown as a red arrow in Fig. 1) due to gravity, trying to push the pendulum back towards the center. When the pendulum is near the center, its momentum dominates causing it to overshoot the center and climb back up to its previous height.

We now follow the pendulum on its cycle. Suppose the pendulum is pulled to the left and released (you can freeze this condition by clicking on Fig. 1 and immediately mousing off the figure). In this position, the force is maximum in the right (i.e. positive) direction. The red force arrow is maximum and the force meter points to +1, indicating the maximum. The potential energy is also maximum here. The momentum and kinetic energy are zero because the velocity is zero.

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