sealed or ported
08-27-2006, 01:35 PM
#11
Both can sound equally great. Available space and a desire for a certain number and size of drivers usually determines which type I'll use. If I really just have to have 2x12's, but I need the space (current set up), then it's sealed. If space is not an issue...ported baby!! Like Dukk said, if you have at least 2 brain cells, then you can make a ported box sound as good or even better than a sealed one.
08-27-2006, 11:59 PM
#12
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Join Date: Feb 2006
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Originally Posted by Ravemeister
I say go sealed, if you like tight and punchy bass. If you really want a certain low-end frequency accentuated then add an eq and play with that. But if you're in the SPL circuit and want some crazy DBs, then go ported but you lose fidelity, personnally, I like to hear the music the way it was recorded but then again I recently became an SQ type person, my SPL days are over.
You're misinformed.
08-28-2006, 01:50 PM
#13
Originally Posted by Dukk
..oh but I disagree about power handling. In my experience, sealed boxes only handle more power if they are undersized...
Wow isn't it coincidental, but Velodyne, Paradigm, Mirage, B&W, Energy, Definitive...and many others has used his design as a template and they all share two things small SEALED box and lots of power...
08-28-2006, 02:12 PM
#14
It's funny about that Carver remark, I just read that today(Im trying to design some boxes for my subs into my trunk and im totally lost)...So I decided to read into it more(can never ever learn to much). and I read that carver"truesubwoofer" and thought that same thing, MANY have done the similar..
08-28-2006, 02:38 PM
#15
unfortunately, in cars we don't have the luxury of a 120-240 volt electrical system( 2400 watts only requires 25-40 amps of current in a home(120 volts), as compared to 250-400 in a car(12 volts)...depending on efficiency). That makes very high powered systems a much bigger problem for most of us to implement in an automobile.
08-28-2006, 02:55 PM
#16
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Join Date: Feb 2006
Posts: 16,855
Originally Posted by mike bisson
You mean like Bob Carver's "Truesubwoofer"? He released it in 1995 13x13x13" 2600watt @60hz playable to 16hz
Wow isn't it coincidental, but Velodyne, Paradigm, Mirage, B&W, Energy, Definitive...and many others has used his design as a template and they all share two things small SEALED box and lots of power...
Wow isn't it coincidental, but Velodyne, Paradigm, Mirage, B&W, Energy, Definitive...and many others has used his design as a template and they all share two things small SEALED box and lots of power...
Right - undersized sealed box. Plus you know as well as I do that the 2600watts is total bullshit. More like 1/3 of that.
Also, I had extended time listening to that Carver woofer. It sounded like the box was undersized. Coulda used more air and a vent
Overall, considering the price, performance, and reality vs. hype factor, IMO it's a POS.
'In general' vented boxes handle more power. Vented bandpass even more.
08-29-2006, 03:19 AM
#17
50 Watt CAFz'r
Join Date: Nov 2005
Posts: 233
hope this helps with the differences.
well here it goes...
Both the Enclosure types have been around for a long time, but there are trade offs to each.
Sealed (or acoutstic suspension) enclosures exhibit a second order, 12db/oct roll off below the resonant freq of the box (fc). Next to the transmission line, the sealed box has the best transient response of all types of enclosures and because of the sealed boxs' shallow roll off, it will exhibit deeper bass for a given (fc) than other types of enclosures. Because of the resistence that the air makes directly to the cone, it raises the drivers (Fs) and changes the (Q) as well. Lower Qtc's will have better transient response and more detailed sound. In car, a Qtc of .7 to 1 is ideal (for those box designer types). Boxes that are too small, raise the Qtc and the (Fc) and the opposite is true for boxes that are too big. Higher Qtc's exhibit higher displacement limited power handling and likewise, lower Qtc's exhibit lower displacement power handling.
For sealed boxes, try using a driver with a Qtc measurement above 0.35. You can also use the formula mentioned earlier about EBP to find out about your specific driver.
Vented boxes exhibit a 4th order (24db/oct) roll off on the bottom end below th (Fb) or tuning frequency. A port increases the mass of the vibrating air and allows lower tuning frequencies (read up on Helmholtz resonator theory). At the tuning freq, the port contributes to the output of the system by increasing the load on the rear of the driver which also reduces cone motion around the tuning freq. Unlike sealed boxes that are grouped by their Qtc's, vented boxes are grouped by their alignments. By changing the tuning, you can change the response with out changing a box design as you would in a sealed box by rebuilding larger or smaller, but responses that deviate from flat in your vented design,are similar to sealed boxes in that contain ringing or transient response issues. In other words, design a vented box to have as flat a response as possible.
Compared to sealed boxes, the vented boxes exhibit much less driver excursion at the tuning frequency, resulting in higher displacement and limited power handling. Additionally the vented box has a lower cut off freq for a given driver than a sealed box does. Many people believe that vented enclosure are 3db more efficient...in actuality, all we are hearing is the ported box exhibiting a lower cut off freq.
Hope this explains some of the differences and some of the trade offs.
Happy designing!
Both the Enclosure types have been around for a long time, but there are trade offs to each.
Sealed (or acoutstic suspension) enclosures exhibit a second order, 12db/oct roll off below the resonant freq of the box (fc). Next to the transmission line, the sealed box has the best transient response of all types of enclosures and because of the sealed boxs' shallow roll off, it will exhibit deeper bass for a given (fc) than other types of enclosures. Because of the resistence that the air makes directly to the cone, it raises the drivers (Fs) and changes the (Q) as well. Lower Qtc's will have better transient response and more detailed sound. In car, a Qtc of .7 to 1 is ideal (for those box designer types). Boxes that are too small, raise the Qtc and the (Fc) and the opposite is true for boxes that are too big. Higher Qtc's exhibit higher displacement limited power handling and likewise, lower Qtc's exhibit lower displacement power handling.
For sealed boxes, try using a driver with a Qtc measurement above 0.35. You can also use the formula mentioned earlier about EBP to find out about your specific driver.
Vented boxes exhibit a 4th order (24db/oct) roll off on the bottom end below th (Fb) or tuning frequency. A port increases the mass of the vibrating air and allows lower tuning frequencies (read up on Helmholtz resonator theory). At the tuning freq, the port contributes to the output of the system by increasing the load on the rear of the driver which also reduces cone motion around the tuning freq. Unlike sealed boxes that are grouped by their Qtc's, vented boxes are grouped by their alignments. By changing the tuning, you can change the response with out changing a box design as you would in a sealed box by rebuilding larger or smaller, but responses that deviate from flat in your vented design,are similar to sealed boxes in that contain ringing or transient response issues. In other words, design a vented box to have as flat a response as possible.
Compared to sealed boxes, the vented boxes exhibit much less driver excursion at the tuning frequency, resulting in higher displacement and limited power handling. Additionally the vented box has a lower cut off freq for a given driver than a sealed box does. Many people believe that vented enclosure are 3db more efficient...in actuality, all we are hearing is the ported box exhibiting a lower cut off freq.
Hope this explains some of the differences and some of the trade offs.
Happy designing!
08-29-2006, 03:10 PM
#19
Originally Posted by Dukk
Right - undersized sealed box. Plus you know as well as I do that the 2600watts is total bullshit. More like 1/3 of that.
Also, I had extended time listening to that Carver woofer. It sounded like the box was undersized. Coulda used more air and a vent
Overall, considering the price, performance, and reality vs. hype factor, IMO it's a POS.
'In general' vented boxes handle more power. Vented bandpass even more.
Also, I had extended time listening to that Carver woofer. It sounded like the box was undersized. Coulda used more air and a vent
Overall, considering the price, performance, and reality vs. hype factor, IMO it's a POS.
'In general' vented boxes handle more power. Vented bandpass even more.
Paul, how much power does a wall circuit have? 2700watts @ 60hz.... Just because you cannot fathom Carver's genius does not mean he is not one.
Also, what did you use it with, what was the room like? Did you hook it up to its' own wall circuit? (required) I had a lot of time listening to and tweeking several in various rooms, it really liked to play @ 60hz and down.
IMO the True Subwoofer changed the home theatre industry forever, and if some of the greatest designers of loudspeakers in the world have followed its' lead than I might have to go with that as opposed to your views.
08-30-2006, 03:03 PM
#20
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Join Date: Feb 2006
Posts: 16,855
Standard household circuit: 110v @ 15amps = 1650watts. 
Where did you get 2700watts? The brochure? 
$6000 Onkyo mostly. 10-22ish foot room. Dedicated circuit. IMO it was weak. I *do* like to believe I know what I am doing Mike.. I've played with my fair share of home theatre woofers to have a credible opinion. You can like it but don't fault me for not.
I did not however have the whiz bang $300 power cord for it though. Maybe THAT was the difference.
Where did you get 2700watts? The brochure?
Also, what did you use it with, what was the room like? Did you hook it up to its' own wall circuit? (required) I had a lot of time listening to and tweeking several in various rooms, it really liked to play @ 60hz and down.
I did not however have the whiz bang $300 power cord for it though. Maybe THAT was the difference.
