If you want to make it stiffer, why not just add some carbon fiber on the outside and the inside? If I'm not mistaken, my Summas are a carbon-fiber / MDF / carbon-fiber sandwich.
The downside of this construction is that it's very labor intensive. The upside is that it's about as solid as a hunk of granite. Even at high volumes, my Summas don't vibrate a bit.
Might be an option for you, particularly if your baffle is already MDF. Just add carbon fiber and you're good to go.
Patrick:
I don't have a specific performance objective with the material vs mdf such as stiffness. It's looking likely I'll have some waveguides cast in polyurethane, and I'd much rather finish out the enclosures using poly boards bonded, rather than some mixture. Also composite materials seem to be growing in popularity with high end makes, so I'd like to just learn a bit about how to work with them.
I've never seen Summas, but I recall someone saying they were a solid surface composite similar to corian. Fiber and resin covered MDF does sound labor intensive, but stupidly strong.
I don't have a specific performance objective with the material vs mdf such as stiffness. It's looking likely I'll have some waveguides cast in polyurethane, and I'd much rather finish out the enclosures using poly boards bonded, rather than some mixture. Also composite materials seem to be growing in popularity with high end makes, so I'd like to just learn a bit about how to work with them.
I've never seen Summas, but I recall someone saying they were a solid surface composite similar to corian. Fiber and resin covered MDF does sound labor intensive, but stupidly strong.
Jason
My appologies, its 5045 - just learned that (I had the number wrong) today when I picked up another batch!!!
John's Summas were a unique set of carbon fiber skins, with a "corian" type of back fill on the baffle and MDF on the sides and back. I do not use fiberglass at all anymore because it's basically an obsolete process given the advanced polymers available these days. Yes it's "stupidly strong", but absurdly heavy.
My enclosures are now all polyurethane. Its light, but strong and very well damped. By all accounts its the future.
My appologies, its 5045 - just learned that (I had the number wrong) today when I picked up another batch!!!
John's Summas were a unique set of carbon fiber skins, with a "corian" type of back fill on the baffle and MDF on the sides and back. I do not use fiberglass at all anymore because it's basically an obsolete process given the advanced polymers available these days. Yes it's "stupidly strong", but absurdly heavy.
My enclosures are now all polyurethane. Its light, but strong and very well damped. By all accounts its the future.
Paul
I answered this once - don't know where it went.
My enclosures are now constructed as basic frames in polyurethane boards and then the waveguide is cast from a polyurethane composite into this frame. The frame is then routed to finish. The whole construction (aside of one small board inside) is polyurethane with no nails or screws at all
I answered this once - don't know where it went.
My enclosures are now constructed as basic frames in polyurethane boards and then the waveguide is cast from a polyurethane composite into this frame. The frame is then routed to finish. The whole construction (aside of one small board inside) is polyurethane with no nails or screws at all
Earl,
All this talk of plastic has me wondering (and has since you began mentioning it). I'm just a bit of a skeptic. Of course I wouldn't expect you to make a common mass market kind of decision with something as important as this.
I had the misfortune once of listening to a plastic speaker in a pub. A tripod mounted, 12", generic horn kind of speaker emblazoned with a plaque bragging of its ABS construction.
I had only once or twice before heard the sound of plastic more than any speaker I'd paid more than $5 for. (There was this early sixties powered tabletop phono with detachable 3 litre fully plastic enclosures with 5" full rangers, for example).
My current bike has a fibreglass fairing which is larger and heavier than others I have owned, and it is more sturdy, not needing much attention. I was once thinking of learning the art of plastic welding for the trouble dealing with the others.
But then we are talking about polypropylene (I think) here. I hope you can see why I'm skeptical. But I do like the idea of using P/U boards. Is it something that can be done in a DIY kind of way?
@paulspencer,
Paul, you were writing an article called "Bass Integration Guide". I bookmarked it a couple of months ago and I was just going through my old bookmarks. Are there any plans for a follow up?
All this talk of plastic has me wondering (and has since you began mentioning it). I'm just a bit of a skeptic. Of course I wouldn't expect you to make a common mass market kind of decision with something as important as this.
I had the misfortune once of listening to a plastic speaker in a pub. A tripod mounted, 12", generic horn kind of speaker emblazoned with a plaque bragging of its ABS construction.
I had only once or twice before heard the sound of plastic more than any speaker I'd paid more than $5 for. (There was this early sixties powered tabletop phono with detachable 3 litre fully plastic enclosures with 5" full rangers, for example).
My current bike has a fibreglass fairing which is larger and heavier than others I have owned, and it is more sturdy, not needing much attention. I was once thinking of learning the art of plastic welding for the trouble dealing with the others.
But then we are talking about polypropylene (I think) here. I hope you can see why I'm skeptical. But I do like the idea of using P/U boards. Is it something that can be done in a DIY kind of way?
@paulspencer,
Paul, you were writing an article called "Bass Integration Guide". I bookmarked it a couple of months ago and I was just going through my old bookmarks. Are there any plans for a follow up?
Allen, I have a draft version of all 3 parts, part 2 is coming out soon and I have to get cracking on it!
Regarding the "plastic" ... there is plastic and there is plastic. There is plastic, then there is MDF, then there is ply, then there is polyurethane! Going up in both performance and cost. I suspect you will find the two "plastics" are worlds apart.
Regarding the "plastic" ... there is plastic and there is plastic. There is plastic, then there is MDF, then there is ply, then there is polyurethane! Going up in both performance and cost. I suspect you will find the two "plastics" are worlds apart.
You need to understand that injection molded ABS and what I do are completely different things. With ABS the wall thickness is very limited, 1/4" is very thick (and very hard to do). My panels are 3/4" on the sides, 1" on the back and 1.25" on the baffle - all this is then heavily braced. The waveguide varies continuously, but is never less than 2" thick. The two methods of construction are not even remotely comparable. ABS is not at all damped and my polyurethane is extremely well damped (mine is a composite for just this reason.)
All of the injection molded ABS speakers that I have see are complete junk. Not even worth considering.
All of the injection molded ABS speakers that I have see are complete junk. Not even worth considering.
Foam boards
This company in California manufactures the foam boards: Machineable Plastic, Resin, Casting Molds, and Fillers - Cedar Ridge, California They have various densities and can cut custom thicknesses. I found them very helpful on the phone.
This company in California manufactures the foam boards: Machineable Plastic, Resin, Casting Molds, and Fillers - Cedar Ridge, California They have various densities and can cut custom thicknesses. I found them very helpful on the phone.
Tring to understand what your work was about, i've searched on google. Seen a lot of your presence on a lot of forums. But nowhere any real response curve, distortion curve etc... (yours looks kind a strange)
Somewhere, i've read that you do not want even to send your systems to reviews. So, sorry to be rude, and, please, apologize, but all that looks a little like snake oil, don't you think ?
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I think each designer have their own views. Earl has some good points, and not all experience can be fully and contiguously conveyed in forums where everyone is expression an opinion now and then. Also there are few reviews that are really in sufficient detail to allow people to know what the reviewer really hears.
As an old sound designer, i've seen a lot of that kind of reviews from a lot so calling "revolutionary" systems during my (not so) long life. I remember one so calling using the enclosure resonances as controled complimentary emission. With the same kind of listening commentaries.That i know for sure, is that all serious manufacturers or designers publish their datas.
I'm pretty involved with horns design, and had made a lot of calculations on spherical waves to design horns. and a lot of measurements, so would be interested by those... if it is serious.
I would like to see the response curve of the motor, it impedance curve with no charge, it impedance curve with the horn, response curves that are not outrageously smoothed etc.
Dr Geddes has posted frequency response, polar response, and invested thousands of hours explaining why he made the design choices he made.
On his own web site he lists the names of the drivers he uses.
Hell, he's published the CROSSOVER. That's unheard of, particularly in an industry where manufacturers routinely use smokescreens and nonsensical claims to obscure the merits of their products.
I've been building horns for about fifteen years. Despite my deep investment in learning how they work, I came to the realization that I simply couldn't make a speaker as well as he could. And then I bought his.
That was a great choice, and I've been a vocal and happy customer for three years now.
I post a lot of data as Markus has highlighted. Far more than the norm, there is no "snake oil" here, I assure you. You may not understand my data presentation, that's quite possible, its not that common, but when you come to understand it you will understand why I present the data this way and not as others do it. I swear by measurements, but you have to take the right measurements.
THD or IMD or any distortion measure that I know of have never been shown to relate to sound quality in any way. Quite the contrary, they have been shown to be rather meaningless. So what would be the point in taking that data and showing it?
I do not send my speakers out for reviews, and I most likely never will. I do, and have, invited anyone, reviewer or not, to visit my showroom and listen and there are numerous reviews of this posted on my site. Setting up a truely supreme set of speakers is not easy and I simply don't trust reviewers to do it right. And you also must not be aware of the review process in this business. It has nothing to do with obtaining accurate reviews.
Trust satisfied customers - they spent a lot of money and have invested a lot of time in listening. I would be happy to put you in touch with any nuimber of satisfied (indeed elated) customers so that you can obtain some accurate "reviews".
It is indeed a sign of the times when you suspect probably the only really honest and transparent loudspeaker manufacturer out there as the one selling the "snake oil".
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Did-you mean that all those old manufacturers like Altec, JBL, Klipsh, Audax, Celestion etc that have bought so much in our knowledges (including your, i suppose) are or where not honest and transparent, publishing their formulas, and explaining their researches and the principle the lie to ?
I have read your white paper (difficult, because English is not my language). I agree on several points. Yes,when you build a two way system you have to take care that the directivity pattern is the same between the 2 transducers at the crossover frequency. And, by the way, it conduct often the horn to have the same diameter than the bass loudspeaker. (That's the way my personal enclosures are designed).
But you do not take care of the vertical patterns? They will have the same effects on local resonances than the horizontal ones, with the same kind of curves you shows (fig 5), because of the vertical distance between the speakers. That is not so important as it is just a question of global energy, don't you think ?. Where i use 24db/oct filters in order to minimize them, limiting the bandwidth they radiate simultaneously, you use very slow cut off The two transducers will radiate simultaneously on a huge bandwidth, with all the phase problems and accidents between us..
About your horn, i don't find anything precise about, but the form is very strange. I was mostly interested with this. My horn were calculated (around year 1990) on spheric waves and seem not to present the same profile than yours.
MHP (la Maison du Haut-Parleur) : concepteur français de kits d'enceintes pour la HI-FI et le Home Cinéma...
That is kind a strange for me. In fact, my horn present a constant directivity, with a flat curve even at 30°. So do not see what is new in your.system.
I have to add that we corrected the motional impedance of our loudspeakers, as well as Zobel, for it present a flat impedance curve. Not your enclosure, if i can see how minimal is your filter.
The last point, witch is very important for me is the vertical alignment of the speakers, in order to get phase coherency (group delay) I had not find anything about this aspect.
That's where digital filtering is a nice tool as you can work to a good and linear group delay, event is the transducers don't have an ideal vertical alignment.
This said, i have no reason to doubt (or to believe) your enclosures sound very well, that is the the way you present the things who had surprised me.
And, because i have no way to listen to them, why would i have to read and believe "reviews" of customers.I believe in measurements both with my ears. And you interesting, but strange way to present some datas does not facilitate their interpretations.
I did not and do not want to be disagreeable. Just , in the case you are a sincere and passionated manufacturer to gives-you a feed back of the feeling some prople like me can have, reading your web site. If it can help.
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