Amplifier Power Requirements

Geoff · 12th April 2002, 01:48 PM

There have been several references recently in other threads to amplifier power requirements, so I thought the following information might be of interest.

Unfortunately I cannot remember the website from which I obtained the data a couple of years ago otherwise I would give the appropriate credit.

Geoff

Geoff · 12th April 2002, 05:01 PM

I have now found the source of these figures. More information on them can be obtained at:

http://www.smr-home-theatre.org/Powe...-How-Much.html

Geoff

tschrama · 12th April 2002, 05:10 PM

nice revealing tabel ... Thanks for the link..

greetings,
Thijs

GRollins · 14th April 2002, 10:04 PM

I tried to post Friday, but my ISP suddenly decided that this site didn't exist for some reason.
Nice reference, Geoff. Seems that I recall that the 'average' living room has about 30-40 dB background noise, so you've got to get up above the noise floor before you can begin to hear anything.
On the other hand, I had to buy a house way out in the country before I could get anything like the quietness that I remember as a kid. I suspect that the 30-40 dB figure is out of date...

Grey

tschrama · 14th April 2002, 10:41 PM

Hi all ...

Your right about some 30 to 40dB SPL background noise, but that doesn't mean that a moderate classical music is played back realisticly at 84dB + 30 to 40dB = 114dB or more. You can easlely hear throuhg some background noise.. I think people don't ussualy listen to music at 110dB.. why? It give you that peeeeeeeeeep after the music has gone.....
greetings..
Thijs

dice45 · 16th April 2002, 12:44 PM

Geoff,

thanxalot! seems like i have done my power need estimations just right

Good read!

mefinnis · 16th April 2002, 03:13 PM

All very true and correct .... but note he differentiates between average and peak power requirements, whereas we are using W-RMS as our amp measure. Remember a 100W-RMS amp can produce far greater peak power - even before it clips.

If you build a power amp in W-RMS to handle the peaks at high volume you are gonna spend some big bucks (both in amplifiers and speakers).

cheers, mark

tschrama · 16th April 2002, 03:18 PM

Happely a CD player doesn't produce any unpredictable peaks... If you know your systems gain (0dB tot 12dB maybe?) you precisely know your MAXIMUM power needed.. this will be in the order of a couple of Watt ..

Greetings,
Thijs

Dirk · 16th April 2002, 07:32 PM

Quote:

Originally posted by mefinnis
All very true and correct .... but note he differentiates between average and peak power requirements, whereas we are using W-RMS as our amp measure. Remember a 100W-RMS amp can produce far greater peak power - even before it clips.

Hi, correct me if I'm wrong, but IMHO the difference between RMS and peak power is usually not so big: if the signal reaches the power supply rails during a transient, it has no other choice than clipping ... At the same time, the RMS power can be measured ... just below clipping (OK, including some power supply rail sag during continuous operation at full power).

Regards, Dirk

Geoff · 16th April 2002, 07:55 PM

Mark

Quote:

Remember a 100W-RMS amp can produce far greater peak power - even before it clips.

I think your comment needs clarification. The peak output power into the rated load impedance is twice the rms power. Higher peak power levels can only be achieved if the load impedance drops due to the speakers characteristics (which may or may not occur at the required frequency) and if the power supply is capable of delivering the additional current.

Also, this higher peak output is only applicable to push-pull output stages. A single-ended Class-A is current limited as well as voltage limited and the peak output power will be no greater than twice the rms power for which the quiescent current was set.

Geoff

12th April 2002, 01:48 PM	#1
Geoff diyAudio Member Join Date: Apr 2001 Location: UK	Amplifier Power Requirements There have been several references recently in other threads to amplifier power requirements, so I thought the following information might be of interest. Unfortunately I cannot remember the website from which I obtained the data a couple of years ago otherwise I would give the appropriate credit. Geoff

16th April 2002, 12:44 PM	#6
dice45 diyAudio Member Join Date: Jan 2002 Location: Munich, Bavaria	Geoff, thanxalot! seems like i have done my power need estimations just right Good read! __________________ Greets, Bernhard

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Help with BTL power requirements	dayveshome	Solid State	5	28th March 2008 11:45 AM
TPA6120 Power Requirements	dfdye	Chip Amps	8	19th February 2007 08:30 AM
LM4780 Power Requirements	otherside	Chip Amps	12	12th July 2006 05:07 PM
Power requirements for biamping	Circlotron	Multi-Way	10	30th October 2002 04:00 PM
Biamping power requirements	woody	Multi-Way	3	3rd January 2002 01:34 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

12th April 2002, 05:01 PM	#2
Geoff diyAudio Member Join Date: Apr 2001 Location: UK	I have now found the source of these figures. More information on them can be obtained at: http://www.smr-home-theatre.org/Powe...-How-Much.html Geoff

12th April 2002, 05:10 PM	#3
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	nice revealing tabel ... Thanks for the link.. greetings, Thijs

14th April 2002, 10:04 PM	#4
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	I tried to post Friday, but my ISP suddenly decided that this site didn't exist for some reason. Nice reference, Geoff. Seems that I recall that the 'average' living room has about 30-40 dB background noise, so you've got to get up above the noise floor before you can begin to hear anything. On the other hand, I had to buy a house way out in the country before I could get anything like the quietness that I remember as a kid. I suspect that the 30-40 dB figure is out of date... Grey

14th April 2002, 10:41 PM	#5
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	Hi all ... Your right about some 30 to 40dB SPL background noise, but that doesn't mean that a moderate classical music is played back realisticly at 84dB + 30 to 40dB = 114dB or more. You can easlely hear throuhg some background noise.. I think people don't ussualy listen to music at 110dB.. why? It give you that peeeeeeeeeep after the music has gone..... greetings.. Thijs

16th April 2002, 03:13 PM	#7
mefinnis diyAudio Member Join Date: Feb 2001 Location: Adelaide, Australia	All very true and correct .... but note he differentiates between average and peak power requirements, whereas we are using W-RMS as our amp measure. Remember a 100W-RMS amp can produce far greater peak power - even before it clips. If you build a power amp in W-RMS to handle the peaks at high volume you are gonna spend some big bucks (both in amplifiers and speakers). cheers, mark

16th April 2002, 03:18 PM	#8
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	Happely a CD player doesn't produce any unpredictable peaks... If you know your systems gain (0dB tot 12dB maybe?) you precisely know your MAXIMUM power needed.. this will be in the order of a couple of Watt .. Greetings, Thijs

16th April 2002, 07:55 PM	#10
Geoff diyAudio Member Join Date: Apr 2001 Location: UK	Mark Quote: Remember a 100W-RMS amp can produce far greater peak power - even before it clips. I think your comment needs clarification. The peak output power into the rated load impedance is twice the rms power. Higher peak power levels can only be achieved if the load impedance drops due to the speakers characteristics (which may or may not occur at the required frequency) and if the power supply is capable of delivering the additional current. Also, this higher peak output is only applicable to push-pull output stages. A single-ended Class-A is current limited as well as voltage limited and the peak output power will be no greater than twice the rms power for which the quiescent current was set. Geoff