Categories
Technology 3D printing Audio DIY Loudspeaker Speakers

Powerful 3D printed 5 inch subwoofer – SW2

Subwoofer Concept

Our previous 3d printed subwoofer, the SW1, is a 13 liter subwoofer with a 6.5″ driver, a matching passive radiator and a plate amp. We wanted to develop something smaller that would still offer the bass extension that satellite speakers so badly need. The result is the SW2 using a Tang Band W5-1138 5″ long-throw driver and the same Dayton Audio DSA175 passive radiator as in the SW1. The enclosure is now only 5 liters and much easier to fit on a desktop. The passive resonator allows tuning the resonance frequency to avoid overlap with room modes, for example. The spherical shape is optimal for material use and stiffness. Combined with the small diameter driver with large surrounds, the appearance is quite unique. If a traditional box is what you want, then this build is not for you.

Measurements

The measured resonance frequency of the passive radiator indicates that some air-coupling occurs due to the downward firing placement. Simulated resonance frequency matches the measured value (53 Hz) when 16 grams of added mass is used. Mass can be further added using washers to tune the response. In practice, the frequency response starts to drop below 50 Hz. The Arylic amplifier offers DSP capabilites and using a computer as the source allows unlimited DSP with zero cost. Therefore, frequency response in not that meaningful especially when considering the room effects, but we have included some measurements to give an idea of the natural response especially around the lower cut-off.

3D printing

The enclosure is printed in one part (234 mm diameter) and takes approximately 1.5 kg of filament. Print time is about 48 hours. The mass can be increased by lining the walls with sound deadening mat. Although the external wall is spherical, there is a cylindrical inner wall that braces the woofer to the passive resonator and, thanks to a single curvature surface, allows easy installment of thick sound deadening mat. The drivers are fastened using 4.2 mm wood screws. There is a geometry file for a gasket for the woofer which can be printed from TPU. Traditional gasketing methods will work, but the 3D printed gasket is seamless and has the screw hole pattern accurately incorporated. The binding posts are recessed deep into the enclosure and only accept banana plugs in that configuration. An O-ring under the binding post washer is recommended and there is a chamfer for it. 3D printing using a wood-filled filament allows easy sanding for a smooth surface finish. The photos show 15 minutes worth of post-processing making this a very easy and fast build without compromising in function and looks.

Images

Sound quality

The subwoofer was compared to the much larger, THX certified Logitech Z623 subwoofer. The sound is very similar, but in a much smaller package. The SW2 is a great companion for small satellite speakers and brings fullness to the bass. Electronic music will benefit from the “boom” offered by this small unit, while other types of music may require turning down the level a bit for a tighter bass.

Links and video

The 3D files can be found in Etsy store:

https://www.etsy.com/shop/RDPhysics

Please support us by using the affiliate link below just before ordering the components:

TangBand W5-1138 on SoundImports.eu

Dayton Audio DSA175-PR on SoundImports.eu

Arylic 2.1 BT amp on SoundImports.eu

Categories
Technology 3D printing Audio DIY Loudspeaker Speakers

3D printed active subwoofer – SW1

Our 3D printed full-range speakers needed something to beef up the lower end of the frequency spectrum. We set out to design a compact subwoofer that can be used together with our FR3 speakers. The result is a 13 liter enclosure with a 6.5″ driver, a matching passive resonator and a plate amp. The passive resonator allows tuning the resonance frequency to match room modes, for example. The plate amp can power satellite speakers and has a fixed high-pass filter. The low-pass cut-off frequency for the subwoofer can be adjusted and the level too, which means that this system can be easily mated with signal sources that do not have equalizing or DSP capabilities in themselves.

3D printing

The enclosure consists of two parts, which are glued together after printing. Total print time is about 100 hours and uses about 4 kg of filament. Support is only needed for the small recess where the plate amp is mounted. Dual-material printing is not needed. The mass of the enclosure can be increased by filling the walls with epoxy through the holes in the back. A geometry file for 3D printing a matching funnel is provided, too. 2 kg additional mass can be obtained this way.

The 3D files can be found on Thingiverse for free:

https://www.thingiverse.com/thing:4802531

Please support us by using the affiliate link below just before ordering the components:

Dayton Audio DSA175 on SoundImports.eu

Dayton Audio DSA175-PR on SoundImports.eu

Lepai LP210PA amp on SoundImports.eu

Video

The video below explains the concept in more detail.

Categories
Audio 3D printing DIY Loudspeaker Speakers Technology

Clean sound and rich detail with full-range speakers – FR1

Construction

The first version of #3D-Fi speakers are spherical (180 mm diameter) full-range loudspeakers with 3 liter internal volume. The box is vented with two rectangular ports on both sides. The ports act as stiffeners and also give more space to assemble the connectors and amplifier inside the enclosure. Internal wall stiffeners are used in order to maximize internal volume as opposed to simply increasing wall thickness, since a small external size is typically desired while internal volume needs to be high enough for the driver to work properly. We use bitumen paint to both seal the enclosure and also to add mass. The enclosure is printed as one part using UPM Formi3D cellulose composite filament. Metallic nuts are pressed on the backside of the flange to receive the machine threaded screws that hold the emitter.

Setup

Our setup uses a laptop PC as a source which allows equalizing the frequency response at the digital source. The signal is transferred via USB to a USB-powered DAC/pre-amplifier with volume control and a power switch. The analog signal is then transferred to one of the speakers where it is amplified using a two-channel chip amplifier board that is powered by a 65 W laptop charger. The amplified signal of the other channel is then transferred to the other speaker for reproduction. The design uses 6 cm full-range emitters without any analog filters or corrections.

The design was updated for Thingiverse:

  • Machine screws and nuts replaced with 2.5 mm hole for wood screws
  • Fully passive design without the amp. Instead, 4 mm holes for binding posts only
  • Sealed enclosure

If you like the design and plan on building one yourself, please support us by using the affiliate link below for ordering the components:

MarkAudio Alpair 6 on SoundImports.eu

Sound

A reference system with Genelec 8040 speakers was used for comparison. The sound of the 3D-Fi speakers is very unique and quite tricky to get the most out of. The full-range emitters are very sensitive to off-axis listening and the listening distance also changes the sound markedly. Even slightly tilting one’s head has an effect. It seems that finding the best spot is challenging and takes time. It’s hard to remember not to move an inch while listening to these speakers. However, all the effort pays off, because there is a reward at the end. The sound stage is unbelievably good and there is a huge presence from such a tiny speaker. The Genelecs sound distant and all over the place compared to the very precise and point-like sound of the 3D-Fi speakers. Obviously the bass is not very deep and the sound pressure levels achievable with 6 cm cones is limited. On the other hand, they seem to tolerate significant bass boost without distortion and in normal listening the cone travel stays in check. Overall, a very difficult set of speakers to get into and they are quite picky with the type of music played, but once a good recording is found together with the right listening conditions…Bliss!

Acknowledgements: We wish to thank UPM for the materials and support. J-P Virtanen took the studio pictures and Markus Markkanen the ones in the library.