When we think about watts in a multi way speaker, are there any convenient, fact based rules for how power is distributed in music an therefore drivers?
According to Eminence:
"As a general rule of thumb, we estimate that the high frequency driver will see about 20% of the system power with a 1.5 kHz-2.5 kHz crossover, 15% with a 3.5 kHz-5 kHz crossover, and 10% with a 5 kHz and up crossover (all based on a minimum 12dB/octave slope)."
https://eminence.com/blogs/blog/high-frequency-driver-power-handling
"As a general rule of thumb, we estimate that the high frequency driver will see about 20% of the system power with a 1.5 kHz-2.5 kHz crossover, 15% with a 3.5 kHz-5 kHz crossover, and 10% with a 5 kHz and up crossover (all based on a minimum 12dB/octave slope)."
https://eminence.com/blogs/blog/high-frequency-driver-power-handling
With a 2-way crossover, the 50-50 power split is generally something in between 300-500 Hz in most types of music.
From the Eminence Loudspeaker Book:
| Crossover frequency (Hz) | Percentage power above crossover point |
| 150 | 80 |
| 200 | 72 |
| 300 | 55 |
| 500 | 40 |
| 1000 | 25 |
| 3000 | 20 |
| 5000 | 10 |
Rule of Thumb. On second read I found the meaning changed quite for the better 😀
@Galu
Thanks for that. I'm honestly a little surprised the typical subwoofer crossover area (~80Hz) doesn't reduce power nearly as much as I though. I thought that would be the 40-50% point. That doesn't happen until ~ 300 Hz according to that.
I'm thinking a lot about 2-way vs. 3-way speakers and 2-way vs. 2-way plus subs as I approach my next project. I'm converting a 2-way with 6.5" mid-woofer to a 3-way and based on this chart it seems the reduction in energy in the (currently) midwoofer is substantial.
Thanks for that. I'm honestly a little surprised the typical subwoofer crossover area (~80Hz) doesn't reduce power nearly as much as I though. I thought that would be the 40-50% point. That doesn't happen until ~ 300 Hz according to that.
I'm thinking a lot about 2-way vs. 3-way speakers and 2-way vs. 2-way plus subs as I approach my next project. I'm converting a 2-way with 6.5" mid-woofer to a 3-way and based on this chart it seems the reduction in energy in the (currently) midwoofer is substantial.
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I guess they were assumimg equal efficiency over all the ways. When a sub is capable of really deeeeeeeep bass then it usually has amn efficiency that is much lower than all the other drivers in the speaker. In this case the "150Hz/80% above" rukle will not be valid anymore.
Regards
Charles
Regards
Charles
Right, but I wasn't really thinking about efficiency so much as how crossover points affect the power level of a specific driver.
We often say that a high pass filter on your satellites will reduce the power the main amps need to produce and therefore what the satellites get but that is apparently is a lot less than I imagined.
I have had four and five way big systems for a couple of decades now and when working out how much power was required for each band I used a 70 volt / 600 Watt into 8 Ohm amp. Via oscilloscope I measured peak voltage and current with a current loop.
The fact the subs took the lions share of the current was no surprise. What I did not expect was the peak voltage requirement was in the mid bass-lower midrange.
Barry.
The fact the subs took the lions share of the current was no surprise. What I did not expect was the peak voltage requirement was in the mid bass-lower midrange.
Barry.
@1audiohack Good insights. I think it's still true in multi-way systems as we tend to prefer 4 Ohm drivers for the mid-bass or in 2-way systems we often find the minimum Z at around 150 Hz or so.
The crossover points will affect the average power level distribution between drivers.
Assuming flat response and equal sensitivity and impedance for each driver in a multi-way system, the peak voltage required for each driver will be identical for peaks of the same sound pressure level.
I made a spreadsheet a while back that would calculate approximate power to drivers across a 4-way crossover. You should be able to do the same pretty simply, just a matter of plotting a matching curve to that scatter chart (Eminence data) and then doing the formulas from there.
Mine wasn't based on the Eminence data (I think I got the info from a reference on Elliott's pages) but it's likely to be very similar.
Mine wasn't based on the Eminence data (I think I got the info from a reference on Elliott's pages) but it's likely to be very similar.
Thanks for all the ideas everyone. my needs are a lot less elaborate than many of you imagine. The eminence table will really help me going forward.
Go on the wayback machine for art ludwig's sound page. He did both peak and average power requirements for music samples and found that while average requirements declined with rising frequency, peak requirements didn't decline so much. You could use somewhat less power per octave in higher frequencies, but perhaps not as much as some of the charts specify. You can get by with much less robust power supples in the treble than in the bass, though.