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Discussion Starter · #1 ·
I have read many times that bass requires more power. I have often wondered whether this is a factual sort of statement, or one of those old wives tales.


Just thinking about it, bass drivers move more air. And that would seem to require more energy.


One aspect of this 'bass needing more power' statement, is that I have seen bass cabs with a sensitivity of 100 dB. If a bass cab can put out 100 dB with one watt of input power, it does not seem like bass has to require a lot more power. What am I missing?


I look forward to any well researched answer anyone can provide on this topic
 

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no expert here but I was reading a thread the other day about bi-amping, and the response was that there is almost no gain partly due to the fact that the tweeter only uses about 10 percent of the power. The lower the frequency the wider the wave. I would imagine a sub with that kind of rating would have to be huge! Also read that stacking a second sub will only increase 6 db, less if subs are in separate locations.
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/15562213


I have read many times that bass requires more power. I have often wondered whether this is a factual sort of statement, or one of those old wives tales.


Just thinking about it, bass drivers move more air. And that would seem to require more energy.


One aspect of this 'bass needing more power' statement, is that I have seen bass cabs with a sensitivity of 100 dB. If a bass cab can put out 100 dB with one watt of input power, it does not seem like bass has to require a lot more power. What am I missing?


I look forward to any well researched answer anyone can provide on this topic

I do not know specifically, but I suspect it comes down to SPL (sound pressure level) vs the efficiency rating. While they are both measured in dB, they are not the same thing. I can easily see how a speaker/sub might have a very high efficiency rating, but only generate a very low SPL.
 

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Actually, it's mostly a question of anatomy. Human ears are nowhere near as sensitive in the low range, so the sound has to be louder in order to be heard.
 

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Interesting thread as I also wondered about this. My pair of standing Polk R50s speakers are connected to JVC 304 and the bass really comes through beautifully without any use of power...not as obnoxiously Punchy as my powered sub-woofer downstair, but nevertheless, makes itself clearly and favorably present.
 

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Discussion Starter · #6 ·
According to Rodd Elliott while explaining a power distribution chart in one of his articles -


"The above power distribution table is approximate (as must be the case), and applies for 'typical' music - whatever that may be. If we look at the case for a crossover frequency of 3kHz, we can see that 85% of the power is in the low frequency spectrum, and only 15% in the high frequencies above 3kHz. It is not difficult to deduce from this that the peak power to the tweeter will be in the order of 15W at full power from the amplifier, with the average at about 1.5W"


Using this same chart, we would come to the conclusion that 40% of the total power usage is below 250hz.


The chart cuts off at 250hz, and there's no clear indication of what frequencies below, say 120hz, would require of total system power for a given channel. It's less than 40% though.


I should also note, that in some testing I did, activating my bass management did not reduce power consumption by a lot (I used a kill A watt meter to check.)


So, while I think the lower frequencies may use more power in some sense than higher frequencies, I think that at bass management cross over points, low frequencies may not be requiring as much power as people think, nor is using a powered sub taking as much of load of their receiver as they may think.
 

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Michael- although your main system didn't use more power I would suspect it would if it had to produce 105 db peaks say @ 20z or deeper as many sub/s do. I use three, 200, 250, and a 300 watt, and still want upgrade subs.
 

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Most top notch powered subwoofers have amplifiers rated at 500 watts/4 ohms, or above. OTOH, most full range speakers will experience lower impedances at higher frequencies, demanding more current to keep the tweeters safe. Tweeters don't require a lot of power but they will self-destruct very quickly if the signal is clipped by insufficient voltage. Of course if you use a sub for frequencies under 100 Hz you should not encounter problems with typical full range speakers unless you drive them to excessive loudness using an underpowered amp.
 

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Right, our ears are less sensitive to low freq, and because wavelengths are longer, generating them involves larger instruments/objects which require more power to energize.


"If a bass cab can put out 100 dB with one watt of input power, it does not seem like bass has to require a lot more power. What am I missing?"


That it takes a large box to do that, and the lower the freq to which it maintains that efficiency (likely not low), the bigger yet.


Hoffman's Iron Law says that of small box, high efficiency, deep bass, you get to pick 2 out of 3.
 
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