【Product Description】 Victor 4-channel Headphones QTH-V7 ・Very old, almost 50 years old. ・Both the box and the main unit are in very good condition considering their age. ・This is a used item. There may also be oversights due to the large number of items. Please purchase with your understanding. 【Operation】 Sound was produced when checking the front and rear channels separately. I couldn't understand the PHASE switching very well. 【Product Details】 High-end headphones capable of 2-channel and 4-channel playback. The QTH-V7 is equipped with a phase switching switch for the front and rear units, preventing the unnatural feeling of sound gathering in the center of the head. The unit uses a dome-type omnidirectional radiation structure diaphragm. Tangential corrugation edges are used for the edge, realizing a sound with a good rise. Artificial leather is used. Type: 2ch/4ch Headphones Type: Sealed type Diaphragm material: 50 micron Mylar Diaphragm diameter: 38mm Diaphragm weight: 185mg (with voice coil) 80mg (without voice coil) Coil winding diameter: 17.9mm Diaphragm shape: Dome type Diaphragm edge: Tangential corrugation Total magnetic flux: 7,500 maxwell Magnetic flux density: 5,300 gauss Reproduction frequency band: 20Hz～20kHz Impedance: 8Ω (each channel/unit only) 11Ω (each plug terminal) Nominal input: 1mW Allowable input: 100mW Distortion rate: 0.5% or less (1mW) Cord: 2m parallel cord with 3P plug Weight: 500g (excluding cord) 575g (including cord)