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The three vertically aligned dome drivers act as a small line array, focusing the sound into a tight vertical coverage pattern while the constant-directivity horn maintains broad horizontal coverage. The bi-amplified M1D incorporates a complementary MOSFET power amplifier module with watts total burst capability, together with active crossover and optimized frequency and phase response correction circuitry. Integral peak and rms limiters protect the loudspeaker components from overexcursion and over-heating.
The M1D incorporates QuickFly rigging as standard, and utilizes connecting links that are secured to the steel and aluminum rigging end frames by quick release pins. An ingenious arrangement of rigging holes allows quick and easy adjustment of cabinet splay for maximum freedom in customizing vertical coverage. RMS allows the full range of operating parameters to be monitored over a network using a Windows computer. The M1D-Sub ultra-compact subwoofer complements the M1D ultra-compact curvilinear array loudspeaker by extending bandwidth with its operating frequency range of 32 Hz to Hz and substantially increasing overall system headroom.
Because it produces a prodigious peak SPL of dB at 1 meter from a compact cabinet, the M1D-Sub allows system designers to minimize array size while maximizing system response. A variety of QuickFly rigging options allows the M1D-Sub to be flown above, below or within an array, or placed at the base of a ground-stacked array. Although it is intended primarily as a companion subwoofer to the M1D, it is perfectly suited to general use where powerful low frequency augmentation is desired. M1D-Sub contains two robust inch cone drivers, each featuring a 2-inch voice coil and a lightweight neodymium magnet structure.
Power rating per driver is AES watts see note 5 on back page. An Intelligent AC power supply selects the correct operating voltage in the range of 90 to V AC at 50 or 60 Hz, allowing international use without manually setting voltage switches. The Intelligent AC supply also performs protective functions to compensate for hostile conditions on the AC mains.
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These functions protect both the loudspeaker and electronics from erratic AC conditions and increase the lifespan of the loudspeaker. An ultra-low-noise fan is fitted, but cooling is primarily provided by a massive external extruded aluminum heat sink. The vented M1D-Sub cabinet is constructed of multi-ply hardwood with a durable finish suited to touring or installed use. A metal grille protects the drivers. All load stresses are transmitted through the rigging frames and associated hardware, not through the wooden cabinets.
RMS allows the full range of operating parameters to be monitored in real time, remotely over a network using a Windows computer. The HP is a self-powered, high-output subwoofer that may be used in both flown and ground-stacked configurations. The system features two specially designed high-power inch cone drivers, engineered to provide optimal performance in subwoofer applications. The two cone drivers are housed in a rectangular, optimally tuned and vented enclosure that is the same width as MICA, and a few inches higher and deeper.
The enclosure geometry makes vertical ground-stacking easy and convenient. Total output power is watts watts peak , providing the system with sufficient headroom to accommodate the most extreme sound reinforcement demands with ease. The circuitry includes TruPower limiting to extend the life of the drivers and hold long-term power compression to less than 1 dB. The amplifier, control electronics, and power supply are integrated into a single, field-replaceable module that is mounted into the rear of the enclosure.
The optional MRF rigging frame uses captive, rigid GuideALinks contained within recessed guides in the lower front and rear corners of the enclosure. A slot and convenient pinned handle allow the link to be moved and pinned for arraying or storage. The versatility of angles achieved by using combinations of front and back positions allows a MICA array suspended under HP subwoofers to be uptilted for balcony coverage up to 15 degrees, or downtilted to 6 degrees with respect to the HP.
The durable enclosure is constructed of premium birch plywood coated with a black, tex- tured hard-shell finish, with a powder-coated, hex-stamped steel grille lined with acoustical black mesh to protect the drivers. The exterior dimensions of the HP are suitable for both European and U. Options for the HP include weather pro- tection and custom color finishes for fixed installations and other applications requiring specific cosmetics. The RMS remote monitor- ing system — standard with the rigging version and optional with other configurations — allows comprehensive monitoring of system parameters on a Windows-based network.
Active: Powered. An active crossover is electrically powered and divides the line-level signal prior to amplification. An active speaker includes an active crossover and built-in amplifier. Amplifier: A component that increases the gain or level of an audio signal. Balanced Input: A connection with three conductors: two identical signal conductors that are degrees out of phase with each other, and one ground. This type of connection is very resistant to line noise.
Bandpass: A two-part filter that cuts both higher and lower frequencies around a center band. A bandpass enclosure cuts high frequencies by acoustic cancellation and low frequencies by natural physical limitations on bass response. Bandwidth: In audio, the range of frequencies a device operates within. In video, the range of frequencies passed from the input to the output.
Bandwidth can also refer to the transmission capacity of an electronic communications device or system; the speed of data transfer…very important when planning a meeting for the attendees to stay connected. Bass: Low frequencies; those below approximately Hz. CD: Compact Disc. Ubiquitous digital audio format. Channel: In components and systems, a channel is a separate signal path.
A four-channel amplifier has at least four separate inputs and four separate outputs. Crossover: A component that divides an audio signal into two or more ranges by frequency, sending, for example, low frequencies to one output and high frequencies to another. An active crossover is powered and divides the line-level audio signal prior to amplification.
A passive crossover uses no external power supply and may be used either at line level or, more commonly, at speaker level to divide the signal after amplification and send the low frequencies to the woofer and the high frequencies to the tweeter. Crossover Frequency: The frequency at which an audio signal is divided. Frequencies below 80 Hz are sent to the subwoofer; signals above 80 Hz are sent to the main speakers.
Decibel dB : A logarithmic measurement unit that describes a sound's relative loudness, though it can also be used to describe the relative difference between two power levels. A decibel is one tenth of a Bel. In sound, decibels generally measure a scale from 0 the threshold of hearing to dB the threshold of pain. A 3dB difference equates to a doubling of power. A 10dB difference is required to double the subjective volume. A 1dB difference over a broad frequency range is noticeable to most people, while a 0. Delay: The time difference between a sonic event and its perception at the listening position sound traveling through space is delayed according to the distance it travels.
People perceive spaciousness by the delay between the arrival of direct and reflected sound larger spaces cause longer delays. Diaphragm: The part of a dynamic loudspeaker attached to the voice coil that produces sound. It usually has the shape of a cone or dome. Diffusion: In audio, the scattering of sound waves, reducing the sense of localization. In video, the scattering of light waves, reducing hot spotting, as in a diffusion screen.
Most include the processing to make the files, and all have the ability to play them back. Dispersion: The spread of sound over a wide area. Distortion: Any undesired change in an audio signal between input and the output. Dolby B: A noise-reduction system that increases the level of high frequencies during recording and decreases them during playback. Dolby C: An improvement on Dolby B that provides about twice as much noise reduction. Dolby Digital: An encoding system that digitally compresses up to 5. When RF-modulated, it was included on some laser discs, which requires an RF-demodulator before the signal can be decoded.
Five channels are full-range; the. A Dolby Digital processor found in most new receivers, preamps, and some DVD players can decode this signal back into the 5. Most films since 's Batman Returns have been recorded in a 5. The sixth channel is matrixed from the left and right surround channels. Often referred to as 6. Sometimes referred to as 7. Software is backwards-compatible with 5. Pro Logic decoders derive left, center, right, and a mono surround channel from two-channel Dolby Surround encoded material via matrix techniques.
Adds improved decoding for two-channel, non-encoded soundtracks and music. Driver: A speaker without an enclosure; also refers to the active element of a speaker system that creates compressions and rarefactions in the air. Manipulating an audio signal digitally to create various possible effects at the output. Often refers to artificially generated surround effects derived from and applied to two-channel sources.
A digital sound recording format, originally developed for theatrical film soundtracks, starting with Jurassic Park. Records 5. Simply complete the following sentence: The function of a PA system is to That wasn't hard, was it? But in case you're struggling, the function of a PA system is to deliver your sound to the audience, and deliver it well. It's as easy as that.
But hang on, it doesn't seem to be all that easy, does it? Whenever have you experienced perfect sound as an audience member? And when have you ever felt that your band's sound has been delivered to the audience as well as it should have been? There must be additional criteria that need to be fulfilled to achieve satisfaction.
And yes, there are. Achieving adequate level is never a problem. It hasn't been a problem since the s, when PA systems as we know them today had fully matured. All you need is a recognition of how many watts you require for a particular venue, usually calculated by rule—of—thumb and reference to past experience, and the budget to hire enough amplifiers and loudspeakers.
Achieving low distortion, low noise and a flat frequency response hasn't quite been fully solved, although if the noise level of your PA is audible to the audience there's a fault somewhere in the system: power amplifiers in general have a better signal—to—noise ratio than just about anything else you'll find in the whole of sound engineering.
The frequency response of PA loudspeakers, however, leaves a lot to be desired, and it is definitely true to say that the only thing that produces more distortion than a loudspeaker is the lead guitarist's screaming Marshall on overdrive. But even though not all is yet perfect regarding the above points, most people find the sound quality of a decent PA system acceptable. And the typical sound of a PA has almost defined people's expectations of what a PA should sound like. A circular argument, perhaps, but there's a lot of truth in it. There's still one point left unanswered: that of clarity.
It is possible for a PA system to be capable of detailed, analytical clarity within itself. But when deployed in a real—life concert scenario it sounds anything but clear. You must have experienced it yourself many times as an audience member — that fuzzy mush of sound that clogs up your ears, but you can't really resolve it into music.
Clarity, therefore, is the last unconquered frontier of PA. It is the last major problem that remains difficult to solve. At this point I need to return to one of the requirements of PA that I previously said had been solved: that the PA system should be loud enough. There's no difficulty in making it loud enough, providing you have the budget — but it has to be loud enough for all members of the audience, and that's a problem that isn't necessarily solved just by spending a lot of money. There are two scenarios here: one where the audience are seated, the other where they are standing and free to move.
If the audience are free to move, it is acceptable to have different levels in different parts of the venue. Those who like it loud will gravitate towards the loudspeakers. Those who perhaps want to chat during the show will move further away. However, if the audience is entirely seated it suddenly becomes much more difficult. You don't want to deafen the front rows of the audience while leaving those at the back struggling to hear. If only certain members of the audience are delivered a level that is adequate, without being too quiet or too loud, the PA has not fully met its purpose.
Let me therefore refine the requirements of PA into this simple statement: all of the audience should enjoy high—quality sound that is loud enough and clear enough. MAPP Online is the Multipurpose Acoustical Modeling Program developed by loudspeaker manufacturer Meyer Sound to model the sound fields developed by its products in a variety of configurations. A sound designer is able to enter data into MAPP Online , including individual loudspeakers and arrays, then click the 'predict' button and get a graphical display of the expected coverage.
Clearly, a system such as this, that is accurate in its predictions, is a tremendous tool for the sound designer. MAPP Online will run on Windows, Macintosh or Unix computers, and data that the user enters is sent to Meyer Sound's servers, where the analysis and prediction is made, then delivered back to your desktop. The example shown is a composite of two predictions made for arrays of Meyer Sound MILO cabinets, one with just three loudspeakers, the other with 20, both at 1kHz.
It is clearly possible to see how much more directional, and how much louder, the larger array is. You can also clearly see the 'side lobes' that develop — an unfortunate by—product of all line arrays that the sound designer must take into account. A paramount rule of PA is to direct the sound towards the audience and not elsewhere. But how often do you see this rule flouted? The best and most classic example of this not being done was in several London Underground stations, some years ago. At the time, the tube network was decaying and falling into disrepair, so several stations were refurbished with bright, modern designs.
Along with the visual aspects, these stations were given new sound systems too. The result was that from any point on the platform, you could hear every loudspeaker, with delays increasing with distance. It was, indeed, possible to stand as close to a speaker as you could and still not understand what was being said! This state of affairs wasn't allowed to continue for long, and now the speakers point as they should — down at the passengers on the platform. So the most important thing is to point the loudspeakers at the people in the most direct way possible.
At the same time, consider how much sound is being 'sprayed' onto the walls and ceiling. The audience will absorb much of the sound energy that strikes them, meaning that it won't be reflected to bounce around the auditorium and cause confusion. But the walls and ceiling are very likely to be reflective, so the more sound that goes in these directions, the more mush—inducing reflections will be created. The EAW CLA37 column loudspeaker uses seven 3—inch drive units to achieve a coverage of degrees horizontal x 30 degrees vertical, thus controlling the vertical dispersion tightly.
It is suitable for speech reinforcement in large reverberant environments if several or many units are distributed amongst the listeners. In a situation where the information content of speech is of primary importance, the classic solution to intelligibility is to use many small loudspeakers and have them close to the people — obviously, pointing at them and not at reflective surfaces.
This works extremely well and the information content gets through clearly. But this solution is not acceptable for a musical performance. The reason for this is that we expect a performance to take place on a stage. We watch the performers on the stage, and we expect the sound to come from the stage too. If the sound were coming from a small speaker mounted at just a couple of metres distance, up and to the side, that would cause a conflict between the visual and the auditory.
Everything might be clear and intelligible, but we wouldn't enjoy the performance. So the multiple small speaker solution doesn't work for performance. We need the sound to seem as much as possible as though it comes from the stage, and for this you can't do better than actually having loudspeakers at the sides of the stage, like a great big stereo system.
However, there are still potential problems The first problem has been mentioned already and has to do with directivity. Loudspeakers naturally have a characteristic directional response — almost omnidirectional at low frequencies, tightening to a focused beam at high frequencies. Put another way, anyone sitting directly in front of a loudspeaker will experience a reasonably flat frequency response, but people sitting further and further to the side will hear less and less high frequencies, so the sound will be increasingly dull. So the 'big stereo system' style of PA suffers in that it sprays the walls and ceiling with low—frequency and low—mid energy that reflects into a confusion of reverberation, and only select members of the audience receive sound with a good balance of frequencies.
A second problem stems from the lack of directional control. Because much of the sound is spread widely, beyond the width of the audience, energy is lost.
Bob “606” McCarthy
The more sound spreads out, the more thinly its energy is spread, and therefore the more level is lost with distance. This is an important point. The reason a sound source becomes apparently quieter as it becomes more distant is primarily because its energy is spread out. Yes, some level is lost through absorption in the air, but not much. It's distance that's the killer. An audience member sitting a long way from the loudspeakers will experience a distant and therefore quiet sound, while audience members close to the speakers are getting their heads blasted off!
Let's think in terms of light. Take a torch bulb. Intrinsically it emits light almost equally in all directions, so by itself it isn't much use for finding your way in the dark. But put a reflector behind it and a lens in front of it, so that its energy is concentrated into a beam, and you will notice immediately that it is now usefully bright.
You'll also notice that the beam extends into the distance. So not only do you see the immediate area in front of your feet, but the area beyond where you direct the beam. The area of coverage is less, but you can now see where you're going. If the same could be done with loudspeakers, there would be two benefits: one, that the sound is focused on the audience and away from reflecting surfaces; and two, that the sound retains its level as it travels.
So the audience members at the back are served as well as those at the front, and the difference in level between front and back is much less. If you understand the theory behind the directional characteristics of sound sources, you'll be in a good position to understand PA loudspeakers and get the best out of them. There are two extremes of directionality, between which there are other interesting cases. One extreme is the point source, which is a source of sound that has zero size.
OK, there's no such thing as zero size, but in practice if a sound source is dimensionally smaller than the wavelength of sound it is emitting, it has the characteristics of a point source. The low—frequency output of a small loudspeaker would be a real—life example. A point source emits sound equally in all directions. There you have it: all you need to know about the point source! Well, not quite all Imagine this very small point source pulsating outwards momentarily, just once.
A sphere of high pressure leaves its surface and radiates outwards, becoming larger and larger. The point source has put a certain amount of energy into this pulse, and that same amount of energy over time has to cover a larger and larger area, the surface area of that continuously expanding sphere. I could at this point bore you to tears with detailed calculations concerning the surface area of a sphere, energy density and stuff like that, but instead I will cut directly to the chase and say this: for a point source, sound pressure decreases by 6dB for every doubling of distance.
We call this the inverse square law. One mistake or over—simplification is that it is commonly said that all sound obeys the inverse square law. This is not so. Only sound from a point source obeys the inverse square law. Any sound source that is not omnidirectional does not obey the inverse square law. If you get so far away from it that visually it recedes to a point, from your point of observation it will appear to obey the inverse square law, but in practical terms this is not relevant to PA.
From this we can derive two interesting facts. The maximum rate at which sound level can decrease with distance is 6dB per doubling of distance. The only way sound can decay at a faster rate than that is if you actively do something to block it. Also, sound sources that are directional decay at a rate that is less than 6dB per doubling of distance. It's interesting to consider the opposite extreme. Would it be possible to have a sound source, the level from which does not decay at all with increasing distance?
Amazingly, the answer is yes. It is possible to have a sound source that is so focused that it will cover an amazing distance with hardly any reduction in level. You want an example? I'll give you two examples: an old—fashioned ship's speaking tube, and a tin—can telephone. We call this kind of sound source a plane source.
In both cases, the sound energy isn't just focused, it is constrained to travel within an enclosed medium so that it cannot spread out at all. And since it cannot spread, no level is lost. In practice, a little level is lost, but nothing's perfect. You can see that this is not a practical way of delivering your sound to the audience, so we will leave it as a curiosity, but a curiosity that demonstrates a useful principle.
The next type of sound source is the whole purpose of this article, and is the salvation of PA as we know it. We call this type of source — fanfare of trumpets — the line source. To understand it, lets go back to the point source for a moment. I said that the point source which is omnidirectional needs to be small in comparison with the wavelength of sound that it is emitting. The converse is true too: when a sound source is larger than the wavelength it is emitting, it becomes more directional. And the larger it is, the more tightly directional it is.
So a really large sound source would be tightly directional. This is what we want: a source that can be focused and directed to cover the audience, but not wasted on other areas of the auditorium. But imagine you're a loudspeaker looking out from the stage to the audience. The audience in front of you are spread widely from left to right, but from top to bottom — in perspective, from the rear rows to the front — there is only a narrow spread.
You can see the problem. If you made a large loudspeaker that focused the sound tightly enough to direct sound accurately in the vertical dimension, it wouldn't cover the full width of the audience. And vice versa: if it covered the full width, you'd end up covering the ceiling as well, and we know that's a bad thing. The solution is to devise a loudspeaker that is tightly focused in the vertical dimension but spreads sound widely in the horizontal dimension.
To do this, the speaker needs to be large vertically, but small horizontally. Like a column, in fact. And here we have it bigger fanfare of trumpets : the column loudspeaker! Did I say 'column loudspeaker'? Sorry, I must use the more up—to—date and exciting terminology: line array.
They are both examples of the line source. Clearly, you're not going to have a full—scale line—array system in the back of your band's Transit van. In fact, playing through a line array for the first time may mark your transition from wannabe band to successful band. But there will come a time, hopefully, when you are called upon to have an influence in the specification of your touring PA system.
At first, the line array looks intimidating. All those cabinets, all that cable. Who's going to go up there and string the whole thing together? The answer is nobody, because the system is assembled at stage level and the whole thing hoisted up. The motorised hoists even have remote controls so that no—one has to shout instructions or converse through an intercom. A line array can actually be set up by as few as two or three people. Any kind of flying, however, involves considerable responsibility, and manufacturers are keen to use the words risk, damage, injury and death frequently in their operators' manuals.
Apparently, the most dangerous part of the rigging process is when the equipment is at stage level. As it rises into the air, providing everything is done correctly and the equipment is in good condition, it flies out of the danger zone. Setting up a conventional PA system on stage involves a certain amount of use of of rules—of—thumb.
Bob McCarthy: Meyer Sound
The line array is far too big a thing to set up in the same way, and once it's set up you don't really want to have to move it, so you need to be sure that the positioning is right, the height is right, the horizontal angling is right, and — most of all it — that the array takes up the optimum J—shaped curve to distribute sound evenly to the front and back of the audience, and everyone in between. To make this possible, manufacturers commonly provide software that can be used to calculate all the necessary parameters, examples of which are shown on the following two pages.
Meyer Sound are good enough also to advise equipping yourself with binoculars, laser measuring tool, pedometer, laser inclinometer and a self—levelling, four—way laser. That should really be a last resort, as any decent venue should have a set of plans with accurate measurements! I often think that one of the best lessons of the past is not to go there again. However, the column loudspeaker has as important a place in the history of PA as the electric guitar does in rock music.
Yes, really. One day there might be people who make a living as historians of PA, and they'll be able to tell us exactly how the column loudspeaker came to be developed. Until then, my guess is that it developed by chance and was found to work effectively.