Output power of amplifiers
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Mark Forums Read

 Solid State Talk all about solid state amplification.

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
TonyTecson
diyAudio Moderator Emeritus

Join Date: May 2003
Location: Maybunga, Pasig City
Quote:
 Originally Posted by forr W are W . W RMS is a misnommer for W. Applying the RMS calculation to power is a nonsense. Note that the power of an amplifier always emanates from the measure of voltage in V in a load in Ω. The specifications of amplifiers using voltage in V across load in Ω would clear up the constant confusion about their power.
yes, to be more precise.....

the 1974 FTC ruling is what we go by, ac voltage developed across a dummy load resistor load tells you the power, the sine wave average power, that is at the onset of clipping or a specified THD...

power ratings in any amp is a useful metric to dimension the parts that goes into the making of an amp, any amp.....when music is playing in such an amp, then that is a different ball of wax altogether...

Last edited by TonyTecson; 30th November 2020 at 06:19 AM.

 30th November 2020, 06:17 AM #22 alcha   diyAudio Member   Join Date: Jun 2013 Location: near Paris I remember reading in an old (very old, about 45-50 years) an article in HiFiNews on how to pass a 3W amplifier into a 100W one, without changing something in it. Changing the mains voltage (for instance, from 230 to 250V). Changing the load (from the usual 8ohms to 2 ohms). Changing the signal, from a pure sinewave to a short pulse. Changing the bandwith of the measure. Changing the duration of the measure (instead of something like an hour, just 10 seconds) Changing the meaning of "power" calculation (from "RMS" to musical to PMPO ...) Just the miracle of words and "alternative facts" !
 30th November 2020, 06:22 AM #23 TonyTecson   diyAudio Moderator Emeritus     Join Date: May 2003 Location: Maybunga, Pasig City and all that is due to the fact that music has much lower energy content than the sine waves use as basis for calculations of amplifier designs, so that even a 1000 watt amplifier will be putting out 5 watts real power into a real speaker playing music... __________________ https://www.facebook.com/tony.tecson
 30th November 2020, 08:06 AM #24 JMFahey   diyAudio Member     Join Date: Mar 2009 Location: Buenos Aires - Argentina At home , maybe. For PRO use such as PA, DJ or Musical Instrument, you will not only put out full power,for long hours, but often overdrive it into distortion. __________________ Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
 30th November 2020, 12:44 PM #25 wg_ski   diyAudio Member   Join Date: Oct 2007 In the instrument world you get to full power for sure, but in the pro /DJ world you really only approach about 1/4 power on average, maybe about half for the subs when playing tracks like Dark Horse (plug-the-sub-in-the-wall bass). That is with A LOT of distortion. And DJs do live with the distortion, it is PART of what sets the roof on fire and therefore necessary. True professional audio rigs aren’t even run *that* hard continuously - the big companies can’t risk a reputation for poor sound and the blown drivers they would get on every gig. The sound is relatively clean at about 10% of power on average if you are using compressors and limiters properly, which kind of corresponds to the newer “1/8 power” standard they are using now for FTC preconditioning and current draw ratings. It used to be 1/3 power back in the 70’s, and very few amps would make the cut. Very few would make it today. And regardless, the distortion is pretty bad at those kind of levels.
 30th November 2020, 05:01 PM #26 OldDIY diyAudio Member   Join Date: Dec 2009 For speakers, this is the power a) at which they can work for a long time without damage; b) withstand a minute; c) withstand the impulse. Distortion (THD) is measured at 82 dB
 30th November 2020, 05:13 PM #27 tvrgeek   diyAudio Member   Join Date: Dec 2009 Location: North Carolinia/Piedmont Theater and PA speakers are far more efficient. Usually very high efficiency horns. So they may need 5 times less power for the same sound level. Bagpipes, or properly warpipes. Designed to be played through the fog to terrorize the enemy. Not in a room. And yea, there is more than one tune written for them even though it seems that is all marching bands can learn. I am not sure what dB they can reach, but as they can cause pain, it is above 110dB.
 1st December 2020, 03:42 AM #28 spladski   diyAudio Member   Join Date: May 2012 In D'Agostino's latest offering the analog meter sensitivity was changed so that customers would have have something to look at. In testing at full power the needles almost bent. Too much to ask for a range switch on a \$125,000 amp.
 1st December 2020, 04:04 AM #29 TonyTecson   diyAudio Moderator Emeritus     Join Date: May 2003 Location: Maybunga, Pasig City still doubtful that what the meter displayed was the real power playing music..... after all how do you measure power in terms of music? has anyone come up with a metric or procedures? that meter can slam the stops and get bent but still that is no measure of real power... i use a power meter feeding the amp to display power while music is playing, power varies when at idle, at low volumes and at very high levels....you will find that it is not constant with use.... this is what i actually use to monitor power real time....https://shopee.ph/20-100A-AC-LCD-Dig...mQFCfoFBtF9OE8 __________________ https://www.facebook.com/tony.tecson Last edited by TonyTecson; 1st December 2020 at 04:33 AM.
 1st December 2020, 04:46 AM #30 spladski   diyAudio Member   Join Date: May 2012 Meters are useful for setup and periodic calibration, especially for high power rigs. That is if they mean something. Cosmetic meters say more about customers than the amps.

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Room Acoustics & Mods     Music     diyAudio.com Articles     Car Audio     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post bonsai171 Solid State 26 25th February 2004 09:24 PM Corn-Picker Solid State 2 24th January 2004 04:10 AM djdan Solid State 9 17th September 2002 05:40 PM

 New To Site? Need Help?

All times are GMT. The time now is 09:33 PM.