Speaker design procedure

[maylar]

I've decided to build a 3-way system from scratch. The only decision I've made so far is that I'd like to use JL Audio 10W0 subwoofers, and probably Peerless drivers (no models selected yet).

My knowledge of speaker design is limited to some equasions I found for determining box volume based on Q and Vas.

What are the general steps that a designer/builder uses to come up with a good design before making sawdust?

And what tuning and measurement steps do you take afterward?

I know each builder might have his own methods, but I'm looking for advice on how to proceed with the intention of having better than average results. Thanks for any insights you can offer.

[RHosch]

First, read a good book on the subject of speaker design and building such as Vince Dickason's The Loudspeaker Design Cookbook. Also, something like Alton Everest's Master Handbook of Acoustics might prove useful. Second, reconsider your choice of subwoofer. If you know nothing of speaker design, equations, measurement techniques, etc., then how could you have picked an appropriate subwoofer already? If you have several lying around already I suppose that could be a valid reason.

Starting with a 3-way isn't the recommended way of learning the art of speaker design. Most people build a few 2-way systems over the course of a couple of years before attempting their first 3-way.

[coolkhoa]

If you're a beginner, I recommend getting an easier book to understand than Vance Dickason's. I would recommend David Weem's second edition book (or if you need an even simpler resource, check out Radio Shack's titles).

[maylar]

Actually, I have the Radio Shack book and have read it. I also have the JL subs left over from a car audio project.

What's the next step?

[roddyama]

Originally posted by maylar
What's the next step?

Dave, your next step is to try and obtain the T/S parameters for your woofer so you can begin to design a box.

[RHosch]

OK, so you've already read a book and seem willing to learn. I'm no expert by any means, so I'll just state the obvious to get the ball rolling.

At this point, you need to answer a few questions that will help direct your design.

(1) What are the primary listening uses of the speaker? Music, movies/theater, multichannel or stereo...? What style music?

(2) What is your budget for all parts and materials? Do you intend to include software in that budget, spend extra for software, or try to use only freeware tools?

(3) What size room do these speakers need to fill?

(4) Do you already have an amplifier or receiver that you want to power them? Are you willing to upgrade to a more powerful amp if required?

(5) Will they be located in a bookshelf? Can you position them away from walls? Do you prefer the look of floorstanders, or smaller bookshelf + separate sub modules?


These questions will help you decide whether to aim for high efficiency, or low cost drivers, or small physical size, or a front or rear ported or sealed system, or some combination of these and similar targets. When you answer these questions, I'm sure others can begin to point you in the direction of appropriate kits, or perhaps even a good starting point for a truly original design.

[Timn8ter]

What are the general steps that a designer/builder uses to come up with a good design before making sawdust?

As was said, get the T/S parameters and decide what type of design you're going after. Sealed, ported, TL, etc.. There are several resources on line for doing calculations for box size and ports if necessary.

After that is when things get more involved, frustrating and time consuming. Read this. From the table of contents find "Articles" then "How to Design a Speaker".

[maylar]

Originally posted by RHosch
OK, so you've already read a book and seem willing to learn. I'm no expert by any means, so I'll just state the obvious to get the ball rolling.

Thank you. That's what I'm looking for. I don't want anyone to design my speakers for me, only to share an outline of what steps people use to come up with a successful design that comes close to expected results when built. Maybe that's a lot to ask...

At this point, you need to answer a few questions that will help direct your design.

(1) What are the primary listening uses of the speaker? Music, movies/theater, multichannel or stereo...? What style music?

(2) What is your budget for all parts and materials? Do you intend to include software in that budget, spend extra for software, or try to use only freeware tools?

(3) What size room do these speakers need to fill?

(4) Do you already have an amplifier or receiver that you want to power them? Are you willing to upgrade to a more powerful amp if required?

(5) Will they be located in a bookshelf? Can you position them away from walls? Do you prefer the look of floorstanders, or smaller bookshelf + separate sub modules?

I very much want to design the system myself. Don't want a kit or someone else's premade project. From what I've read, a sealed enclosure suits my tastes. And I really want a 10" 3-way (just because).

1) Primary use is main speakers in a stereo system. All types of music, mostly rock and classical and sometimes HipHop or rap (my kid's music). I like clean midrange and deep bass. My ears suck (too many rock concerts) for highs, but I don't want harsh highs that annoy friends and family.

Most often the listening level will be VERY low, ambient music. Once in a while it'll be cranked up. I'm sure this is a consideration on driver choices.

2) Prefer to use freeware computer tools, as I don't intend to do this again. I already have electronic test equipment that I've collected for 30 years (I'm an EE and always been interested in audio). Budget for raw drivers is maybe $250.

3) Room is a hardwood floor apartment dining room 12X16, but that can change. I want these speakers to last me 20 years.

4) Amplifier power is not an issue. In fact my reason for making these is to have test speakers that I can use for my DIY amp project. I intend to use passive crossovers for now off a 20 watt stereo, then switch to active when my amp is built.

5) The cabinets will be floor mounted, close to walls.

Do I pick drivers next? Thanks again.

[RHosch]

Looks like a standard 3-way tower will suit your application just fine. The comment about relatively low listening levels is important, as it IMO opens up the possibility of using first order crossovers... at least between tweeter and mid. That would have an impact on suitable drivers.

Your next step, having apparently settled on a sealed 3-way floorstander, is to settle on a "general" configuration that you like. MTM with integrated sub? Standard tweet/mid/woofer tower? First, second, or fourth order slopes? (I'm not too fond of 3rd order, but that is my preference).

I'd suggest one of two routes to take at this point regarding the crossover: first order with wide bandwitdh high sensitivity drivers if you want to use that 20wpc channel receiver indefinitely, or fourth order Linkwitz-Riley crossover design with the assumption that the passive network will soon be replaced with a more accurate active one.

[Timn8ter]

You may be able to find drivers from Vifa that meet your criteria and budget. Look here.