Agree completely if their SPL matches. Making a TL is more cumbersome.With my very little experience .... currently i feel the best thing (atleast in terms of ease) is to do the following:
Put the bass driver in a box ... and leave the mid+tweeter or FR on OB
(ofcourse...you did a lot of work in this route)
Stuffing in Speaker - Need guidance
- Thread starter sudhirbhosale
- Start date
Matches my observations as well.
Matching SPL is easy if you use an active crossover and separate amplifiers for the drivers
That's one of the main reason for me to go active way but for a different reason, I use this benefit as tone control as many recordings have too much bass injected while mixing.
I have seen a general resistance towards active way though. But have not seen anyone (yet) coming back from active way once tried.
I use both passive and active depending on situation, but will always prefer active when things are under my control.
sudhirbhosale
Active Member
This is an important question and I am not the right person to even try answering that, still will do so for the sake of continuing this discussion and putting whatever little common sense telling me the "could be"answer.
The speaker in Sudheer's post seems to have closed back drivers (both) which does not excite cabinet interior space.
Closed/vented/ported/TL needs stuffing to absorb energy that the back motion of drivers inject into the cabinet. So that, those energies do not hamper front motion of the driver to produce sound we listen at room. TL speakers use the air column of the line hence it need not be stuffed completely, so that the air column does not get disturbed in forming.
Stuffing does reduce sound energy, but do not cancel it, hence sound will be generated inside cabinet and through the port. Stuffing can reduce this energy hence will reduce Sound Pressure Level inside the cabinet (at exit too). Low frequencies (LF), having more inertia of greater air mass is not reduced as much as high frequency ones. that's why we can hear LFs through the exit port. And these internal energy of LFs are at the same time impact LF sound quality of the front wave. So, proper stuffing can make a good compromise of reducing internal war of waves and increasing supporting outer energy through ports/lines. Drivers on the other hand are on the same principal designed differently to suit closed cabinet speakers.
Tabla use the space inside to create the resonance, hence stuffing that space will reduce reverb/augmentation. Same goes for other percussion instrument and string instruments like Guitar (open cabinet), Sarod (closed).
I will be immensely happy if this common sense answer is rejected or corrected with more technical answer to the actual question.
keith_correa
Well-Known Member
This explains it well!
there is supposed to be a graph in that link .... somehow it is not showing up ....
i have a doubt ... if we use closed back drivers, and if they do not excite cabinet internal space.... what is the purpose of the cabinet in this case ...
In a closed box if the wavelength is longer than the longest dimension then no resonances occur. The air just appears to the driver as a mass with spring, it just stiffens the movement. This is the compliance controlled region. T/S parameters help to model this frequency region.
When the wavelengths become smaller (as frequency goes up) internal resonances develop, the first one to occur is the one corresponding to the longest dimension. As frequency goes up other resonances develop corresponding to smaller dimensions. Not all resonances are heard outside depending on the driver and many other factors.
In order to deal with the resonances, one approach is to dampen them, take for example Linkwitz Pluto and LXMini, both use a long pipe that has strong resonance due to the large dimension. It is suppressed by stuffing.
Other approach is to model the resonance and use it to advantage, this is done in transmission line designs, the stuffing is just light enough to dampen other resonances higher up, the primary ones are not damped by design.
Many roads to Rome.
When the wavelengths become smaller (as frequency goes up) internal resonances develop, the first one to occur is the one corresponding to the longest dimension. As frequency goes up other resonances develop corresponding to smaller dimensions. Not all resonances are heard outside depending on the driver and many other factors.
In order to deal with the resonances, one approach is to dampen them, take for example Linkwitz Pluto and LXMini, both use a long pipe that has strong resonance due to the large dimension. It is suppressed by stuffing.
Other approach is to model the resonance and use it to advantage, this is done in transmission line designs, the stuffing is just light enough to dampen other resonances higher up, the primary ones are not damped by design.
Many roads to Rome.
Thanks a lot for the inputs....
By the way, this is just a thought, (may be impractical)
Just behind the driver, or on the rear wall, if we place any irregular shaped solid objects, do they help in scattering the sound waves in all directions ??? (Instead of hitting the rear and front walls repeatedly) Atleast the standing waves will get scattered ???
Or, if we add thin wooden pieces as braces connecting the left and right walls, at a 45degree angle, will they divert the sound waves reflect down at an angle, instead of hitting the rear wall directly....
(Not sure if I explained my idea properly)
keith_correa
Well-Known Member
keith_correa
Well-Known Member
Very effective but will need stuffing [light?] too because the wedges will just raise the frequency of the standing waves.
Little laborious....but this can be done by glueing many scrap wooden pieces
But the question is, can we do it as we like? Or it should be very calculative and optimum, and backed by some theory. ....
keith_correa
Well-Known Member
I would take the "ghetto" approach because I'm like that!Little laborious....but this can be done by glueing many scrap wooden pieces
But the question is, can we do it as we like? Or it should be very calculative and optimum, and backed by some theory. ....
I would look for material that will take up minimal volume. I would glue up a stack of corrugated sheets at least an inch thick. Then with a knife I would carve out the wedges at least 4 inches long. No calculations used here - just eyeballing the B&W DM302 wedges
I would then stick those to any one inner wall.
But one can go crazy with stuff like this - knock yourself out!
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