Right, except the line isn't so fine, The bigger enclosure will boost the lowest frequncies the most, but not enough to flatten the response.
Now in the case of sealed enclosures, the energy from the rear is not really how you want to look at it. It's more about how stiff the "air spring" is... sealed enclosures are less efficent because the speaker is working against a harder spring (ATBE).
I can't give you a detailed explanation of port function beyond what I have. I would have to get out MY book. And HORNS are a whole 'nother thing.
Okay. I was under the assumption that sealed subwoofers were inefficient because half of the radiated energy from the driver was wasted because it's trapped in the enclosure and can't contribute to overall output.
I mean, the front wave can't interfere with the back wave, right ?
The air in the enclosure (back pressure in the cabinet) acts like a spring to control cone motion. Correct ? And to counteract the force of internal air pressure in the cabinet, sealed subwoofers generally have to boost the electronic signal. . .increasing driver excursion and therefore increasing distortion.
Am I right ? About ported design, I don't think you elaborated on that. You are the engineer. . . I'm sure you can explain the function to me.
Please. I feel like I'm being taught at school. . after school lessons. . .heh
--Sincerely,
I mean, the front wave can't interfere with the back wave, right ?
The air in the enclosure (back pressure in the cabinet) acts like a spring to control cone motion. Correct ? And to counteract the force of internal air pressure in the cabinet, sealed subwoofers generally have to boost the electronic signal. . .increasing driver excursion and therefore increasing distortion.
Am I right ? About ported design, I don't think you elaborated on that. You are the engineer. . .
I'm sure you can explain the function to me.Please.
I feel like I'm being taught at school. . after school lessons. . .heh--Sincerely,
In comparison to a horn type speaker that is a correct statement. It's just not how you "look at things" in the design of sealed enclosures. The energy invested in air pressure when the cone retracts, is in part returned to the cone when it extends. I ain't even going there.
Yes, and this is good thing... it's called "tight" not rumbling or boomy (unless the music is)... accurate.
Yes, the amplifier must supply more power to create the same excursion when compared to a non-sealed enclosure.
Generally no, this may cause the amplifier to distort if it is undersized. Cone distortion is another matter beyond this discussion and should not be huge concern anyway as it is generally the result of an over-driven cone.
No, I didn't elaborate on ports much... did I?
It's just not how you "look at things" in the design of sealed enclosures.
Why ?
The energy invested in air pressure when the cone retracts, is in part returned to the cone when it extends. I ain't even going there.
I don't understand. The front wave cannot interfere with the back wave otherwise there would be bass cancellation. Correct ?
Generally no, this may cause the amplifier to distort if it is undersized. Cone distortion is another matter beyond this discussion and should not be huge concern anyway as it is generally the result of an over-driven cone.
I am talking about all things being equal here. In a sealed cab, the driver must work harder to achieve the same volume level as in a ported cab. More excursion means more distortion.
And just putting more power into the voice coils isn't necessarily a good idea right ? What about power compression ?
--Sincerely,
Why ?
The energy invested in air pressure when the cone retracts, is in part returned to the cone when it extends. I ain't even going there.
I don't understand. The front wave cannot interfere with the back wave otherwise there would be bass cancellation. Correct ?
Generally no, this may cause the amplifier to distort if it is undersized. Cone distortion is another matter beyond this discussion and should not be huge concern anyway as it is generally the result of an over-driven cone.
I am talking about all things being equal here. In a sealed cab, the driver must work harder to achieve the same volume level as in a ported cab. More excursion means more distortion.
And just putting more power into the voice coils isn't necessarily a good idea right ? What about power compression ?
--Sincerely,
Yes power compression occurs at high power levels,ie above probably 50% of RMS rating. The issue of WHEN it matters with program material is another.
Yes the two waves are in antiphase,and do not cancel in a sealed enclosure.
Sealed will always be the least efficient. But the price for a less steep rolloff has to be something.
If you dont buy one decent book,youl get little bits here and there from all over the net,with an incomplete picture,that takes longer to fill.
Start by learning the bass range,thats easier.My local library had a few good loudspeaker textbooks to read.
http://www.diysubwoofers.org
http://www.jlaudio.com 'tutorials'
www.jblpro.com 'tech papers ' 'sound system design manual'
Yes the two waves are in antiphase,and do not cancel in a sealed enclosure.
Sealed will always be the least efficient. But the price for a less steep rolloff has to be something.
If you dont buy one decent book,youl get little bits here and there from all over the net,with an incomplete picture,that takes longer to fill.
Start by learning the bass range,thats easier.My local library had a few good loudspeaker textbooks to read.
http://www.diysubwoofers.org
http://www.jlaudio.com 'tutorials'
www.jblpro.com 'tech papers ' 'sound system design manual'
Vaughan said:
Bigger enclosures don't give deeper bass, but drivers which deliver deeper bass with reasonable efficiency generally require bigger enclosures
To get the right answer, you must ask the right question.I could make you a 4" woofer that could get down to 10Hz flat anechoically in a 1 liter box, but you wouldn't be able to hear it.
The back wave is not effectively a wave at low frequencies, below the lowest modal frequency (where the wavelength is longer than the cabinet) the back wave merely pressurizes the entire enclosure. This pressure acts against the cone and is modeled in software as a simple spring (compliance), which increases the stiffness of the speakers own suspension and raises the resonant frequency. In the modal region where box resonances occur, the waves are reflected back at the cone and cause ripples, due to cancellations and additions, in the frequency response. This is where damping material helps by absorbing this energy and reducing reflections. Damping material and stuffing has a different mechanism at low frequencies, where it acts like a shock absorber.
Bass reflex enclosures do not have less pressure buildup, they actually have more than sealed boxes around tuning, less pressure below tuning and the same above tuning. Basically anywhere a bass reflex box has more output than an equally sized sealed box, it has more pressure in the box.
Vaughan said:
You can't understand this stuff without math. You can reach a comfort level with analogies, but not real understanding. You will always be confused by statements that conflict with that simple hand waving understanding.
Hi just wanted to jump in and ask, being a newbie also, what level does the Loudspeaker cook book explain at or is progressive like much text books?
I also have a hard time grasping some of the mathmatical equations, porbly pure lazy thought on my part, but i am so new i want somthing to read that i wont just open look at for min and then fall rite back into a beer induced stooper that im already in and feel like i spent 30 bucks on a book that will sit on the shelf and i can pretend i read it.
My first DYI project is a Sub with plans from Ascendent audio for the 12" Assassin in 3cube box and Rythmik plate amp so im not exactly setting the DYI world on fire with creativity. (although im wondering if i should put any stuffing in the box or just leave it empty? The box will be tuned to 20hz. ported)
But I really wana buy a book and the LoudSpeaker cook book is the most recomended so after all this is it the best bet to really get newbies feet wet on the ins and outs or is it a helpfull guide for the already informed?
Sorry bout the long post but i believe its still on topic of this thread. lol
I also have a hard time grasping some of the mathmatical equations, porbly pure lazy thought on my part, but i am so new i want somthing to read that i wont just open look at for min and then fall rite back into a beer induced stooper that im already in and feel like i spent 30 bucks on a book that will sit on the shelf and i can pretend i read it.
My first DYI project is a Sub with plans from Ascendent audio for the 12" Assassin in 3cube box and Rythmik plate amp so im not exactly setting the DYI world on fire with creativity. (although im wondering if i should put any stuffing in the box or just leave it empty? The box will be tuned to 20hz. ported)
But I really wana buy a book and the LoudSpeaker cook book is the most recomended so after all this is it the best bet to really get newbies feet wet on the ins and outs or is it a helpfull guide for the already informed?
Sorry bout the long post but i believe its still on topic of this thread. lol
Bigger enclosures don't give deeper bass, but drivers which deliver deeper bass with reasonable efficiency generally require bigger enclosures To get the right answer, you must ask the right question.
Now you are confusing me again. Everyone keeps telling me that bigger enclosures give deeper bass. I've read articles that tell you that bigger enclosures give deeper bass. Speaker designers have told e this too. That they are more efficient. People in this thread have also.
And now you say that bigger enclosures don't give deeper bass ? So who is correct now ? I thought bigger enclosures have less air resistance on the driver, and that cone excursion was less restricted given the greater overall volume.
I am getting more and more confused because there are conflicting opinions on what is going on here.
BTW, in terms of math, just how advanced are you talking here ? Because I won't want to fork out $40 on a book that I may never understand.
I just need advice.
--Sincerely,
Now you are confusing me again. Everyone keeps telling me that bigger enclosures give deeper bass. I've read articles that tell you that bigger enclosures give deeper bass. Speaker designers have told e this too. That they are more efficient. People in this thread have also.
And now you say that bigger enclosures don't give deeper bass ? So who is correct now ? I thought bigger enclosures have less air resistance on the driver, and that cone excursion was less restricted given the greater overall volume.
I am getting more and more confused because there are conflicting opinions on what is going on here.
BTW, in terms of math, just how advanced are you talking here ? Because I won't want to fork out $40 on a book that I may never understand.
I just need advice.
--Sincerely,
Generally, and all other things being equal... a larger enclosure offers a lessor spring for the cone to operate against... this in turn will allow greater efficiency.
Now, this happens at the expense of accuracy. The speaker will vibrate more at its natural frequency... so at other frequencies it will be relativley quieter.
As Ron pointed out it is a function of the drivers properties that determine how low the frequency response will be. The enclosure does have an influence.
You can look at it roughly like this. The smaller the enclosure... the more important the enclosure is. The larger the enclosure... the more important the driver becomes.
Why ported enclosures? If all is tuned correctly, a ported enclosure fools the driver into thinking it is in a small enclosure at the drivers natural frequency (to help bring down the peak). And the converse applies as well... the driver is fooled into thinking it is in a larger enclosure at frequencies away from the drivers natural frequency (to bring up the weak areas).
Now, this happens at the expense of accuracy. The speaker will vibrate more at its natural frequency... so at other frequencies it will be relativley quieter.
As Ron pointed out it is a function of the drivers properties that determine how low the frequency response will be. The enclosure does have an influence.
You can look at it roughly like this. The smaller the enclosure... the more important the enclosure is. The larger the enclosure... the more important the driver becomes.
Why ported enclosures? If all is tuned correctly, a ported enclosure fools the driver into thinking it is in a small enclosure at the drivers natural frequency (to help bring down the peak). And the converse applies as well... the driver is fooled into thinking it is in a larger enclosure at frequencies away from the drivers natural frequency (to bring up the weak areas).
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