the12volt.com spacer
the12volt.com spacer
the12volt.com - Free Technical Information for Mobile Electronics Installers, Enthusiasts, and Do-It-Yourselfers since 1999 Subwoofer Wiring Configurations
the12volt.com spacer
the12volt.com - Free Technical Information for Mobile Electronics Installers
the12volt.com - Free Technical Information for Mobile Electronics Installers
BasicsCar AudioCar SecurityCruise ControlsDiodesDoor LocksOhm's LawPassive CrossoversRelaysResistorsSubwoofer Enclosures Search
the12volt.com - Free Technical Information for Mobile Electronics Installers
the12volt.com - Free Technical Information for Mobile Electronics Installers
the12volt.com - Free Technical Information for Mobile Electronics Installers
Application GuideCalculators, Charts, DiagramsDownloads/ManualsFind InstallersForumsGlossarySubwoofer WiringToolsVehicle Wiring Recent Topics
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
  the12volt.com spacer

the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Diodes
Glossary of Terms
Ohm's Law
Relays
Resistors
Tools and Equipment
Wire Sizes
Introduction
Parallel & Series Calcs
Passive Crossovers
Port Length Calculators
Subwoofer Box Calculators
Subwoofer Enclosure Types
Subwoofer Wiring Wizard
Thiele - Small Parameters
Miscellaneous
Relay Diagrams
Vehicle Wiring Database
Introduction
Alarm Accessories
Alarm Modules
Alarm Sensors
Basic Connections
Illuminated Entry
Light Flash
Power Door Locks
Starter Interrupts
Installation Pictorials
Relay Diagrams
Vehicle Wiring Database
Introduction
Electrical Connections
Mechanical Connections
Servo Settings
VSS and Tach Info
Vehicle Wiring Databse
All Forums
Buy & Sell Equipment
Car Audio
Car Audio Hot Topics
Car Security & Convenience
Car Security Hot Topics
Car Security Pictorials
Cellular & Communications
Cruise Controls
Employment
Fiberglass & Fabrication
General Discussion
Lights, Neon, LEDs, HIDs
Marine Electronics
Miscellaneous
Mobile Video & Navigation
Motorcycle Electronics
Music, Favorite Songs
Relays
Rides & Systems Gallery
Vehicle Information
Recent Forum Topics
Forum Help & How To
Forum & Site Notices
Books & DVDs
Calculators
Charts
Diagrams
Downloads - Manuals
Find an Installer
Forums - Q&A
Glossary of Terms
Insurance for Car Stereos
Links
Mobile Tech News
Relay Diagrams
The Application Guide
Vehicle Wiring Database
About the12volt
Support Us
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer

 
the12volt.com spacer

the12volt's install bay
Mobile Electronics Forums

Welcome Guest :)
Display List of Forum MembersMember List  Forum SearchSearch  RegisterRegister  LoginLogin
Custom Search
the12volt`s installbay - Mobile Electronics Forums the12volt's install bay / Car Audio

Subject Topic: how to calculate amplifier RMS output? (Topic Closed Topic Closed)

Post ReplyPost New Topic
the12volt's install bay
Author
Message      << Prev Topic  |  Next Topic >>
darwindarwin
Member
Member
spacespace

Joined: September 13, 2003
Location:
Indonesia
Posts: 12
Posted: September 14, 2003 at 11:54 AM - IP Logged  

How to calculate amplifier RMS output?

does 400 watt max subwoofer usually have 200 watt RMS?

Back to Top Search for other posts by darwindarwin
Hi Guest
Not a member?
Register

Already a member?
Sign In  
DYohn
Moderator
Moderator
spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace

Joined: April 22, 2003
Location:
Arizona,
United States
Posts: 10,625
Posted: September 14, 2003 at 6:52 PM - IP Logged  

This article is a good overview of amplifier power ratings.

Loudspeaker power ratings are very diffrent.  You cannot always make any real correlation between RMS and "peak" values, as it depends on the manufacturer and how honest they are.

Back to Top Search for other posts by DYohn
BBQ Warrior
Member
Member
spacespace

Joined: September 14, 2003
Location:
United States
Posts: 6
Posted: September 14, 2003 at 9:46 PM - IP Logged  

you need a signal generator, odcilliscope, indutive dummy load at specific impedance and power dissapation to handle the load applied, microsoft excell (or a scientific calculator and a whole lotta paper & pen).

set your signal generator to the frequency you want to test, hook up dummy load to output of amp, and the o-scope is hooked up parallel to the load.

Power in watts is = to Voltage X Voltage / resistance

so if the voltage reads 10VPeak and resistance / inductance is 4 ohms it would be (10*10)/4 or 25 watts peak

you adjust the gain till distortion is just starting to appear in the o-scope display, Peak voltage would give you max watts, to figure RMS (Root Mean Square) you multiply the peak by 0.707, to get AVG output multiply the peak by 0.637, you can also use this to figure out how linear your push-pull stages are by figuring the negative side of the sine wave.  THD figures are very hard to calculate so I wont go into that.

so if its 50v peak on top and 46v peak on the bottom on a given frequency this would be the outcome: MAX  = 625 Watts, RMS = 312 Watts, AVG = 253 Watts and Pulse Linearity = 85%, that would mean that your amps capability to creat negative cone movement would be 85% of its forward ability.  Frequency linearity wold be compiled by repeating these steps across the audio spectrum and averaging that #. 

Unfortunately the equipment to do a test like this would cost in the neighborhood of 5 to 7 thousand dollars, and it wold take about two working days to fully test one amp.  So probably none of us will be doing that any time soon.

Sad to say many of the manufacturers abuse thier ratings, If all had to be measured at 0.01% THD (total Harmonic Distortion) we could more easily test apples to apples.  also, some amps such as the older alpine V12's had a regulated power supply so it produced max output at 12Vdc. whereas the Phoenix Gold amps were unregulated so if you had an alternator with an adjustabe regulator you could tweat it to 15.5 ot 16VDC and squeezee more power out of the amp.  Thats how the M100 was originally rated as a 20 watt amp, 10Wx2 RMS @ 4ohms @ 0.005%THD @ 12VDC,  but the same amp bridged mono into 3.2 ohms and 16VDC would produce around 700 Watts RMS at 0.10% THD.  The other manufacturers (rockford, alpine, and others) got pissed off and the next year IASCA changed the rulings and that same amp had to be rated 50x2.  (my system went from (5-M100's) being 100Watts Class IASCA to 250 watts).  Soon other manufacturers started playing the impedance game to create "cheater" amps (Can I say Orion?) and now no one really rates thier amps the same.

Well that got log and I could keep going but, all I can say is: If it sounds good and you enjoy it, who really cares about the numbers anyways?

Have fun

Back to Top Search for other posts by BBQ Warrior
darwindarwin
Member
Member
spacespace

Joined: September 13, 2003
Location:
Indonesia
Posts: 12
Posted: September 15, 2003 at 2:04 AM - IP Logged  

I don't have odcilliscope, can i measure it with multi meter?

If can,..  how?

Back to Top Search for other posts by darwindarwin
bberman1
Gold
Gold
spacespace

Joined: March 11, 2002
Location:
United States
Posts: 2,327
Posted: September 16, 2003 at 11:51 AM - IP Logged  

HOW TO CHECK RMS WITH VOLTAGE METER

Set the MM to A/C voltage....play some tunes and watch peak voltage....square this then divide that number by the impedance load. This gives a close idea of the RMS that the amp is putting out.

Back to Top Search for other posts by bberman1


the12volt`s installbay - Mobile Electronics Forums the12volt's install bay / Car Audio
 

Sorry, you can NOT post a reply.
This topic is closed.

  Post ReplyPost New Topic
Printable version Printable version

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum





space
the12volt.com spacer
google plus
Search the12volt.com
Custom Search
Follow the12volt.com: Follow the12volt.com on Facebook
Share, print & email this page:
Wednesday, October 22, 2014 Copyright © 1999-2014 the12volt.com Donate to the12volt.com Privacy Policy Advertising
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
BasicsCar AudioCar SecurityCruise ControlsDiodesDoor LocksOhm's LawPassive CrossoversRelaysResistorsSubwoofer Enclosures Search
the12volt.com - Free Technical Information for Mobile Electronics Installers
the12volt.com - Free Technical Information for Mobile Electronics Installers
the12volt.com - Free Technical Information for Mobile Electronics Installers
Application GuideCalculators, Charts, DiagramsDownloads/ManualsFind InstallersForumsGlossarySubwoofer WiringToolsVehicle Wiring Recent Topics
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com - Free Technical Information for Mobile Electronics Installers, Enthusiasts, and Do-It-Yourselfers since 1999 Donate to the12volt.com
the12volt.com spacer
the12volt.com spacer