APEX stands for Additive system of Photographic EXposure, which was proposed in the 1960 ASA standard for monochrome film speed, ASA PH2.5-1960, as a means of simplifying exposure computation.

Exposure equation

Until the late 1960s, cameras did not have built-in exposure meters, and many photographers did not have external exposure meters. Consequently, it often was necessary to calculate exposure from lighting conditions. The relationship of recommended photographic exposure to a scene's average luminance is given by the camera exposure equation

where

is the relative aperture (f-number)

is the exposure time ("shutter speed") in seconds

is the average scene luminance ("brightness")

is the ASA arithmetic film speed

is the reflected-light meter calibration constant

Use of the symbol for luminance reflects photographic industry practice at the time of ASA PH2.5-1960; current SI practice prefers the symbol . German sources typically used for the relative aperture. Many authors now use and for relative aperture and exposure time.

AVE is Alta Velocidad Española, a high speed train used in Spain.

AVE, Ave, Avé or variant, may also refer to:

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12AX7 (also known as ECC83) is a miniature dual triode vacuum tube with high voltage gain. It was developed around 1946 by RCA engineers in Camden, New Jersey, under developmental number A-4522. It was released for public sale under the 12AX7 identifier on September 15, 1947. The 12AX7 was originally intended as replacement for the 6SL7 family of dual-triode amplifier tubes for audio applications. It is popular with tube amplifier enthusiasts, and its ongoing use in such equipment makes it one of the few small-signal vacuum tubes in continuous production since it was introduced.

History

The 12AX7 is basically two 6AV6 triodes in one package. The 6AV6 was a miniature repackaging (with just a single cathode) of the triode and twin diodes from the octal 6SQ7 (a double-diode triode used in AM radios), which itself was very similar to the older type 75 triode-diode dating from 1930.

As of 2012 the 12AX7 was made in various versions by two factories in Russia (Winged C, formerly Svetlana, and New Sensor, which produces tubes under the Sovtek, Electro-Harmonix, Svetlana, Tung-Sol, and other brands for which the firm has acquired trademark rights), one in China (Shuguang), and one in Slovakia (JJ), for a total annual production estimated at two million units. The vast majority are used in new-production guitar amplifiers or for replacements in guitar and audio equipment.