design - RD Physics

Artificial intelligence in loudspeaker design

Artificial intelligence is a tool that loudspeaker designers can use when they want to think outside the box and come up with modern and unique designs. We will focus on image-based AI in this text because that is easily available to the public and does not require engineering considerations. Although AI-generated images seem to take cues from existing designs, AI can merge features in a novel way. For example, merging loudspeakers and furniture or blending the loudspeakers with the interior design. Instead of specific technical or topological solutions, think of it more like a mood board or general family of concepts. The greatest benefit of artificial intelligence in the design process is generating a multitude of new concepts in a short period of time.

Clever combination of furniture and loudspeakers. Posted by Lucas D. on the Facebook group AI Loudspeaker and Stereo Design.

How to get started

One of the most popular tools currently is MidJourney, which creates “unique imagery from short text descriptions”. You can start using AI algorithms like MidJourney to generate new designs by simply coming up with your own unique prompts. The easiest way to start using MidJourney is to join one of their newbie channels, create your own server and invite the bot there (see video at the end of this article).

Another option is using DALL-E, which is oriented more towards generating art, but also image editing. DALL-E is developed by OpenAI, who are known for GPT-4.

A great upcoming alternative is Imagine: AI Art Generator by Vyro AI. It is available for iOS and Android operating systems. The free trial has video ads, limited settings and watermarks.

AI-generated image when prompting for a sphere-shaped loudspeaker.

Contrary to what some guides tell you, direct messaging prompts directly to the MidJourney bot does not work in the free trial version. You have approximately 25 free prompts (0.4 hrs GPU time) without a subscription. Upscaling, generating variations and repeating a prompt (“rerolling”) uses up your GPU time quota. The most inexpensive subscription plan is $8/month at the time of writing this and it gives you 3.3 hrs of GPU time and ownership of results.

If You are not a Paid Member, You don’t own the Assets You create. Instead, Midjourney grants You a license to the Assets under the Creative Commons Noncommercial 4.0 Attribution International License./…/By default, Your images are publically viewable and remixable.
MidJourney Terms of Service

Examples of AI-generated loudspeakers

Coming up with useful prompts can be challenging and the output is seldom what you had in mind. That’s the beauty of it though. To give you an idea of what kind of results can be obtained, we have listed some of the more successful prompts and their corresponding results. They are by no means the best that can be achieved, but rather a result of simply experimenting with AI. We have included some comparisons MidJourney vs. DALL-E to give you an idea of what kind of results to expect. First, let’s give both image-generating AIs something ordinary like:

/imagine small loudspeaker with scandinavian design in a livingroom

Results from MidJourney

Results from DALL-E

Result from Imagine

Next, let’s ask something more specific:

/imagine studio monitor loudspeaker with waveguide in recording studio environment

Result from MidJourney

Result from Imagine

Since RD Physics develops 3D-printed loudspeakers, let’s see how well the AIs understand that and how creative they get:

/imagine 3D printed loudspeaker in livingroom

MidJourney

DALL-E

Imagine

You can also upload images to your Discord server and use the URL of those as part of your MidJourney prompt or upload an image to DALL-E and create variations. Below you see what happened when we uploaded a photograph of our Circular Sound Eikosa speaker and placed it in another environment using MidJourney and asked DALL-E to create variations:

/imagine <image URL> on a table in a scandinavian livingroom white colour

Placing into another environment with MidJourney

Asking DALL-E to create variations

As you can see above, MidJourney will often mess up the shape of the original input photograph. For some reason, the pentagonal face of the speaker always becomes hexagonal and the icosahedral shape is also lost. You can also directly ask for a shape in the prompt (with varying success):

/imagine small icosahedron shaped loudspeaker in livingroom

MidJourney

DALL-E

Imagine

Future Outlook

We asked ChatGPT to explain the potential benefits of AI in loudspeaker design and here’s what it had to say (edited for brevity):

Firstly, AI can help to optimize the design of loudspeakers for specific applications. By analyzing data from simulations and experiments, AI algorithms can identify the optimal shapes, sizes, and materials for loudspeakers that are intended for different uses.

Secondly, AI can help to reduce the time and cost of designing and testing loudspeakers. With AI, simulations can be run to test different design parameters, allowing designers to quickly identify the best designs without the need for expensive and time-consuming physical testing.

Thirdly, by analyzing large amounts of data, AI algorithms can identify patterns and correlations that might be missed by human designers. This can result in more precise designs that perform better and are more consistent across different manufacturing runs.

Overall, using AI for designing loudspeakers can result in more optimized designs, faster design iterations, and more accurate and precise designs, all of which can lead to improved sound quality and performance.
ChatGPT

Conclusion

The easiest way to implement AI in loudspeaker design is to use a visual tool like MidJourney. It does not consider acoustics, materials, or 3D dimensional structures. Knowledge in those fields is needed to evaluate the feasibility of each concept created. Nevertheless, AI-generated images can be of assistance in the ideation phase when one would typically use sketching or other quick visualization methods to explore new designs.

Posted by David M. on the Facebook group AI Loudspeaker and Stereo Design

At first glance, these ideas may seem way too complex to fabricate. That is true if confined to traditional woodworking methods. However, 3D printing is a technology that can help in making these intricate designs become reality. The design freedom that 3D printing allows is not limitless, but unparalleled. Many of the AI-generated loudspeaker designs could not be fabricated economically in any other way. For advice regarding 3D printing in audio, we recommend our DIY blog and the Facebook group 3D Audio and Hi-Fi Projects. Have fun experimenting and remember that the AI only knows what it has been taught and only does what it is told.

Below is a video explaining how to set up MidJourney with Discord.

Introduction

It is striking how often 3D printed speakers take the shape of a sphere and that is also how RD Physics started with the FR1 full-range speaker. What are the benefits of spherical loudspeaker enclosures and why are they so popular?

Rigid and void of panel vibrations
Minimum material use for a given volume
Potentially avoid edge diffraction
Omnidirectional up to a relatively high frequency and controlled baffle “step”
Aesthetically pleasing with a single circular driver
Difficult to manufacture any other way than 3D printing

As RD Physics has extensive experience in these types of enclosures, we have decided to share our learning in one blog post. The models are presented in chronological order allowing the reader to understand the development that took place over the years of building and listening to various versions of the FR. Most of the designs are offered open-source to the community.

FR1 – Full-range bliss in a compact form

The FR1 is a spherical (180 mm diameter) full-range loudspeaker with a sealed enclosure. Internal wall stiffeners are used in order to maximize internal volume as opposed to simply increasing wall thickness, which robs internal volume. We use Noise Killer paint to both seal the enclosure and also to add mass and damping. The sound of the FR1 speakers is very unique and quite tricky to get the most out of. The full-range emitters are very directional and the listening distance also changes the sound markedly.

Model	RD Physics FR1
Driver	Mark Audio Alpair 6M 2.5″
Enclosure	3 liters sealed
Material	UPM Formi3D
Construction	Internal webbing with Noise Killer damping
Tilt	Fixed at 15 degrees

FR2 – Exotic carbon fiber skin reduces resonances

Additive manufacturing (AM) has many benefits over traditional construction methods, such as design freedom, fast product development, and integration of functions into one part. There are drawbacks as well. The plastic AM parts tend to be low in mass and not very stiff. Air-tight walls are sometimes difficult to achieve, too. Adding mass by increasing the fill density of the print is not a good solution, since it adds build-time and material cost. Stiffeners and bitumen paint were used in FR1. However, the stiffeners were cumbersome to paint with bitumen and it did not add significant weight. For FR2, we used the vent as a part of the mechanical structure and used a thicker wall. But some additional means were needed to bring 3D printed enclosures on par with traditional cabinet materials.

Carbon fiber in loudspeaker building

Dry carbon fiber tow was wound around the enclosure and then wetted with epoxy resin. The composite skin was sanded after curing and additional coats of epoxy were added. The result is a unique unidirectional carbon fiber surface finish. The composite shell adds mass and stiffness to the enclosure. The loudspeaker sits on four feet printed from TPU material, which allows rotation.

Model	RD Physics FR2
Driver	Mark Audio Alpair 7MS 3″
Enclosure	5 liters vented
Material	UPM Formi3D + CFRP
Construction	Structural port and carbon fiber skin
Tilt	TPU feet allow tilt ~0-15 degrees

FR3 – Metal-filled filament for mass and rigidity

The FR1 used internal ribbing and Noise Killer paint to reduce enclosure resonance. The FR2 used an external carbon fiber shell. Both approaches were a bit cumbersome and laborious. For the third version, we wanted to fully use the capabilities of 3D-printing. Therefore, a high-density metal-filled filament was used an internal gyroid-shaped support was used even where overhanging surfaces would not have required it. In addition, height and tilt can be adjusted using three threaded rods that form a tripod. The finished enclosure with three 14 mm trapezoid-threaded nuts bonded to it weighs 1.2 kg. The RS100 drivers have a distinct on-axis peak at the upper treble, which actually works nicely for those who like a bright sound. Those who don’t should toe-in the speakers a bit.

Model	RD Physics FR3
Driver	Dayton Audio RS100 4″
Enclosure	2 liters sealed
Material	Colorfabb steel fill
Construction	Gyroid infill as an internal stiffener
Tilt	14 mm leadscrew tripod

FR4 – Refining the concept further

The metal-filled filament used in the FR3 was too brittle and difficult to post-process. The FR4 uses wood-filled filament, which is more ductile and easier to sand if needed. The surface is quite nice straight out of the printer thanks to the matte surface. A quick touch with an orbital sander gives a smooth finish. Leadscrew nuts are bonded into recesses in the enclosure and allow for adjustment of the legs. Small TPU feet can be printed and placed at the ends of the leadscrews in order to avoid scratching the desktop. These are satellite speakers and need a subwoofer to complement the lower frequency spectrum.

Model	RD Physics FR4
Driver	Tangband W3-1878 3″
Enclosure	1 liter sealed
Material	AddNorth Textura
Construction	Gyroid infill as an internal stiffener
Tilt	12 mm leadscrew tripod

FR5 – Returning to square one

Reviewing the FR project so far, we came to the conclusion that all things considered, the original FR1 is the DIY project that was the most fun to build and listen to. It’s simple but rewarding once dialed in. For the FR5 we went back to basics by ditching the tripod and returning to a simple white spherical enclosure. The tilt adjustment is handled by a TPU mounting ring that allows a large adjustment range. The Scan Speak 10F driver is one of the best for voice reproduction, but our subjective view is that it needs a tweeter in addition to a subwoofer making it suitable for three-way builds only.

Model	RD Physics FR5
Driver	Scan Speak 10F 3″
Enclosure	2 liters sealed
Material	AddNorth Textura
Construction	Stiffeners and alu-butyl sound-deadening mat
Tilt	TPU ring +-30 degrees

3D files and components

In the table below you’ll find links to the drivers used in each version as well as the geometry files needed for slicing the toolpaths. Support us by clicking on the Soundimports affiliate links before buying anything from them (we get a small commission and it won’t cost you a dime). Thank you!

Model	Components	3D files
FR1	Alpair6M at Soundimports	FR1 at Thingiverse
FR2	Alpair7MS at Soundimports	FR2 at Thingiverse
FR3	RS100 at Soundimports	FR3 at Thingiverse
FR4	W3-1878 at Soundimports	FR4 at Etsy Shop
FR5	10F at Soundimports	FR5 at Thingiverse

Videos

Acknowledgements

We wish to thank UPM for the Formi3D materials and support. Photos taken by J-P Virtanen and Markus Markkanen. Erell Bodinier handled the carbon fiber skinning.

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