![]() Now with a ported box of typical construction a minimum motion notch would exist centered at the tuning frequency. You can have loud and low distortion low bass or loud and low distortion upper bass, but hard to get both. While it may need less power for a given output and have lower distortion in that range, it would probably fall short by a factor of 2-4 of those HT subwoofers at 35hz and below (3-6db). However it may be limited below 35hz by exceeding its linear excursion. #Abc box audio driver#If we stick this driver in a modest/large ported box and tune it to 20hz it may actually come very close to the maximum output of a typical 18” HT driver. It’s sensitivity is 99db (but not at the low frequencies for which it will be used). Now imagine that it’s got a RE of 2ohms, a BL or 32, and xmech of 60mm. #Abc box audio pro#This would be a very high performance pro subwoofer but those specs might seem modest at best compared to an HT driver. Take an 18” driver with 2000 watts rms power handling and 15mm xmax. #Abc box audio drivers#Not all pro drivers can replace typical HT subs so this isn’t a blanket statement, but many can. Knowing all that, I like pro audio drivers with modest xmax compared to pro drivers but often larger coils, lower inductance, and higher power handling. With subwoofers the mechanical limits of the driver can contribute to these distortions so controlling high excursion with ports can be a good thing, as long as you haven’t traded other problems. ![]() Because we are dealing with non-linear distortion it’s inportant to remember that smaller amounts of these distortions are audible when at higher volumes. In fact some forms of distortion at certain volumes are very audible at very low levels (fractions of a percent). There is a complete misnomer that we are insensitive to distortion at low frequencies, which is not true. For example, to produce 20hz to 100hz up to 120db at 80hz, with little distortion. So when do you use this and why am I bringing it up?īecause I define a subwoofer by its ability to meet certain performance characteristics with a minimum of distortion. I see no value in using this with typical home theater subwoofer drivers of say 20mm xmax one way (or more) and 1-2000 watts power handling (or often less). As such, it provides no advantage for such drivers. Here is why that is important, if a driver has high linear xmax and modest power handling, then such drivers would not exceed their xmax before exceeding their thermal limits around and above the port tuning frequency. In fact, if the ports are linear, it would thus also provide a reduction in distortion.ĭistortion reduction and excursion control, and the distortion reduction is a direct result of the excursion control. I believe Don Keele was the first to discuss this kind of enclosure, and it’s primary purpose is excursion control. What does this complex setup do, it creates two minimum motion notches roughly one octave apart of similar Q (which can be varied by the internal damping). That means we have two chambers, a direct radiating driver, two external ports (one in each chamber) and one internal port (series loading the first chamber to the second chamber/port. Finally that second chamber has a third port of again, the same given length. Between the chambers is another port of the same given length. On the larger chamber is a port of a given length. It’s a box with a response similar to a 4th order reflex enclosure but dividing the internal volume into two chambers. #Abc box audio software#It’s actually the name given by the software author for a kind of series tuned dual reflex enclosure known as an Aperiodic Bichamber enclosure. You probably thought it was a joke, some kind of placeholder for something. None the less, I’m going to describe and foreshadow a planned future project and explain a little of why.įor those familiar with Hornresp, you may have noted an enclosure option called an ABC box. ![]() I very much hope this turns into a real project to share and not just an exercise in theory and modeling. ![]()
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