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Chris A

A K-402-Based Full-Range Multiple-Entry Horn

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Wow, I’ll be following this 4shoo .  I have all the ingredients to do them except the woofers.  

I have 8 Kappa C woofers in the garage now... I hope they sound as good as the Crites. I also have 7 or 8 EV DH1As.

 

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On 12/23/2019 at 10:53 AM, Ron E said:

I have 8 Kappa C woofers in the garage now... I hope they sound as good as the Crites. I also have 7 or 8 EV DH1As.

 

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Are you doing 2 or 3 way? If 3 way which tweeters are you planning on using?

 

 

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Are you doing 2 or 3 way? If 3 way which tweeters are you planning on using?
 
 
We are going to try them as a 2 way first, and then either go with Dave's tweeters, or maybe swap out for the BMS 2 way drivers if neededl

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1 minute ago, Ron E said:

We are going to try them as a 2 way first, and then either go with Dave's tweeters, or maybe swap out for the BMS 2 way drivers if neededl

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I upgraded my chorus ll DIY center to a 17 by 10in zxpc horn. Was running 2 way with ev dh1a and with eq did not sound bad. Now I am running a de10 danley style and like it better. (Tweeter mounted on horn)   

 

Have you considered running tweeters as meh? The bms2'S do looking interesting and should be easier to deal with.  

Looks like an interesting project, I will look forward to seeing your progress.

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I upgraded my chorus ll DIY center to a 17 by 10in zxpc horn. Was running 2 way with ev dh1a and with eq did not sound bad. Now I am running a de10 danley style and like it better. (Tweeter mounted on horn)   
 
Have you considered running tweeters as meh? The bms2'S do looking interesting and should be easier to deal with.  
Looks like an interesting project, I will look forward to seeing your progress.
I had the DH1As from when I had my JBL2360As... I kept them when I decided to go the MEH route. To be honest I am not even sure now that I can hear high enough to warrant a super tweeter. I say this because I currently have some RP160Ms, and everyone says that have a rising top end... I do not hear a bright hi end at all. When we start to tune the MEHs, I plan on also running the RP160Ms with REW also to see if it is me or not. When we ran the EV DH1As we ran a 12db shelf to get the highs up in a fully treated HT.

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On 2/19/2019 at 3:53 PM, Chris A said:

No issues with measurements or simulations.  Just engineering knowledge of how stiff the horn should be...and the stiffer, the better. There are even some people that have used concrete as a horn material (but I don't recommend that, however, since it makes the horns into boat anchors--and they cannot be made in thinner sections).

 

No resonances that I can identify, but until I get a horn made and test it A-B fashion...  The clamping of the horn's flange on the mouth end to the box gets about 95% of the issues.  The rest of the story on thicker horn material is just good engineering practice.

 

Chris

 

Any better practices those of us that are getting close to building one should follow?  Stiffening of the horn?  Attaching woofers differently? Padding on inside of box surfaces needed?

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More on the subject at a later date.  I just bulled my way through it using the tools that I have on hand.  It turns out that the holes aren't that sensitive (unlike the dimensions in the throat area).  I'm already working on more efficient ways to do it.

Chris

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The mounted woofers on their pads significantly increase the stiffness of the horn side walls when screwed down to the horn, but the top and bottom horn walls could use some extra stiffening.  (I have a solution in mind already.) 

Has any further development of the physical design been done?  Thoughts on more efficient cutting of the horn? (not sure how you did it )  Perhaps some way to take a single "plug" out that would be relatively easily replaced/reversed.    Perhaps a template file we could print out?

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I'm using 3/4" MDF salvaged from an earlier piece of office furniture for each woofer mounting pad, with the woofers held in place by larger wood screws.  The mounting pads are screwed to the horns, also using 12 x 1 1/4 wood screws top and bottom.  That is a tricky part--tapping drill holes into the horn in the right places to anchor the screws. 

Pictures of this?  Suggestions on procedure?

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On 12/21/2019 at 2:45 PM, Ron E said:

I finally have 4 K402s, and will be making Chris's MEH very soon. I will be trying a boxless, and a boxed version with Chris's assistance.

 

On 12/23/2019 at 8:34 AM, Delicious2 said:

Wow, I’ll be following this 4shoo 😸👍.  I have all the ingredients to do them except the woofers.  

 

Looking forward to seeing your builds.

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On 12/27/2019 at 1:43 PM, Delicious2 said:

Any better practices those of us that are getting close to building one should follow?  Stiffening of the horn?  Attaching woofers differently? Padding on inside of box surfaces needed?...Has any further development of the physical design been done?  Thoughts on more efficient cutting of the horn? (not sure how you did it )  Perhaps some way to take a single "plug" out that would be relatively easily replaced/reversed.    Perhaps a template file we could print out? Pictures of this?  Suggestions on procedure?

Send me a PM on the subject and describe what you need.  I've done more detailed build discussions in other PMs to Ron E and Cantilope.  I used a hole saw to cut the off-axis ports in the horn and woofer mounting pads (already attached) in one drilling operation per side (two holes cut per port to form elongated ports, two ports per woofer) along the side walls of the K-402 intersecting the top and bottom sides, leaving as much flat area between the ports is as possible to maintain off-axis reflectivity of the horn around the crossover frequency (nominally 500-600 Hz). 

 

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The main requirements for the off-axis ports are the distance to the beginning lip of the off-axis ports from the lip of the throat (apex) port, and the total port area open to the woofers, with wide countersunk ports on the woofer side of the horn in the woofer mounting pads in order to reduce the apparent thickness of the port that the woofers feel acoustically. 

 

There are no real differences in construction approach that I'd recommend using Klipsch K-402s than what I did with the prototype.  The woofer mounting pads are pretty easy to cut out having the woofers in hand with the K402(s) to use a pencil to draw the patterns on the woofer mounting pad material

 

I'd recommend as much acoustic batting internally as easily can be fit into the box along the walls in order to control internal box reflections, but there's no advantage to stuffing the boxes full with absorption since the woofers do not gain performance from having a larger box than what I'd used (i.e., a KPT-305 box).  If I can ever get a mold that works, the differences will be somewhat greater since no horn modifications will be required, and the horn will be thicker/stiffer.

 

Chris

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On 12/28/2019 at 3:20 PM, Chris A said:

with wide countersunk ports on the woofer side of the horn in the woofer mounting pads in order to reduce the apparent thickness of the port that the woofers feel acoustically. 

Got any pics of this?  Was any additional shaping of the ports needed for example to join the two hole saw holes?

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I didn't take pictures of the K-402-MEH woofer mounting pads after I modified the woofer side of the ports to countersink them, but here's a picture from one of Bill Waslo's "synergy horn" designs on diyAudio that shows the technique:

 

1190574175_WasloMEHportcountersinking.jpg.70a302b6fa8964179af890af79c2a422.jpg

 

Chris

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Chris I have a question. When I am working on speakers like La Scalas would the beveling of the slot the woofer is mounted to make a material difference? Would it have improved the S-MWM for instance?

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Would you be so kind to explain how did you attached the wooden pieces to K402 horn? 

The ones that woofers are attached to.

On picture that is posted I can only see only the screws that go directly to the horn. How do these screws go into the horn wall? Is the wall of the horn so thick that it can accomodate the screw?

 

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For ease of assembly (and if you anticipate removing and reassembling the woofer mounting pads over time), I would recommend use of through holes and countersunk head bolts inserted on the front side of the horn--just like Danley mounts their woofers in their Synergy line except that only four bolts are required to fasten the woofer mounting pad to the K-402: two near the throat end of the horn and two at the opposite end of the woofer mounting pad about 2/3s of the distance to the mouth of the horn.  

 

A detail of the Danley SH-50 horn through bolts is shown below (i.e., the top and bottom horn sides).  Note that the ports on the side walls are bass reflex ports (which I don't use and don't recommend if using a DSP crossover to flatten the SPL response like in all the K-402-MEHs.

 

1377431-a86f579a-fs-danley-sh50-synergy-

 

The prototype K-402-MEH that is the center loudspeaker in my 5.2 array uses non-through holes tapped into the horn in the right places to fasten the woofer mounting pad to the horn, which works well but still results in a little deformation of the inner surface of the horn--which can be carefully sanded down flat again.  The screws that mount the woofers to the woofer mounting pads are self-tapping wood screws, as shown in the pictures of the K-402-MEH that I posted above.

 

Chris

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18 hours ago, Dave A said:

Chris I have a question. When I am working on speakers like La Scalas would the beveling of the slot the woofer is mounted to make a material difference? Would it have improved the S-MWM for instance?

The answer is yes but the degree of improvement is unknown, i.e., it may be a subtle improvement to fabricate the wide beveled edges on the woofer side.  A "knife edge port" will result in better high frequency SPL response at the crossover frequency band, just like in the MEHs shown above.

 

Chris

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Great easy to do mod though and it all adds up.

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On 4/25/2020 at 7:13 AM, Chris A said:

I didn't take pictures of the K-402-MEH woofer mounting pads after I modified the woofer side of the ports to countersink them, but here's a picture from one of Bill Waslo's "synergy horn" designs on diyAudio that shows the technique:

 

1190574175_WasloMEHportcountersinking.jpg.70a302b6fa8964179af890af79c2a422.jpg

 

Chris

See how the midrange mounting spots are countersunk to allow for surround travel?  That's not done here for the woofers but how about the Crites or other woofers specified for our K-402 MEHs?  Is the woofer surround ever near hitting the mounting panel?

Synergy driver mounting cuts.JPG

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On 4/30/2020 at 12:58 PM, Delicious2 said:

how about the Crites or other woofers specified for our K-402 MEHs?  Is the woofer surround ever near hitting the mounting panel?

 

My K-33s and Crites woofers (and others) have an attached gasket that provides ample clearance for mounting the driver face down to a smooth flat surface. 

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Chris, is your full-range MEH kit still in the cards? I know last summer you were waiting for the moulds. 

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Yes, it is, but progress has been suspended temporarily due to family health issues.  It will take a while before I'm able to return to MEH mold development.  It's been promising, but we are talking about a 25-35 pound (11.3--15.9 kg) horn in one part. It's a complicated mold.  After the horn itself, the box is a comparatively simple matter.

 

An alternative is to buy a pair of KPT-305s from Klipsch and modify them if you want them sooner (like I did for the K-402-MEH prototype).   I see Digitronic Italy apparently handles Klipsch Professional (cinema products) in the EU, which may still include the UK as I understand it.

 

Chris

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Read through all this, from start to finish. Can't believe how flat the spl/phase plot is. Simply Awesome! Thank you Chris for sharing this.

I have most parts to do this and would like to dive in and get started.

I have a Lynx Audio Aurora8, would this work? Or do I have to get a Xilica unit to do all the necessary adjustments?

Thanks in advance for your help

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