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Playing the weighting game with touring amps

Erica Basnicki 27 November 2012
Playing the weighting game with touring amps

Every production needs the best tools for each job. In every territory, however, live sound faces tighter budgets for each event. So, how can you take less gear to achieve the same results? One department that might be able to help is the power supply: very powerful, highly efficient amplifiers with built in DSP enable the pressured tour manager to lighten the load while avoiding compromise.
  Placing external DSP inside each amplifier reduces rack space and maybe, even, vehicle size. And the more lightweight each module is, the less fuel you use. The more efficient they are, the less venue or generator power is needed. All in all, using the right power amps is at the heart of modern industry economics, with a direct hit on profit margins all through the supply chain.   FUEL BILLS In today’s economy, the power-to-weight ratio might well turn out to be the most important decision that every PA company needs to make.

Each manufacturer makes its own claims: “If we compare the industry standard MA5002VZ to the I-Tech 12000HD we have available today,” points out Brian Pickowitz, business segment manager at Crown Audio, “not only do you go from 3U to 2U, but the I-Tech 12000HD weighs 22.68kg less and puts out 2,725 more watts per channel.”
  “High power with low weight is one of the major requirements for touring amplifiers,” states Dynacord product manager Martin Traut. “Unfortunately it’s not clear to everybody what ‘high power’ stands for, other than a nice value in the spec-sheet:particularly for touring applications, the specified power needs to get delivered under any demanding condition such as low frequencies at low impedances.”
  “It’s definitely important,” adds Klas Dalbjorn of Lab.gruppen, “but there’s much more to it. Make them reliable; make sure they can handle fluctuating mains voltage; make the package compact; have easy-to-use software with fast setup and powerful grouping capacity.”
  XTA-MC2 brand manager Waring Hayes expands further. “Current mantra does dictate this, but we’re always mindful of maintaining the highest level of sound quality under all operating conditions. E-Series amplifiers are switching designs – the smaller amplifiers are hybrids of linear amplifiers and switching supplies, larger designs are switching amplifiers with switching supplies. One major design philosophy common to them all is the fact that behind great sound quality is a great power supply, and its ability to generate huge power for short durations from local storage – not pulling massive surges from the mains.
  “However, it shouldn’t all be about power. Maybe we should consider less power used more efficiently? Switching amps are significantly better than linear amps at transferring more of what goes in the mains inlet to the speakers, which is great, but do we need a sledgehammer to crack a nut all the time? Being able to use a lower-power amp results in savings – running costs are becoming a greater consideration these days, even in the touring market.”   A CERTAIN RATIO So has the industry reached a plateau in the ratio of power to weight? Some are sceptical of unlimited advances: “To go much beyond the PLM 20000Q in a single phase will be very challenging,” admits Dalbjorn.

At MC2, Hayes is also cautious. “Amplifier power has already reached astronomical levels,” he says, “with several manufacturers now producing designs that appear to be a factor of 10 over what would have been available only 10 years ago. This rate of power increase is unlikely to be sustainable. There may be small, incremental changes in power output, but until we reach a point where engineers are happy to connect all their subs to a single amplifier the output power levels we have currently reached will probably flatten out.
  “The major factors that stop modern amplifiers becoming more powerful are how effectively they can draw power from the mains supply and how hard they can drive loudspeakers without damaging them. XTA processing goes a long way towards this: RMS limiting keeps the voice coil temperatures down and peak limiting controls over-exertion. As for advances in weight reduction, these will come naturally as the switching devices available become ever faster and more efficient. This will allow reduction of heat sinks and the size and weight of magnetic components.”
  Others are very confident that no such limit exists. “Absolutely not,” asserts Brian Pickowitz. “We just launched our I-Tech 4X3500HD four-channel amplifier which puts 2,400W per channel at 4 ohms, all channels driven. It’s part of our DriveCore Series, with proprietary technology that allows us to continue to push the envelope when it comes to power density and weight. Basically, if you look at one of our two-channel I-Tech HD amplifiers, one-third of it is power supply and two-thirds is two channels’ worth of amplification. DriveCore technology allows us to shrink parts counts within the amplifier and produce better power density in smaller packages. Reducing the size and weight of Crown amplifiers will only continue into the future.”
  Powersoft’s Luca Giorgi agrees. “The power-to-size ratio will always improve, because it’s related to advances in electronics integration. But there’s another question that could have an impact on the direction of the technology: how far will the increase in power go? We believe that the undisclosed capabilities of Class-D technologies to drive very unconventional loads would be the next step – together with the multichannel trend. Consider this, too: the power-to-size ratio would be very interesting if power modules with very high performance could be integrated into high-power, self-powered cabinets.”
  “Plateau? Not at all,” adds Nexo’s Joseph Carcopino. “From our 30 years of knowledge about speakers we know that the power handling capacity of speakers is increasing at a very regular rate. There is still plenty of headroom for amplifier power increasing. But one of the physicals limit which we have to beat now is the standard 230V/16 A mains plug. Although Nexo was to my knowledge the first pro-audio manufacturer to introduce a multichannel power amplifier with two mains cords for increasing input power, we see today the manufacture of three-phase amplifiers that will again raise the maximum input power for an audio amplifier.”   ENGINE ROOM The market never stands still. Camco’s new Vortex 8 Silver Series, for example, makes a statement in terms of interface: its 8,600W of power in 2-ohm or 4-ohm applications is controlled without any knobs or switches on either the front or back of the chassis. Parameters are accessed via a screen and gain slider reducing, according to Camco “wear and tear factors on moving parts while delivering a forward thinking approach to function, safety and plain good looks.”
  But standalone amplifier makers are in some ways swimming against the tide. “With both amps and processing being integrated together and into speakers themselves, how do amplifier manufacturers not directly linked to speaker brands keep ahead of the game?” asks MC2’s Waring Hayes. “By making their amplifiers sound the best and bring out the best in any speaker system. By playing harder – and sounding better while doing so – and protecting better to get more out of the speakers while not stressing them further in the process. The only way to do this is to know more about the speakers’ capabilities – not just suggested crossover frequencies and corrective EQ and phase settings, but the mechanical characteristics and both long and short-term maximums.
  “This closer relationship between amplifier and speakers is achievable in a closed system such as a powered box, but much harder to establish in a situation where the amplifier and speaker system are unrelated and ‘know nothing’ of each other. Some manufacturers have attempted to improve this state of affairs by offering the ability to include more driver-related parameters in the overall system setup, but this is of course dependent on speaker manufacturers making this information available – or even having access to it in the first place. Amplifiers not tied in to a specific manufacturer’s speaker systems must establish new methods of making their designs both more intelligent and also less complex to configure. It’s a tricky balance to get right!”
  From next month, Yamaha’s CL series of digital mixing consoles and Nexo’s powered TD controllers will use the new Yamaha-Nexo NXDT104 Dante network card to advance the integration and control of the NXAMP via the consoles’ touchscreen displays. The integration allows NXAMP discovery and patching operations that hitherto needed a computer running the Dante Controller software application.
  According to Yoshi Tsugawa, CEO of Nexo: “We intend to take all operations and processes that are troublesome, time-consuming, complex or uncertain and make them fast, easy, assured and safe. This development marks another step in that direction.”
  Such pooling of resources is able to take advantage of several evolutionary steps that seem to come together beneath the hood of the 21st century power amplifier. “Class D technology and its variants is now mature and established in the pro-audio market,” explains Joseph Carcopino, “so we’re now seeing young engineers brought up with this knowledge and building the next generation with a power efficiency unimaginable a few years ago. The power electronics industry also has new components, with new materials, that solve some of the historical pitfalls with standard components.
  “In the end, the democratisation of computing resources and industrial CPU has made signal processing part of the game. So my feeling is that the ‘one-guy’ amplifier companies that were very common in the early years of this industry will have difficulties competing with companies that have an overall knowledge of power electronics, signal processing, industrial converters, isolators and so on. And I think that our [Yamaha-Nexo] combined knowledge between speakers, amplifiers and signal processors puts us in a good position for the future.”
  “Crown is in a good spot for the future,” chimes Brian Pickowitz. “We have DriveCore technology that will help us achieve higher power, more efficient amplifiers with less weight. Combine that with the synergies at Harman in signal processing and loudspeaker design and you’ll see complete system packages that exceed the expectations of not only our customers, but their customers as well.”
  And so it is in the engine rooms of pro audio: brands are ganging together to push their weight around.  
Story: Phil Ward  

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