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Chris A

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

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On 1/1/2021 at 8:17 AM, NBPK402 said:

I actually like the more raw vocals sound better...

 

What are your impressions of the speakers now?

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I am loving them more everyday...best horn speakers I have ever owned. I still need to get some more acoustic panels made though to get the echo down. Sounds like a night club when I turn it up, but at lower level the echo is not as bass

LOL

 

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18 minutes ago, NBPK402 said:

I am loving them more everyday...best horn speakers I have ever owned. I still need to get some more acoustic panels made though to get the echo down. Sounda like a night club when I turn it up. ALOL

 

Very nice. Your room is big enough to host a night club, so a little more diffusion and some absorbers will make things just right.

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I am debating on absorption panels below 12' and poly diffuser panels 12' to 16' not sure if that will work or not. I think I still have 3 boxes of Roxul r60 2" left.

 

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@Chris A,    You recently posted a brief comment on another thread about working on a project out in your garage. Is it related to the K-402 MEH?

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It's a related MEH, but not based on a K-402 horn.  It will be just a little smaller but still with [at least a] 90 x 60 degree coverage--much like the K-402.

 

The plywood buy will wait until I get inoculated for SARS II so I can pick it out locally.  My first shot is estimated to be scheduled in 2-3 weeks (but I'll believe it when it occurs).  I'm certainly looking forward to it. 

 

I don't want to reveal what it is until I'm assured that it will work as planned via tests and listening.  There are also a couple of design twists that can be used with it.  Automatic time alignment is one of the givens in any proper MEH design. I think that you'll like it.  It may be surprising to you...

 

Chris

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A thread on the new Celestion Axi2050 Axiperiodic driver that directly applied to the K-402-MEH:

Chris

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Interesting how there is new technology forming with the Celestion driver and with Danleys new home audio line. Not together, but there have been alot of discussions lately about the 2.

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Hi,

I’m going to dumb this thread way down. After reading about copying the 402 down to sub 1mm precision, and the difficulty of purchasing raw 402’s, (some seem to have obtained them, others can’t, I’m confused on this) is there a consensus on best way forward to try to construct a large MEH?  I’ve seen Synergy Calc, Unity ideas which seem to be straightforward plywood designs with none of the subtle shaping of a 402.  Anybody scale these up to 402 size? Any ideas on possible sound quality of the crude, simple geometry of these plywood designs? Myself, and probably others, are interested in attempting a MEH, but myself for sure lack any by the most basic understanding of horn design.  
I plan on attempting a Synergy Calc build, but would be nice to have some basic, practical knowledge for the non laser scan, CNC, 3D printing crowd out here.  I know horn geometry is complex, but is a simplified version likely to yield impressive results?

Lot of speculation to answer, I know, just wanted to bring it down to cabinetmaker level. 

thanks so much, the info here is amazing!

Ted

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16 hours ago, VDS said:

the difficulty of purchasing raw 402’s, (some seem to have obtained them, others can’t, I’m confused on this)

They are available in North America--for a price (i.e., >$1200 each, with a stand and 2" K-691 compression driver attached).  Generally, they're not available outside North America--and this is something that Klipsch has apparently chosen to preclude.

 

16 hours ago, VDS said:

is there a consensus on best way forward to try to construct a large MEH?  I’ve seen Synergy Calc, Unity ideas which seem to be straightforward plywood designs with none of the subtle shaping of a 402.  Anybody scale these up to 402 size?

I have a couple of full-range MEH designs that will work, using Bill Waslo's Synergy Calc spreadsheet as the medium of communication of these designs. 

 

16 hours ago, VDS said:

Any ideas on possible sound quality of the crude, simple geometry of these plywood designs? Myself, and probably others, are interested in attempting a MEH, but myself for sure lack any by the most basic understanding of horn design.  

I think the dual-flare Danley-type horns be the 99% solution for those that don't want to go the route of using K-402 horns, which is been effectively priced too far above market value, or otherwise made unavailable outside US/Canada.  I talked about this type of horn in this thread last May, and I'm now convinced that the extra angst of trying to get the K-402 is not worth the effort:

 

 

Here is an example spreadsheet design that will drop into a Cornwall box (with suitable attention to detail):

 

Synergy Calc-90x60 deg Cornwall drop-in horn.xls

 

and a Cutlist Optimizer layout of the rectangular cuts from a 4'x8' piece of plywood or MDF:

 

1102257017_CutlistOptimizerscreenshot.thumb.GIF.f8040dd4b21add1f9645b5f879f46ec7.GIF

 

I haven't built/tested this yet, and I think a lot of folks are leery of trying to build their own full-range MEH like this, but I strongly believe the design is good enough acoustically as-is.  The devil is in the details, of course, but anyone that is experienced in woodworking would be good to go.  I believe that you need to use K-33-like woofers, but with 8-ohm nominal impedance rather than 4-ohm impedance so you can wire them in parallel.  This would be something like a K-45 woofer.

 

I won't be able to start the build on this for another month or so (awaiting my second SARS-CoV-II vaccination in about 3 weeks as of this date). I'm not interested in going to Home Depot or any other lumber supply until about 2-3 weeks after my second dose (mid-late April), and that is the time delay that is presently being inserted into this deal.

 

Chris

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13 hours ago, Chris A said:

 

I'm not interested in going to Home Depot or any other lumber supply until about 2-3 weeks after my second dose (mid-late April), that that is the time delay that is presently being inserted into this deal.

 

Chris

 

 

That is wise decision. Wait until your body develop decent immunity against the virus. That usually takes about 3 weeks after vaccination. Even better after the second shot.

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On 3/17/2021 at 11:43 AM, Chris A said:

design that will drop into a Cornwall box

 

This plan is to remove the motor-board from an existing Cornwall and use that as the outer box for your new plywood MEH ?

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3 hours ago, Khornukopia said:

This plan is to remove the motor-board from an existing Cornwall and use that as the outer box for your new plywood MEH ?

Yes.  A drop-in full-size horn that mounts one or two woofers (i.e., it could use the single existing K-33 woofer instead of two woofers) is the idea above.

 

The drop-in multiple entry horn into the Cornwall cabinet can also reuse the K-55 midrange driver--if desired--or you can replace both the K-77 tweeter and K-55 midrange drivers with  a good quality 1.4", 1.5". or 2" throat compression driver to cover both the midrange and tweeter frequency bands in a two-way design--which is the way I'd probably go to keep everything simpler. [The existing 1" compression drivers just don't have quite enough bandwidth to cross with the woofer on the low end and also extend its output all the way to 20 kHz on the top end.]

 

The reason to change the K-55 and the tweeter out is that the K-55 midrange driver can't be placed close enough to the Cornwalls tweeter and cross at the required 4-5 kHz that the tweeter needs to cross at (i.e., the two drivers can't be placed close enough together with be within 1/4 wavelength at the crossover frequency).  The tweeter's horn is integral to the driver, so both the K-77 (or whichever tweeter model is actually used in the Cornwall you own) must be replaced with a tweeter that can extend its crossover frequency down to about 1 to 1.5 kHz.

 

Chris

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Is the Cornwall cabinet deep enough?

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Yes.  The depth of the horn can be adjusted to accommodate different depth compression drivers by using the "lowest frequency at which horizontal pattern control to be kept" frequency (push it upwards to reduce the depth), and the "ratio of final horizontal first expansion width to overall horiz width" entries in Bill Waslo's Synergy Calc spreadsheet to decrease the horn depth, if necessary.

 

Chris

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19 hours ago, NBPK402 said:

Is the Cornwall cabinet deep enough?

 

18 hours ago, Chris A said:

Yes.  The depth of the horn can be adjusted to accommodate ...

 

So, you are building a smaller horn to fit a pre-existing box you have at home? 

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So, you are building a smaller horn to fit a pre-existing box you have at home? 
No...my response was about the poster with the cornwalls. I am building a smaller square k402, in a custom cabinet.

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8 minutes ago, NBPK402 said:

No...my response was about the poster with the cornwalls. I am building a smaller square k402, in a custom cabinet.

 

Yes, of course. And I just learned that it is best to quote previous posts just one forum member at a time.  🙂

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Any size MEH can be made using Waslo's Synergy Calc spreadsheet.  I've been asked about slightly smaller or perhaps more "canned" MEH designs in the past. This is but one response to those requests that is a size/shape that's acceptable to many people here already.  The advantages of using an MEH design are numerous, and the disadvantages are few to none (i.e., you need a $200 DSP crossover [two-way] and an additional stereo amplifier). 

 

So the idea in this case is to reuse a Cornwall and at least one of its drivers (the K-33 woofer)--and perhaps two (K-55 midrange and K-33 woofer)--and have the front baffle and tweeter left over in case you want to reassemble everything back into a stock Cornwall for resale (but reversible MEHs are perhaps a topic that's really outside the scope of this thread).  It makes a lot more sense to me than perhaps other third-party "improvements" that I see posted on this forum. 

 

The Cornwall-based MEH (the drop-in horn itself) can be built out of plywood and dropped into the existing Cornwall box, then attach the drivers.   Everything can be dialed in using something like a miniDSP 2x4 HD (for two-way) or 4x10 HD (for three-way).  I believe that the finished MEH loudspeaker, completely dialed in and placed properly in-room with suitable acoustic treatments, would probably give JubScalas more than a run for their money, and certainly be in a class that can compete with two-way Jubilees, especially in rooms that lack sufficient space for loudspeakers the size of Jubilees.

__________________________________________________

 

I considered an MEH that's perhaps the size of a Heresy, etc., but you wind up with a Heresy woofer in a box (a 12" woofer) that loses directivity below ~600 Hz due to its small mouth size, and then you still need a higher frequency driver (perhaps a 1" to 2" compression driver--or a dipole AMT-1-like driver that needs added horn loading to cross with the 12" woofer).  In other words, it doesn't behave like a full-range MEH, which is my exclusive focus if using multiple entry horns, so I don't see it's worth the effort of building an MEH.

 

When I think of the Celestion Axi2050 2" compression driver, which can easily cover the range 225 Hz to 20 kHz in one driver/horn/amplifier channel (given a proper-sized horn to support the needed directivity and provide the impedance matching to air--i.e., a K-402 horn), this makes me realize that the MEH concept is nothing but a novelty unless it's a full-range MEH design.  The Axi2050 can cover that wide band without need for crossover filters (within that frequency band) and extra amplifier channels, but it still needs DSP to dial-in the EQ.  So if you're going to the trouble to produce an MEH, my thinking is that it doesn't make any real sense unless it's a full-range MEH that can reach down to frequencies well below 60 Hz.

 

Chris

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Quote

 

Chris/all-

 

Newbie alert here, no question too daft.  I'm planning on building your K402 MEH's and have been considering using dual JBL 2226H 15" woofers wired in series for a 16ohm load, 600W, in place of the Crites 1526C.  The JBL 2226H's requires 2-3 cubic feet volume sealed enclosure. I'm curious if you have reservations about using these?  The best place to start is model the MEH in Hornresp or another model, I just have not learned Hornresp yet (its on my list).  I understand they would be possibly overpowered, but i like that get down to 30hz if i decide t use them in outdoor applications (friends concert at the farm).  I would pair them with the appropriate Crown Amp.  on the point above, what would you think about using dual 18" on the long wall of the horn, to create a full range horn that reaches down to the 20s? 

 

Feel free to offend if it gets the point across.

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