how much power for which frequency range?

[Dominique]

hi,

I know there are rules of thumb for 2- or 3-way speakers, but how do you know how much power a driver or the active amps (in active loudspeakers) really need?

Isn't there something like a graph of power over frequency for "standard" music , or several music styles somewhere on the web?

Or volume in dB over Frequency, then I could (still would have to figure out) calculate the power needs...

Thanks for helping!
Cheers,
Dominique

[rmcferon]

You can find some information here:Benefits of Bi-Amping (Not Quite Magic, But Close) - Part 1

Topic 1.3 is Power Distribution and SPL.

[audio-kraut]

From experience - three ways use most power in the midrange, 80 - 2000Hz.

In my system I used a 60 W for >2kHz
a 200W for 80 - 2kHz
a 200W for >80Hz

I could bring the midrange bryston 4B ST (>300W/channel) to go into thermal cutout with a two way satellite MTM layout and each M capable of > 100W (about 86% efficient). The system was equalized to deal mainly with the peaks for in room response, only slightly elevating the throughs.
The sub amp would still be running.

[Andy G]

Here isa little Excel spreadsheet based on info in a "Fane" PA loudspeaker booklet I have somewhere.

http://users.tpg.com.au/users/gradds/powersharing.htm

[Michail Bugaria]

Hi

Here is nice tool - DrivePower

The program for definition of a parity of capacities drivers in acoustic system.

http://www.diy-audio.narod.ru/files/DP_v1.1.rar

Switch in Eng "ßçûê -> English"

[Dominique]

Thanks a lot to you all!
I've read and tried your suggestions and found a bit more. I'll compare the data and reply tomorrow.

@Michail
Unfortunately the linked file isn't complete

Cheers,
Dominique

[Michail Bugaria]

Dominique, the program was not started at all?
Probably it of that the program presence of library midas.dll is necessary (it in archive with program)
For Win98 should copy it in folder Windows\System and for winXP in Windows\System32

This program will work only for windows-family OS I guess...

Hope it will help

[AndrewT]

Hi,
the power spread through the frequency range is more of an average thing and does not relate well to peak values in the signal.

IF the speakers are of the same sensitivity, then it is usual to find that the PEAK signal is similar anywhere in the frequency spectrum.

The result of this is that the peak voltage to be fed to each speaker is similar and since we are comparing equal sensitivity we are also equalising impedance.

In other words the peak power requirement is similar all the way through the frequency range.


HOWEVER, when you start mixing speakers of different sensitivity you will find that the drive requirement becomes skewed very much away from treble towards bass.
An example could be 1000W into a 84db 4ohm bass driver, 100W into a 93db 8ohm mid range driver and just 25W into a 98db 8ohm treble driver. This skewing is so common many fall into the trap of thinking it has something to do with the spectral spread of power in the signal. Don't be fooled.

[Dominique]

Originally posted by AndrewT
An example could be 1000W into a 84db 4ohm bass driver, 100W into a 93db 8ohm mid range driver and just 25W into a 98db 8ohm treble driver. This skewing is so common many fall into the trap of thinking it has something to do with the spectral spread of power in the signal. Don't be fooled.

Well, at least there is a relation between the spectral spread of needed power in the amplifier and the spectral spread of power in the signal.

But now you leave me a bit confused.
As I understand it, some factors may distort this relation, as the size of the room for example.

Unfortunately I have to go now, thanks for joining the discussion!
Cheers,
DOminique

[Dominique]

@Michail
No, the rar doesn't even open, it seems to be incomplete.