Need help with power needed

Nora · 25th April 2011, 10:52 AM

Hello!
I'm designing a system with end result 30-80dBm sound.
I will need to either design or source an amplifier for the recorded sound source and buy a speaker.
A little google turned up that 70dBm is the sound of piano practice and 80 the loudness of lawnmower.
Then I used an online calculator and found out that 70dB is 1000kW.

1. How does this 1000kW relate to the speaker that I choose?
2. If my sound source is a memory chip on an embedded systems board, how do I get the sound to this level.
3. Sound source is something I will record and is similar to drum beat. Any suggestions on how to get it to speaker are welcome.

I'm looking for generalities....not necessarily amplifier designs!
Thanks!
Nora

metalsculptor · 25th April 2011, 11:03 AM

A typical HiFi speaker had a sensitivity of 85 dB/W @ 1M a 2W amplifier would give a about 90 dB at the onset of clipping with an 85 dB/W @ 1 M speaker. For an embedded system, the power supply would be the main factor in choosing an amplifier.
More sensitive speakers would need less power.

Zero D · 25th April 2011, 11:04 AM

What's the www of the online calculator you used ?

Quote:

Then I used an online calculator and found out that 70dB is 1000kW

That is just WRONG ! Or maybe you mistyped

Mooly · 11:32 AM

Have a read at post #52 here,
MJR-7 Mosfet Amplifier of M. Renardson

Edit... and also,
So how much power do you really need for domestic listening ?

Nora · 25th April 2011, 01:00 PM

Here is one of the calculators
Online Decibel Watts Calculator
I type in 70 and get 10,000,000 Watts ... what am I doing wrong?
Thanks!:

metalsculptor · 25th April 2011, 02:03 PM

Quote:

Originally Posted by Nora

Here is one of the calculators
Online Decibel Watts Calculator
I type in 70 and get 10,000,000 Watts ... what am I doing wrong?
Thanks!:

Nothing except using the wrong calculator for your purpose, decibels is a relative measure and that calculator was relative to 1W, fine if you are calculating power gain in a transmitter but it has nothing to do with SPL from a loudspeaker.

Nora · 25th April 2011, 02:11 PM

OK Thanks.
I like post #52, thanks Mooly, for figuring out the power needed.
Seems like a 1 Watt speaker should give me what I need.
N

25th April 2011, 10:52 AM	#1
Nora diyAudio Member Join Date: Jan 2006 Location: New York	Need help with power needed Hello! I'm designing a system with end result 30-80dBm sound. I will need to either design or source an amplifier for the recorded sound source and buy a speaker. A little google turned up that 70dBm is the sound of piano practice and 80 the loudness of lawnmower. Then I used an online calculator and found out that 70dB is 1000kW. 1. How does this 1000kW relate to the speaker that I choose? 2. If my sound source is a memory chip on an embedded systems board, how do I get the sound to this level. 3. Sound source is something I will record and is similar to drum beat. Any suggestions on how to get it to speaker are welcome. I'm looking for generalities....not necessarily amplifier designs! Thanks! Nora

25th April 2011, 11:29 AM	#4
Mooly diyAudio Member Join Date: Sep 2007	Have a read at post #52 here, MJR-7 Mosfet Amplifier of M. Renardson Edit... and also, So how much power do you really need for domestic listening ? __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.* Last edited by Mooly; 25th April 2011 at 11:32 AM.

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
Power Supply Help Needed	RickD	Power Supplies	4	26th October 2010 10:23 AM
Power cap .........needed ???	onis_uk	Class D	2	6th April 2010 11:40 PM
Some help needed with a power amp	hyvärinen	Solid State	11	12th November 2006 09:28 AM
More power needed!	stubs	Solid State	7	12th September 2006 08:37 AM
power suply help needed !!!!!!!	mircea	Chip Amps	0	28th June 2004 03:33 PM

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

25th April 2011, 11:03 AM	#2
metalsculptor diyAudio Member Join Date: Sep 2010 Location: Melbourne	A typical HiFi speaker had a sensitivity of 85 dB/W @ 1M a 2W amplifier would give a about 90 dB at the onset of clipping with an 85 dB/W @ 1 M speaker. For an embedded system, the power supply would be the main factor in choosing an amplifier. More sensitive speakers would need less power.

25th April 2011, 01:00 PM	#5
Nora diyAudio Member Join Date: Jan 2006 Location: New York	Here is one of the calculators Online Decibel Watts Calculator I type in 70 and get 10,000,000 Watts ... what am I doing wrong? Thanks!:

25th April 2011, 02:11 PM	#7
Nora diyAudio Member Join Date: Jan 2006 Location: New York	OK Thanks. I like post #52, thanks Mooly, for figuring out the power needed. Seems like a 1 Watt speaker should give me what I need. N

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)