The Repository->DIY->Proven Designs

Q: I don't get it.  Every time I ask questions on DIY forums, people start suggesting that I build a proven design.

A: Well, have you ever built a speaker before?

Q: No, but why should that matter?  Why can't I come up with my own design?  I'm not an idiot.  

A: Believe me, by suggesting you build a proven design, they are in no way insulting you, or calling you incompetent.  In fact, when DIYers suggest this, it's because they actually want you to succeed.

Q: But where's the originality and creativity in just building someone else's design?  The world needs people who can come up with new ideas.

A:  I agree, and you're certainly entitled to "think outside the box."  But what people are trying to help you with is the fact that designing a speaker is a far more complex task than it seems.

Q:  It's just some drivers and a crossover which you can put in a box you like the looks of.

A:  That's like saying that playing playing a piano concerto is just pressing a bunch of keys.

Q:  Ouch.  OK fine.  So tell me why you think speaker design is "so complicated." 

A:  All right.  I'm going to get a bit technical, so hang in there with me.  The first thing most often considered in a design is the box and bass alignment.  The two most common bass alignments for woofers are vented and sealed, but transmission lines, horns, infinite baffles, and dipoles can sometimes be an option as well.  However, every woofer is usually best suited for only one of those applications.  To figure out which one, we examine its electrical and mechanical strength (Qes and Qms), and come up with a figure called its Qts, which, depending on its value will tell the designer which bass alignment will work the best.  Next, we need to know the equivalent air volume (Vas) of the driver.  Using this number in conjunction with the Qts and the drivers' resonant frequency (Fs), we can start designing appropriate cabinets and alignments to get the proper bass response from a driver.  Getting this step wrong means that the speaker's bass will either be way too weak, or overbearing and boomy... neither of which is fun to listen to.

Q: Can't you just get the best bass from a big woofer, and just sort of add stuffing or fiberglass until it sounds right?

A: It's a common misconception that a "huge" woofer is gonna make super-deep, visceral bass.  Actually, the point of having a woofer with a lot of surface area is to increase its Sound Pressure Level.  You'd be surprised; an 8" or 10" woofer can easily extend down to the bottom range of human hearing (20 Hz or lower), when it's in the properly tuned enclosure.  Now please, pay attention.  We still haven't gotten past step #1.

So, now that we have a general idea of our box volume, we can start considering how we want the cabinet to look and where we might want to arrange the drivers on the baffle.  A lot of beginners (myself included, once upon a time) think you can just fenestrate drivers anywhere on the baffle, so long as it looks cool.  Visions of rows of tweeters and midranges are sketched up--and often shot down by the DIY community.  

Q: Yeah, probably because they can't handle any new ideas.

A:  Don't kid yourself.  We weren't born yesterday.  A quick glance at home speakers from the 70s by companies like Marantz, Cerwin Vega, and Sansui shows that these sort of designs were once popular.  But the reason manufacturers don't do this anymore is because through the magic of computer simulation, we've learned that "comb filtering" was a serious problem with most of these designs, and we have since optimized driver layouts so that speakers sound as uniform as possible from as wide a listening axis as possible.  

Q:  What does "comb filtering" sound like?  Some sort of synthesizer effect or a guitar's wah-wah pedal?  

A:  No.  What happens is that, depending on where you are listening to a speaker, relative to its location, you will experience "dead spots" where the treble and mids become quiet and difficult to distinguish.  These dead spots, if you plotted them on a map of the room, would look neatly arranged, like the tines on a comb.

So, to avoid as much comb filtering as possible, driver layouts are often simulated on some sort of software first.  The designer may still try a few different physical baffle arrangements, but the simulation saves him a lot of wood and backache from cutting out all the possible combos and trying them out.

Q:  Great.  So now we're down to the crossover.  Just buy one that matches the crossover points of the drivers, right?

A:  Well, you can, but the end speaker still probably won't sound all that impressive.

Q:  Why not?  I'll just use really good drivers.

A:  I wish I could say that building a speaker is like building a computer--that you just match up bus speeds and buy the latest high-quality gear you can and you've got a rip-roaring machine.  Speakers are a strange analog animal, though, and getting high-quality performance from them is a delicate balancing act, where components are calculated, simulated, listened to, tweaked, measured, evaluated, and revised again and again until you have a speaker that is truly "transient" and transparent.  And you'll know when you hear a speaker that gets this right.  You'll hear depth and detail in music that you've never heard before, but the speakers will be non-fatiguing to listen to, and will just sort of effortlessly reproduce the music without using any sort of trickery on their own part.  It is that sound that makes people pay thousands and tens of thousands of dollars for HiFi speakers.  And yes, it is definitely possible for a DIY speaker to achieve that sound, but not with an off-the-shelf crossover.

Q:  So what's so special about a "custom designed" crossover?

A:  As I was saying, speakers present all sorts of strange analog quirks.  A crossover designer almost becomes one of those "plate spinners" from the circus, as he tries to successfully manage several factors at once: filter order needed to attenuate the unwanted frequencies (aka: "stopband"), combining Acoustic Phase introduced by the filter and physical offset of the drivers, flat frequency response, gently-tapered power response, and keeping electrical Impedance and Impedance Phase safe for a given amplifier.  Hopefully, when all those factors are in-check, the speaker will be sounding pretty good--but often there's still more tweaking to go until the speaker starts sounding "right" in terms of effortlessly reproducing a recording.  Then, to really complicate things, changing the value of one component in a filter often cascades through the rest of the components in that filter.  For example, a designer might increase the value of a capacitor, which may suddenly require the use a smaller-value inductor and perhaps a larger-value resistor... and so on down the line.

Q:  Really?  But in my car, I can just install better speakers and a better amp and I can hear an improvement.

A:  You raise a good point, but the two worlds just aren't the same.  In car audio, they say you can "throw parts at a problem," but HiFi speakers require a whole different kind of effort.  As I said before, crossover design is a delicate balancing act.

Q:  So making a speaker sound good is hard to do?

A:  Yes, it is.   The crossover in a HiFi speaker is like its brain.  And as a result, a badly-designed crossover can make extremely expensive Scandinavian drivers sound like crap.  Alternatively, a well-designed crossover can take "cheap" Chinese drivers and make them sound excellent.

Now, as with many things in life, there is an easy way and a hard way to learn the ropes. Honestly, most DIYers' first design is something they'd rather not talk about.  We were all stubborn once: insisting on using XYZ drivers, designing any enclosure we thought was cool, and using just about anything for a crossover.  And the results were baaaad.  Pretty much all of us have been humbled by our first "inventions," and it is this experience that people are trying to help you avoid when they suggest you build a proven design.

Q:  Well, I'm going to be smart about it.  I want to do all my research, and find out everything there is to know about crossovers before I build my speaker.

A: Be my guest!  I don't mean to dissuade you, but you are probably headed for an "in over your head" feeling.  But there's nothing wrong with doing your first design from scratch, following the rules and trying to use good design principles; but no matter how hard we try, maiden voyages are often pretty rough.  Many veteran DIYers stubbornly built their first design from the ground up--and then consecutively built better and better projects.  As with most skills, this is an iterative "practice makes perfect" approach, and it will work.

What's really cool about DIY audio, though, is that there is another road to success--a shortcut, if you will.  You can follow someone else's plans (which have already been approved by many listeners as "high quality"), and turn a pile of parts into something that puts out a jaw-droppingly good sound.  

Q:  So you're saying "take someone else's plans, and focus on the woodworking?"

A:  Yes.  Good cabinet construction is one of those things that seems easy until you get your hands dirty and do it.  There's a lot of work involved!  Even if you're an extremely skilled woodworker, you'll still be doing a few inventive tricks you never had to before.  The woodworking process is project in its own right.  Put your initial energy into making a beautiful cabinet... and take the burden off yourself of somehow making the cabinet sound good once the woodworking is done.  

You will feel no less proud at the completion of your project if you've used someone else's crossover; in fact, chances are you won't be able to wipe the smile of satisfaction off your face every time you look at and listen to your new speakers.  By doing someone else's design, you're not "selling out" or "being too conventional."   You're really just spending your money wisely: if it's going to cost you a few hundred dollars in parts, wouldn't you like to be guaranteed that the end result will sound really freakin' good?  

But don't let me stop you from taking a risk.  If you feel as though you are on a mission to design your own speaker from the ground up, then you should do it.  This will all make sense to you after you finish.


Comments

Mark65 @ 03-03-2009

Excellent! I kind of worry about the conversations that you're having with yourself, though...... 

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Andy_G @ 03-03-2009

Nice work Paul.

I like to think of myself as "outside the box" with my speakers, but I started building (many, many years ago) using manufacturers recommendations, maybe 10-15 pairs of speakers done this way !

I then progressed to "modifying" manufacturers and other DIYer recommendations, I also build a couple of "exact" designs from other DIYers for other people.

I think DITers need to get an "understanding" of what works and what doesn't, and there really is no way a person can have that understanding when building their first, or second or... speaker. It takes many!

look at your own progress. a few speakers, unsure of yourself, but with a bit to pushing, and the "understanding" gained from those early efforts, enabled you to take a foggy idea and implement a very good design. I am still impressed  

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Teran @ 03-03-2009

One addition I would make is that very often that off-the-shelf design is going to have to be modified slightly for the builder's particular room/placement/aesthetics/etc. This is going to require enough modification to box tuning/padding/bsc/etc. that the builder will still end up creating several forum threads trying to get enough of an understanding needed to get it half-way right. After all that, they will still have less than 10% of the knowledge necessary to design a decent speaker. But, their ears will get a little training and they will understand a lot more of the terms/concepts involved. Better, they will understand how much more there is to know.

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MT Speakers @ 03-03-2009

+1
I got interested in speaker building about 2 months ago. It took me a while to figure out that if I wanted to get the most for my money, I should go with a proven design. So I settled on the Zaph SR-71. Now as I'm building them and studying their design, I am just beginning to know what I don't know about speaker design.

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brianpowers27 @ 03-03-2009

Paul,

This is a good read. It somehow feels incomplete though. I expected to see the section about your first build... Pick a nice 6.5" poly and match it to a low fs tweeter.... (:

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Erick O @ 03-03-2009

That is exactly what I did. Glad to see i'm not alone. Intending to make "garage speakers" I picked up a goldwood 6-1/2" poly and a Tang Band 28-847SD and crossed with a textbook crossover at 3500hz. Not bad sounding, but not great.

That being said, i do believe the experience of making the cabinets was good. If I had spent the money on a good proven design and had the cabinets turn out like they did, I would have been upset. Again not bad, but I am hard on myself when things arent perfect. Though when you crunch the numbers a proven design wouldn't have cost all that much more then what I spent. Shame on me anyway. Any experience is priceless though. Now I know my tools better and i'm ready. I have a tritrix kit on the way and now i'm fairly certain i can get a good result.

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OldDude50 @ 03-03-2009

Paul, just one comment about why to pick a proven design.

It is not simply the technical expertise of the designers that you get with a proven design, it is the "ears" of a good designer that you also get. For example, look at Curt Campbell's Tritrix. Curt admits that it does not measure "flat." Yet, I have heard no one say that they don't like the sound.

Or, for a first project, buy a pair of Insignias from Best Buy, modifiy one using Dennis Murphy's cross-over, leave one alone and listen to them one at a time on an A-B receiver or amp. The difference is huge. Perhaps more than any other project, this one can help the new builder really hear the difference that a set of "experienced" ears can make.

There is so much junk out there in the ready-to-buy world that a new builder has heard that many don't know what a truely good set of speakers sound like. Building a "reference" set, from a proven design, can help a new builder with his own design by giving him or her, well, a reference.

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brianpowers27 @ 03-03-2009

+1. It is hard to know you got it right if you have never heard a great pair of speakers.

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BigGuyZ @ 03-03-2009

I think that part of it is that bringing people into a hobby is easier if the entry cost is low. Now I’m not only talking about money here- as speaker building can be quite $$. What I’m talking about is the initial investment of time needed to participate. When I built my first speakers, I took a chance and went with a kit from an online. I was comforted by the fact that the designer of the kit is very well-known, as at the time I wouldn’t have thought a hobbyist would be able to design something of quality. Also, the crossovers were pre-assembled, so there was no worry about how to best lay them out and connect them. So, all I had to do was build the cabinets. As a result, I feel I got what I wanted out of the experience, and now I’m looking for a more advanced design, where I’ll be building the crossover, and I can make some changes to the design as well.

I don’t think that I’ll ever get to the point of doing my own design- or making crossover tweeks even- but since I went with something that I was comfortable with (because it was proven), I ended up with a new hobby that I’m enjoyed (and cursed).

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---k---  @ 03-03-2009

Paul,

That's great, as usual. I'll continue to point people that post those type of questions to your website.

Reading it, I just kept thinking that building someone deign also teaches so many skills that can be used to avoid mistakes on the next project. There are so many ways of doing things. Some of the build threads I see online are often not the easiest way of doing things. Building a cheap pre-designed speaker would teach all those little things, such as:

1) laying out crossovers on a board small enough to get through the woofer hole.
2) Don't glue your crossovers in, so when you have to fix one of your mistakes you can easily get it out.
3) Don't put so many braces in your box that you have no room left inside for your crossovers.

I'm sure we can go on.

I wonder if links to Speaker Building 201 would be helpful. Also, links to Unibox, PCD, and BDS would be helpful. It might quickly overwhelm them into retreat.

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Curt C @ 03-03-2009

Your FAQ's are great resources Paul.
Nice addition...

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Jed K. @ 03-03-2009

I like Paul's style. Straight to the point, and the dialogue format is "approachable." Well done Paul.

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ropey man @ 03-03-2009

Paul,
I must say, brilliant. Having an explanation behind the theory is nice. It does an excellent job explaining the idea behind doing things this way. It also helps first timers and noobs understand why. Its not getting "pawned off" or pushed away because people don't want to help, but its like playing a sport. Nobody jumps right in and starts. You have to practice to work your way up into the game. Very good Paul, very good!

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mike1234 @ 03-03-2009

Well... I have to say one should aim high without fear of falling hard. But that's just my opinion. Please keep in mind this is coming from an indiviudal who has yet to build even one speaker so take this with a grain of salt. I guess I just like the opportunity to fail miserably but I do tend to study and prepare longer than most before taking the leap. I still have much to learn before I try my first hurdle but I won't be setting it so low that I won't feel like I accomplish something of real value.

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brianpowers27 @ 03-03-2009

It seems like everyone has to learn from mistakes. Whether or not they are yours or mine is a different story.

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lasse @ 03-03-2009

Forgive my asking Mike, but you have like 3200 posts and haven´t yet built a speaker?

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mike1234 @ 03-03-2009

There's nothing to forgive, Lasse. You are correct. I like to talk too much and don't really have much of value to say. Sad, isn't it?
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lasse @ 03-03-2009

Aah, NOW I see what you are saying in your previous post. (it took three more readings) Please forgive my ignorance in english. Being a Swede, I hope this can be forgiven.

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mike1234 @ 03-03-2009

You had every right to mention your concern. My opinion is on a diffuse array topics rather than focused on speaker building. I feel the same way about any endeavor. If one can't build something he/she is really happy with, though lots of tweaking may be necessary, he shouldn't bother with it. I think one should aim for the goal he wishes to achieve and make it happen. I don't believe in settling on something lesser unless it's truly necessary. I suppose it's a measure of passion for something. If the passion isn't intense enough to set the very highest standards then said passion isn't great enough. Again, this is just my opinion.

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Ryan M @ 03-04-2009

Great read Paul!

I haven't yet built my first speakers and I started down the road you describe but luckily I was persuaded in time. I wish I'd read that before I spent all that time planning something that probably never would have worked out since I didn't realize there was anything more to a XO then the textbook designs.

So for my first build I'm making Zaph's WgTMM's and can (after doing a lot of reading) appreciate what goes into designing speakers let alone 'let it all hang out' and expose your design to the internet. I've never had exposure to much better than wallymart boombox systems and I'm really anxious to hear what a good design sounds like.

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gc1 @ 03-05-2009

For my 2 cents, I would add the notion that for a "first build"; it might be a "test box"... great tool for learning to build boxes, match drivers, and is still usable after many other builds. You can make a few "generic" baffles (mounted with wood screws), try different damping material combos, and try different vertical/etc placement of these test boxes to learn the importance of radiating positions.

GC

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brianpowers27 @ 03-05-2009

That is a great idea. I have thought about something similar that would use bar clamps. You could also create a standard box, even if it didn't match the baffle. Using a board on the inside you could even adjust the depth.

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arlis_1957 @ 03-05-2009

paul, very nice faq indeen.

Q: I cant spin plates, what should i do?

A: Buy the recession buster from madisound and the other parts from parts express and don't worry, be happy.

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intjonmiller @ 08-06-1020

 At the risk of raising the dead here, I just read Paul's writeup (actually his whole site; THANK YOU!) and a problem I've struggled with for several years, since my first design (which I did without reading anything on the subject, I just put things together to see how it sounded; hadn't even occurred to me yet to look anything up): How do I know how good what I've created actually is if I've never heard, much less recently heard, an excellent loudspeaker? I don't have a reference pair and I don't have any measurement equipment. And I don't have a budget to do more than my current project, so it's very difficult to build a "proven" design first.

Has anyone considered renting out their reference builds? I have spent zero time analyzing this idea. Just wanted to put it out there.

What is the best-bang-for-the-buck in terms of good reference speakers? How about the easiest to build, so I don't have to spend weeks putting together reference speakers just to compare with the ones I actually want to perfect?

My general feeling is just as Paul wrote on his site (in describing people like me): building something someone else designed doesn't appeal to me like something new and unique does. It's not that I think mine will be better than theirs, just that it will be mine.


By the way, I LOVE the general cooperative nature of the DIY audio community. So many other hobbies seem full of people who don't want to help others. This is one of the most attractive aspects of this hobby, at least for me.

Thanks for any thoughts!

- Jon

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LouC @ 08-06-2010

I think you did a really nice job on the FAQ's! My suggestion for one more reason to start with a proven design -- finding mistakes. We all make them -- even the old timers. Starting with a blueprint makes it easier to find problems (like miswired crossovers and drivers) and learn how to "debug". Once a neophyte has a successful build, he also can learn a lot from reverse engineering the design.

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johnastockman @ 08-06-2010

Already having a well-designed speaker for reference was the reason I originally came here asking why my fixed-number XO formulas and pre-mades weren't working AFA listenable SQ goes. I've heard countless times about a friend or family member going on about how good their brand-name speakers sounded...until they brought them over and we listened to a DIY design. That tripe about you-don't-learn-anything-about-how-to-design/build-a-speaker-from-doing-a-proven-design is not true.

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DIYNut42 @ 08-06-2010

Good read! I just got hooked on speaker building about 3 months ago. Decided to go with a set of TriTrix TL's for my first build. Before that I had just thought about throwing something together, and going about it in a trial and error fashion. Not only would that have been expensive, but I was also affraid I might be so disapointed that I would never want to build a set again. I appreciate the hard work that some of these guys have put into the designs, and for now I will stick to reading the "recipie" to learn more before I start designing my own.

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ocdSHACK @ 08-07-2010

For me, a DIY design and a Proven Design accomplish 2 different things. If you really want to learn, do your own design. If you really want an awesome speaker that doesn't cost much, choose a proven design. I learn by doing it, or attempting to do it, myself. This does include getting help from the people who really know what they're doing. But If I want a speaker I know will sound great, I'd build a proven design. If I'm building a speaker to save money, save time, or reliably sound great, it's proven all they way. But, some things aren't learned until you do it yourself.

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robertclark @ 08-07-2010

Paul,
I want to thank you for taking the time to share your thoughts in your OP. It was a good read and helpful.

One thing that I've appreciated most about this site is the depth of passion that people in the DIY speaker community have about the hobby (did I say hobby?) and of their willingness to freely help others.

I stared out by building a well documented, proven design a few years ago and it proved to be a good learning experience for me. Since then, I've continued to gain valuable insight from others that are involved in the hobby (Wolf, Shawn, Pete, Curt, and others).

I've had the opportunity to attended several DIY GTG's, "talk shop" with people who openly share their experience with me and got to hear /evaluate several top notch designs.

Collectively, it has helped me to gain a better understanding of what it really takes to design a loudspeaker and it has encouraged me to get to the place where I can attempt a design of my own. You gotta' crawl before you can walk.

I appreciate the positive atmospere that exists here (unlike some of the others which I won't name). No offence to anyone but I hope that we can all endeavor to maintan that here.

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WayneN @ 08-07-2010

Excellent write-up!

I have yet to build my first set of speakers even though I have had all the parts for months now but I will as soon as all the other major projects are taken care of.
I’m so looking forward to hearing what a good designed speaker sounds like.

Thanks again for taking the time to do this!

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r-carpenter @ 08-08-2010

I am a pro cabinet maker and have been building and designing for a few years. BUT! Even given the fact that I can make an overly complicated beautiful looking cabinet without too much hesitation, the first time I build, I've made mistakes. And if I wasn't so sure of myself and actually read info on this forum, I'd be saving myself lots of time and would have better speakers to begin with.

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MrkCrwly @ 08-09-2010

Your proven design FAQ is a hoot. Not only informative and persuasive but a fun read. Nothing better than someone talking to their imaginary friends. Excellent advice.
Currently I have no intention of designing the guts of the speakers I build. My passion lies in the woodworking aspects of this hobby. I have built a few clocks and I didn't design the movements in those either. Thanks to you and all the other designers for providing us with great alternatives to choose from.

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dano @ 08-10-2010

Let me give new builders a firsthand perspective on building proven designs or doing your own. Designing a good speaker is difficult even if you have some background in audio. Several years ago I owned a car stereo shop. I designed and helped build several auto sound stereos, and I understand basic crossovers and know how to design sub boxes. However don't have experience building home speakers.
I'll try to keep this short, but some of you would be first time designers could benefit from this. I bought some of the bravox buyouts and decided to design my own speakers. After all I'm pretty smart, I’ve built good car systems, know basic crossover design, and can model sub boxes. It can't be that hard right.
WRONG WRONG WRONG
Sure if all you want is to cross the tweeter so it doesn't burn up and make the woofers rumble a little its not. But if you want a really good speaker that images well, has balanced frequency response, low distortion and sounds great, sit down.
You can't imagine how complex something as simple as a speaker can be, or how much knowledge must be acquired to design one successfully. Building your own design can also be quite expensive. Coils and caps are quite expensive and if you get the crossovers wrong you could easily get stuck with hundreds of dollars in parts you can't use.
I have studied so hard, modeled so many different versions, and traced so many curves I'm burned out and don't know if I'll even finish my speakers. I'll finish and I'm confident I'll make a good speaker. I don't have a choice because I already bought the woofers.
I'm not trying to discourage anyone, but it would have been so much easier if I had built a proven design or two and learned speaker design slowly instead of taking the cram course I've taken.
This is just my opinion and my experience. Take it as you will.

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