27 May '11
We have received a few emails about driver failures. We continue to stand behind our driver and will offer full warranty, repair or replacement for any headphone issue including this one. There is no co-relation between serial numbers on headphones and driver. The Driver assembly is done separately and the headband is done in a different facility ahead of time. These failures seem to occur after the final testing phase, a little while later. We have received some of the defective units back and we have done failure analysis on them. The defective units seem to be connected to a small batch of raw material. This issue is limited to a roll of the material lamination and we have added additional tests, QC processes etc to completely eliminate this issue.
Our manufacturing process includes several stages of testing and inspection of raw materials, components, subassemblies and final product. We have changed and revamped our production process and quality processes to do extended tests and quality control in order to catch potential problems like these that are not apparent initially.
Critical component of each transducer is diaphragm. We are now doing an additional 100% visual test on each diaphragm under microscope for uniformity of traces and have very high criteria for approval. Electrical tests are performed for circuit continuity and impedance matching. We have also added an extended very high power test to eliminate potentially bad circuits.
Normally assembled transducers are being tested for frequency response and distortion. Measurements are performed in IEC Baffle. At this stage we match transducer pairs for sensitivity and frequency response within +/-0.5dB.
For final testing we have added high power tests with sine tones with average SPL over 120dB.
Assembled headphones are being measured with Neumann KU 100 Artificial Head for Frequency Response and Distortion. Before Shipping we have now added a long burn in test on every headphone with Pink Noise at average level of 95 dB. We continue to stand behind our driver and will offer full warranty, repair and replacement for any headphone issue. We are quite confident these additional tests will ensure that these issues do not occur again. We have worked with our suppliers to completely eliminate this issue in future.