• Basic electricity formulas

    Although it not specific to sound, we include this document with some basic electricity formulas. They can be found in any electricity textbook, but we have added them to the DoPA Library for reference.

    Ohm's law

    The most basic formulas derive from Ohm's law, which specifies that the electric current between two points is proportional to the potential difference (voltage) between them and inversely proportional to the resistance between them. The formula is:
    V
    I = ———
    Z


    where I is the current (intensity) in amps and V is the voltage in volts. Since we use alternating current in audio, we have replaced resistance with impedance (Z, and this could also be resistance R), measured in ohms. Clearing Z and V we have these other two formulas:

    V
    Z = ———
    I

    and
    V = I*Z

    Joule's law

    Electrical power is the rate at which an electrical circuit transfers electrical energy. It is measured in watts, after the engineer James Watt famous for his advances in steam engines.

    This formula is erroneously assigned to Ohm's law even though the original law did not include it. Joule's law determines that electrical power is given by the product of voltage and current:
     
    P = V*I
     

    Combinations of both laws

    When we combine both laws (Ohm's law which determines the current and Joule's law which determines the power) we obtain numerous derived formulas which are added to the original ones. A usual way of bringing them all together is by means of this circle of formulas:






  • Ad

  • News

    Over 700 exhibitors confirmed for ISE 2022

    Integrated Systems Events informs that over 700 exhibitors already committed to ISE 2022, including bellwether brands Barco, Crestron, KNX, Kramer, LG, Panasonic, Samsung, and Sony – the show floor has been redesigned and will also feature... Read more

    JBL Professional introduces EON700 Series portable PA loudspeakers with Bluetooth


    JBL Professional yesterday introduced the EON700 Series portable PA loudspeakers and subwoofer with Bluetooth.

    With four models available, including the 10-inch EON710, the 12-inch EON712 and the 15-inch EON715 powered PA speakers and... Read more

    Biamp Launches Parlé audio and video conferencing bars

    Biamp, supplier of professional audiovisual solutions, has announced the launch of Parlé™ audio and video conferencing bars, a line of professional grade audiovisual conferencing solutions for... Read more

    Studio Technologies now shipping StudioComm system

    Studio Technologies, manufacturer of audio, video, and fiber-optic solutions, is now shipping the StudioComm System with Dante® Support, consisting of the Model... Read more
  • Recent articles

    Intelligibility and its measurement

    1. What is intelligibility?

    The state or quality of being understood. It can apply to an idea or a writing, but in our context it relates to the spoken word and, less commonly, to music.... Read more

    Choosing loudspeaker cable

    The importance of cables for the connection between the amplifier and the speaker is often controversial. Hi-fi aficionados spend fortunes on cables that promise spectacular results, and our short auditory memory and subjectivity lead many to confirm these improvements in their systems.... Read more

    Constant voltage systems (70V, 100V lines)

    Constant voltage, high impedance or line transformer systems are often a somewhat confusing concept for professionals used to rock and roll. They are actually very simple to design, among other things because they are intended to be installed by electricians and the like, with little experience in sound systems. In this article we will try to clarify the simple concepts needed to understand this type of system.... Read more
  • PAcalculate app