Texas Instruments PCM 4104Each year, Pro Sound News queries audio design engineers about their semiconductor usage and the impact on the products that users employ. In 2011, previously reported trends continue to dominate analog component selection.
Peter Montessi, president of analog specialists A Designs Audio and Pete’s Place Audio, is working with proven components new to his designs, specifically the THAT Corp 1200-series InGenius balanced line receiver IC, “which fits our needs perfectly for one of our products.” Until recently, Montessi says he has not employed such building-block components, with current use “mainly for VU metering. This allows us to build a smaller PCB with surface mount as a daughter board saving costs and space.” Empirical Labs president and chief engineer Dave Derr says he also turns to THAT for VCAs and RMS detectors as they “work great and require little trimming.” David Clemontson, managing director for design consulting firm High Gain Design, says that he generally employs monolithic function parts “only when there is an advantage to doing so. For instance, semiconductor manufacturers can laser-trim resistors cost-effectively, where board-level manufacturers do not. He adds that, “For traditional features, I use the same old parts,” with new features requiring new non-audio parts.
Derr says Empirical Labs is largely using traditional components, but they are “swapping out some components since going RoHS [European Restriction of Hazardous Substances regulations, which include a ban on lead solder], as RoHS has increased our failure rates, many folds.” Clemontson says also that higher voltage (>36 volt) components are disappearing “because the industry always pushes faster, denser, low-voltage processes.” For these parts, he says he’s “gravitated to using Texas Instruments parts” as TI has assured him they are committed to the needs of the Industrial Instrumentation market. “To a large extent, pro audio is piggybacking off of that much larger market.”
Montessi calls the availability of the legacy components core to products he’s manufactured for 12 years “a sore spot.” He explains that “just about every part we use is becoming more difficult to source and more expensive as well…No one wants to stock and have product sitting on the shelf collecting dust and not bringing in working capital. So vendors are now building to order.” Lead times are now two to three times longer, he adds. “I do my best to keep prices down, but with all things considered, raising retails at this time is a slow death for any company.”
Clemontson says there’s little room for adaptation in approach “if the product requires ‘pro’ level analog outputs like +24 dBu. Short of using transformers, you need high-voltage process parts to generate those outputs…If switching regulators are used, significant power savings can be had by using lower rail voltages on selected circuits.”
“Buying larger quantities for stock, and price breaks,” is how Derr copes with component scarcity. “Large orders of inventory has been our best investment,” he explains, “often saving us 30 percent because of quantity breaks. You have to have great cash flow though, to do this safely.” Montessi says that, “The best you can do is ‘Eat It!’ until the storm blows over. I have not increased our prices for two years.”
Surface-mount components are cropping up more in new design. “ We are moving into SMT components in the near future,” says Derr, while Clemontson is embracing “surface mount always except for film caps, which can melt in SMT form. The cost of thru-hole installation labor is prohibitive.” Montessi says that his companies decline to use surface-mount components in the audio path. “Surface mount is the wave of the future, and I understand that,” he explains, “but the one drawback that it has is ‘repair’…education plays a major roll in servicing for both thru hole and surface mount.”
Clemontson says that modern pro conversion part requirements are “all about converter group delay, so that narrows down the parts selection to the usual suspects.” For interface with formats such as USB and FireWire, he minimally admits to using “home-grown FPGA + standard PHY chipsets.” He calls the hardware component “mostly trivial,” though cautions: “Don’t even think about implementing a new interface unless you are absolutely certain you have the driver aspect covered… As the interfaces get more complex (like AVB), the software component is even more important.”
THAT Corp 4320 Analog Dynamics EngineDesigners need “super-low-noise regulators” for power supplies, says Derr. “Aren’t we getting tired of lackluster performance from the 78XX and 79XX regulator parts? Come on, IC manufacturers! The market for a low-noise, inexpensive, pin-compatible regulator for these old 78xx and 79xx parts is friggin’ huge!”
Clemontson says the paradigm shift towards computer bus-powered and lowvoltage portable devices “definitely” presents design challenges, though “only on outputs…But the issue is power, not voltage. For example, a +48V phantom mic can draw up to about a watt. How then does one put eight mic inputs on a USB device that is limited to 2.5 watts?” Derr adds that compromises are somewhat mitigated where gear “is working differentially so you can cancel noise.”
For his DSP designs, Clemontson says the components chosen are dependent “on the algorithms and development environment.” There are “absolutely” advantages with different families of processors, he continues. “For example, highly pipelined architectures can achieve very high performance, but only on certain algorithms.” Derr prognosticates, “It’s possible general-purpose processors may take over much of the DSP market,” he says, “since they are always using higher clocks, more versatile, and are going to floating-point math.”
Clemontson has also embraced FPGA processing-digital building blocks that are programmed for tailor-made processing. He explains, “The cost advantage is tremendous if the algorithm is simple, the channel count is high, and the need for programmability is low.”
Native processing, audio DSP done inside a computer’s CPU, is “absolutely” becoming more advanced and attractive to Derr, who cites “a gradual stream of improvements.” Clemontson qualifies his affection for native processing: “Getting the OS to do what you want it to do when it needs to be done is always a problem unless you write the kernel yourself.”
Asked for advice to share with endusers on a quest for quality, Clemontson says, “The truth is that the audio quality of even the cheapest product is generally really, really good. So shop for features you need first. If you are told there is a sound quality difference between two products, force yourself through a double-blind listening test.” Derr reminds that, “Newer is not always better. Put off upgrading software on your computer for as long as possible!” Montessi calls gear selection “an age-old problem for the consumer… try and demo any and all units that you are considering on purchasing…you should demo the units in your studio with your setup and your room to see what works best for you.” Be wary online, he adds, else you might be “taking someone’s opinion that (more than likely) is just a scam artist that has no clue and has never even turned a pro piece of gear on in a studio or anywhere else, for that matter.”
In parting, Clemontson urges other designers to educate themselves: “Semiconductor physics rules our world now, and we need to learn those rules.”
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