Frugel-Horn Mk3 Builds & Build Questions

This thread is soley for the purpose of beta test builds of FH3, development of the documentation.

Please only post feedback, QC, problems, sucesses, failures. Drivers tried, associated damping, any measurements. Pictures illustarting specific issues or solutions. Finished speakers & general pics in the other thread.

If you are going to generate a build log, please start a new thread and post a link here.

Beta builds of the plan document will be posted here. I also envision a document with builds & build pictures, and a (set of?) 3D models.

QC posts, bug reports, and posts with implementation suggestions will be removed as they are implemented into the document(s).


Note: any commerical entity intent on manufacturing complete speakers or flat-paks for resale will need to follow the guidelines on the Frugal-Horn site: Frugel-Horn plans

Frugel-Horn Mk3 Gallery

Most recent plan update in post 601.

SketchUp 3D model 22-august-2010
i was wondering about access post-build for adjusting stuffing etc. thinking of a removable top section ( temporary) any ideas suggestions?

A couple of thoughts, based on several builds of test mules with removable panels:

The cut plans are drawn with internal panels, top, bottom and front baffle at 140mm, which assumes they are all set inside the curved side panels.

Depending on how you're planning on "finishing" when all has settled (i.e with the boxes be painted, veneered or plastic laminated?), you could either:

1) Temporarily attach one side panel with a few wood screws and seal with foam weatherstrip tape for the experimenting with panel damping and stuffing. Once that's finalized, remove the foam tape, glue down (using the existing screw locations as temporarily "clamps", then remove the screws and proceed to fill holes and finish (paint/veneer, etc.); or

2) To make (a section of ) the driver mounting panel easily removable, it's more practical to adjust part dimensions for the front panel to overlay the sides ( in other words 170mm). To retain structural rigidity, I'd keep the removable section as short as possible, overlap a dado and seal with foam tape. (see attached quickie sketch)

The latter option does of course mean resizing sides and front panels, and while I haven't run a new cut plan, it could complicate the already very tight yield from a 5x5 sheet.


  • fh3top.pdf
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I suspect that most, if not all of the damping adjustments will be various amounts of polyfluff just below the driver in the section going down to the choke. One can get at this thru the driver hole. Optimum damping of the pointy bit has not been fully determined, but the amount that Chris put in our mules + lining on surfaces near the driver worked well for the FE126En, with a bit more required below the driver on the MA drivers (we haven't confirmed this). If you are pulling them out from the walls, and don't mind the bass a bit ripe (but controlled), the same damping as for the FE126En + a deflector (i'm currently using my Auston A166 ones) seems to work fine.

Chris, can you estimate how much you put into the point?

Also: what Chris has shown is also what you would do for a build (without supraBaffle) for being able to swap drivers.

Chris, can you estimate how much you put into the point?

I was afraid you'd ask that - sorry, no.

Also: what Chris has shown is also what you would do for a build (without supraBaffle) for being able to swap drivers.

presumably, only a really crazy person would be routinely swapping drivers just for the fun of it (oops, that describes most of us here, n-est ce pas?)
I think the side grid drawing are not needed...

The 69"radius is smaller than I had first thought from looking at the photos.

A swing arm jig to my router would make the panels easy to cut, the rest of the build is very easy. A DIY dream.

Thanks for all you guys do.......

Since the chord/segment sketch was intended for manual lay-out of (template for) hand-machined (as opposed to CNC) side panels, I wonder if it should also include dimensions for layout of angled front, as per:


  • fh3-2.pdf
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Here is the 18mm plan. Hopefully it will give some clues to convert to 17.4mm.

Conversion to a larger material than the ref 15mm requires moving back the back panel by the extra thickness, raising the height of the point the same (because this is the extra thickness of the divider, length of horn remains the same to the choke point), and using a half-round to define the choke (or an approximation). Then all the outer panels increase into the outside, and the divider panel towards the back.

The front and the back are not parallel.



  • FH3b-plan18mm.pdf
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