When I first got into DIY audio, it was a mail order world: Heath, Allied, Lafayette, EICO. High end audio retailers were as thin on the ground as they are now. It didn't stop us from hearing equipment. It also didn't stop us from buying just on the basis of specs, data and reviews.
Today it's becoming an internet world and same holds true. Except I think it's actually easier to get good information now.
Good intentions, I think, more than anything. The first few mm of an OS waveguide are critical and a Summa type enclosure and crossover are not trivial builds.
I remember my dad corresponding with Klipsch who told him he thought it was an awfully difficult project for amateurs and "good luck" and he hoped we wouldn't be disappointed. The tone was condescending, to say the least. When we got it done we wrote him back saying we we were very pleased with the results, he replied saying that's nice and assuring us his product, he was certain, sounded better. I dunno about that, really, much later I heard his product and it sounded pretty close - point is, we hit good enough for us at the time.
Last year, or perhaps the year before, I said I got some preliminary things together and was thinking about building a Summa type speaker and got a, (non-condescending), response from Earl, pointing out difficulties in store for me. He wasn't offering kits at the time and I'm sure there was no ulterior motive.
Anyway, I continued with figuring out how to get it done. (I live in an apartment so things do have to be planned rigorously so I can use borrowed work space quickly). I got it worked out and costs calculated. Since then Earl has decided to sell kits. MY DIY project is only going to cost me a bit less than a kit, if I don't make any mistakes.
Has this stopped me from thinking about building a 2 way wave guided speaker? Nope. I've got some Hi-Vi B3N speakers that need tweeters, and that earlier discussion here about domes and waveguides has me thinking about "micro-summas" which I can build at home and put in the back room.
I see there's been lots of action since I started writing this with lots of interruptions. Some good thoughts expressed.
Today it's becoming an internet world and same holds true. Except I think it's actually easier to get good information now.
Good intentions, I think, more than anything. The first few mm of an OS waveguide are critical and a Summa type enclosure and crossover are not trivial builds.
I remember my dad corresponding with Klipsch who told him he thought it was an awfully difficult project for amateurs and "good luck" and he hoped we wouldn't be disappointed. The tone was condescending, to say the least. When we got it done we wrote him back saying we we were very pleased with the results, he replied saying that's nice and assuring us his product, he was certain, sounded better. I dunno about that, really, much later I heard his product and it sounded pretty close - point is, we hit good enough for us at the time.
Last year, or perhaps the year before, I said I got some preliminary things together and was thinking about building a Summa type speaker and got a, (non-condescending), response from Earl, pointing out difficulties in store for me. He wasn't offering kits at the time and I'm sure there was no ulterior motive.
Anyway, I continued with figuring out how to get it done. (I live in an apartment so things do have to be planned rigorously so I can use borrowed work space quickly). I got it worked out and costs calculated. Since then Earl has decided to sell kits. MY DIY project is only going to cost me a bit less than a kit, if I don't make any mistakes.
Has this stopped me from thinking about building a 2 way wave guided speaker? Nope. I've got some Hi-Vi B3N speakers that need tweeters, and that earlier discussion here about domes and waveguides has me thinking about "micro-summas" which I can build at home and put in the back room.
I see there's been lots of action since I started writing this with lots of interruptions. Some good thoughts expressed.
These are very funny sets of expectations being presented.
Dr Geddes makes a living doing this stuff and he has also been somewhat generous about sharing some of his knowledge and experience. He should be commended for that and not chastised.
The threads are long, they go off topic, and the nuggets of science and engineering unfortunately get lumped in with the uneducated opinions and speculation. Yes, that does make our (DIYers) homework more difficult. This is hardly the fault of Dr Geddes and we should not expect him to clean up the mess and make a nice cookbook (that takes time and where is the pay off). He has published articles on this stuff and does discuss some of the issues in his books (which I suspect return fairly little in financial terms). Why should "our" education be his responsibility?
Alas, many have not done their homework and the questions are at a level that demonstrates that. I know I get frustrated when folks ask me questions that are more easily tackled by them taking a hour to read the material and do the calculations.
Personally, I think there are much more interesting and more fundamental questions (specifically his assumptions about "what is important" in speaker design.... and why) that we might want to engage Dr Geddes in (not just trying to get a cookbook on constructing clones).
Just my opinion ....
Dr Geddes makes a living doing this stuff and he has also been somewhat generous about sharing some of his knowledge and experience. He should be commended for that and not chastised.
The threads are long, they go off topic, and the nuggets of science and engineering unfortunately get lumped in with the uneducated opinions and speculation. Yes, that does make our (DIYers) homework more difficult. This is hardly the fault of Dr Geddes and we should not expect him to clean up the mess and make a nice cookbook (that takes time and where is the pay off). He has published articles on this stuff and does discuss some of the issues in his books (which I suspect return fairly little in financial terms). Why should "our" education be his responsibility?
Alas, many have not done their homework and the questions are at a level that demonstrates that. I know I get frustrated when folks ask me questions that are more easily tackled by them taking a hour to read the material and do the calculations.
Personally, I think there are much more interesting and more fundamental questions (specifically his assumptions about "what is important" in speaker design.... and why) that we might want to engage Dr Geddes in (not just trying to get a cookbook on constructing clones).
Just my opinion ....
Hold on, I see no one chastising him and certainly not me. There is some duality here though but at least he's honest about it. I can turn a blind eye to it if its interesting and it is.
Earl has all day, everyday to explore these things. He's lucky. I don't have the luxury of spending days or even weeks trawling through threads, links and white papers. So I guess that means I'm out. Earl's given lots of info already but its scattered and mixed. To gather this information is no small task never mind fully digesting and understanding it.
Was it really such a bad thing to ask for a guide from the man himself for those that are curious?
Think I'll stick to ploughing my own world class speakers - hey we're DIY'ers, we all build the best speakers right?
BTW Earl, thanks for the link to your Waveguide PDF.
You misunderstood me.
I don't think it is wrong to ask, rather I was commenting on the implied expectations. Let's use an analogy to hot rodding a 1966 Mustang. You can pay some one to do it for you but that is not really a DIYing. Or you can come up with a plan about what is most important in terms of performance etc (for that individual) and how might you maximize that. This would of course require the person to learn about the topic and gain some background. Without that background, you would not be able to ask sensible questions. There would be no learning and it would eliminate much of the DIY experience (my own definition). In that case, you might as will pay someone to do it for you.
Two thoughts. First, the Peavy article (by Hughes?) will get you most of the way there. It is not the same OS flare, but it will provide some of the benefit, it is easy to build, and it is easy to follow. I don't think it would be a great learning experience, but you would end up with a very usable product.
Second thought, when reading Dr Geddes work (I have not read it all), it is clear that there is a set of assumptions and priorities about what makes for a good speaker cabinet (no cabinet can do everything perfectly ...). There is also a set of priorities and assumptions about how a cabinet should "interact" with a room. These are extremely important and his design features have followed from this set of priorities. Having a set of priorities and compromises is at the base of any engineering project. So my second thought is that discussing these assumptions and where they came from is much more interesting (at least to me) than the cookbook. I suspect it might be of more interest to Dr Geddes also (but I am only guessing).
It might be that what you are looking for in a cabinet (priorities) is completely different. This last point is probably of some importance since most of us will never actually get a chance to listen to one beforehand.
Again, simply my opinion ....
I don't think it is wrong to ask, rather I was commenting on the implied expectations. Let's use an analogy to hot rodding a 1966 Mustang. You can pay some one to do it for you but that is not really a DIYing. Or you can come up with a plan about what is most important in terms of performance etc (for that individual) and how might you maximize that. This would of course require the person to learn about the topic and gain some background. Without that background, you would not be able to ask sensible questions. There would be no learning and it would eliminate much of the DIY experience (my own definition). In that case, you might as will pay someone to do it for you.
Two thoughts. First, the Peavy article (by Hughes?) will get you most of the way there. It is not the same OS flare, but it will provide some of the benefit, it is easy to build, and it is easy to follow. I don't think it would be a great learning experience, but you would end up with a very usable product.
Second thought, when reading Dr Geddes work (I have not read it all), it is clear that there is a set of assumptions and priorities about what makes for a good speaker cabinet (no cabinet can do everything perfectly ...). There is also a set of priorities and assumptions about how a cabinet should "interact" with a room. These are extremely important and his design features have followed from this set of priorities. Having a set of priorities and compromises is at the base of any engineering project. So my second thought is that discussing these assumptions and where they came from is much more interesting (at least to me) than the cookbook. I suspect it might be of more interest to Dr Geddes also (but I am only guessing).
It might be that what you are looking for in a cabinet (priorities) is completely different. This last point is probably of some importance since most of us will never actually get a chance to listen to one beforehand.
Again, simply my opinion ....
I find its a good thing to have Earl here and I have been inspired by his work, but that doenst mean I will copy his work, nor do I believe its "the end of all speakers" ... and besides, I am building things to have fun
As much as we like Earl here, question is if Earl wants to be here.
We cant be on each others toes all the time and there will be some bashing around from time to time
Earl is a grown man and he will have to deal with that in his own way
Personally, I dont care one way or the other, and you surely wont see me on my knees ... I think its all up to Earl whether he want to be here or not
Please bare over with me if I misplaced some words
As much as we like Earl here, question is if Earl wants to be here.
We cant be on each others toes all the time and there will be some bashing around from time to time
Earl is a grown man and he will have to deal with that in his own way
Personally, I dont care one way or the other, and you surely wont see me on my knees ... I think its all up to Earl whether he want to be here or not
Please bare over with me if I misplaced some words
I'm happy to have Earl's expertise here as well, but some of this stuff has been debunked time after time and he just keeps saying it:
This is a repeat of your "there's accurate and then there's everything else" argument. Neither your speakers nor anyone else's are perfect reproducers therefore they're all in the category "everything else" complete with assumptions, intentional trade offs, and probably missing a trick or two you haven't even discovered yet. You do a lot more research than most people on which trade offs are most audible and I applaud you for that and hope you continue because I find the psychoacoustic info even more interesting than the ttechnical details of waveguides, but that doesn't mean the summas are the one true speaker everyone would (and SHOULD) prefer. I know you don't like it but speakers sound different and everyone has a right to their own preferences.
You obviously find something rewarding in talking about speakers here or you wouldn't put up with all the BS people send your way. If you'd stop thinking of yourself and your speakers as perfect when we all know everything and everyone in the real world departs from the ideal I think the conversation would be even more enjoyable. What's the old saying, "don't mistake the map for the territory"? Of course it is the conflict and proclamations of perfection that are the rewarding parts to you then carry on...
This is a repeat of your "there's accurate and then there's everything else" argument. Neither your speakers nor anyone else's are perfect reproducers therefore they're all in the category "everything else" complete with assumptions, intentional trade offs, and probably missing a trick or two you haven't even discovered yet. You do a lot more research than most people on which trade offs are most audible and I applaud you for that and hope you continue because I find the psychoacoustic info even more interesting than the ttechnical details of waveguides, but that doesn't mean the summas are the one true speaker everyone would (and SHOULD) prefer. I know you don't like it but speakers sound different and everyone has a right to their own preferences.
You obviously find something rewarding in talking about speakers here or you wouldn't put up with all the BS people send your way. If you'd stop thinking of yourself and your speakers as perfect when we all know everything and everyone in the real world departs from the ideal I think the conversation would be even more enjoyable. What's the old saying, "don't mistake the map for the territory"? Of course it is the conflict and proclamations of perfection that are the rewarding parts to you then carry on...
Calculations for the OS waveguide profile can be found here: http://mywebsite.bigpond.com/dmcbean/
Then you have to figure out a way to construct it. The minimal tooling approach for a single pair is probably to make it by laminating successively larger circles, each representing a point on the curve. Then, *integrate the layers* with a filler such as automotive body filler and sand carefully, especially the throat region. The driver throat should be matched within a fraction of a millimeter to the horn opening.
Now you have to design a crossover to mate the two drivers. Dr. Geddes has indicated that he time aligns and level matches the drivers in the crossover. This is not trivial with a passive crossover. But it's not difficult with digital crossovers and biamping. Shinobiwan has extensive experience here. Dr Geddes has described in his website white paper, the crossover frequency for the Summa. For smaller versions he may have described it elsewhere, I'll leave that exercise for others.
You can determine it for your combination of horn a woofer by doing measurements of the polar response of the horn and woofer separately. Place your crossover near the frequency where the polar response is converging for the two.
Make a good solid box with internal oak cross braces to tie the opposing panels together. These braces should relatively small in cross section to minimize internal reflections. Avoid parallel panels, if possible. And use a good radius (2cm or more if you can) on the box edges, especially on the front panel.
That should net you a pretty good speaker.
Sheldon
Then you have to figure out a way to construct it. The minimal tooling approach for a single pair is probably to make it by laminating successively larger circles, each representing a point on the curve. Then, *integrate the layers* with a filler such as automotive body filler and sand carefully, especially the throat region. The driver throat should be matched within a fraction of a millimeter to the horn opening.
Now you have to design a crossover to mate the two drivers. Dr. Geddes has indicated that he time aligns and level matches the drivers in the crossover. This is not trivial with a passive crossover. But it's not difficult with digital crossovers and biamping. Shinobiwan has extensive experience here. Dr Geddes has described in his website white paper, the crossover frequency for the Summa. For smaller versions he may have described it elsewhere, I'll leave that exercise for others.
You can determine it for your combination of horn a woofer by doing measurements of the polar response of the horn and woofer separately. Place your crossover near the frequency where the polar response is converging for the two.
Make a good solid box with internal oak cross braces to tie the opposing panels together. These braces should relatively small in cross section to minimize internal reflections. Avoid parallel panels, if possible. And use a good radius (2cm or more if you can) on the box edges, especially on the front panel.
That should net you a pretty good speaker.
Sheldon
Re: Re: waveguides
I guess you are just too casual.
I think the way you get the shape was quite clear, and once you get that done in a CAD file, get someone to NC it for you if you wish. Lots of people have also posted methods of makeing these things.ShinOBIWAN said:
Agreed, I've been casually following this thread myself but I still wouldn't fully know how to build my own waveguide according to the recipe that Earl has cooked up.
Maybe I'm dumb?
I guess you are just too casual.
The thing that amazes me is that everything that people are asking for I have already done. Like my assumptions for speaker design - its a several page paper on my website. And the equation for the OS waveguide contour has been stated so many times I couldn't count them. And this is all organized together, you just have to read it.
And I have never said that I or my loudspeakers were perfect, but I do believe that we are both in the top ten.
And I have never said that I or my loudspeakers were perfect, but I do believe that we are both in the top ten.
I think a good teacher gives students enough information to let them explore and look for other possibilities if they wish. I think Earl has done this very well. We can never get everyone to agree with anything, that's why we have elections. But at least we can use information we agree to individually and explore new possibilities.