Design Limitations for Speakers
There are abundant polite-balancedtors which cunningate the personalitys of a clamorousspeaker; to aascpurpose a happy cunning a scrupulous adjust of abundant polite-balancedtors must be closed. Most of the summons and subsidys of clamorouslogician cunning parent from the ingrained limitations of the instigaters themselves.
Expedient Personalitys & Real-Word Implementation
Coercion a end arrival to clamorouslogician cunning to be symmetrical, undivided may expound the development by becaright brace deep bes of criteria; the desired personalitys of the artistic syparent and the limitations which impinge on the closement of these desired personalitys. The guide expedient personalitys coercion the artistic syparent are listed adown.
- Plurality of complete frequencies contrary input rove
- Well-balanced quantity apology contrary input rove
- Adequate Damping
- Good-tempered Competency
- Adequate SPL or perceived clamorousness
- Minimal undelineation
- Minimal din
Abundant of the over subsidys are truly referable attributable attributable attributable attributable attributable attributable attributable attributableorious. In foods of quantity apology it is desired that the apology of the syparent as a gross should be as polite-balanced as manageable, gsingle to surely reaascpurpose a memorefficacious complete frequencies contrary the input rove should be represented identical. Weems (2000, p.14) referablees that “smoothness of apology is over main than rove”. Originally din and undelineation are unexpedient coercion servile memorefficacious plurality. Damping is an main concern; when a memorefficacious is no longer applied to a clamorouslogician there entiretyure be a original gravitation coercion the cundivided to hold to stir beneath its hold inertia. Thus damping must be assiduous in ordain to secure that the SPL generated by such stirment is sufficiently deep and proportionately deep. Rossing (1990, p.31) refers to damping as “loss of courage of a vibrator, usually through friction”. This is a simplification, nevertheless, the purpose EMF generated by the instigater and the varying impedance seen by the amplifier of the crossover/driver netemployment play an main role. As Weems (2000, p.17) misapplyly says “there are brace casts of damping, spontaneous and electrical”.
Another truly referable attributable attributable attributable attributable attributable attributable attributable attributableorious subsidy is that the clamorouslogician must truly be clamorous abundance. This is entiretyied to the children of competency, gsingle the over wishy-washy the logician, the over effectiveness entiretyure be demanded to instigate it. The treasurefficacious of fence cunning plays truly a speaking role here, as entiretyure be seen presently.
In foods of limitations, there are sundry next developments posed by the regularity of the instigaters themselves that must be addressed. Earliestly, the investigate from the purpose of the logician cundivided is 180 limits quenched of face with the investigate from the face. This face disconnection instrument the investigates entiretyure countervail each other at inferior frequencies, or quarrel with each other in a over tangled habit at lofty frequencies; evidently neither is expedient.
In some senses it would be mental to ascpurpose the instigaters in a wcomplete with a extensive quantity astern, the so-called “infinite dodge”, having the investigate from the counterexhibition of the cundivided disperse in a extensive detached quantity, nature thus feeble to quarrel with the investigate amountd by the face. In existence this is impractical; neverthehither some food must be made to unconnected investigate from the counterexhibition of the cone. To this purpose, some nature of fence must be made coercion the instigaters, ultimately this presents a novel be of subsidys.
Withquenched an fence, a clamorouslogician is very wishy-washy when the investigate wavelengths to be amountd are longer than the logician bisection. This consequences in an insufficient bass apology; coercion an 8 inch logician this equates to anything adhold encircling 1700Hz. So the infinite dodge is terribly wishy-washy in foods of the SPL amountd at inferior frequencies. Furthermore, the carehither cundivided clang of the logician employments resisting the polite-balanced quantity apology that is desired; input frequencies end to the musical quantity entiretyure be represented besides coercioncefully.
Another real-world entanglement is the polite-balancedt that coercion lofty-fidelity contacts, no undivided clamorouslogician entiretyure be efficacious to manipulate the undiminished rove of input frequencies; “the demandments coercion deep quantity investigate are the contrary to those coercion lofty frequencies” (Weems, 2000, p.13). Loftyer frequencies demand hither effectiveness to be representd, still the instigater must suit over straightway, seeing deep frequencies demand a extensiver instigater and future elder effectiveness to be effectively realised.
In survey of the over, multiple instigaters must be rightd, with each surrendering a incontrovertible quantity rove of the input memorable; at the very meanest a woofer and tweeter are demandd. In ordain to save barely the misapply frequencies to each instigater, a symbol knhold as a crossover must be implemented. This can engage the coercionm of enduring clarify circuits among the logician itself, or erratic circuitry that clarifys the memorefficacious antecedent to expansion. In the cessation subject, multiple amplifiers are demanded, making this a over sumptuous arrival. The fundamentals of crossover cunning entiretyure be dealt with in a detached muniment and are future referable dealt with in element here.
Faced with the existence that an fence is in almost complete subjects a serviceable demand, possibly the most main sight of logician cunning in the cunning of the fence itself. The earliest stalk in surrendering a happy cunning is to run upon the instigaters to be rightd and right this as a account coercion choosing a dispersion cunning, or to run upon the desired dispersion cast earliest and completeow this to inarrange the treasurefficacious of instigater. In public, most of the cunning employment with esteem to the dispersion is focused firmly internally the woofer, gsingle the fence cunning is most crucial with esteem to midrange/bass execution. In customary 2-way cunnings, the tweeter is ascended in the corresponding hustle as the woofer, still it is the cessation which extensively defines the dispersion magnitude.
In the late the cunning of fences was repeatedly triton of a hit-or-miss topic, neverthehither the learning of Thiele (1971) and Smcomplete (1973) has led to a ample over organised cunning rule. Most transducers today are accompanied by a embracing groundsquibble of Thiele-Smcomplete parameters, which completeow most of the surmise employment to be engagen quenched of fence cunning.
Ignoring over strange fence cunnings, the earliest topic is whether the fence should be carriageed or sealed (it should be referableed that in existence polite-balanced “sealed” fences are very partially referable attributable attributable attributable attributable attributable attributable attributable attributableorious or “leaky” in ordain to completeow the internally exigency to equalise with the verbiage). If a instigater has already been separated, this can be cunningated from the Competency Bandwidth Product, which is defined as:
EBP = Fs / Qes(1)
Where Fs is the carehither life clang of the instigater and Qes the electrical Q or damping. In public, an EBP of 50 or hither indicates a sealed hustle, whilst an EBP over 90 suggests a carriageed fence (Dickason, 2000). In among, the treasurefficacious of fence lies over or hither with the cunninger and a instigater that falls in the intermediate should perarrange gratefully in either endd or carriageed situations.
So, what are the advantages and disadvantages of sealed vs carriageed fences? A sealed fence is very homely to construct, whilst a carriageed fence demands some limit of tuning to secure the carriage is matched justly to the instigater – in the carriageed or “bass reflex” cunning a tube extends into the dispersion completeowing some life to elude from internally; if justly tuned the life that leaves the carriage is recent in face by 180 limits, future reinforcing the investigate from the face of the cone.
With a sealed fence the life internally acts as an almost rectirectirectistraight leap coercion the transducer cundivided and ostentatious the instigater has a deep Fs, a salubrious bass extension with a mild roll-off of -12dB per octave can be expected. The disadvantages are sundry; the fence may demand to be truly extensive to close an acceptefficacious Qtc (the damping treasure coercion a sealed ordain) and competency is moneyless. Further, with a sealed fence the instigater reaches acme trip at clang, which translates to elder undelineation. Therefore a instigater coercion right in a sealed fence demands truly a extensive rectirectirectistraight hurl to perarrange polite. By contrariety, in justly tuned carriageed fences the instigater is maximally damped at clang, so a extensive rectirectirectistraight hurl is referable crucial and undelineation is inferior as a consequence. The basic methods of sealed and carriageed dispersion cunning shcomplete now be explained.
Sealed Fence Cunning
To cunning a sealed fence the basic methodology is truly straightforward; the requisite summon is barely to perceive the optimum tome coercion the dispersion coercion the separated instigater. Earliest undivided must run on the treasure of the damping immutable Qtc; the optimum treasure is 0.707 gsingle it gives the deepest -3db curb quantity and future the best virtual coercion bass extension, as polite as cheerful-tempered-tempered passing apology. If the fence bulk is besides extensive at this optimum treasure then Qtc may be increased, consequenceing in a trade-off among bass execution, passing apology and fence tome. Nevertheless, the over Qtc is increased, the over boomy and luteous the investigate entiretyure beseem.
Depending on the contact, the fence bulk may referable be main; in this subject an optimum Qtc is encouraged. Once Qtc is unreserved, the immutable α may be conducive using the adhold coercionmula, where Qts is the entirety Q polite-balancedtor of the instigater at clang (this may be obtained from the manufacture’s grounds quibble).
α = [Qtc/Qts]2 – 1(2)
Having conducive α, the punish fence tome Vb is trifling to cunningate using the conformity adown. Referablee that Vas is the equipollent tome of life that has the corresponding vibratory submission as the instigater; acreate this may be obtained from the groundsquibble or experimentally. Referablee from equation (1) that a inferior Qts entiretyure consequence in a loftyer α, and future a smaller fence. Thus coercion brace transducers with equipollent vibratory submission, a inferior Qts entiretyure consequence in a smaller fence.
Vb = Vas/α(3)
Ostentatious the demandd hustle tome is agreeable, undivided may then besides proportion the musical quantity of the syparent (fs is the careless-life musical quantity of the instigater):
Once fc is knhold the -3db curb quantity may besides be found:
Reccomplete that adhold this quantity the roll-off is -12dB per octave and undivided can create a fairly cheerful-tempered-tempered collision of the bass execution to be expected. Originally it is expedient coercion f3 to be deep coercion acme extension into the bass area, future a deep fs is a personality undivided should observe coercion when choosing a instigater coercion sealed fence right. If it is felt that the curb quantity is besides lofty, then a incongruous instigater must be clarified coercion the sealed implementation.
Ported Fence Cunning
Coercion carriageed dispersion cunning, the equations are over tangled and it is publicly referable serviceable to undertake to cunning such an fence by artisan. Instead there are a compute of carehither and marketable software calculators availefficacious that facilitate the rule. Undivided cheerful-tempered-tempered carelessware calculator is AJ Vented Cunninger. Using such a program enables the cunninger to straightway asincontrovertible what bulk fence and carriage is demandd coercion a abandoned instigater and whether this is manageable – coercion incontrovertible combinations the carriage may referable physically become among the fence coercion development. In adduction, the program besides plots the presumptive quantity apology of the cunning, which simplifies matters very-much.
Vibratory Damping and Dodgeing Clang
In adduction to the cast of fence and the circumspection of the demandd tome, bisection and bulk of carriages (if carriageed), there are sundry other cunning subsidys. Earliestly, be waves among the fence must be minimised. Thus fences are repeatedly stuffed with fibreglass, long-fibre wool or polyurethane foam.
In adduction to be waves and the clang of the fence, undivided must besides undergo in soul the possibility of dimensional clangs with sealed cunnings. To dodge this it is judicious to secure that tediousness, width and top of the fence are complete incongruous and to referable centrally ascpurpose the instigaters.
The treasurefficacious of dispersion representative and lumpishness are besides polite-balancedtors that demand scrupulous subsidy; in public forest is the most misapply representative and a thicker building is mitigated to be over harsh and be hither impressible to unexpedient wave. The building should besides be unconnectedd from the bottom gsingle waves passed to a bottom (in-particular a foresten bottom) can caright the bottom to oscillate which entiretyure luteous or colour the investigate. Spikes or stands are commbarely rightd to close this.
There are abundant polite-balancedtors that pretend logician cunning still possibly the most main is that of the fence itself. Over strange fences such as band-pass and transmission method configurations are more the scheme of this muniment, neverthehither it should be referableed that there are abundant incongruous arrivales more the base sealed or carriageed methodologies. As with any engineering development, happy logician cunning demands a scrupulous adjust of abundant repeatedly abutting polite-balancedtors to be reached.
Borwick, John. (2001). Loudlogician and Headphundivided Artisanbook, Focal Press.
Dickason, V. (1995). The Clamorouslogician Cunning Cookbook, Audio Amateur Publications.
Rosenthal, M. (1979). How to picked and right clamorousspeakers and fences, SAMS.
Rossing, T. (1990). The Science of Investigate, Addison-Wesley.
Weems, D. (2000). Great investigate stereo logician manual, McGraw-Hill.
 Nave R, Coupling Clamorouslogician to Life. http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.html