TH and intellectual property


2016-05-01 5:00 pm
Hi everybody. I have a question regarding intellectual property. I know many of you are professionals in this industry, and I would really appreciate some input.

Over the years I have become super intrigued by the tapped horn concept and I have build some my self, but I am fairly new to speakerbuilding. Today I am working on a compact pa/full range project that involves a small 10" TH. Just recently I became aware that TH is patented by Tom Danley, and I cannot find any understandable literature that explains what the practical limitations are on my part. Does it mean that any tapped horn build is illegal to sell? Lets say that I skipped a few stages in my speaker building experience and was able to build something really nice from my small diy workshop, am I breaking some law or stealing intellectual property if I was to sell some of my home made projects commercially?

As I started to explore the danley website, I came across the synergy horn. Now I have the same question regarding the synergy/unity concept. Would the patent prohibit anyone from legally selling his/hers own synergy/unity design commercially? And what is it that the patent controls? Is it a general patent that includes all point source audio from a horn, or a more detailed specific patent that allows for others to sell their own smaller design?

I'm not any where near to sell something commercially, that would be years in the future. All I have for now is hornresp, a few ideas and some time on my hands. But it is nice to know what I am legally allowed to dream of achieving. I am a guy with some ideas myself, so it is important for me to respect intellectual property.

Thanks for any inputs!


If you want to build the cabinets to sell them, then you're probably violating the patent - you're using the information there to make your own profits. In that case, you'd have to talk to the patent holder about arranging a licence to sell that product.

If, however, you built the speakers, used them for a few years as part of your PA system and then decided to sell the speakers, I think you're on safer ground. 2nd hand custom/DIY equipment rarely sells for the cost of the components, let alone anything for the cabinet. You're unlikely to profit from the sale of the speakers.

NB - I'm not a lawyer. This is just my understanding of the situation.

You absolutely must get the relevant patents (easy-ish on the internet these days) and firstly check that they are in force and fees paid. (patent office website). It is easy to mix up an application and a granted patent.

If it is a granted patent check for coverage - to get worldwide coverage needs lots of granted patents. Areas get missed out as commercially unimportant. Getting a granted and maintained worldwide patent is stupidly expensive, because as the patent gets older the fees get higher. Most patents lapse - there is simply not enough commercial value to maintain them. And in many cases patents are created simply to prevent anyone else from getting a patent, thus freeing up the commercial exploitation. Plenty of people will write BS on the websites and literature to provide an illusion of patented product to put people off.

Then, if you think your region is covered by a granted patent, regardless of the blurb, the important stuff is the claims at the end. The content of the claims is the ONLY thing that is protected -until the patent lapses or is challenged and set aside.

If your construction is covered by those claims then you CANNOT place a product on the market unless you have permission from the owner. A licence is not necessarily expensive.

It does not stop you making your own to play with and one of the conditions of a patent being granted is that there is sufficient information published within the text to enable anyone of reasonable skill and knowledge within that subject field to build and test the claims. But you cannot then sell these items within the lifetime of the patent.


2007-10-10 5:21 pm
I think it really only depends if you’re on anyone’s radar or not. In any business, if you’re big enough, someone is going to look for an excuse or technicality to shut you down. If it’s not patent infringement it will be something else. One of many reasons why, if you are going to be in the sound business, as a business, with the intention of making a living, you’re advised only to buy brand new name brand equipment. If you’re out gigging once in a while with some home brew TH subs I doubt anyone will care, especially if you need to keep a day job to pay for your mortgage and health plan. And if you were sued, it would likely initially be just a cease and desist order - in which case you’d break out the saw, build a set of front loaders, and be back out at the end of the month. The IRS, OTOH, will want blood, even if you only have ever made a few thousand bucks.
Hummm. But what happens if I build my own boxes for live performances only?
How much differentiation is needed to avoid patent infringement? - Quora

I think wg_ski pretty much nailed it, above.

Lawyers cost a lot of money, even for a "cease & desist" order. No one is going to waste their time coming after you if you're not making enough money off it, and for personal use, who would even know?

I suppose that if you were running a rental outfit, and put something in the rider about "TH" or "just like Danley" then you be in for some real trouble, but not for personal use.

I'm in the music industry, and with music, it's very clear. Heck, you can even use a bit hit in an industrial video, used for in-house promotion or training, and it's perfectly legal. - You just can't use it to sell a product. (without licensing it.)

FWIW, I think Tom Danley deserves every dollar he gets for the TH concept. Brilliant and certainly innovative.

However, I don't see anything special, or particularly "patent-able" about his Synergy horn concept. In fact, it's been done before, in various ways, by EAW and others. Well, that's patents for you.
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A related question:

I'm very interested in making my own version of Danley's dual 12" TH.
IMO it's the perfect design for a smallish, portable sub. (It's even push-pull)

So, supposed someone here reverse-engineered the design, or simply created their own from existing TH concepts, and posted the details on this forum. Would that be a patent infringement, if they didn't specifically mention the name "Danley" ?
Using the name would be a Trademark infringement rather than Patent.
It would be a patent infringement if it was reverse engineered accurately enough to use exactly the same principles in exactly the same way.
IIRC, Ivan B of Danley has pointed out a few times that most peoples' DIY TH's miss out some particular characteristic of the real things, so you'd probably be OK if you didn't make an exact copy.