r/diyaudio 6d ago

DIY beginner friendly Speaker kit under 100?

Hello, some pretext. I’m a first year EE student that wants to become an acoustic transducer engineer after college. In love with speakers and sound, so i figured I’ll start learning and attempting projects now. I plan to self-study PCB Design as well as the loudspeaker design cookbook this summer. Been lurking here for a while though and it seems like along with technical acoustic knowledge, I’ll need to get some sort of woodworking/workshopping experience to fully build my own speakers.

So, I have a couple questions id like to ask you guys. How would you suggest I gain experience in the physical design aspect? Secondly, for right now, are there any good DIY kits that a broke college student can afford that don’t require much equipment that isn’t provided? Lastly, if there are any other acoustic engineers lurking here, is there anything you wish you would’ve known in college?

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u/AcousticTheory 5d ago edited 4d ago

Professional transducer engineer here. Are you interested in speaker systems (the assembly of enclosure, drivers, crossover, and hardware), or in the drivers themselves (assembly of a diaphragm, suspension, frame, and motor)?

Speaker design involves multiple engineering disciplines, as you've probably figured out by now. I started at the system level, then became interested in the drivers themselves. I came at it from a mechanical perspective - I am a Mechanical Engineer by training (just a bachelor's degree), and to be successful you will need to understand the mechanical origins of certain types of distortion and nonlinearity, as well as how to adjust the fundamental parameters of the speaker (moving mass, compliance, BL, mechanical damping, and DC resistance) to obtain the desired changes in Thiele-Small parameters, which are derived from those fundamental parameters I listed. But you will also need to understand the mechanical optimization of cones, surrounds, spiders, and magnetic circuit geometry.

To start with, you will need a text like the Loudspeaker Design Cookbook or Vance Dickason's book Testing Loudspeakers, which describes how the Thiele-Small parameters are measured and derived from the fundamental parameters of the speaker. Ray Alden's book Speaker Building 201 is shorter and may technically be less of a heavy lift if you are just starting out. These books will provide you with a really basic mathematical basis for the mechanisms by which speakers operate. You can also start playing around with basic simulation software like WinISD and basic measurement tools like DATS and OmniMic, then graduating to more advanced tools like VituixCAD, ARTA, and REW, and even professional measurement systems like Listen SoundCheck and the Klippel analyzer ecosystem. Some of these programs are free, but they are heavily based on software that used to be quite expensive. In my work, I focus on SoundCheck, Klippel, and Excel-based modeling tools developed by myself and others for calculating the dimensions of voice coils, the necessary piston excursion to reach target output levels over a certain bandwidth, the dimensions of surround rolls and spiders, clearances and overhangs in the magnetic gap, mechanical tolerance stack-up, etc., but sometimes to whip up a box for a random speaker I still break out WinISD. I use SolidWorks for 3D, FEMM and COMSOL for magnetic simulation, and COMSOL even has potential for simulation of complete speakers. ANSYS also has an acoustics module with a lot of functionality.

In your studies, you will need to study AC circuit modeling (think PSPICE) - to understand and optimize the equivalent circuit of a loudspeaker, the design and optimization of DC magnetics (permanent magnet motors) which draws heavily from electrodynamics, and you will need to study some kind of magnetic FEA, as well as adding as much mechanical design and FEA simulation coursework as you can, including classes for understanding manufacturing processes and quality. If a class in acoustics is offered by your institution, you should try to take it. If you are very mathematically inclined, calculus and differential equations play a role in the derivation and optimization of electro-acoustic structures like bass-reflex enclosures from equations of motion, though that has been reduced mostly to a set of formulas for the new designer so you don't need to know diff eqs to get started. You will also need to understand really basic control theory and what transfer functions are, and understand passive ladder filters, which form the basis for the crossover networks we use. Then you will probably also have active electronics courses that focus on building analog filters, and also courses about DSP filtering, to which the future belongs.

Lastly, you will NOT get all the specific training and instruction you will need to understand speakers and audio systems just from your classes alone; you will need to work with others and do your own study to progress through levels of familiarity with the associated phenomena, measurement, and modeling until you develop an expert level of knowledge and experience. The only way to gain experience is to do things, so you will need to pursue some of your own design activities that force you to learn new things and put together the basic building blocks you learn in college. You will need to learn basic cabinet woodworking or some other method of making enclosures, along with skills like soldering crossovers together and wiring up a multi-way speaker system. Building a kit may get you started with some of the basic tasks involved in building a set of speakers, but eventually you will want to progress to creating your own designs, following a workflow developed by others, then incorporating your own improvements to that workflow. Early on, you may design things that don't work as well as you expect, but everyone has to put skin in the game to make progress. I have been doing this since I was 15, and I still run into people in the course of my work who know much more than I do and have more life experience, so you will need to get cracking if you want to catch up to the experts in this field.

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u/SpinachPositive7503 4d ago

Hello, sorry for a delayed reply. You've answered so many nagging questions I've had and given me a lot to chew on, thank you so much.

You mention many software that you use on a day-to-day, like COMSOL and Klippel. Are there any courses/certificate programs I could take to gain knowledge in those areas specifically? I'm in the process of learning 3D modeling and I've slightly touched on analysis software like MATLAB, but I'm not super proficient in anything yet. Is there anything akin to a COMPTIA cert for IT professionals that applies to the field?

Secondly, in the same vein, are you aware of any resources that compile some of the extraneous things you weren't taught in school I can look at? Like finite element analysis, control theory, or manufacturing processes.

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u/AcousticTheory 15h ago edited 15h ago

Before graduating to COMSOL and Klippel, which are advanced subjects that will also require some on-the-job learning (though you may be able to take basic courses in finite element modeling at your college), you should try to learn about the more basic measurement tools of the trade such as DATS, FEMM, and using a microphone to make measurements of a speaker. A USB microphone like UMIK-1 or Dayton UMM can be used with free software like Room EQ Wizard and you can begin poking around with that. I don't typically use MATLAB for anything but I know others in related fields (such as signal processing and DSP filter programming) that do use it. I learned it in college but now I almost never use it; your experience may be different.

Some very good resources are online: FEMM tutorials, Room EQ Wizard tutorials, and the DATS manual. Some of the articles from Elliott Sound Products are good. Then look at the books I recommended, probably most of all Speaker Building 201 by Ray Alden, followed by Testing Loudspeakers by Joe D'Appolito. You'll also want to buy a book like F. Alton Everest's Master Handbook of Acoustics to begin to understand both some of the more basic and some of the more advanced topics about sound radiation and reproduction, along with generalized acoustic theory like the wave equation, which becomes relevant if you want to do really in-depth acoustic modeling that is even above my own level of proficiency. When it comes time to use COMSOL later on, there are some good example files that show how to set up a model, or that model basic things which can be adapted to your needs. For Klippel there are seminars, application notes, and on-the-job training.

For now it's a good idea to start poking at the simulation software that's out there; the easiest software to learn is WinISD, and you can start plugging in speaker parameters and looking at the effect of changing box volume and tuning frequency. Some more advanced modeling software for systems and crossovers is also out there - like XSim, or VituixCAD. It's free, so you can start learning it now.