baszha Posted August 5, 2018 Share Posted August 5, 2018 I know that WPC means watts per channel, but what does RMS mean and how is it used Quote Link to comment Share on other sites More sharing options...
Budman Posted August 5, 2018 Share Posted August 5, 2018 google 1 Quote Link to comment Share on other sites More sharing options...
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JohnKuthe Posted August 5, 2018 Share Posted August 5, 2018 36 minutes ago, baszha said: I know that WPC means watts per channel, but what does RMS mean and how is it used RMS = Root Mean Square. It's a mathematical way of determining an "average" amplitude of an alternating waveform such as sound produces. John Kuthe... 1 Quote Link to comment Share on other sites More sharing options...
baszha Posted August 6, 2018 Author Share Posted August 6, 2018 12 hours ago, JohnKuthe said: RMS = Root Mean Square. It's a mathematical way of determining an "average" amplitude of an alternating waveform such as sound produces. John Kuthe... Thank you John, So which is a higher WPC....140 or say 275 RMS. I am looking at a Emotiva XPA 3 cannel amp to power my fronts. The Emotiva puts out 275 RRMS. I am looking for 250 Wpc. but I am confused at how much wpc 275rms is. Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted August 6, 2018 Share Posted August 6, 2018 The RMS is a more accurate rating to judge power from amp. No matter what is said, you are buying way more power than needed for our horns. I assure you 25 true clean watts, preferable class A, are all that is needed. If you do not believe me it is easy to check power used with a AC volt meter at speaker. Play music as loud as you ever listen to and measure AC volts used on peaks. use this calculator http://www.ohmslawcalculator.com/ohms-law-calculator and put ohms of speakers in one box and highest AC reading in the other box and calculate and be ready of a shock when you see less than 2 watts or thereabout on peaks. Nothing actually wrong buying Formula One car to go 70 mph if you have the money to spend though. Quote Link to comment Share on other sites More sharing options...
willland Posted August 6, 2018 Share Posted August 6, 2018 1 hour ago, baszha said: So which is a higher WPC....140 or say 275 RMS. Well of course 275RMS is higher than 140. Plenty of headroom for your RF-82s and RC-62. Your front speakers will never(rarely if ever) see anywhere near 275w/ch even with peaks. Bill 1 Quote Link to comment Share on other sites More sharing options...
JohnJ Posted August 6, 2018 Share Posted August 6, 2018 I remember it being translated to laymans terms as rated minimum watts/channel. Continuous wattage not the peak wattage that goes way higher. 1 Quote Link to comment Share on other sites More sharing options...
JohnKuthe Posted August 6, 2018 Share Posted August 6, 2018 2 hours ago, JohnJ said: I remember it being translated to laymans terms as rated minimum watts/channel. Continuous wattage not the peak wattage that goes way higher. Yep! And to handle those ridiculously high transient needs for audio power, the more cleanly powerful an amp you have the better. The ideal is to never require your amp to reproduce anything so powerful that will cause it to go into distortion. PS: I have a Bachelor's degree in Electrical Engineering so I know "way more" about electricity and magnetism than most people. :-) John Kuthe... 4 Quote Link to comment Share on other sites More sharing options...
JohnJ Posted August 6, 2018 Share Posted August 6, 2018 On 8/6/2018 at 10:27 AM, JohnKuthe said: Yep! And to handle those ridiculously high transient needs for audio power, the more cleanly powerful an amp you have the better. The ideal is to never require your amp to reproduce anything so powerful that will cause it to go into distortion. Amen !! Yep don't ask a machine or anything else to put out 90% + and you might not be disappointed with it. Had one low powered 40 wpc continuous rms Nakamichi the I could put at 3 to 4 pm on the pot all day long and it never clipped. Never had anything else I ran close to 2:00. Then again Nelson Pass designed that one. I'm getting plenty of db at high noon on the current rig although I put it to 1:00 briefly before. 2 Quote Link to comment Share on other sites More sharing options...
willland Posted August 6, 2018 Share Posted August 6, 2018 1 hour ago, JohnKuthe said: PS: I have a Bachelor's degree in Electrical Engineering so I know "way more" about electricity and magnetism than most people. 🙂 Awesome, another member with solid credentials. I only pretend sometimes that I know what I am talking about. Bill 4 Quote Link to comment Share on other sites More sharing options...
JohnKuthe Posted August 6, 2018 Share Posted August 6, 2018 57 minutes ago, willland said: Awesome, another member with solid credentials. I only pretend sometimes that I know what I am talking about. Bill Well, I knew all this much (RMS and all, SWR too!) when I was in HIGH SCHOOL. I know a LOT about electricity and audio equipment theory too. So much so I was the progenitor of a band in 1979 called Cheep Effects: on which I played an old patch cord MOOG Synthesizer! Our first songs were done on my Pioneer CTf-1000 cassette deck with a separate playback and record head, and I connected a microphone and played back the tape monitor delay signal, which makes the coolest swoopy echoey sounds! I was playing with that when my friend from next door came over and I said Hey Craig! Check this out! And Cheep Effects was born! 1979! Lasted a couple of 90min cassettes, two studio songs and that was about it! And I have most all the Cheep Effects stuff DIGITIZED and on my hard drive! Cool stuff!! :-) I'm gonna sell it online someday soon. Hope too anyway. John Kuthe... 1 Quote Link to comment Share on other sites More sharing options...
baszha Posted August 7, 2018 Author Share Posted August 7, 2018 On 8/6/2018 at 4:34 AM, wdecho said: The RMS is a more accurate rating to judge power from amp. No matter what is said, you are buying way more power than needed for our horns. I assure you 25 true clean watts, preferable class A, are all that is needed. If you do not believe me it is easy to check power used with a AC volt meter at speaker. Play music as loud as you ever listen to and measure AC volts used on peaks. use this calculator http://www.ohmslawcalculator.com/ohms-law-calculator and put ohms of speakers in one box and highest AC reading in the other box and calculate and be ready of a shock when you see less than 2 watts or thereabout on peaks. Nothing actually wrong buying Formula One car to go 70 mph if you have the money to spend though. Thanks wdecho for the comment. I just want to make sure I have the power needed to run those speakers at their best. Quote Link to comment Share on other sites More sharing options...
robert_kc Posted August 7, 2018 Share Posted August 7, 2018 The question "how much amp power is adequate" cannot be answered without knowing: The sensitivity rating of your speakers. (Sensitivity is rated on a logarithmic scale. As a result, different speakers can need significantly differing amounts of amplifier power.) The size of your listening room The types of music you listen to Whether you listen to modern "hi-res" recordings that can have relatively high dynamic range (depending on genre) Whether you use a powered subwoofer with crossover before the main amp, thereby off-loading the main amp and speakers How loud you like to listen FYI, many people who use high-sensitivity Klipsch speakers use tube amps with less than 10wpc. (Because of different clipping characteristics, solid state amps generally need significantly more power than tube amps in order to perform satisfactorily.) Quote Link to comment Share on other sites More sharing options...
JohnJ Posted August 7, 2018 Share Posted August 7, 2018 Funky Feedback/Distortion there! @JohnKuthe 1 Quote Link to comment Share on other sites More sharing options...
JohnKuthe Posted August 7, 2018 Share Posted August 7, 2018 9 minutes ago, JohnJ said: Funky Feedback/Distortion there! @JohnKuthe Thanks! We aimed not to please but to have fun and say some important things. I'm glad there were actual musical talented folks in our band who could actually PLAY instruments. Our other studio song was much melodic and somewhat conventional. John Kuthe... 2 Quote Link to comment Share on other sites More sharing options...
baszha Posted August 8, 2018 Author Share Posted August 8, 2018 Thanks everybody for your comments 1 Quote Link to comment Share on other sites More sharing options...
Dave1290 Posted August 8, 2018 Share Posted August 8, 2018 @JohnKutheHad that "and let Jimi take over" influence! 😎 2 Quote Link to comment Share on other sites More sharing options...
efzauner Posted August 9, 2018 Share Posted August 9, 2018 RMS Root Mean Square For the gory details check wiki https://en.wikipedia.org/wiki/Root_mean_square Can't really do a better job. But basically squaring the voltage before averaging it over time (often a period if it is a simple waveform) , then taking the square root. So all values are positive. The reason you square the voltage before averaging the values is because for power calculations, Power is proportional to the square of voltage, so you have to give more weight to higher voltages. In other words, if voltage is 2 volts for half the period, and 4 volts for the second half, you cannot simply average them to (2+4)/2 = 3. You have to take square root of (4+16)/2 = square root 10 = 3.33 For audio power it means using the RMS voltage of the signal, then using Power= V^2/R where R is usually a pure 8 or 4 ohm resistor. So of you have a 10Volt amplitude signal (that is -10v to 10v) sinewave signal, the RMS value is 10/sqrt(2) or 7.07 volts to calculate the power into 8 ohms.. it is P=7.07^2 / 8 The term "rms power" as used for audio is actually incorrect as you do not take the square root of the average of the square of power. The term implies "calculate power using the RMS voltage" If you had a varying signal as in real music, you could average out the power over time, but it makes no engineering sense to take the RMS average of power over time. 1 Quote Link to comment Share on other sites More sharing options...
Andy W Posted August 10, 2018 Share Posted August 10, 2018 On 8/8/2018 at 10:12 PM, efzauner said: The term "rms power" as used for audio is actually incorrect as you do not take the square root of the average of the square of power. The term implies "calculate power using the RMS voltage" Correct. Saying "RMS power" or "Watts RMS" is a misnomer -- there is no such thing as a "Watt RMS", but people have using it for so long that it have entered into the vernacular. And the typical RMS calculation (peak voltage of the sine wave divided by the square root of two) is only true for sine waves. For pure square waves the RMS voltage is the peak voltage. Quote Link to comment Share on other sites More sharing options...
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