comparison between volume and power

Shelah · 15th December 2012, 08:17 AM

dear all,

is there a way of finding out how amplifier power and the volume of a sound box are matched?

KatieandDad · 15th December 2012, 08:19 AM

It's called sensitivity.

Shelah · 15th December 2012, 08:35 AM

okay now lets say i have a 18'' sub cabinet that is about 160 litres, what power do i need in this case?

freax · 08:49 AM

haha, maybe a bit more information about the speaker driver would be a good start.

KatieandDad · 15th December 2012, 02:49 PM

You need to find out how sensitive your speaker system is.

Build it without an amplifier to start with. I'm at work at the moment so I don't have the exact figures in front of me. Most speakers are quoted at a dB level at 1m when fed with a signal of 2.83V RMS.

So, if you feed it with a signal of 2.83V RMS and get 88 dB of sound, your speaker will have a sensitivity of 88 dB/W at 1m.

Once you have this figure you can then ascertain how much power you need to obtain the volume that you looking for.

ßart West-VL. · 16th December 2012, 06:16 AM

+1 What KatieandDad said. And each time you double the power, ad 3dB.
so:
2W - 91dB
4W - 94dB
8W - 97dB
16W ...

Mark.Clappers · 17th December 2012, 08:29 AM

Quote:

Originally Posted by KatieandDad

You need to find out how sensitive your speaker system is.

Build it without an amplifier to start with. I'm at work at the moment so I don't have the exact figures in front of me. Most speakers are quoted at a dB level at 1m when fed with a signal of 2.83V RMS.

So, if you feed it with a signal of 2.83V RMS and get 88 dB of sound, your speaker will have a sensitivity of 88 dB/W at 1m.

Once you have this figure you can then ascertain how much power you need to obtain the volume that you looking for.

I like to add 1 thing here, this only holds true for an 8 Ohm driver. Usually sensitivity is spec'd xdB/W @1m. Important is whether this is into half space or full space. And don't forget to take power compression into consideration.

more10 · 17th December 2012, 08:35 AM

Quote:

okay now lets say i have a 18'' sub cabinet that is about 160 litres, what power do i need in this case?

You cannot have too much power :-). An amp with more power has better damping factor, so it will sound better even if you don't use all power. A bigger amp will have better power supply, helping out in transients at lower power levels. Also a big amp will not clip. Clipping is very bad for you drivers.

15th December 2012, 08:17 AM	#1
Shelah diyAudio Member Join Date: Oct 2010	comparison between volume and power dear all, is there a way of finding out how amplifier power and the volume of a sound box are matched?

15th December 2012, 08:42 AM	#4
freax Owner and operator of irc.tenettenba.info diyAudio Member Join Date: Sep 2007 Location: NSW	haha, maybe a bit more information about the speaker driver would be a good start. __________________ Last edited by freax; 15th December 2012 at 08:49 AM.

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15th December 2012, 08:19 AM	#2
KatieandDad diyAudio Member Join Date: Nov 2011 Location: UK	It's called sensitivity.

15th December 2012, 08:35 AM	#3
Shelah diyAudio Member Join Date: Oct 2010	okay now lets say i have a 18'' sub cabinet that is about 160 litres, what power do i need in this case?

15th December 2012, 02:49 PM	#5
KatieandDad diyAudio Member Join Date: Nov 2011 Location: UK	You need to find out how sensitive your speaker system is. Build it without an amplifier to start with. I'm at work at the moment so I don't have the exact figures in front of me. Most speakers are quoted at a dB level at 1m when fed with a signal of 2.83V RMS. So, if you feed it with a signal of 2.83V RMS and get 88 dB of sound, your speaker will have a sensitivity of 88 dB/W at 1m. Once you have this figure you can then ascertain how much power you need to obtain the volume that you looking for.