The topic of trapezoid shaped cabinets came up on another discussion board a few years ago. Because this style of design has been so prevalent since the mid 1980s, most people under the age of 30 assumed that loudspeakers had to be that shape.
As Tony said this is not true. From a performance point of view the difference is negligible, and very very few are designed to be arrayed at the same angle as the side walls. However with a decent table saw it is not too difficult to cut the angles.
Reasons why I use a trapezoid design are:
1. I don't find them much more trouble to make.
2. The shape visually slims the cabinet.
3. I can fix the baffle size and use the taper to adjust the cabinet volume.
4. It sometimes enables a more efficient use of a sheet of ply.
If number 1 didn't apply then I wouldn't worry about 2 and 4, and I would ajust 3, the cabinet volume, by some other means.
For most loudspeaker based on the bass reflex style, plans are not really necessary. An internal volume and tuning frequency should allow anyone to produce something similar. More useful would be any cross over and eq settings. These will have far more impact on the performance of the cabinet than getting the taper angle of the cabinet walls correct.
YAS THATS TRUE
REQUIRED in New cabinet:- CALCULATING DRIVER PARAMETER & INTERNAL VOLUME LITERS(VB),(FB) also very IMP FREQUENCY TUNNIG.
The word “speaker” is the shortened form of the word “loudspeaker” and it refers to a device that converts electrical signals into sound waves that we can hear.
Why do drivers come in so many different sizes? Because it is nearly impossible to make one piston driver that can reproduce sound waves over the entire 20 Hz to 20 kHz frequency range of human hearing. To produce low frequencies a driver needs to have a large diaphragm and enough mass to resonate at a low frequency. To produce high frequencies a driver needs to have a small diaphragm with a low mass. Obviously, these requirements are in opposition so drivers are usually designed to produce only a portion of the sound. This gives rise to multi-way speaker systems like the two-way system shown above. It uses a tweeter for the high frequencies and a woofer for the low frequencies.
The job of the crossover network is to divide the audio signal. For this reason, crossover networks are sometimes called “dividing networks”. The frequency where the sound is divided is called the “crossover frequency”. Ideally, a crossover frequency is chosen which protects the tweeter, allowing it to produce only those frequencies that it can reproduce the best, and allows both the response and coverage pattern of the woofer to blend well with the tweeter. Note: The “coverage pattern” is the shape of the listening area where a driver will provide a relatively uniform direct sound pressure level.
I m a sound engg student i just learn how to create new idea & discuss with all. any suggestion plz reply me
Since reading this thread, I've been trying to remember the first time we did a trap cab. It's certainly true that a lot of, shall we say younger builders, think that this is the norm. In most cases when people put their cabs together, there is little thought for the technical side of it, and don't realize that the angles on the box sometimes have no bearing on the proper dispersion angles, that are decided by the components used. Most ASS horns that were built were much longer than they had to be. I discovered long ago that if the wave forms crossed over each other somewhere out there in front of the cab, there was no coupling effect. For me, this has always been a major consideration with dispersion angles. This means that, whether our box was square or trap., it didn't make any difference. There is a small case for an angled cab containing a mid speaker. The angles can help knock the stuffing out of direct waves coming back and forth on the speaker, although this would only apply to the waves that were shorter than the box itself. Bass is not affected by the shape of the box as the waves are far too big.
I guess the Spektra range of cabs were the first trap cabs for me, and this was done to follow a fashion.
If I were going into production with the necessary machinery and assembly jigs then I would undoubtedly make most of my cabs trap. shaped, if only because I think they look so much better than a plain old rectangular box.
With my own boxes I try to minimise the visual aspect by making them as narrow as possible given the driver size and then using wrap around grills. The picture I posted a while ago of my double 12" jobby shows this very well.
For a given box design just net volume and port sizes are all that's required. I think that anyone serious about making loudspeakers should then have learned the necessary skills to take it from there.
Its a bit like taking up golf and then playing St. Andrews without even going for any lessons or spending time on the driving range, not to be advised