Trying To Prove A Point

[E-Stat]

Yup, many actively bi/tri/quad amped speakers use more power as you go from the tweet to the bass driver. Cabasse's 'La Sphere' is an example of this.

My wording was a bit awkward. What I meant was that as one moves from low to high, have you seen the power output also rise?

The ATC speaker I cited as an example uses five times as much power at the bottom than the top. I have never, for example, seen a speaker using 100 watts on the bottom and five hundred at the top!

rw

[audio amateur]

My wording was a bit awkward. What I meant was that as one moves from low to high, have you seen the power output also rise?

The ATC speaker I cited as an example uses five times as much power at the bottom than the top. I have never, for example, seen a speaker using 100 watts on the bottom and five hundred at the top!

rw

I'm not sure why you say your wording as awkward, because as far as I am concerned we are both agreeing on the same thing.

[E-Stat]

I'm not sure why you say your wording as awkward, because as far as I am concerned we are both agreeing on the same thing.

You're right - at first I thought you didn't get my point.

rw

[Mr Peabody]

AA, are you saying it takes more power for tweeters? If you have some example of that, it's definitely an abnormality because it sure isn't the norm.

[BallinWithNash]

Haha, thanks Peabody and everyone else for the help. It is much appreciated. And your idea of getting him to find evidence that highs require more power is a good idea .. ill try it.

[audio amateur]

AA, are you saying it takes more power for tweeters? If you have some example of that, it's definitely an abnormality because it sure isn't the norm.

No no, all the opposite. What exactly, from what I said, makes you two think that? I thought I made myself clear the first time...

[Mr Peabody]

I misunderstood this statement. But we're all on the same page now, that's what counts

Yup, many actively bi/tri/quad amped speakers { use more power as you go from the tweet to the bass driver} . Cabasse's 'La Sphere' is an example of this.

"

[audio amateur]

Ok cool. Didn't mean to sound offensive but I thought it was quite clear then Estat said that and then you so...
Talking of which if a speaker has a supposedly very flat frequency response (is capable of the lowest octaves, top of the line Dynaudio for example) then how come IT doesn't need more power on the bottom end? (Geoff pointed this out already). Anyone?

[E-Stat]

Ok cool. Didn't mean to sound offensive but I thought it was quite clear then Estat said that and then you so...

It was all my fault.

...then how come IT doesn't need more power on the bottom end? (Geoff pointed this out already). Anyone?

Perhaps you've asked the wrong question. The active monitors I found use lightweight class D amps so perhaps they chose to use one design for both. Unless they are horribly inefficient, one does not usually need 200 watts to drive a tweeter! I found another model (M3) that is a three way using one amp for the woofer and the other for the midrange/tweeter.

rw

[Mr Peabody]

Dynaudio or any speaker will apply the majority of it's received input power toward the woofers.

[Geoffcin]

Dynaudio or any speaker will apply the majority of it's received input power toward the woofers.

It does absolutely nothing of the kind.

If you input a watt of power, (say a sine wave) into a Dynaudio, or JMLabs, or Magnepan, the speaker it directs that energy to the driver it is intended for.

Simplified, a low frequency tone it is directed toward the woofer, and the tweeter is blocked from the signal. If it's a high frequency tone, it is directed to the tweeter, and the signal is blocked from the woofer. Obviously there are a myriad of permutations that are possible in a crossover,(slopes/order/phase/ect.) but as I've described it that is the essence of the passive crossover system that is used in the majority of consumer speakers.

I'm surprised Kexodusc hasn't chimed in on this, as crossover theory is something any good DIY guy knows by heart.

While it might SEEM that a woofer is less efficient than a tweeter this is not always the case. Some woofers are very efficient and some tweeters are not. Some designs lend themselves to high efficiency bass response (think horns) some not. A good speaker designer balances the drivers to create a speaker with a flat response that covers the maximum range.

[Mr Peabody]

Geoffcin it sounds like you are mixing the frequency up with the power. Of course, the crossover seperates the low from high frequencies at the designated points but the woofer will require more power to do it's job than the tweeter.

[hermanv]

On average tweeters require less power for a given SPL. Crossovers often have resistor attenuators in the tweeter circuit.

It's also important to recognize the difference between perceived level and actual level. White noise (same level at all frequencies) will typically sound bright. Pink noise (decreasing energy vs frequency) will usually sound more like a flat spectrum.

On bi or tri amped systems the woofer driver nearly always get the more powerful amplifier with 10 to 1 not being unusual.

[Mr Peabody]

Notice in this article where it says the crossover divides the input signal into the frequency range for each driver AND each driver only receives the POWER required for that frequency range. Which means a woofer may require 30 watts of a signal to reproduce a low frequency where the tweeter only needds 1 or less. http://en.wikipedia.org/wiki/Loudspe..._system_design

When we built cabinets using Electro-Voice drivers they had a horn whose power handling was only 5 watts. The overall power handling of the cabinet was massive however. The horn was sold with it's specific module to ensure no more than 5 watts was ever seen by the horn.

Here's a good article in plain language that explains how the crossover is used to limit power as the frequency goes higher. Hence, if a box speaker such as Dynaudio receiver an input signal the woofer WILL receiver the MAJORITY of power. http://www.the12volt.com/caraudio/cross.asp

Additional proof with nice graphs: http://www.st-andrews.ac.uk/~www_pa/...ing/page4.html

[Geoffcin]

Geoffcin it sounds like you are mixing the frequency up with the power. Of course, the crossover seperates the low from high frequencies at the designated points but the woofer will require more power to do it's job than the tweeter.

Rather than argue the point, as it seems to be hard to "prove" any point here, I point you to what any speaker builder would use before choosing a driver, the spec sheet. Take a look at this one;

http://www.madisound.com/catalog/PDF/eton/12-680.pdf

This is a very good woofer, and is flat from 2000Hz all the way down to 100Hz where your engineering skill as a speaker designer would take over with the cabinet design for bass reinforcement.

Matched with a tweeter with a similar sensitivity the final design, say this one;

http://www.madisound.com/catalog/PDF/ST1108.pdf

a 1 watt input at 100Hz in this speaker would produce a SPL of the SAME volume as a 10kHz input signal, there is NO need for more power to the woofer!

According to your theory, this speaker (or all!) would need Eq to be flat, which simply is NOT the case. A speaker that is nominally flat will produce an SPL of the same volume regardless of the signal Hz whether the woofer is producing the tone or the tweeter.

[audio amateur]

So, according to what you're saying Peabody, crossovers not only filter the frequencies for the specific driver but also the power?? I'm confused...

[audio amateur]

Perhaps you've asked the wrong question. The active monitors I found use lightweight class D amps so perhaps they chose to use one design for both. Unless they are horribly inefficient, one does not usually need 200 watts to drive a tweeter! I found another model (M3) that is a three way using one amp for the woofer and the other for the midrange/tweeter.

rw

I'm not talking about active speakers now but normal passive speakers.

[Geoffcin]

On average tweeters require less power for a given SPL. Crossovers often have resistor attenuators in the tweeter circuit.

It's also important to recognize the difference between perceived level and actual level. White noise (same level at all frequencies) will typically sound bright. Pink noise (decreasing energy vs frequency) will usually sound more like a flat spectrum.

On bi or tri amped systems the woofer driver nearly always get the more powerful amplifier with 10 to 1 not being unusual.

Most crossovers are designed with inductors and capacitors. A crossover is a FILTER system, not an eq system. Resistors are only used with non-matching components, and they do NOT eq. the speaker other than to match components overall output.

Woofers are by nature able to handle more power by virtue of being larger and able to dissipate more heat. Also, even though you can put a 10X more powerful amp on a woofer, that does NOT mean that the woofer would actually NEED 10x more power to create the same SPL.

[Mr Peabody]

Geoffcin, I refer you to the links I posted. The original point of the thread was whether it takes more power to reproduce lower frequencies and in fact it does. The crossover not only directs the various frequencies to the drivers but it also disperses the needed power. The higher the frequency the less power needed, the less power directed that way.

If you mic the speaker's output from the front you may see what you are talking about a quasi flat response but internally that woofer will use way more of the input POWER than the tweeter.

[Mr Peabody]

AA, please read the links I posted in earlier post, it will explain better than I can. The crossover does not "filter" power. By the size of the coils and caps as it relates to frequency directs the power, the power reduces as the frequency goes higher.

G, not sure really what tangent you are off on, no one said anything about a speaker EQ'ing. You have a set input power to a speaker, via what I stated to AA the majority of that said power will go to the woofer. Reason being the woofer requires way more power to reproduce low frequencies than a tweeter does to reproduce highs. Perhaps it will make more sense if you read from the links I posted.

[Geoffcin]

I don't claim to be an expert on the subject, but I can tell you that a woofer that produces a 90dB SPL from 1 watt at 100Hz uses the same energy as a tweeter that produces that same SPL from 1 watt at 10kHz. The woofer doesn't NEED more power, nor does a crossover somehow redirects power to it other than filter out the frequencies that were not intended for it.

[audio amateur]

P, I've had a look at the links and from what I've read it just talks about filters and filtering frequencies to the different drivers.

I've always thought like Geoff but I'm having doubts now. Why do active speakers use more power on the bass if there is no need for it? Unless the woofers they use are less efficient than their tweeters and thus require more gain (power) on the woofs.

[Geoffcin]

P, I've had a look at the links and from what I've read it just talks about filters and filtering frequencies to the different drivers.

I've always thought like Geoff but I'm having doubts now. Why do active speakers use more power on the bass if there is no need for it? Unless the woofers they use are less efficient than their tweeters and thus require more gain (power) on the woofs.

The main reason for active speakers using more power on the woofers is that they can. By actively eq'ing the woofer and applying more power, you can use a smaller woofer and a smaller enclosure to produce the same bass. You can also eq for a flatter response. This is exactly what Axiom does with their subs, and from the one I reviewed this technology works superbly.

[harley .guy07]

the only thing that I will add is the simple structures of speaker drivers. In what I have seen and worked with a woofer with a 3 inch woice coil driving an 8 inch cone from a magnet that has a 150 ounce stucture(this is all for example reasons) will take more electromagnetic force than a 1 inch soft dome tweeter with a 1 inch coice coil and neo magnet. The reason why some of your smaller subwoofers use higher power amps is because of the stiffer cone material, longer xmax(throw), and higher power handling motor structure of the woofer. this is to try to maximize what a woofer of that size would normally do. And for the most part it works with the exception of overall spl output at the lowest of frequencies.

But my main thing is to concider the motor structure of a woofer driving a cone that is that big in diameter and tell me that this will not take more power than a tweeter with a motor structure that is under half the size of the woofer besides the fact that it is driving a dome or cone that is 1/8 to 1/12 the woofers size. I am just thinking about the electromagnetic force needed to move examples of each of these drivers and thinking there is no way the tweeter would need as much electromagnetic force to move it as the woofer. Thats what i have always believed and it makes sense. look at most peoples systems. 500 to 1000 watt amps driving powered subs of 12 to 15 inches in diameter with 2 1/2 to 4 inch voice coils and huge magnet structures. And in that same system they have 150 to 200 watts per channel running tower speakers with midwoofers and tweeters. not to say there are not exceptions but it will be hard for me to believe that the points I have made don't make sense.

[Mr Peabody]

AA, did you see this link from my earlier post? I don't know how much more simpler it could be: http://www.the12volt.com/caraudio/cross.asp

G, if a bass note requires equal power as a high note show me some proof as you are defying physics.