Weeb Labs
Addicted to Fun and Learning
For the past year or so, @ItsMeAubey and I have been experimenting with various evidence-based loudspeaker designs. The task has been to develop a well behaved active speaker that can be assembled by almost anybody, using inexpensive off-the-shelf components and DSP.
The temporary title for this project is "Directron" (a joke aimed at Directiva) and to date, we have iterated through three major redesigns. We have ten primary design objectives and those are:
The first generation of our speaker consists of floorstanding cabinets with a great deal of bracing and a four-way design. We selected the following drivers (all Dayton Audio brand):
At the moment, I am awaiting CNC cuts for the first generation cabinet and you can see a CAD render of the construction below. The second image is a slightly older render but it will suffice as a simple rear view.
We have also performed a great deal of simulation and experimentation within VCAD for this design but the data provided by Dayton is somewhat limited and so it won't be possible to fully characterize the speaker's behavior until it is assembled.
This is a somewhat older screenshot, prior to more precise optimizations. When designing the first generation, constant and wide directivity was secondary to smooth directivity, which means that horizontal beam width isn't particularly large. The expectation is 50 degrees, narrowing above 10KHz.
Data for the second generation is not readily accessible to me at the moment but the primary changes were rear drivers for cardioid behavior and the replacement of the ND25FW with a SEAS DXT tweeter. To my knowledge, this generation was purely theoretical and we don't intend to build it.
For the current (third) generation, we are experimenting with a dual tweeter design which incorporates the Dayton ND14 and ND20 units along with the previous component selection for a total of six drivers.
This generation is something of an experiment and prioritizes the widest, most uniform horizontal directivity possible. We are giving serious consideration to the prospect of fabricating the cabinets as two separate pieces; one containing the subwoofers (second JAB5 in cascade mode) and the other containing the remaining four drivers. As the main cabinet would already contain an RS180 capable of reaching frequencies below 50Hz, we believe this would both simplify assembly and introduce a certain degree of modularity. Builders would have the option of assembling only the portion required.
At the time of writing, it is quite late at night and this opening post is already rather lengthy, so I will conclude it here for the moment. Should you happen to spot a problem or wish to raise a concern which I have not addressed herein, by all means do point it out but please also bear in mind that we have discussed and researched this project to death over the last year. Many dozens of drivers, baffles and cabinet designs have been considered but summarizing all of it here would take hours!
As always, thank you very much for reading and we will continuously update this thread with new developments. We will also likely be using the Discord server linked in my signature for realtime discussion, so feel free to stop by.
The temporary title for this project is "Directron" (a joke aimed at Directiva) and to date, we have iterated through three major redesigns. We have ten primary design objectives and those are:
- Low distortion
- High SPL capability (>105dB)
- Sub-bass capability with an F3 below 27Hz
- Smooth directivity, later revised to wide and near-constant directivity
- Extremely inert cabinet
- Based upon one or two JAB5 DSP amplifiers (slave cascade mode)
- Utilizes affordable but high performance off-the-shelf drivers from brands such as Dayton Audio
- Cabinet published as STEP/DXF/PDFs which can readily be sent to any cheap CNC service for fabrication
- Lossless, low latency wireless capability (optional)
- Cardioid behavior (optional)
The first generation of our speaker consists of floorstanding cabinets with a great deal of bracing and a four-way design. We selected the following drivers (all Dayton Audio brand):
- Epique E180 (Subwoofer)
- DS175 (Passive Radiators)
- RS180 (Midbass)
- RS52AN (Midrange Dome)
- ND25FW (Waveguided Tweeter)
At the moment, I am awaiting CNC cuts for the first generation cabinet and you can see a CAD render of the construction below. The second image is a slightly older render but it will suffice as a simple rear view.
We have also performed a great deal of simulation and experimentation within VCAD for this design but the data provided by Dayton is somewhat limited and so it won't be possible to fully characterize the speaker's behavior until it is assembled.
This is a somewhat older screenshot, prior to more precise optimizations. When designing the first generation, constant and wide directivity was secondary to smooth directivity, which means that horizontal beam width isn't particularly large. The expectation is 50 degrees, narrowing above 10KHz.
Data for the second generation is not readily accessible to me at the moment but the primary changes were rear drivers for cardioid behavior and the replacement of the ND25FW with a SEAS DXT tweeter. To my knowledge, this generation was purely theoretical and we don't intend to build it.
For the current (third) generation, we are experimenting with a dual tweeter design which incorporates the Dayton ND14 and ND20 units along with the previous component selection for a total of six drivers.
This generation is something of an experiment and prioritizes the widest, most uniform horizontal directivity possible. We are giving serious consideration to the prospect of fabricating the cabinets as two separate pieces; one containing the subwoofers (second JAB5 in cascade mode) and the other containing the remaining four drivers. As the main cabinet would already contain an RS180 capable of reaching frequencies below 50Hz, we believe this would both simplify assembly and introduce a certain degree of modularity. Builders would have the option of assembling only the portion required.
At the time of writing, it is quite late at night and this opening post is already rather lengthy, so I will conclude it here for the moment. Should you happen to spot a problem or wish to raise a concern which I have not addressed herein, by all means do point it out but please also bear in mind that we have discussed and researched this project to death over the last year. Many dozens of drivers, baffles and cabinet designs have been considered but summarizing all of it here would take hours!
As always, thank you very much for reading and we will continuously update this thread with new developments. We will also likely be using the Discord server linked in my signature for realtime discussion, so feel free to stop by.
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