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Topic: Reflex port

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Loudspeaker

Lumped component

Frequency

Operational amplifier

Passive radiator

	Bass reflex - Wikipedia, the free encyclopedia
		Bass reflex (also known as a ported, vented box or reflex port) is a type of loudspeaker enclosure that utilizes the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies as compared to a typical closed box loudspeaker.
		The effect of the various speaker parameters, enclosure sizes and port (and duct) dimensions on the performance of bass reflex systems was not well understood until the early 1970s.
		The ported box system is more complex than the sealed box system, and as such it generally has poorer transient response.
	en.wikipedia.org /wiki/Bass_reflex (624 words)

	Speaker system - Patent 6618488
		The bass reflex duct 16 is arranged at a position corresponding to an approximate center portion of the rear surface of the speaker 14 but spaced from the speaker 14 and arranged to lead to a bass reflex port 18 penetrating the other substantially triangular surface of the speaker box 12.
		Since the resonance frequency is mainly determined by the interior volume of the speaker box 12 and the size of the bass reflex duct 16, a clearance is necessary between the bass reflex duct 16 and the duct 20, and between the duct 20 and an inner surface of the speaker box 12.
		Thus, the bass reflex port 18 may be provided at the back or at the side of the speaker 14, or at the surface on which the speaker 14 is provided.
	www.freepatentsonline.com /6618488.html (2421 words)

	MONITORS DEMYSTIFIED
		But at the port's resonant frequency (which is defined by the cross-sectional area and length of the tube, and the volume of the box), the slug moves in phase with the driver, adding significant extra acoustic output and reducing the movement of the drive unit cone.
		Firstly, the extension of low-frequency bandwidth produced by reflex loading comes at the expense of dynamic accuracy, as the amplifier now not only has to control the movement of the drive unit cone but also the air in the tube.
		The characteristic frequency of the ringing overhang is equal to the resonant frequency of the reflex port.
	www.soundonsound.com /sos/oct00/articles/monitor.htm?session=43bd08c9b3a387969045286fdd2be627 (3130 words)

	Sub Utopia Beryllium.
		The bass reflex decompression port design is of paramount importance and has a direct effect on the characteristics and performances of the loudspeaker in the bass range section.
		On a common port, the different frictions on the walls are slowing down the airflow: the wave is then bent, giving rise to new distortions and turbulences due to a violent output decompression producing noise.
		The TFP port ensures a progressive air decompression in order to obtain a constant speed along the whole part of the port’s section and a coherent output wave form.
	www.focal.tm.fr /gb/home/utopiabe/tek/tfpport.htm (750 words)

	Reflex RTP reflector/mixer (Site not responding. Last check: 2007-10-30)
		By using a textual name in addition to the port number to identify a session, multiple conference sessions using the same UDP port number can be active on the reflector simultaneously.
		To set up a conference session the participants signal their intention to participate to the reflector, indicating the UDP port number to be used, and identifying the particular conference session to join by a textual name.
		The reflex RTP reflector/mixer was developed by Alkit Communications as a part of the 'Alkit Confero' conferencing and collaboration software suite.
	w2.alkit.se /reflex (794 words)

	Stereophile: B&W 705 loudspeaker
		The saddle at 40Hz in the magnitude trace indicates the tuning frequency of the big-mouthed port.
		Although there is a peak in the port's output at 900Hz, the frequency of the glitch in the impedance traces, it is well down in level.
		The nearfield response of the woofer with the reflex port blocked is plotted in red.
	stereophile.com /standloudspeakers/204bw/index4.html (1173 words)

	Definitions
		An adjustable bass reflex port that makes it possible to tune a subwoofer according to its location in the room and the taste of the user.
		A vented loudspeaker enclosure in which the rear waves from the woofer(s) emerge through an opening or bass reflex port that is tuned to the woofer characteristics.
		Reflex loading is often used to extend the low frequency response and increase the efficiency of a speaker system.
	www.audiovideoexperience.com /definitions.htm (5475 words)

	Stereophile: Amphion Helium² loudspeaker
		This graph was taken with the reflex port open; the saddle centered on 54Hz in the magnitude trace suggests that this is the tuning frequency of the rear-facing port.
		Turning to the acoustic outputs of the drive-units, to the left-hand side of fig.4 are shown the lower-frequency responses of the woofer when reflex-loaded (green trace), the woofer when sealed-box–loaded (red), and the port (blue), all measured in the nearfield.
		All the acoustic output radiates from the port at this frequency, demonstrated in fig.4 by the broad peak in the blue trace centered on 54Hz.
	www.stereophile.com /loudspeakerreviews/105amphion/index4.html (1093 words)

	Welcome to the Reflexreader site!
		The Reflex 72 V2 reader is part of a new family of Smart Card Readers that include support for multiple interfaces, multiple reader devices and relevant security standards.
		In addition, the Reflex 72 V2 is the industry's first to offer on-board flash, allowing future firmware and application enhancements that guarantee against obsolescence.
		The Reflex 20 v.3 is a Smart Card reader that is designed to be used in a Type 11 PCMCIA slot.
	www.reflexreaders.com (236 words)

	Generating Tones with Reflexes (Site not responding. Last check: 2007-10-30)
		The reflex routine uses two timers, a reflex enabler, and a digital output.
		There is some latency between disabling the reflex and when it actually stops since the reflex must cycle to the point where it checks the reflex enabler.
		Attempting to launch the reflex while it is already running may cause a timer conflict error.
	www.acroname.com /brainstem/examples/tone/tone.html (501 words)

	Recording Apparatus (Site not responding. Last check: 2007-10-30)
		The recording apparatus consists of a tuned bass-reflex port -- stopped similar to a organ diapason for tuning puposes, and to ensure a deficiency of upper partials.
		Attached to this port is a suction cup of a modified telephone pickup coil.
		Tuning of the port was arrived at by formula and empirical experience.
	www.borderlands.com /newstuff/research/humrecord.htm (175 words)

	REFLEX - Brown & Sharpe, a division of Hexagon Metrology, Inc.
		During your measurement routine, REFLEX software automatically recognizes the shape of the feature you are measuring.
		REFLEX uses a unique "speedometer" that graphically indicates the quality of the measurement data being collected, based on the speed of the probe.
		REFLEX lets you transfer measurement data via an RS-232 serial port to a host computer for data archiving and statistical analysis.
	www.brownandsharpe.com /software_reflex.asp (315 words)

	Fibre Channel Arbitrated Loop Hub
		The Bitstrip TW incorporates several active features, such as Gadzoox' Reflex intelligent port bypass and per port data regeneration, which ensure reliable, trouble free, plug and play operation as well as a high degree of data integrity.
		The Reflex feature, an intelligent port detection an bypass capability, dynamically reconfigures the arbitrated loop network to preserve communication between all operating devices.
		Using Reflex, the Bitstrip TW manages movement of nodes on and off the network, constantly monitoring nodes for failure, cable disconnection or network reconfiguration.
	www.dm-int.com /fc-al_hub.html (452 words)

	Humble Homemade Hifi
		Placing the reflex port in the front baffle is a very wise thing to do.
		The reflex port is kept clear but the top of the reflex tunnel is also covered with lead bitumen and carpet tiles.
		The internal volume is only 4 litres and the bass-reflex ports are tuned to 68Hz.The images show the separate output for the woofer and the reflex port as also the summed output.
	www.humblehomemadehifi.com /HATT.html (1795 words)

	diyAudio Forums - Reflex Port Equivalents.
		For example, design calls for 1 port 35MM diameter x 125mm long, what would a 50mm diameter port have to be in length to do the same job.
		It's just the volume of air in the port that's important really (in the electrical analogue it's the moving mass which is the important thing, which is calculated from the volume of air in the port).
		The most important correction factor is the end corrections due to flanged or unflanged ports which somebody smarter than me will no doubt be able to quote equations for off the top of their head.
	www.diyaudio.com /forums/showthread.php?postid=87400 (321 words)

	Bandit
		Note that since the ports are located near the driver there could be some crosstalk between the measurements with the driver response creeping into the port responses.
		According to the nearfield responses of the ports it can be seen that the bottom port is resonating at 150 Hz which causes a dip in the driver response at that frequency and reduces the driver excursion as a result.
		It appears that the top port is resonating in the 67 Hz to 75 Hz range while the bottom port is also contributing to the 75 Hz output as well.
	www.rjbaudio.com /Bandit/bandit.html (4343 words)

	Lumped component - Wikipedia, the free encyclopedia
		A reflex port may be approximated as an inductor whose value is proportional to the effective length of the port divided by its cross-sectional area.
		This approximation relies on the shortest wavelength of interest being significantly larger than the longest dimension of the port.
		Certain types of damping material can be approximated as a resistor.
	en.wikipedia.org /wiki/Lumped_component (314 words)

	Minimus 7
		The bass port is intended to add to the quantity of bass the speaker has, which it does somewhat, but at the expense of quality.
		The port is also too small as the air mach speed is 0.34 which generates a noise and there is substantial phase shift in the reflex version.
		The larger cabinet of the Pro X7s sounds OK with the port open but it still suffers some phase shift and there is some air noise in the port at higher output levels as the vent mach is 0.44.
	www.angelfire.com /vt/audio/minimus.html (1131 words)

	Fibre-Channel Switches - US Logic
		The Denali switch is a three port switch that can either function in stand-alone mode or in a cascaded mode with up to 256 area switches "chained together".
		Reflex then automatically reconfigures the loop to ensure uninterrupted network integrity between all operating devices.
		Newly enables ports are also automatically detected and registered onto the operating loop without causing disruption to established data paths.
	www.uslogic.com /fc/code/fcden.html (517 words)

	Bass Reflex Loudspeakers (Site not responding. Last check: 2007-10-30)
		The bass-reflex enclosure makes use of a tuned port which projects some of the sound energy from the back of the loudspeaker, energy which is lost in a sealed enclosure.
		But care must be taken to avoid the back-to-front cancelation of low frequencies which characterizes unenclosed loudspeakers.
		This has the effect of projecting bass frequencies from the port in phase with the sound from the front of the cone, at least at the resonant frequency.
	hyperphysics.phy-astr.gsu.edu /hbase/audio/basref.html (155 words)

	aritcles of hifi stuff
		If the loudspeaker have a vented box type with a reflex port at the front, so the loudspeaker must be placing far form the back wall.
		This is to minimize the reflex form the back wall that keep on canceling the loudspeaker bass and treble respond.
		Now for a a vented box that have a reflex port at the back, the loudspeaker have to be placing more far from a previous type of enclosure.
	www.members.tripod.com /nanhifi/positioning.htm (802 words)

	RECORDING Music >> Forums >> Acoustics & Design >> TUBE OR NOT TUBE ( a philosophical speaker dillemma )
		When listening to the dynaudio, everybody in the room felt the lack of bass arround 40 hz near the center of the room due to the natural modes of the room (4.10 meters length) this was predictable.
		Now a bass reflex port between the two ressonances has a dip and since those monitors have different bass ports they will have that dip occuring at different frequencies.
		That's why a good designed ported speaker can handle more power than a closed one (as long as the speaker is protected under it's resonance frequency where the speaker feels almost nothing and wiill try to make large excursion).
	www.recording.org /ftopict-32402.html (1328 words)

	Page Title
		Both routes will yield results that are very similar and altering the operating conditions in one enclosure type will show very similar changes to the response in the other enclosure type.
		Any reflex port can be tapered just as long as its overall length is not changed and the internal volume remains the same.
		Bottom line is that the port should be circular in section and flared at both ends in a manner as smooth as possible.
	www.speakerplans.com /page94.html (327 words)

	Reflex Security VSA (Virtual Security Appliance) for Server Virtualization
		Reflex VSA allows enterprises deploying virtual computing technology to secure virtualized networks with firewall protection and intrusion prevention.
		The patent-pending technology fills the security void left by traditional network security solutions that reside outside of the virtual machine host and are not fully capable of detecting and protecting against breaches inside virtualized resources.
		The Reflex VSA will initially support the VMware ESX server (VMware is a division of EMC Corporation).
	www.reflexsecurity.com /news/reflex_vsa.php (623 words)

	Did the C38 use aluminum grille frames? - Lansing Heritage Forums
		Apparently JBL was using panels to mirror their 075 (or 175?) for stereo with a panel in the other corner having a circular cutout to serve as the reflex port.
		John Y. I found that "reflex Port" to be the most curious part of the picture.
		I remember the C36 and C38 as having a rectangular port near the bottom of the baffle board, and two cutouts for proper positioning of the tweeters.
	www.audioheritage.org /vbulletin/showthread.php?t=1729 (885 words)

	MONITORS versus HI-FI SPEAKERS
		Problem two is that the necessarily tiny reflex ports used in small speakers behave in a far-from-linear fashion at anything but low volume levels.
		Given that one end of the port terminates in a small volume of air inside a mostly enclosed box, while the other terminates in the outside world at atmospheric pressure, it's hardly surprising that it doesn't behave the same way for air moving in as it does for air moving out.
		The first thing to note is just how much harmonic distortion a reflex port generates, even at low levels, and even when extravagantly flared and dimpled like the BandW's (such design features are supposed to minimise the effects of the port).
	www.soundonsound.com /sos/Jul02/articles/monitors2.asp (3506 words)

	Enclosure Design and Construction for the Lowther DX Series of Drivers
		In a bass reflex cabinet, the air in the box is compressed to a uniform pressure to form an air spring.
		Placing the port on the back of the bass reflex enclosure may require more standoff from the rear wall and lead to room placement problems.
		The diameter of the hole for the port, in the front panel, was cut about 1/4 of an inch oversized.
	www.quarter-wave.com /Project04/Enclosure_Design.html (1570 words)

	Audio Asylum Thread Printer
		But what if the port expands, how do you work out the length it has to be and the beginning (throat) and end (mouth) areas for a given frequency.
		Also, a none expanding port will only be tuned to one frequency, will this still apply to an expanding port, or will it be tuned across a frequency range.
		Bottom line (if you 'buy-in' to this logic) is that the port should be circular in section and flared at both ends in a manner as smooth as possible.
	www.audioasylum.com /scripts/t.pl?f=hug&m=22120 (1297 words)

	Dynaudio Audience 122C Reviews (Site not responding. Last check: 2007-10-30)
		The port is on the back, making it best-suited for use out away from the wall on stands, although a wall bracket is available.
		As this speaker is more likely to be used in a cabinet near a TV set, the company decided to move the port from the back to the front, and again there is a foam plug you can stick in the port to dampen the woofer’s movement in the low bass.
		Again, the ports have been moved around to the front, and the bass can be further tuned using the provided foam plugs.
	www.dynaudiousa.com /products/audience/122cent/aud122crev.htm (5163 words)

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