conteaza unde vine pus bas reflex-ul??

[csl1131]

adica ar conta daca e deasupra la difuzor, sau sub difuzor, sau cat de departe/aproape e de dif basul reflex????

[caudiodesign]

Teoretic nu conteaza.Practic trebuie montat la cel putin un diametru fata de oricare perete al incintei.Daca il pui pe spate,ai grija ca incinta sa nu fie foarte aproape de perete.Uneori,e mai indicat sa-l pui pe spate,pentru ca rezonantele de port nu se mai aud.La fel,la montarea pe spate,ar fi bine ca daca te uiti prin el sa nu vezi difuzorul.

[Mircea Bartic]

nu prea conteaza in practica, cu mentiunea ca daca il pui in partea de jos a incintei, se va cupla cu planseul si vei avea un mic castig in zona subbasilor

[Vizitator Ado]

In cazul in care este pus in partea de jos a incintei, conteaza daca este plasat in fata sau in spate?

[ICEMAN]

conteaza... daca asculti in aer liber si nu ai un perete in spate... basul reflex de pe tub se duce la mama dracu :rolleyes:

[caudiodesign]

Iceman,tubul de bass reflex nu este un element reproducator in sine, el doar ajuta difuzorul.Vorbind in aer liber, tubul poate fi pus oriunde,atat timp cat nu-i afecteaza frecventa de rezonanta.Chiar Doru Petrescu zicea, am impresia,ca in mod ideal,tubul de bass reflex ar trebui scos pe fereastra.

[ICEMAN]

acum nu stiu ce sa zic dar pe acolo iese o gramada de presiune care iti misca plamanii... daca o dai pe geam... eu cred ca ramai fara... la fel si in aer liber unde se duce in spate in loc sa ii rupa plamanu lu ala care danseaza in fatza subului... poate ma insel eu, dar logik cam asa ar fi nu?

[radue]

Toate bass-reflex-urile pentru sonorizari le au in fata, pe langa peretii incintei.Un exemplu este incinta celor de la dB Technologies ( i-am uitat numele sistemului )activa, cu dif de 18" care are reflexurile in colturi, sub forma de triunghi.

[FIXVID]

caudiodesign

practic trebuie montat la cel putin un diametru fata de oricare perete al incintei.

in schema asta se monteaza centrul tubului la un diametru de perete http://www.stocare.as.ro/incinte/VBT115B2.pdf sau si tu asta vroiai sa zici ?

[FIXVID]

in caz ca am un tub si nu corespunde cu dimensiunile celei cerute de schema ce tre sa iau in considerare? volumu tubului sa fie acelasi ? de ex imi trebe tub cu fi=50mm si l=70mm si io am tub cu fi=80 si l=100 .. ce fac tai din lungime ? dar cat? carei formula cu care poti calcula dimensiunile unui tub pt o incinta considerand ca nam auzit de bas box?

[dividivus]

1.06 - Can I use two short ports to replace one long port of the same diameter?

No! The resonance frequency (Fb) is proportional to the cross-sectional area of the port, and inversely proportional to the length. If you increase the effective cross-sectional area by adding another port, the length will have to INCREASE as well, otherwise Fb will go up!

 

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2.03 - Where should I place the port(s)?

If your system calls for the use of ports, these can be placed on any side of the enclosure, once the intended location meets the following requirements:

The exit of the port should be at least one port diameter away from any external surface.

The entrance of the port should be at least one port diameter away from any internal surface, including the driver.

2.04 - Is the shape of the box important?

Box dimension ratios are not important, once the system is only going to be used to produce low bass frequencies. Just make sure that you leave enough space between the driver's magnet and the rear panel - usually up to 3" of clearance is requred, to allow unrestricted operation of the pole piece's vent (if the pole piece is vented, of course).

 

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http://www.carstereo.com/help/Articles.cfm?id=21

[radue]

Nu si nu. Cum a scris si dividivus daca vei folosi un tub cu diam mai mare si lungime mai mica frecventa de acordare va fi mai ridcata si vei obtine un rezultat destul de diferit.Cred ca ar trebui sa fie mai lung decat cel mic, dar nu stiu cam cu cat.Poti incerca si WinISD cu rezultate destul de bune. :yawinkle:

[csl1131]

cu bassbox, sau winisd, sau alte programe de genul asta, bagi la porul de bas reflex portul care il ai tu, si pe urma il schimbi cu viitorul care vrei sa il pui,si te uiti sa aiba aceeasi frecventa de acordaj, si gata...

[dividivus]

Iceman,tubul de bass reflex nu este un element reproducator in sine, el doar ajuta difuzorul.Vorbind in aer liber, tubul poate fi pus oriunde,atat timp cat nu-i afecteaza frecventa de rezonanta.Chiar Doru Petrescu zicea, am impresia,ca in mod ideal,tubul de bass reflex ar trebui scos pe fereastra.

VENTED ENCLOSURES: Also the same as Bass Reflex, Ported, or Passive Radiator. Here, an aperture in the box provides a means for the rear output of the cone to contribute to the total output of the system. However, it only contributes over a very narrow range of frequencies. In fact, in a properly designed system, the front output of the cone is reduced at the same time the output of port increases, so the port does not re-enforce the output of the woofer, it REPLACES the output of the woofer at these frequencies. This, if done properly, can significantly reduce distortion and increase power handling at very low frequencies, a region that can be difficult for drivers. Vented systems can be up to 3 dB more efficient than a sealed box system that has the same bass cutoff frequency and size. Sunt de acord cu cele scrise mai sus, cu exceptia ?or Passive Radiator? care nu este o incinta ventilata (desi foloseste acelasi principiu, dar portul este schimbat cu o membrana).Am citat acest pasaj de pe internet (http://www.thespeakerstore.com/glossary/enclosures.htm) pentru a raspunde ca totusi este un element de reproductie a sunetului.PS pt Fixvid: Mai sus am pus la sfarsitul postului un link, unde arata formula cu care se calculeaza tubul de port.

[dividivus]

M-am tot gandit si eu la modul de functionare a portului, dar nu mi-am gasit o explicatie buna, asa ca am cautat pe internet. Iata ce am gasit.

 

http://www.ddaudio.com/dd/caraudio/encl ... rtInfo.asp

 

Citez:

 

HOW DOES A PORT WORK

Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does.

?..

The use of a larger than normal port will allow the user to find the cars peak frequency for greatest SPL. Reducing the port opening will lower the box tuning frequency and provide loading to the woofer over a wider bandwidth. This will improve the transient response and impact of the system. The higher tuning frequency redirects the woofers radiating energy into a narrow band which when tuned to coincide with the vehicles peaks can yield dramatic SPL numbers. The focus of attention here should be to tune the system to each application. Although the general box recommendation will yield very satisfying results, competing at the highest levels of SPL or SQ contests, or simply yielding the best possible results are directly related to methodical tuning.