The development goal was an small audiophile subwoofer suitable for living rooms and home theaters
With the constant change of our living space needs, the black Cinema series should also be supplemented sensibly. The handy subwoofer Moyo Cinema makes the beginning here with its two colleagues, the Drone Cones. The focus here is on the living room suitability. Due to the compact design, there are more living room-suitable combination options up to the home theater. Whereby it should not be called here: Home cinema OR stereo, but AND. But to create subwoofers almost free of sound coloration and to pack the chassis in dimensions suitable for living space. 60 to 90 liters of housing volume may be indifferent to one or the other, but the ravages of time no longer meet - the ready-made speaker industry has long enforced small housing dimensions. For lovers of large-volume cabinets, we already have many in the program, small subwoofers we have so far treated somewhat stepmotherly.
But how do these passive radiators actually work?
But how do these passive radiators actually work?
Drone Cones
The Drone Cones - as the passive radiators are affectionately called here - represent the vented cabinet variant, i.e. bass reflex tubes, in their design and performance characteristics.
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.
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.
Enclosure
The cabinet construction is shown on the basis of our cabinet kit:
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.
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.
The assembly starts with the bottom panel, followed by the case stiffener (it is not mandatory to use it, especially for this case size and in our case the subwoofer module is not installed in the case). First all lamellos are wetted with glue, then the back panel ...
... followed by the sides with the cutouts for the drone cones.
Then the side panels are connected to the rear panel, 24 mm as in the prepared housing kit should be used here. However, you can use MDF just as well. The denser the material, the better. For those who don't know: OSB panels are not suitable for subwoofer cabinets because their air permeability is extremely high - and who wants the cabinet to play along in the bass range?
And now: Put the lid on and wipe everything well.
Fasten everything well with tension belts and / or screw clamps.
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.
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.
For a deeper black, I opted for Clou water-based stain. I've had good experiences with the microfiber roller: it doesn't lint.
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.
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.
The last step is to glue on the baffle.
... and then everything well tightened or forced.
After drying, you can break the edges and sand away any glue residue, if any.
Lumberjack wood oil colorless I always wanted to try.
Lumberjack wood oil colorless I always wanted to try.
... It can be applied very well with an old cotton rag, a sponge would also have worked.
So, Lumberjack and I have finished.
So, Lumberjack and I have finished.
The drone cones are given the right weight class. Screw on the washers and off you go to your new home.
The bass driver joins his passive colleagues, so the team would be complete.
The driver still lay a good energy supply.
Pre-drill for the screws - and screw everything tight.
Pre-drill the pole terminals and screw them tight.
Pre-drill for the screws - and screw everything tight.
Pre-drill the pole terminals and screw them tight.
Drawing
The standard drawing for the do-it-yourselfer who wants to dispense with the ready-made housing cut to size supplied is also published here:
As for the diversity of our housing blanks, you can choose from several options.
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.
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.
Transducers
The goal is a small subwoofer with 30 liters of enclosure volume. The SB23MFCL45-4 is suitable for this purpose. The calculation results in a lower cutoff frequency (f3) of 28.7 Hz for 30 liters.
With a minimum BR tube of 10 cm diameter (1/3 of the membrane area), this would already have to have a length of just under 80 cm, which is already no longer practical.
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 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.
Comparison:
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.
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.
The required additional mass is achieved by means of large and small washers, which are included in the kit in the correct quantity.
The impedance measurement shows that the calculation is correct. The impedance minimum between the two "humps" corresponds to the tuning frequency.
Moyo SUB23: Nearfield black/SB23
Green: Passive diaphragms
Red: Sum.
Impedance tuning frequency: 29.47 Hz = f3 28.7 Hz.
Moyo SUB23: Nearfield black/SB23
Green: Passive diaphragms
Red: Sum.
Impedance tuning frequency: 29.47 Hz = f3 28.7 Hz.
Conclusion
Modern subwoofer as a single or in a double arrangement distributed in the room. Universal to our different Cinema kits and can also be used for other high-quality speakers. You can even control two of these bass cubes via an active module. Have fun with the assembly and afterwards with the listening!
Marcus
Marcus
