The development goal was an small audiophile subwoofer suitable for living rooms and home theaters
But how do these passive radiators actually work?
The advantages of the Drone Cones lie in their wonderful ability to keep sound colorations as low as possible, because they occur at the reflex tube on the one hand by flow noise and on the other hand by the unwanted forwarding of backward from the chassis radiated mid-frequency components. In addition, the size-sound relation is much more favorable:
With the Moyo, the goal was to make it as compact as possible so that it would fit seamlessly into the new series, both visually and acoustically. Its future colleagues follow this trend.
With normal vented cabinets, however, there's a catch: the required tunnel length of one or more bass reflex tubes or channels would far exceed the cabinet depth. That's why Drone Cones, because a passive cone, unlike a bass reflex port, does not require additional cabinet volume, which is especially noticeable with deep tunings in small cabinets.
With a passive diaphragm, it depends on the correct calculation of the diaphragm area and the exact dimensioning of the diaphragm weight. The handling of passive diaphragms also speaks for itself when calculating the loss factors.
The lower cutoff frequency is minimally higher than with bass reflex tuning, but more on that later. Misleading is the idea that passive diaphragms perform their service only at low frequencies and mechanically separate from the chassis as soon as the pitch gets higher, so that the bass reproduction would be improved. Wrong: passive diaphragms work in phase with the drivers at certain low frequencies, splitting the acoustic load and thus reducing the diaphragm excursion of the woofer itself. Otherwise, passive diaphragms work like reflex ports and thus also have the same advantages, such as an increase in power handling and a reduction in distortion. It also reduces the subsonic susceptibility of the driver.
When choosing the right driver combination, it should be noted that poor impulse response is more likely if the woofer and passive radiator have the same diaphragm area and centering spider, i.e. are identical in construction except for the magnet. However, if the suspension of the passive cone is more compliant than that of the woofer, the impulse response will behave similarly to its vented (bass reflex) counterparts.
In short, passive diaphragms have their own sound quality because they do not suffer from tunnel resonances and the transmission of standing waves. It is simply a sound behavior that creates its own fan community.
So it makes it easier for the non-do-it-yourselfer to get started in our hobby, because three large chassis cutouts at once is just not an easy task, also by choosing a combination of different woods, in this case beech multiplex and black stained MDF. The reason I subjected the black MDF to an additional staining process was due to the slight gray haze of the board I used. Other combinations such as raw MDF and birch multiplex are of course also available.
A tip for do-it-yourself beginners: If you don't have enough clamping straps or clamps, you can also let the case dry first after each step. After all, the do-it-yourselfer has no time pressure, but unfortunately we do.
TIP: An empty jam jar helps to mix a sachet of stain with water, which is good for the hobby cash. The whole thing please let dry well overnight.
Lumberjack wood oil colorless I always wanted to try.
So, Lumberjack and I have finished.
Pre-drill for the screws - and screw everything tight.
Pre-drill the pole terminals and screw them tight.
All kits (blanks) are supplied with Lamello flat dowels for easy assembly.
Unless otherwise mentioned or ordered, the blanks are made of 24 mm MDF raw. Optionally can be manufactured in MDF primer white, MDF black, beech or birch multiplex (each at extra cost).
It is also possible to miter the carcase (sides/bottom/lid). In this case, the front is put on and the back panel is inserted. Please use the contact form for inquiries.
The remedy is provided by the two passive diaphragms SP22R from SEAS, which corresponds to twice the diaphragm area of the SB23. By distributing them on opposite sides of the cabinet, they work impulse-compensated.
The left diagram with two passive diaphragms (auxiliary bass radiator) leads to the same result as the reflex tube version. Red the proportion of the two SP22R, blue the SB23 and black the sum.
Moyo SUB23: Nearfield black/SB23
Green: Passive diaphragms
Impedance tuning frequency: 29.47 Hz = f3 28.7 Hz.