Tape speed is not the only factor affecting the quality of the recording. Other factors affecting quality include track width, oxide formulation, and backing material and thickness. The design and quality of the recorder are also important factors, in many ways that are not applicable to digital recording systems. The machine's speed stability (wow-and-flutter), head gap size, head quality, and general head design and technology, and the machine's alignment (mostly a maintenance issue, but also a matter of design—how well and precisely it can be aligned) electro-mechanically affect the quality of the recording. The regulation of tape tension affects contact between the tape and the heads and has a very significant impact on the recording and reproduction of high frequencies. The track width of the machine, which is a question of format rather than individual machine design, is one of two major machine factors controlling signal-to-noise ratio (assuming the electronics have high enough S/N ratio not to be a factor), the other being tape speed. S/N ratio varies directly with track width, due to the Gaussian nature of tape noise; doubling the track width doubles the S/N ratio (hence, with good electronics and comparable heads, 8-track cartridges should have half the signal-to-noise ratio of quarter-track " tape at the same speed, IPS.)