Jun
What is better for low and deep bass; a port or a passive radiator?
I am planning on doing a home theater subwoofer build and I am looking for overall deep and loud bass. Of the above two options, which one will lets me accomplish this?
The performance of conventional passive-radiator loudspeaker systems and vented-box loudspeaker systems are substantially the same. Passive-radiator loudspeaker systems are a type or variant of vented-box loudspeaker. They closely follow the same design principles and methodology used for vented-box loudspeakers and offer similar performance to their vented/ported/bass-reflex enclosure counterparts. Passive radiator enclosure designs do NOT offer greater low-frequency extension or output than similar vented enclosure designs.
Passive-radiator designs offer their own advantages and disadvantages over their vented/ported/bass-reflex cousins. Advantages include the elimination of vent colorations, such as vent pipe resonances, wind noise from air turbulence that can often result from improper vent design and internal (mechanical) noise that can be reflected through vents or ports. Properly designed vents for low-frequency enclosures require a minimum vent area. The required minimum vent area will increase incrementally in direct proportion to an increase in the total volume displacement and a decrease in the box tuning frequency. Likewise, for the common ducted vent or port design the larger the vent area the longer the duct length. As one might imagine long vent ducts can easily cause problems or difficulty designing smaller loudspeaker enclosures. Passive radiators used in place of ducted vents or ports solve these problems.
Also, it is important to remember that many—if not all—conventional moving-coil drivers vary widely from their published Thiele-Small parameters. Thus relying upon a manufacturer's published Thiele-Small parameters often creates difficulty when it comes to precisely tuning a vent or vents in a vented-box enclosure. The use of passive radiators greatly simplifies the physical box tuning process.
The disadvantages of standard passive-radiator enclosure designs is a steeper low-frequency roll-off, which in turn results in somewhat poorer transient performance, a higher cut-off frequency and slightly greater overall system loss, i.e., Q-sub-L, in comparison to their vented counterparts. The augmented passive-radiator design, attributed to Hossbach and Clarke most notably, effectively eliminates the disadvantages associated with conventional passive-radiator designs while offering additional performance advantages. The downside to the augmented passive-radiator design is that you would have to construct your own augmented passive radiator as there are no commercial off-the-shelf augmented passive radiators available.
One of the most popular “vented-box” subwoofer designs is the 2:1 passive-radiator design. Head over to the Home Theater Shack forums and read some of the discussions and tests of various DIY and commercial subwoofer designs.
######################## RESOURCES ########################
diyAudio.com Wiki: types of subwoofer
http://www.diyaudio.com/wiki/index.php?page=types+of+subwoofer
Does anybody know the meathod to work out the porting for my bass cabenet? [sic]
http://answers.yahoo.com/question/index?qid=20080421141305AAdKp8f
Home Theater Shack forums
http://www.hometheatershack.com/forums/
– New Passive Radiators from Creative Sound
http://www.hometheatershack.com/forums/diy-subwoofers/6268-new-passive-radiators-creative-sound.html?pp=50
– 4 18" 5400’s and 8 passives “WOW!”
http://www.hometheatershack.com/forums/diy-subwoofers/9281-4-18-5400s-8-passives-wow.html?pp=50
– DIY TC Sounds LMS-5400 18" + 2×18" PR 200L *new*
http://www.hometheatershack.com/forums/subwoofer-tests/8156-diy-tc-sounds-lms-5400-18-2×18-page-ranking-200l-new.html?pp=50
– TC Sounds LMS-5400 18" sealed 75L vs. 200L *special test*
http://www.hometheatershack.com/forums/subwoofer-tests/12195-tc-sounds-lms-5400-18-sealed-75l-vs-200l-special-test.html?pp=50
– Home Audio Subwoofers - Subwoofer Tests - Fall 2007
http://www.hometheatershack.com/forums/home-audio-subwoofers/6656-subwoofer-tests-fall-2007-a.html?pp=50
Comments on Earl Geddes’ “Acoustic Lever” design:
http://www.audioroundtable.com/ProSpeakers/messages/188.html
http://www.audioroundtable.com/ProSpeakers/messages/208.html
http://www.audioroundtable.com/ProSpeakers/messages/209.html
GedLee LLC
http://www.gedlee.com
Loudspeaker Design Cookbook
http://www.audioxpress.com/bksprods/products/bkaa68.htm
audioXpress (Old Colony) Loudspeaker Reference Books
http://www.audioxpress.com/bksprods/BKSLOUREF.htm
Loudspeaker Design and Construction Resources
http://docs.google.com/View?id=dhpmqnbb_8cqqcq2gx
(Note: the resources will be updated on a regular basis)
################## TECHNICAL RESOURCES ##################
An Analysis of Design Conditions for a Phase-Inverter Speaker System with a Drone Cone
Nomura, Y.; Kitamura, Z.
IEEE Transactions on Audio and Electroacoustics
Oct 1973; Volume: 21, Issue: 5; pp. 397- 407
ISSN: 0018-9278
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1162502
Passive-Radiator Loudspeaker Systems Part 1: Analysis
Small, Richard H.
JAES Volume 22 Issue 8 pp. 592-601; October 1974
http://www.aes.org/e-lib/browse.cfm?elib=2739
Passive-Radiator Loudspeaker Systems, Part 2: Synthesis
Small, Richard H.
JAES Volume 22 Issue 9 pp. 683-689; November 1974
http://www.aes.org/e-lib/browse.cfm?elib=2731
The Drone-Cone, Phase-Inverter Loudspeaker
Olson, Harry F.
JAES Volume 21 Issue 7 pp. 582, 583; September 1973
http://www.aes.org/e-lib/browse.cfm?elib=1947
Recent Developments in Direct-Radiator High-Fidelity Loudspeakers
Olson, Harry F.; Preston, John; May, Everett G.
JAES Volume 2 Issue 4 pp. 219-227; October 1954
http://www.aes.org/e-lib/browse.cfm?elib=47
Design of Acoustic Lever Loudspeaker Systems, Part One
Phillips, Alan S.
AES Convention: 109 (September 2000) [Preprint] Paper Number: 5279
http://www.aes.org/e-lib/browse.cfm?elib=9059
The Acoustic Lever Loudspeaker Enclosure
Geddes, Earl R.
JAES Volume 47 Issue 1/2 pp. 3-13; February 1999
http://www.aes.org/e-lib/browse.cfm?elib=12118
Augmented Passive Radiator Loudspeaker Systems, Part 1
Clarke, Thomas L.
JAES Volume 29 Number 6 pp. 394-404; June 1981
http://www.aes.org/e-lib/browse.cfm?elib=3906
Augmented Passive Radiator Loudspeaker Systems, Part 2
Clarke, Thomas L.
JAES Volume 29 Number 7/8 pp. 511-516; July/August 1981
http://www.aes.org/e-lib/browse.cfm?elib=3896
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United States Patent 6,782,112 (August 24, 2004)
Low Frequency Transducer Enclosure
Geddes, Earl R.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6782112.PN.&OS=PN/6782112&RS=PN/6782112
United States Patent 6,704,426 (March 9, 2004)
Loudspeaker System
Croft, III, James J.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6704426.PN.&OS=PN/6704426&RS=PN/6704426
United States Patent 4,076,097 (February 28, 1978)
Augmented Passive Radiator Loudspeaker
Clarke, Thomas Lowe
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4076097.PN.&OS=PN/4076097&RS=PN/4076097
United States Patent 3,772,466 (November 13, 1973)
Loudspeaker System
Hossbach, Erich
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=3772466.PN.&OS=PN/3772466&RS=PN/3772466
United States Patent 4,350,847 (September 21, 1982)
Subwoofer System Using a Passive Radiator
Polk, Matthew S.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4350847.PN.&OS=PN/4350847&RS=PN/4350847
United States Patent 3,669,215 (June 13, 1972)
Passive Radiator for Use in a Bass Reflex Loudspeaker System
Kikuchi, Takeo; Hashino, Hisaaki
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=3669215.PN.&OS=PN/3669215&RS=PN/3669215
(If you would like to download U.S. Patents I recommend using the free patent search tool on www.pat2pdf.org)
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I cannot believe how much bass this sub puts out! Hell, it still sounds crazy just with the Bass flat!
FBT introduces the MITUS sound reinforcement range during the last Frankfurt Prolight & Sound 2009. The MITUS includes active and passive models, with a compact line array system and flyable subwoofer. Moreover, the company launches the new FORMULA 143 FXA powered mixer, 2 x 850W rms built-in Class D power amplifier with switch mode power supply. The FBT stand at Frankfurt also showcased the QUBE AUDIO top range of touring and installation speakers, the FBT AUDIO CONTRACTOR public address and system integration range, highlighting the latest models of conference and interpretation systems, as well as the latest release of the VAIS 1000 voice evacuation system.