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An attempt to build K-402-MEH clone in wood


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Hey there people!

 

So I've been fascinated by the whole idea of Synergy type speakers. Read a lot on DIYAudio forum and even tried to build a few using off the shelf horns. They sounded OK, but i still had that bug inside that made me want more. Then I stumbled upon ChrisA's thread on a synergy type speaker based on K-402 horn. Gone through the whole thread and through many more others, read up benefits of full horn loaded systems, modulation distortion, constant directivity and all that jazz and that made me crave a pair of K-402-MEHs even more.

 

Buying a set of horns was out of my budget, so i started exercising an idea of building the whole system from scratch. I found a thread  on an Australian forum, where a guy made a pair of K-402 replicas out of wood and XPS foam. The guy had already made huge part of the job on estimating the size of the horn, expansion rate, where it starts to curve and the curves themselves. So i opened SketchUp and started playing with the model based on images of his horn.

 

After i was satisfied with the model of the horn, I began working on other parts - the box, placement of HF driver and woofers, small parts that help hold the whole thing together. 

 

This is how the model looked first:

 

image.thumb.png.e5999029b28e7b097a849764cd64e29c.png

 

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But i knew that i am not an engineer or an experienced woodworker and since i was not going to (or was capable of) assemble the whole thing by myself, i was in need of a help of a professional who would work on the model and made sure that all the elements fit together nicely, that the parts could be machined on a CNC and prepare the drawings necessary for production.

 

Here are some shots of how the model looked after the guy i hired modified it:

 

image.png.90878a537c3a4d4e6f5967cf16c39467.png

 

image.png.da1f84ed3408d282d57e3878b02f068c.png

 

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In the end I had drawings and STL files so those could be used while CNCing the parts.

 

Now all major parts are ready and guys from local woodworking shop are assembling those:

 

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I will be using Faital HF204 for HF duties and Beyma SM-115N for LF. Bought them already. As for the amp, i will use an old AV receiver. Beymas are 8Ohm but i will connect them in parallel, so there is enough power in the receiver to drive them. And i will probably not need deafening sound pressure levels. Will consider swapping the receiver for something of higher quality if i am not satisfied. 

 

I have a room that is relatively big - 12X6 meters which is about ~40X20Ft. Speakers will be in the corners. If i am not satisfied with LF performance i will build a couple of tapped horns (have a few ideas on those).

 

I want to thank ChrisA for all the help he provided via private messaging and patience to my questions. Without him I would never come up with an idea of building this speaker in the first place and without his help i would build some garbage :)

 

So i hope this project turns out well. Can't wait to bring those monsters in my house and start the tuning process.

 

--------------------------------

 

While the project is still in the building stage, I decided to share 3D files i used with the community. Hope this is helpful and somebody will duplicate the whole project or some parts of it. Most of the info is in Russian, but the text isn't really necessary for understanding which parts goes where. This is not a complete clone of Chris's MEH or K-402 clone. This is as close as i could get with the information i had.

Files are available at this link.

 

Edited by StabMe
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1 hour ago, StabMe said:

So i hope this project turns out well. Can't wait to bring those monsters in my house and start the tuning process.

Very cool indeed! Let us know how they sound. I've had USA and Synergy horns, all purchased "sound unheard." I'll never go back to anything else after 55 years of DIY speaker building and Klipsch ownership (yes, I started really young, OK?).

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1 hour ago, StabMe said:

So i hope this project turns out well. Can't wait to bring those monsters in my house and start the tuning process.

 do you own this particular design , did you register it , patent it ----etc --

 

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Posted (edited)
20 minutes ago, RandyH000 said:

 do you own this particular design , did you register it , patent it ----etc --

 

 

Own? Of course not. I think this design is owned by Klipsch. Well, at least the horn itself. And i just looked what other guys on the forums did with the horn and tried to replicate it by playing in SketchUp. BTW, i used SketchUp just a few times before to design a speaker stand. I hope there is no violation of any law by what I am doing. Well, i guess there shouldn't be, since I am not getting any profit from it.

 

57 minutes ago, parlophone1 said:

Great work, congratulations.

I have seen the process on Australian forum, but never had the courage and resources to try it myself.

Please do share information after they are finished 😊

 

This forum provides a lot of inspiration. Of course I will share all the info here - where else will I find like minded people like pals from this place? All the others are quite sure I am crazy :)

 

35 minutes ago, ClaudeJ1 said:

Very cool indeed! Let us know how they sound. I've had USA and Synergy horns, all purchased "sound unheard." I'll never go back to anything else after 55 years of DIY speaker building and Klipsch ownership (yes, I started really young, OK?).

 

Claude, I've read a lot about your QPie  horn. By the graph and looks of it, it must provide great dynamics and slap. How would you compare synergy horns with the Pie? I hope that the horn I am building, having that huge mouth area and being corner loaded, does provide some loading in the midbass, but i am not quite sure if it will provide 'true' midbass horn sound. 

Edited by StabMe
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25 minutes ago, RandyH000 said:

do you own this particular design , did you register it , patent it ----etc --

I'm not sure what the concern is here.  This subject has been discussed many times in the past (more than 5 years ago). There are no active patents on this particular MEH design.  The original "Unity Horn" patent expired on 8/12/2014 due to non-payment of patent fees:

 

https://patents.google.com/patent/US6411718#legalEvents

 

There never was a patent on the K-402 horn. It was also introduced to the market greater than 20 years ago, a patent of which would have run out if there ever was one.

 

The concept of a patent is that the owner of the patent has exclusive rights to the IP for a defined period of time (20 years from the patent application date for USPTO general patents). After that point in time, the IP is free and clear. Anyone can use the IP after that date (and that's the way the government intends the deal to be, BTW, so that others can use the information to their benefit and those of customers).  Only trade secrets and trademarks last longer.  So as long as you don't try to call it "a K-402" or "a Synergy horn", there are no legal issues.  I have always called it an "MEH": a Multiple-Entry Horn--which I believe it's called in the expired patent.  Note that patent 6411718 wasn't the first MEH to be patented--those go back to the early 1960s or even earlier.

 

Chris

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14 minutes ago, Chris A said:

 The original "Unity Horn" patent expired on 8/12/2014 due to non-payment of patent fees:

 it is not cheap to register /maintain/ trademarks/ copyrights or patents - 

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True (for patent fees)--but those are the laws governing patents, and the government wants it that way (for the benefit of society, in general). 

 

If the patent generates significant income over time, those patent fees will be negligible for patent holders to pay, and they will be paid to protect the IP for a full 20 years. 

 

However, if the invention isn't profitable, the fees typically aren't paid and the invention moves into public domain, which is where the government wants all inventions to be after their inventors get their defined protection period (right of invention). 

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This looks great!  I have definitely thought of doing exactly this myself.  Like you, I have been intrigued by the K-402 MEH concept, and like you, I have seen the Australian K-402 clone and contemplated doing the same thing.  I will probably attempt something like this in the near future.  I'd love to take a look at any sketchup or STL files that you would be willing to share.

 

Would also love to hear your impressions once you get them up and running!

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3 hours ago, StabMe said:

Claude, I've read a lot about your QPie  horn. By the graph and looks of it, it must provide great dynamics and slap. How would you compare synergy horns with the Pie? I hope that the horn I am building, having that huge mouth area and being corner loaded, does provide some loading in the midbass, but i am not quite sure if it will provide 'true' midbass horn sound. 

Many people have built the Quarter Pie and been happy with it's MWM-like sound while saving 40% floor space. The Quarter Pie is NOT necessary for you, since the MEH you're building will take care of the bass just fine. You may want to add a tapped horn sub, however, if you want to get down to the teens in infrasonic bass response in addition to full range of the MEH.

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3 hours ago, Chris A said:

Note that patent 6411718 wasn't the first MEH to be patented--those go back to the early 1960s or even earlier.

 

Chris

True. However between that and the original Jensen attempt, Tom Danley is the only one that got Synergy Horns and Tapped Horns to WORK and has prolifically produced many scaled up/down variation to sell with his Business Partner.

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15 hours ago, Tarheel TJ said:

This looks great!  I have definitely thought of doing exactly this myself.  Like you, I have been intrigued by the K-402 MEH concept, and like you, I have seen the Australian K-402 clone and contemplated doing the same thing.  I will probably attempt something like this in the near future.  I'd love to take a look at any sketchup or STL files that you would be willing to share.

 

Would also love to hear your impressions once you get them up and running!

 

Yeah, those two build were quite inspirational for me so I couldn't resist the temptation and started tinkering with SketchUp which lead to building a pair. I don't mind sharing the plans with the community. There are a few errors in the drawings, I will fix them and then share the whole package. I got so much info from this forum, I hope those plans and drawings bring at least some value.

 

16 hours ago, ClaudeJ1 said:

Many people have built the Quarter Pie and been happy with it's MWM-like sound while saving 40% floor space. The Quarter Pie is NOT necessary for you, since the MEH you're building will take care of the bass just fine. You may want to add a tapped horn sub, however, if you want to get down to the teens in infrasonic bass response in addition to full range of the MEH.

 

That is good to hear! A question - since MEH will require some boost at the lower end to reach 20Hz and lower, is there a risk or increased distortion? Maybe that would be a good reason to build a pair of tapped horns? I am working on a plan of TH design that reaches to about 20Hz with a flat curve based on a Kicker L7 12" car subwoofer that i have laying around:

 

image.png.c9c8fd2cbe030b6339df54e5e1e10a41.png

 

Although, group delay seems a bit high:

 

image.png.6f39d4ec618cf7288873cfe7dff256f2.png

 

 

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3 hours ago, StabMe said:

Although, group delay seems a bit high:

Group delay in super low frequencies has very little consequence in the listening, unless your are Superman. So your plan is good and sound. Pun intended. Go with my "coffee table sub" which is the LAB 12 design, very similar to your simulations here with amazingly good performance.

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On 3/23/2021 at 5:15 PM, ClaudeJ1 said:

Group delay in super low frequencies has very little consequence in the listening, unless your are Superman. So your plan is good and sound. Pun intended. Go with my "coffee table sub" which is the LAB 12 design, very similar to your simulations here with amazingly good performance.

 

Sadly I am not a superhuman, so I will go ahead and start designing the SUB for this system.

 

17 hours ago, Lbk said:

Are you using a 9.5 length port like  Chris A, it looks shorter?

 

image.png.03e1927d4594f7aa9fbb9c83162ed923.png

 

Here is how it looks in SketchUp.

 

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Hi StabMe, and all,

 

Super nice project ! Looks very well made!  Looking forward to your listening impressions 😀

 

I guess i maybe got inspired the same way you did, by ChrisA's praise of his K-402 MEH, and the clone-like build by the Australian fellow named Oohms........

My build uses curved XPS foamboard secondary flares, wrapped with glass cloth and epoxy, to try to match the geometry  Oohm layed out. 

Think I got reasonably close, but yours is no doubt a better match.

Anyway, mine use a bms4594he CD, crossed to a pair of faital 10pr300's at 500Hz.  All my speaker builds are designed to cross to subs at 100Hz, so I didn't  need anything bigger than 10"s.

 

It looks like your port size is about 1/10 Sd.  Is that correct?  1/10 has been my stand ratio on a handful of MEH builds, using 12", 10", and 8" low/mids.

How high do you plan to run the 15"s ?

syn7 pair.jpg

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2 hours ago, StabMe said:

 

Sadly I am not a superhuman, so I will go ahead and start designing the SUB for this system.

 

 

image.png.03e1927d4594f7aa9fbb9c83162ed923.png

 

Here is how it looks in SketchUp.

 

Perfect, thank you much!

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