DIY Loudspeakers: Can You Build "Better" Than Professional Designs?

Loudspeakers are in a class by themselves. No matter where you find yourself on the audio enthusiast spectrum, there is no doubt that people have very strong feelings about them.  This article discusses why so many enthusiasts feel like they’ve got a grasp on making their own loudspeakers based on:

• The kind of design approach they like
• Features/build quality they think are important
• What kind of drivers they like (ie. dome, cone, flat, pleated, electrostatic, metal, plastic, paper, hybrid, half-roll surround, inverted half-roll surround, accordion surround, cast basket, stamped-steel basket, neo magnets, ceramic magnets, Alnico magnets, etc.)
• Philosophical design preferences (first-arrival axial vs. far-field power, sharp near-field imaging vs. diffuse wide-dispersion spaciousness, etc.)
• Tonal-philosophical approaches: “accurate,” “musical,” “forgiving,” “detailed,” “lifelike,” “forward,” “laid back,” “punchy,” “exciting,” “polite.”
• Bass-alignment preferences (sealed, ported, transmission-line, passive radiator, etc.)
• Multiple smaller woofers or fewer big ones
• Angled/front-rear/bipole mids/tweets or all forward-facing
• Single driver in each passband (concerned about comb-filtering and interference) or multiple drivers in each band for greater power-handling and dynamics (the heck with near-field imaging)
• Bi-amp connectors or if they think that’s snake oil
• 3” MDF front baffle thickness or beyond a certain point, you’re just kidding yourself

And so on. The variations are endless, and so are the viewpoints.

So you can see, enthusiasts have strong opinions on everything, from cabinet construction to internal wiring to feet/spikes, to cabinet finish quality to grille design to crossover topology to crossover component choices to hookup options. Everything.

Not only do they have strong opinions, but hard-core audio enthusiasts are the harshest critics of commercially-available speakers. They second-guess designers’ and engineers’ decisions, they question why a manufacturer choose to name or price or market their product in a particular way, and above all, they praise or criticize the speaker’s sound according to their own purely-arbitrary yardstick of acceptability, citing any or all of their favored aforementioned factors as supposed “proof” as to why the Venus Godzilla 4 tower does or does not sound as good as it should.

There are two really interesting aspects of an audio enthusiast’s reaction to speakers:

1.     DIY Loudspeakers but what about DIY Electronics, Cars or Breakfast Cereal?

They don’t have anywhere near as strong an opinion about power amps or CD players or DACs or pre-pros. They have opinions, firmly-held even, but not as deeply ingrained as they feel about speakers.

Yeah, OK, you may truly believe that an Adcom power amp doesn’t sound as “sweet” and “musical” as say a Parasound Halo or a McIntosh, but you likely don’t hold that position as fervently as you do with speakers.

Maybe that’s because most audio enthusiasts (I’m defining “audio enthusiast” as a highly-interested end user of the equipment, but someone not professionally involved in the industry) feel more at home with speakers than any other audio component. This enthusiast has a good working knowledge of basic electronics and/or acoustics, but probably doesn’t have a formal engineering background. Their technical knowledge has been picked up through the years by reading the buff magazines, going to hi-fi shows and talking to company personnel.  Discussing loudspeaker things for hours on end with their fellow enthusiasts and perhaps even belonging to local audio organizations can help them identify with how a speaker works.  They can see first-hand how the drivers make their sound. Amplifiers are a bit more mysterious in that you can’t actually see the output transistors doing their thing. You can’t visualize the circuitry performing its tasks. But you can see a woofer moving in and out and you can see that there are no baffle obstructions around the tweeter hindering its off-axis output. You can rap on the cabinet and feel its solidity.  You can see the cast-aluminum woofer basket and just know that it contributes to a better-articulated bass sound.

Therefore the typical audio enthusiast feels they know speakers, even though they may or may not really understand the inner workings of an amplifier, may or may not understand the benefits/drawbacks to various electronics design approaches, may or may not understand which types of amps produce what kinds of distortion spectra, may or may not understand the relationship between “watts” and SPL, may or may not understand S/N, slew rate, TIM, THD and IM, current capacity and headroom.

In any event, it does not seem to be anywhere near as much fun to argue about amplifier design as it is to argue about speaker design.

Which brings us to aspect number two:

2.     Opinions over Facts?

Audio enthusiasts hold fast onto their opinions about speakers regardless of the degree of technical/design/engineering knowledge they have about acoustics and electronics.

This is fascinating, isn’t it? Even if Joe Q. Listener is an accountant, he’ll insist to the day he dies that the reason the Godzilla 4 sounds better to him than the Jupiter Marvel is because the Godzilla uses internal Monster wiring, has a 3^rd-order HP network with Solen bypass caps (Joe can’t even define “3^rd order”) and its two 8” woofers are “faster” than the Jupiter’s single 12” driver.

This kind of thinking is rampant among audio enthusiasts in the speaker end of this industry. Non-engineers insist all the time that they “know” why this speaker sounds this way and what would make that speaker “better.”

Nonetheless,

• They have no way to try out their ideas.
• They have no way to measure their proposed designs or modifications. (Except for those very few hobbyists who bought computer-based measuring software a year or two ago and a moderately-priced microphone, then amusingly manage to convince themselves that they are somehow the very-near equivalent of a real speaker engineer with 20+ years’ experience and dozens of successful products of all kinds under their belt)
• They have absolutely no understanding of the relationship between material cost and retail price.
• They have close to zero understanding about the practicalities or processes of manufacturing on a large scale, packaging and shipping.

None of this is meant to denigrate the speaker hobbyist/customer. People are certainly entitled to their opinions and impressions as to why a product performs as it does. After all, you don’t have to be an automotive engineer to render an opinion on whether you prefer the Mustang over the Camaro and whether you think the Mustang would benefit from more power or stiffer shocks.

But opinions are one thing. The speaker industry is probably unique in the high-tech consumer products field in that its followers—amateurs, admittedly—actually think they can design and build the product themselves. They often think they can do it better than the speaker company itself!

No one would ever try to build his own Mustang or his own iPad from scratch.

But give someone access to a good cabinet shop, a Parts Express catalog, and the latest edition of Vance Dickason’s Loudspeaker Cookbook, and look out! Vastly superior speaker systems are right around the corner.

In fact in the after-market car audio business, this is exactly how it’s done: amateur enthusiasts gather up the best information they can, misconceptions and all, and fearlessly plow ahead into the New World of DIY Speaker Excellence. Some of them actually manage to be pretty good too, against all odds.

But home audio is another matter. We take things, and ourselves, far more seriously in home audio—real audio—than mere ‘car stereo guys.’

Besides, taking it all seriously is so much fun, and that’s the point: It should be fun.

So, having said all this, we pose the following questions to you:

• What are some of your favorite commercial home speaker designs of both past and present and why?
• How would you improve them?
• What obvious shortcoming does it have that you just can’t understand why the manufacturer did that?
• If you had a ‘clean sheet of paper,’ what would you design in the various size/price categories? Drivers? Bass alignment? Crossover? Features? Cabinet construction? Finish?

• Modest-sized bookshelf
• Medium-sized floorstander
• Powered sub?
• Home theater array (mains, center, surrounds)
• Full-sized tower, SOTA, your dream speaker?

• Do you have the most respect for a cost-no-object design, an over-achieving budget unit or a medium-priced speaker that delivers very close to top-of-the-line performance?
• What would your design be? Fire away!

We look forward to hearing your ideas on loudspeaker design and sharing your DIY projects.  After all, the hobby of building can be as fun and perhaps even more rewarding when listening on your own creations.