Where can I learn about making crossovers & cabinets? Lots of questions.

[JonW]

I’m itching to try and build a pair of speakers in the future. I know very little about this, so I’m trying to learn the basics now. Been reading a lot on this forum- super place. And I just finished reading the book “Speaker Building 201” by Ray Alden. Good book, but more of the theory, general approach, methods that one can use. It’s time to put some of it all to practice. But I’m still lacking some pretty rudimentary knowledge. I’ve got lots of questions. I’ll list some below. Not expecting you folks to answer them all, although feel free if you like! Perhaps I can be pointed toward a source(s) that will be helpful.

Crossovers:
-I understand the concepts and all. I know nothing about electronics. I’ve looked at lots of the circuit diagrams posted here as well as the accompanying photos. I try to follow the paths around in the photos and the diagrams. They never seem to match to what I’d expect. So I’m reading the diagrams wrong. I need some help here. Not to mention in actually trying to build one. From a theoretical perspective, I only know what I soldering iron is supposed to do.
-Is there a “crossovers for dummies” anywhere?
-How do you connect a finished crossover to the drivers? The photos seem to show some white plastic things (“terminals?”) that could accept wire. But those parts never seem to be in parts lists. What else is missing from those lists that I don’t know about?


Speaker Cabinets:
-How do you attach all the MDF/wood panels or sides? I know you can use simple butt joints, rabbeted joints, 45 degree cuts with a spline added, etc. But what is most common, for the novice woodworker? It seems that a lot of people here just use butt joints. Is that really OK?
-If, say, you connect 4 of the sides with a 45 degree cut and spline (or something else fancy), how do you put on sides 5 and 6?
-Is glue really enough to hold the whole thing together?
-Can I make the cabinets all out of wood, rather than MDF? I realize MDF is preferable, but how much sound quality do I loose by using wood? Maybe a baltic brich plywood or something heavy. Wood just looks so much better and is so much easier to work with (less dust). Maybe with enough bracing wood is OK?
-For bracing, can it just be some flat wood around the edges, or is something more complex required? How do you know when you have enough (or too few) braces?
-For ports, do they have to be in any particular part of the box?
-Offsetting drivers from the center line? I understand the concept. It looks like most people here offset the tweeter, but not the mid/woofer?
-If I needed to tweak the crossover after building the speaker, might it be good to have a little door of some sort in the back, to gain access?
-How do you put on veneer and actually have it come out looking good?
-Maybe have an area at the bottom of the speaker for sand. Are there any tricks to doing this or just the obvious?


General approach:
-Do I start with something cheap or make the speakers that I really want? I’ve got a pair of Totem Forests that I like a lot. Maybe I should try and clone those (or make a MTM variant, etc.). But that will get expensive, I’d imagine. I’m happy to spend the cash to get speakers that I’ll enjoy. But I’ll probably screw up a lot of things the first go around? So make some cheap speakers to start. But then I’ll have some lousy speakers on my hands…

[ThomasW]

Proper loudspeaker design and engineering, and crossover design are VERY complicated things. So this is where we tell you to start off building one of the designs that are sticky threads at the top of this forum. That way you're guaranteed to get a good sounding speaker.

If you read the very first post in the long Modual MTM thread you'll see what's involved when Jon designs a speaker. Now he's been doing this for 30+yrs so he's a bit more advanced that most DIYers.....

[JonMarsh]

Jon, it's probably rather overwhelming to jump into like you may want to.

The truth is, there are many ways to do things. It would be daunting to try to learn everything about cabinet construction AND crossover design concepts AND measuring drivers AND putting it all together on your very first project.

Some of the very first HiFi speakers I built used pre-veneered MDF, which requires cutting miter sections, dadoing, and some other slightly more advanced cabinet construction techniques. But, then you only have to do a minimum amount of veneering.

With a little care basic butt joints will work fine, though augmenting them with biscuit joins is a good idea. Uh oh, I just probably increased the confusion factor. Go check out a tools site for "biscuit jointer" (I have a DeWalt DW682K).

Veneering can be done with contact cement; IMO that's most suitable for plastic laminates, like Nevermar or Formica. I prefer using iron on techniques with PVA glue (like Titebond). See the M8ta big thread for a little about that, or again, use the search engine.

I'm a little tight on time this evening, but I'll come back later this week and take a stab at most of your questions in some detail. Hopefully not too much....

Actually, you have a lot of good questions, at least your clearly observant.

[KeithM]

I’m itching to try and build a pair of speakers in the future. I know very little about this, so I’m trying to learn the basics now. Been reading a lot on this forum- super place. And I just finished reading the book “Speaker Building 201” by Ray Alden. Good book, but more of the theory, general approach, methods that one can use. It’s time to put some of it all to practice. But I’m still lacking some pretty rudimentary knowledge. I’ve got lots of questions. I’ll list some below. Not expecting you folks to answer them all, although feel free if you like! Perhaps I can be pointed toward a source(s) that will be helpful.

Crossovers:
-I understand the concepts and all. I know nothing about electronics. I’ve looked at lots of the circuit diagrams posted here as well as the accompanying photos. I try to follow the paths around in the photos and the diagrams. They never seem to match to what I’d expect. So I’m reading the diagrams wrong. I need some help here. Not to mention in actually trying to build one. From a theoretical perspective, I only know what I soldering iron is supposed to do.
-Is there a “crossovers for dummies” anywhere?
-How do you connect a finished crossover to the drivers? The photos seem to show some white plastic things (“terminals?”) that could accept wire. But those parts never seem to be in parts lists. What else is missing from those lists that I don’t know about?
Those are terminals, you just have to find them. You'll also need acoustic damping, and wood glue and screws(if not listed)



Speaker Cabinets:
-How do you attach all the MDF/wood panels or sides? I know you can use simple butt joints, rabbeted joints, 45 degree cuts with a spline added, etc. But what is most common, for the novice woodworker? It seems that a lot of people here just use butt joints. Is that really OK?
Yes, it's the easiest and really doesn't make a lot of difference from what I see.
-If, say, you connect 4 of the sides with a 45 degree cut and spline (or something else fancy), how do you put on sides 5 and 6?
-Is glue really enough to hold the whole thing together?
I recess the screws in my projects(recessing drill bit) and fill it with wood putty.

-Can I make the cabinets all out of wood, rather than MDF? I realize MDF is preferable, but how much sound quality do I loose by using wood? Maybe a baltic brich plywood or something heavy. Wood just looks so much better and is so much easier to work with (less dust). Maybe with enough bracing wood is OK?
Braced adaquately, it should work. Another thing to do is veneer it and get the wood effect.
-For bracing, can it just be some flat wood around the edges, or is something more complex required? How do you know when you have enough (or too few) braces? When you're box rattles, it isn't adaquately braced. There isn't really a limit to how much you can use, as long as your box size is still right.
-For ports, do they have to be in any particular part of the box? from the back is the most common.
-Offsetting drivers from the center line? I understand the concept. It looks like most people here offset the tweeter, but not the mid/woofer? As long as the vertical distance is different, it doesn't matter too much. Just don't mount a driver right in the middle(horizontally and vertically) you'll be fine.
-If I needed to tweak the crossover after building the speaker, might it be good to have a little door of some sort in the back, to gain access? I'd hold the back on with screws until final assembly.
-How do you put on veneer and actually have it come out looking good? practice
-Maybe have an area at the bottom of the speaker for sand. Are there any tricks to doing this or just the obvious? Just a simple box


General approach:
-Do I start with something cheap or make the speakers that I really want? I’ve got a pair of Totem Forests that I like a lot. Maybe I should try and clone those (or make a MTM variant, etc.). But that will get expensive, I’d imagine. I’m happy to spend the cash to get speakers that I’ll enjoy. But I’ll probably screw up a lot of things the first go around? So make some cheap speakers to start. But then I’ll have some lousy speakers on my hands…

I'd make something you think you can actually use and that will sound the same/better than what you have. If you don't upgrade, what's the point in speding the money?

[Dennis H]

Yup, I'm with Keith. And I'd suggest learning to crawl before you try entering the 100m dash in the Olympics.

You could build any of the designs in the threads here and learn a whole bunch before you try a design/build from scratch. Using the prefab PE cabinets will still give you plenty of woodworking experience cutting the driver holes, installing ports, etc. and you'll end up with a good looking speaker. Using an already-designed crossover will give a good-sounding result. You can measure them and try to figure out why the designer did what he did -- start with reverse engineering and work up to your own original designs later. You'll find plenty of challenges with that approach and blow your friends away when you say "I made that" as their jaws drop over how good they sound. Next thing you know, those Totems will be on eBay and you'll be building speakers to replace them.

[EDS]

Not trying to hijack the thread, I just would like some further detail on this and I'm sure all newbies to speaker building would to.

Offsetting drivers from the center line? I understand the concept. It looks like most people here offset the tweeter, but not the mid/woofer?

As long as the vertical distance is different, it doesn't matter too much. Just don't mount a driver right in the middle(horizontally and vertically) you'll be fine.

Anything to could tell me or show me on this topic would be appreciated. Thanks.

[Evil Twin]

Positioning on the baffle, and design of the baffle, influences both the boundary loading (where the driver goes from 2pi to 4pi space radiation), and diffraction (ripples in the "force" which occur at the baffle edge to a degree dependent on the discontinuity (large roundovers are good and minimize this) and the wavelength (spacing from the driver to the edges).

Minimizing these effects isn't easy, and one of the best compromises is to spread the effects out over a wider range of frequencies (different parts of the edge) by using asymmetrical spacing with golden means ratios.

The concept is that a low amplitude effect at a wide range of frequencies is less noticable than a large amplitude effect concentrated at one frequency.

Look at the midrange panel portion of the Arvo Part design, or the original M8a MkIV two way. Or the Elaine Marie. In many cases, there isn't enough room for asymmetric location of the midwoofers, but the transistion frequencies may be high enough it doesn't matter so much.

Use the FRD Consortium's Baffle Diffraction Simulator, which models both effects, or built in tools in design programs like LSPCAD's BH tool.

[cjd]

Some of the steps and things to consider are *sort-of* included in the pages upon pages in the RS 3-way thread as well.

I started small and dirt cheap. Actually, I hung around and read a LOT for a while, then started messing with modeling tools and some of PE's provided data files. When I got to the point of thinking I understood enough, I went ahead with said cheap design. Yuck. Took me a bunch of revisions to get it to a point where it was OK. And it's not really *that* OK coming back to it after much more experience. It's been a few years at least, probably closer to 4. And I pick this stuff up kind-of intuitively.

I also already knew the woodworking end of things.

So, don't worry about getting anywhere - enjoy the ride.

C

[JonW]

Hi Folks,

Thanks very much for the insights and wisdom. So it sounds like there’s no one quick way to learn all that stuff. I wasn’t expecting it, but kind of hoping you might say ‘Read this book and all speaker knowledge will descend upon you.’ The book I just read was good and I learned a lot. But it left me with more questions than before I started it.

Like many of you said, maybe a good way for me to get started is to try and take on one of the sticky thread speakers. I’ve read some or all of each thread so far. But just to learn. Not with an eye toward picking one. So I’ll go back and see if any of them would be particularly good for me to start with. I’m open to suggestions there or any other insights.

No prefab cabinets for me, though. I really want to learn how to make a nice cabinet. And I’ve now got a teeny bit of circle cutting experience from the subwoofer I’m in the middle of. But regular speakers look to be a big step up in complexity. So it was good I’m starting with the sub.

Looks like fun. Thanks.

-Jon

[peterS]

speaker design cookbook by vance dickenson and www.bcae1.com should get you started

[JonW]

speaker design cookbook by vance dickenson and www.bcae1.com should get you started

Thanks for the recommendation. That book has been mentioned before. I'll have to pick up a copy and see if I can learn a few things.

Edit: I just placed an order for that book.

[Paul H]

You might also try a little web surfing at woodworking sites like woodworking.com to pick up some tips on cabinet making.

Paul