By PSW Staff • July 6, 2011 This calculator provides the required electrical power (power output from the amplifier) to produce a desired Sound Pressure Level (SPL) at a given distance, along with an amount of headroom to keep the amplifier(s) out of clip. Example: You are designing a system where the farthest listening position from the loudspeaker is 100 meters, and the desired Sound Pressure Level is 85 dB SPL. The loudspeaker chosen for the job has a sensitivity rating of 95 dB. With the minimum recommended amplifier headroom of 3 dB, the you need to choose an amplifier that can supply at least 1,995 watts to the loudspeaker. Equations used to calculate the data: dBW = Lreq – Lsens + 20 * Log (D2/Dref) + HR W = 10 to the power of (dBW / 10) Where: Lreq = required SPL at listener Lsens = loudspeaker sensitivity (1W/1M) D2 = loudspeaker-to-listener distance Dref = reference distance HR = desired amplifier headroom dBW = ratio of power referenced to 1 watt W = power required Comments Have something to say about this PSW content? Leave a comment! Cancel reply Scroll past the ”Post Comment” button below to view any existing comments. Your email address will not be published. Required fields are marked *Comment Name * Email * Website This site uses Akismet to reduce spam. Learn how your comment data is processed. jhonnash says Hardly a mix is completed these days without the engineer placing a compressor across the mix bus, even if they’re not sure exactly why they’re doing it. jhonnash says Hardly a mix is completed these days without the engineer placing a compressor across the mix bus, even if they’re not sure exactly why they’re doing it. ged ged prep ged training ged online johns says Hello,I love reading through your blog, I wanted to leave a little comment to support you and wish you a good continuation. Wishing you the best of luck for all your blogging efforts.70-642 papers// 70-643 exam questions// 70-646 pdf// 70-647 prep// 70-648 questions// 70-649 papers// 70-652 exam questions// 70-659 pdf// Tagged with: Amplifier World Audio Crown Live Sound Reinforcement · all topics Subscribe to Live Sound International Subscribe to Live Sound International magazine. Stay up-to-date, get the latest pro audio news, products and resources each month with Live Sound.