Profile: Grado Labs, Inc. specializes in design engineering for the high-end audio and recording industries. We offer headphone and phono cartridges. All our headphones have a vented diaphragm design that incorporates a large air chamber. This design concept lowers the frequency resonance (distortion) of the diaphragm, and extends bass response. The diaphragm is made of a low mass polymer, carefully formed to broaden resonant modes to reduce their amplitude. The diaphragm mass is determined with the compliance of the suspension in mind, so that the desired low frequency resonance is achieved. The diaphragm's total mass is calculated to provide a full 20 KHZ bandwidth, while avoiding break-up at lower frequencies. The Professional, Statement, Reference Series, and along with the Prestige Series SR325is, SR225i & SR125i feature voice-coils that are wound from ultra-high purity, long crystal (UHPLC) oxygen free copper. The copper is slowly drawn through the die in extremely small increments, and is annealed following each drawing operation. Ultra-high conductivity copper yields the clearest transmission, and lowest coloration possible. The sound of UHPLC copper is smoother, cleaner and more dynamic. All use very high power neodymium magnets to provide maximum efficiency and better sound. Each headphone driver is made to our high standards, then pair-matched for exact imaging. These headphones also utilize UHPLC copper in the connecting cable.