A balanced armature is a sound transducer design primarily intended to increase the electrical efficiency of the element by eliminating the stress on the diaphragm characteristic of many other magnetic transducer systems. As shown schematically in the first diagram, it consists of a moving magnetic armature that is pivoted so it can move in the field of the permanent magnet. When precisely centered in the magnetic field there is no net force on the armature, hence the term 'balanced.' As illustrated in the second diagram, when there is electric current through the coil, it magnetizes the armature one way or the other, causing it to rotate slightly one way or the other about the pivot thus moving the diaphragm to make sound.
I’m a former Mixer and DJ and I’d highly recommend the Beyer T1 for mixing. It is not absolutely flat, but it is an all around proper Audio Technicians Headphone. For flat response, I might eyeball the HD800 but the low end might not be the best if you are often mixing tracks with solid low ends. Flat might not always be the best option ( my opinion ). If you need to mix heavy bass tracks, it is better to have a headphone that responds better to low end EQ and is generally accepted as a more well rounded headphone.
Over-ear and on-ear headphones effectively block out outside sounds, allowing you to hear your music or whatever else you're listening to crisply and without distraction. Over-ear headphones are sometimes known as full-size headphones because they completely envelop the wearer's ear. This results in what's known as passive noise reduction, which makes these some of the most-preferred headphones available. The only drawback is that your ears and the skin around your ears can get warm and sweaty. These are usually the heaviest type of headphones.