tub bass vs incinta bass

[DorinD]

Nexus, goarnele alea sint pe 2"? Ce dimensiuni au ca poate ma intereseaza pe mine? Si din ce material, par sa fie din aluminiu?

[adi_0106]

da asa este sunt carcase srie pe ele electronica romanesti. prob ca io nu vreau sa fac boxe ci subwoofere. pun un dif mare de 30 cm intr-una. dar am dubii la modelul incintei, inchisa sau deschisa????

iar io am tweeterele puse sub forma de sateliti deci nu sunt in carcasa.pt ca vreau sa le pun si pe masina. in concluzie 2 subwoofere + 2 sateliti.

Dupa cum am mai zis si mai sus....cutiile originale sunt INCHISE, si daca cei de la Electronica le-au facut asa, nu cred ca are rost sa le faci tu bass-reflex sau alte gauri pe acolo :shock:

[Mircea Bartic]

Nexus, goarnele alea sint pe 2"? Ce dimensiuni au ca poate ma intereseaza pe mine? Si din ce material, par sa fie din aluminiu?

goarnele sunt de 1" si sunt din ABS (cred)dimensiunile exterioare 240x500mmx250mm adancime (aproximativ)

[Bujor Stefan]

Vezi ca la Senia (in magazinul Muzica) sunt niste difuzoare Eminence de 12" care merg si in incinta inchisa, iar volumul recomandat se inadreaza in cel pe care-l ofera Melomanele http://www.and-roll.ro/listprod.php?idr=377 (cauta Gamma 12).

Puterea e de 300W si te asigur ca e adevarata.

Calitatea este de asemenea la cele mai inalte cote si cum nu poti sa le ai pe toate in viata, pretul e de aproape 3700000.

Daca iti faci ambele boxe asa, evacuezi blocul.

 

Nu stiu de ce vi s-au parut filtrele "bombe". Pentru ca au mai multe piese pe ele decat alea din magazin de 300 mii?

Le-am masurat impreuna cu un prieten si au aceleasi valori pe componente ca cele masurate, au frecventele de taiere identice, in ele s-a depus foarte multa munca.

[Vizitator Baken]

daca e sa am de ales intre un tub si o incinta cu bass reflex avand acelasi dif care ar suna mai bine pentru camera????? dar pentru masina?? avand in vedere ca cele 2 incinte sa fie calc bine in functie de par. T/s ai dif

Fratilor permiteti sa imi dau si eu cu pararea. Am citit pe help de la BassBox ceva de unde stationare cica care s-ar forma la colturile interne ale incintei acustice, de aceea se spunea acolo ca formele sferice sunt cele mai indicate si cubul trebuie evitat cu orice pret. Deci dupa mine tubul e calea....................Parerea Mea>:)Pentru cei care nu au ramas coringenti la Engleza aici aveti textul.....:(he purpose of the loudspeaker enclosure or box is to trap unwanted sound emanating from the back of the driver and to add acoustic resistance so the driver can work more efficiently at low frequencies. For high-fidelity sound reproduction, the loudspeaker should not alter (“color”) the sound but should faithfully reproduce the original signal. With these concepts in mind, this topic will introduce some basic tips to help with box construction.Avoiding Standing WavesMost boxes are roughly shoebox or rectangular in shape. Technically speaking, this is a square prism. Unfortunately, these box shapes have a built-in flaw: box shapes with two or more sets of parallel sides will be prone to a phenomenon called “standing” waves. Standing waves are sound waves that reflect back and forth between two parallel sides inside the box. The frequency of a standing wave will have a wavelength equal to twice the distance between the two sides. For example, if two parallel walls are 24 inches (61 cm) apart, the standing wave that will develop between them will have a wavelength of 48 inches (122 cm). This corresponds to approximately 283 Hz. You can use the wavelength calculator in BassBox Pro to convert from the wavelength to the frequency.A cube is generally a bad box shape since all of its parallel sides are equidistant. This means that all the standings waves inside the box will have the same frequency and will sum together, making them louder. This reduces the fidelity of the loudspeaker. But all is not lost if you really like the cube shape because there are ways to overcome standing wave problems. Here are a few suggestions:• Add damping to the interior of the box. Bear in mind, that most of the commonly-used absorption materials have poor absorption coefficients at low frequencies. If your box is large, you should probably calculate the frequencies of the standing waves and check the absorption coefficients at those frequencies for the damping material you plan to use. Also, see the Damping tab of the Box Properties window.• Add one or more angled walls to the interior of the box. In this way, the outside of the box still has parallel walls, but the inside does not. These walls must be rigid and either have openings or be short in one dimension so that air can flow around them without any restrictions. Without parallel walls, standing waves will not develop.• The frequencies of the standing waves can be spread apart so they do not sum together. This is accomplished with the “optimum square prism” box shape in BassBox Pro. It uses a 1.62 : 1 : 0.62 ratio between its three dimensions (height, width, depth) to spread apart the frequencies of the standing waves.• Pick a box shape without parallel sides such as a four-sided pyramid.DiffractionThe diffraction caused by some box shapes can have a very significant effect on fidelity. For example, a cube can introduce a ±5 dB variation to the amplitude response of a loudspeaker (depending upon the area of the mounting surface). A shape that produces very smooth amplitude response is a sphere. Unfortunately a sphere is not a very practical shape to use for many designs. Here are a few suggestions to help minimize diffraction:• Locate the drivers so they are not the same distance from any two or more edges.• Mount all drivers flush in the front panel.• Round the edges and corners of the box. They must be rounded rather severely to be effective.MaterialsIt has been suggested that the best loudspeaker box would be constructed with 12 inch thick lead. Others have constructed boxes with cement. Why such dense materials? Because a box with flimsy construction will vibrate or flex while the driver pumps air. And this will add distortion (coloration) and absorb power that would otherwise produce sound. Wood is not a very good material and yet it is the most common material from which boxes are made. Fortunately, good design and attention to detail can overcome the flexibility of wood and make a wooden box work very well.What kind of wood is best? The most dense and least flexible. However, such hard woods are often very expensive. Plywood is not a good choice because it often has voids hidden in its laminations. Particle board (also know as “pressed board” or “chip board”) is a good inexpensive choice that is most often used.In addition to reducing standing waves, adding damping material to the interior of the box can also reduce the unwanted resonances of wooden walls.ConstructionSeveral construction tips follow. Of these, the two most important ones are airtight construction and rigid construction.• A well constructed airtight box will have each joint glued and caulked. Wires that are run through a side will be carefully caulked where they pass through a wall. Obviously, a vented or bandpass box will not be airtight because it has a vent but all other aspects of the enclosure should be airtight just as with a closed box design. Make sure the driver is mounted to the box with an airtight seal. Use caulk if the driver does not have a suitable seal for this purpose.• The walls of the box should not flex at all when the piston of the driver moves. Braces or cleats are usually fastened to the walls to make them more rigid and to divide the walls into smaller areas, each with their own resonant frequency. Braces can be added in any number of ways. One method is shown below:When you rap on the sides of a well constructed box with your knuckles you should not hear any “hollowness.”• Use an appropriate amount of damping material for the design. A small closed box often works well when stuffed 50% full (or more) with generous amounts of damping material because it makes the box “appear” to be larger. This helps to extend the low-frequency response a little. A medium or large closed box often has adequate volume without the need for lots of damping material. In this case, the damping material is used primarily to suppress unwanted standing waves and box resonances. Simply cover each surface inside the box with damping material. Vented, bandpass and passive radiator boxes are more sensitive to changes in the apparent box volume and usually have damping material added only to one of each pair of parallel sides. The goal being to absorb box resonances without affecting the apparent volume of the box. However, in actual practice, adding more damping material seldom causes vented or passive radiator designs any harm. The most important part of the box to damp are those surfaces which are directly behind or near to the driver.• With multi-way loudspeakers, mount the drivers in a vertical line array for the best horizontal dispersion. And mount the drivers off-center so that diffraction will be minimized. An example three-way design is shown below:Lobing can usually be minimized by locating drivers with a shared crossover frequency as close together as possible. Try to keep the distance between their centers less than the wavelength of the crossover frequency. The tweeter should usually be located on top, closest to ear level since most direction cues come from the mid and higher frequencies. Driver placement can be greatly affected by the phase response of the crossover network. However, this leads into a subject that is beyond the scope of this manual.• If a vented or bandpass box design is used, position the vent so that nothing obstructs the air flow in or out of the vent. A “rule of thumb” is to keep the end of the vent which is inside the box at least one diameter away from any internal walls.Vent Placement Tips for Bandpass BoxesSometimes a chamber in a bandpass box is too small to accommodate the required vent length. Here are two ways to deal with this problem:• Pass the vent through the adjoining chamber as shown in the illustration below. Be careful that no air leaks in or out of the chamber through which the vent passes.In some cases the vent may be too long or short to do this and you can try using an elbow to direct the vent to a different side of the box as shown below. Note: If an elbow is used, be prepared to make adjustments to the duct length in order to achieve the desired resonance.• Another way to handle a vent that won’t fit inside a chamber is to allow the vent to project beyond the wall of the box as shown below. This is often a convenient way to direct the sound from an enclosure in the trunk of an automobile up to the rear deck.Note: Some of these examples may require you to manually adjust the vent length in order to achieve the desired resonance. Remember that BassBox Pro assumes that each end of the vent will be located away from any obstructions that would affect the air flow.Caution: Very long vent lengths may produce a “pipe” resonance. Try to avoid excessive vent lengths. One way to reduce the required vent length is to increase the internal volume of the chamber. Remember that the resonant frequency of the chamber is a function of both its volume and the vent dimensions. If the resonant frequency is held constant, the smaller the chamber volume, the longer the vent must be and visa versa.There are many other important considerations when designing a loudspeaker system such as the signal alignment between drivers, avoiding harmful reflections, crossover network design, high-frequency and mid-frequency driver selection, etc. Unfortunately these subjects are beyond the scope of this topic.Copyright 1992-98 by Harris Technologies, Inc.

[Sharky]

in legatura cu undele stationare imi explici cum incap ele intr-un tub/cutie daca acesta nu urca peste 150Hz?

[Vizitator Baken]

in legatura cu undele stationare imi explici cum incap ele intr-un tub/cutie daca acesta nu urca peste 150Hz?

Poate nu am inteles eu corect :? ce spunea pe acolo, dar din cate am dedus aceste unde stationare se adauga la frecventa sau mai bine zis oscileaza cu vreo +- 5db in jurul frecventei :shock: , deci nu depinde de perioada frecventei, acest fenomen apare la orice frecventa, rezultatul fiind o caracteristica neliniara. Asta am inteles eu din toata afacerea asta, dar poate ca la o frecventa de 150 Hz acea variatie de 5 dB nu e sesizabila, cu toate ca un subwooferul in functie bineinteles de dif, pe la vreo 50 hz, dB cobora vertiginos. Daca la acesta coborare mai adaugi si o variatie de 5 dB vei auzi ceva de genul unor pocnituri. De aceea multi care au facut tuburi de bass au spus ca sunetul este unul uniform chiar daca diful nu era asa de grozav. Daca acest tub este construit din carton atunci si micile variatii de presiuni sau neliniaritati de frecventa vor fi amortizate de elasticitatea materialul (scopul materialul fonoabsorbant).Dar cum nu sunt de meserie :oops: aceste lucruri sun doar speculati sau mai bine zis informatii culese de pe ici si colo + o logica individuala :idea: .Peace Out...... :wink:

[Sharky]

Speculatii clar. :lol: Unde stationare apar intre 2 pereti cand lungimea dintre ei e egala cu lungimea de unda.Avand in vedere ca subu sta sub 150Hz, lungimea de unda e sub 2 m poti sa stai tu liniustit ca nu o sa ai probleme cu undele stationare(sau o sa ai daca iti faci boxe cu una din dimensiuni de 2m :shock: )