Based in Hong Kong, DB Enterprises HK Ltd establishes a critical liaison between technology companies and OEM manufacturers in the audio industry. But sometimes simply promoting the benefits of a certain material or technology is not enough since many manufacturers will want to test and measure an actual product before committing a new project. As DB Enterprises' CEO Dave Lindberg explains, after extensively promoting VM Sound's Liquid Silicone Rubber surround technology as an ideal solution for headphones, earbuds, and micro-speaker applications, they decided to make four standard configuration headphone drivers directly available, ready for evaluation and production.
Headphone drivers from VM Sound with liquid silicone rubber (LSR) surround technology offer improved linearity and are ideal to support active noise cancelling (ANC) designs, where frequency response needs to be optimized. This is critical in headphone development due to the high performance and extreme consistency in a high yield production process.
The company is now shipping four off-the-shelf headphone drivers that DB Enterprises decided to produce on their own, making new options available for headphone manufacturers using the LSR technology. The new headphone drivers include 40mm, 13.4mm, 9.2mm, and 7mm models and they are all available with variants of diaphragm materials, including Nomex, aluminum, magnesium alloys or other types of composite materials, such as Rohacell.
According to Dave Lindberg, these combinations ideally show the advantages over traditional drivers using Mylar, or PET, or other glue-bonded methods of building headphone drivers in small sizes, avoiding the production inconsistency problems that are common with those designs. "Basically you are hot-pressing several layers of Mylar or PET to create a diaphragm and so the the thickness is quite varied, which translates to issues with changes in SPL from one driver to the other. Those drivers also flop around a bit, creating some phase issues."
"When trying to glue tiny diaphragms together, the mass of the glue is very difficult to sustain, and trying to automate a process adding a tiny 25 millimeter dome to an x millimeter surround that bonds to a frame is a very challenging process to master consistently. This again translates to similar problems such as the mylar domes. With the LSR drivers what you really get is a lot better power handling, a lot more consistency, typically twice the amplitude compared to the other styles of headphone drivers, and also a very low THD with that high handling. The SPL consistency is very tight - usually around within a 1.5 dB tolerance from driver to driver - which makes it very good for ANC headphones when you're trying to match drivers, or even just trying to match drivers in any kind of headphone application. Another cool thing is that the liquid silicone rubber is a lot more resilient against temperature fluctuations so that means the F0 remains very stable, anywhere between -40 to +80 degrees Celsius," Lindberg adds.
Among the new drivers readily available, the 40mm Nomex model uses an LSR surround design done in three dimensions with a diaphragm surrounded frame only. DB Enterprises is able to supply complete driver units, all the way to 7mm Nomex and aluminum, which are the smallest size available today, since that is the kind of physical limit for doing these surrounds molds down to 50 μm - a very thin profile. But even the 7mm drivers can use a slightly thicker surround that can be contoured and adjusted in three dimensions to suit specific acoustic requirements.
These drivers from VM Sound are also very precisely assembled with a highly consistent molding process of bonding the dome to a frame in one single shot. DB Enterprises has data sheets and is ready to ship the 40mm, the 13.4mm, the 9.2 and the 7mm drivers. The company is also ready to ship samples and invites manufacturers to get in touch for customized LSR surround projects. "We even have some mock-up headphones done in case anyone wants to listen to these drivers without running it through a test fixture," says Dave Lindbergh.
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