I am cooking up my next speaker design. For me (maybe everyone) the hardest part is the low frequency section. Once I get above 100 hz, things seem easy.
I was thinking of a pair of Anarchy 6.5" 25hz Tapped Horns per side, but the whole patent thing has me discouraged. I also thought about qty 4, 8" OB H frame drivers per side, and I may still do that, but the size is a little large.
So as I sat around thinking, I remembered the Ripole design. That seemed interesting size wise. I also remembered an "in wall" sub that Bohlender & Graebener (B&G) had produced, and wondered if I could mash those two ideas into a Tiny Array of Ripoles (TAR) system.
The B&G sub looked like this.
Anybody up for the challenge of helping me design TAR system with say 12 - 4" drivers?
Regarding "prior art," is anyone aware of anyone else trying this?
I was thinking of a pair of Anarchy 6.5" 25hz Tapped Horns per side, but the whole patent thing has me discouraged. I also thought about qty 4, 8" OB H frame drivers per side, and I may still do that, but the size is a little large.
So as I sat around thinking, I remembered the Ripole design. That seemed interesting size wise. I also remembered an "in wall" sub that Bohlender & Graebener (B&G) had produced, and wondered if I could mash those two ideas into a Tiny Array of Ripoles (TAR) system.
The B&G sub looked like this.
Anybody up for the challenge of helping me design TAR system with say 12 - 4" drivers?
Regarding "prior art," is anyone aware of anyone else trying this?
Because the line cross sectional area is less than the driver Sd in a ripole, the air loads the driver. This has the effect of increasing Qts and decreasing Fs, because the air mass in the line adds to the total moving mass. If you are using those 8" woofers that's good and bad. You can benefit from the increase in Qts, but it comes at the expense of overall sensitivity and those drivers were already quite inefficient. Also, a ripole will have a huge resonance peak, although it might be up at 200Hz for an 8" driver cavity.
Also, no matter how you slice it, if you are trying to use those four 8" drivers that you mentioned in your other thread the result will probably be underwhelming, whether you use a ripole or OB. Like I mentioned, a long H-frame can work but it will be physically large.
If you would just get ONE good quality 12" driver that is well suited for OB/dipole the result will likely be better than all four of your 8inch drivers, combined. Even better, you can go with one of those Eminence Alpha 15A drivers. Xmax is not high, but they are very well suited for U-frame or H-frame and you can just copy MJK's design. They are also not expensive. Save your 8in drivers for some other project.
Also, no matter how you slice it, if you are trying to use those four 8" drivers that you mentioned in your other thread the result will probably be underwhelming, whether you use a ripole or OB. Like I mentioned, a long H-frame can work but it will be physically large.
If you would just get ONE good quality 12" driver that is well suited for OB/dipole the result will likely be better than all four of your 8inch drivers, combined. Even better, you can go with one of those Eminence Alpha 15A drivers. Xmax is not high, but they are very well suited for U-frame or H-frame and you can just copy MJK's design. They are also not expensive. Save your 8in drivers for some other project.
I see. That does not sound very promising at all. Why? Well compare the total swept volume between the 4 inchers and your 8 inch drivers. (swept volume is Sd times Xmax) How many 4 inch drivers are needed to equal one 8 incher? What is the Fs and sensitivity of the 4 inch drivers? What is their power rating? My guess is that these parameters are probably not well suited for use in a ripole subwoofer.
You need some serious displacement, more than for a closed box even, because of the huge amount of cancellation between the front and back of the ripole (or any OB, 'frame, etc.).
Points for creativity, though.
Tapped horn and ripole (or really any type of OB) are polar opposites, they really couldn't be any different. Mentioning both in the same post makes me believe that you really don't understand how inefficient OB is in the low bass.
A 4 inch driver in a decent tapped horn is likely going to ~= a 15 inch driver in OB (ripole, dipole, doesn't matter).
Even a floor to ceiling ripole line array with 4 inch drivers probably isn't going to be as loud as my tapped horn with a single 6.5 inch driver.
A 4 inch driver in a decent tapped horn is likely going to ~= a 15 inch driver in OB (ripole, dipole, doesn't matter).
Even a floor to ceiling ripole line array with 4 inch drivers probably isn't going to be as loud as my tapped horn with a single 6.5 inch driver.
Actually I am aware of the efficiency differences. Which is why in the Anarchy there is 1 6" driver, and in my fantasy "TAR" there are 12 perhaps as many as 24, 4" drivers.
So I realize the differences, and with a di/ripole there is no replacement for displacement, as motorheads say.
I must admit that I haven't thought through the details, but I felt someone here might be interested in the concept enough to help me work through driver selection and possible outcomes.
Did anyone even look at the link I provided? Here is another, in case y'all missed it;
www.manualslib.com/manual/625777/Bg-Radia-Bgx.html
So I realize the differences, and with a di/ripole there is no replacement for displacement, as motorheads say.
I must admit that I haven't thought through the details, but I felt someone here might be interested in the concept enough to help me work through driver selection and possible outcomes.
Did anyone even look at the link I provided? Here is another, in case y'all missed it;
www.manualslib.com/manual/625777/Bg-Radia-Bgx.html
What's wrong with a plain vented box? I'm curious, do you have specific design goals that push you towards a tapped horn or ripole?
That BG Radia design uses that many small woofers because it has the design constraints (1) shallow depth for in wall mounting and (2) low cabinet vibration. One way to fulfil these constraints is by using small opposing woofers, of which you then need a lot to get sufficient output. As mentioned before, using many small drivers instead of a single larger one is expensive, so it only makes sense to do that if there is a reason to.
That BG Radia design uses that many small woofers because it has the design constraints (1) shallow depth for in wall mounting and (2) low cabinet vibration. One way to fulfil these constraints is by using small opposing woofers, of which you then need a lot to get sufficient output. As mentioned before, using many small drivers instead of a single larger one is expensive, so it only makes sense to do that if there is a reason to.
Last edited:
I am trying to design a low frequency module with a small frontal area. Two of the Anarchy THs or one or two narrow tower of ripoles seemed to fill the aesthetic requirements.
The Anarchy TH looks good, but Danley has a patent on the TH design, and I have no desire to violate a patent, either legally or morally. The rest of this speaker system will be OB so there is really no place for a side firing sub, and the sound characteristics could be an issue as well.
Do a tl then. Transmission lines are remarkably similar to tapped horns but there's a notch you have to deal with by either placing it outside the passband or making it behave.
I don't see it as infringing on anything anyway. The layout of the tapped horn has been used since at least the 1950s. Danley's contribution was to figure out how to predict the frequency response (which could have been done anytime in the last 20 years by someone with Akabak) and actually use the concept in a modern design.
Build what you want.
Jensen Transflex circa somewhere around 1954 I think.
I don't see it as infringing on anything anyway. The layout of the tapped horn has been used since at least the 1950s. Danley's contribution was to figure out how to predict the frequency response (which could have been done anytime in the last 20 years by someone with Akabak) and actually use the concept in a modern design.
Build what you want.
Jensen Transflex circa somewhere around 1954 I think.
By reproducing a design for yourself, that you do not sell to anyone or profit from it in any way, is not patent infringement. If you are planning to advertise or sell the product of your work, then do not copy any patented material (at least directly without at least adding something to make it "different").
There's prior-art of that as well. It's been posted a few times here. I think JAG is correct in his analysis of what TD did. I'd go even further and say that that TD found a way to significantly extend the passband of a 1/4 wave resonator by judicial position of the driver in the path to basically "fill the gaps". It's not uncommon to see TD's THs quoted with a response that extends from below 35 Hz to above 200 Hz. Compare that to the Anarchy's FR. I refer to designs like the latter as "compromised THs", as there's no similar focus on extending bandwidth, likely to keep box size down.
This is what I thought until someone corrected me. So I looked it up and it turns out even personal projects are patent infringement. Not that I care, not that the patent holders care. Most people on a diy forum were never going to be customers anyway and we don't take money from their pockets. Danley didn't seem upset at all that the TH_SPUD plans leaked, not that it was difficult to figure out what's in there anyway.
I wouldn't produce them with the intention of selling them though, I see a pretty clear line there. But even that will be ok in a few years when the patent expires.
Aceinc,
William Glen had already done that in 1956, his "Acoustic Horn Assembly is what DSL later called a "Tapped Horn". Glen's horn used stuffing in the horn path as an acoustic low pass so the driver could be used "full range" without the usual TH peaks and dips in the upper octaves.
Art
Attachments
Sell them. That should be fine as long as you are not selling a couple dozen of them. It's done all the time, if fact I might be selling the one I made in 2009 quite soon.
Or just take the drivers out, burn the cabs and resuse the drivers.
Just don't make them for the intent of selling them for a profit and all is well.
Theoretically the patent system was created to encourage the sharing of ideas with the benefit of a few years of IP protection in return. But the patent system is a big broken mess now. Patents are given out for stupid things like how to swing on a swing and other ideas that have been in the public domain since the beginning of time. Companies keep patented ideas alive by changing one small detail and refiling again and again. Some companies try to patent every single thing they think of just to prevent anyone else from using the idea. Patents are not enforceable unless you can afford to enforce them against the largest company that wishes to steal your ideas.
The patent system is a broken joke. I don't spend any time worrying about whether I'm breaking patent law for my personal projects. Nobody cares. Just don't make patented stuff for the purpose of selling it for profit and nobody is even going to be mildly concerned what you do in the privacy of your own home.
Or just take the drivers out, burn the cabs and resuse the drivers.
Just don't make them for the intent of selling them for a profit and all is well.
Theoretically the patent system was created to encourage the sharing of ideas with the benefit of a few years of IP protection in return. But the patent system is a big broken mess now. Patents are given out for stupid things like how to swing on a swing and other ideas that have been in the public domain since the beginning of time. Companies keep patented ideas alive by changing one small detail and refiling again and again. Some companies try to patent every single thing they think of just to prevent anyone else from using the idea. Patents are not enforceable unless you can afford to enforce them against the largest company that wishes to steal your ideas.
The patent system is a broken joke. I don't spend any time worrying about whether I'm breaking patent law for my personal projects. Nobody cares. Just don't make patented stuff for the purpose of selling it for profit and nobody is even going to be mildly concerned what you do in the privacy of your own home.
Yeah, Jensen 1954 & Glenn 1956 were WELL ahead of their time ! And don't forget Thuras, who invented the reflex in 1932 ! Then there's the horn guys, before & after them too.
It's a pity no sound recordings were available @ the time to make Full use of the Very clever designs.
Plus a lot of people might have forgotten, or some weren't even aware of the Jensen & Glenn designs, so between the 60's - 90's they were ignored ! Danley et al, should be held in high esteem, for working out the maths etc to further develop these inventions, into truly greater designs.
It's a pity no sound recordings were available @ the time to make Full use of the Very clever designs.
Plus a lot of people might have forgotten, or some weren't even aware of the Jensen & Glenn designs, so between the 60's - 90's they were ignored ! Danley et al, should be held in high esteem, for working out the maths etc to further develop these inventions, into truly greater designs.
You do not have to worry so much about patents unless you are commercialising the object or its produce. So don't 1)sell them; 2)use them for profit, as in a PA system, or 3) reverse engineer and publish plans for it(you can tell someone how to figure out what to do, but not what to do).
As to many small drivers, remember that (clean)displacement is SD times Xmax, and little drivers have small Xmax as well as small SD. If you want the champion of small front and high output try Bill Fitzmaurice's TruckTuba. It can be made only 4-5" wide(the depth will be 24" but so is a lot of furniture). You can buy the plans and you will have paid for the rights.
As to many small drivers, remember that (clean)displacement is SD times Xmax, and little drivers have small Xmax as well as small SD. If you want the champion of small front and high output try Bill Fitzmaurice's TruckTuba. It can be made only 4-5" wide(the depth will be 24" but so is a lot of furniture). You can buy the plans and you will have paid for the rights.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.