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Frugel-Horn Mk3

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					                               Frugel-Horn Mk3
                                          beta document 25-october-2010




A development of the original Frugel-Horn with emphasis on easier build, more
driver versatility, and a bit taller.                                                      Drawings/Contents (provisional)

Topologically a tapped hypex horn (approximated with 2 conical sections), a choke          i0/ Intro
point to act as a low pass filter, followed by a eapidly flaring terminus. The curve on    i1/ Notes
the mouth carried over from Ron Clarke's contribution to the original, it helps the
narrow mouth allow the wavefront to greater approximate that leaving a circular            FHx/ Plan 15mm
horn.                                                                                      FHx/ Plan 12mm
                                                                                           FHx/ Plan 18mm
Testing with Fostex FE126En, Mark Audio CHR-70, Alpair7, and CSS EL70, shows a             FHx/ Plan 5/8"
tolerance for a wide range of drivers. Suitable drivers should fall into, or be near the   FHx/ Plan 3/4"
envelope of parameters defined by this set of drivers. Additional drivers will be          FHx/ Alternate Choke Point Execution
added as tested.                                                                           FHx/ Side pattern creation

Adjustment & tuning is accomplished with varying amounts of damping, and                   A0/ Damping
proximity to wall/corner.
                                                                                           A1/ SupraBaffle
Use of deflectors & supraBaffles yet to be explored.                                       A2/ SupraBaffle Shapes

Note: any commerical entity intent on manufacturing complete speakers or                   A3/Deflector
flat-paks for resale will need to follow the guidelines on the Frugal-Horn
site: www.frugal-horn.com/use.html                                                         C1/ 5x5 cut 15mm
                                                                                           C2/ 4x8 cut 15mm (1220x2440mm)
                                                                                           Cxxx/ more cuts
                            sponsors & cheerleaders                                        please email me <david@planet10-hifi.com> with
                                                                                           corrections & suggestions to make this document
                                                                                           more useful
                                       Notes:
                                                                                                         Frugel-Horn Mk3 0v8
                                       1/ drawn with 15mm material
                                       2/ optional ~300 mm wide/diameter supra-baffle not                sheet FH3-0 – 15mm Plan
                                       shown. Its purpose is to move the baffle-step drop off to
                                       where the horn action starts flattening lower midrange FR         designed by S Lindgren | drawn by dld
                                       3/ intended for Fostex FE126En, CHR-70, Alpair 7, EL70            30-august-2010
                                       4/ damping will differ for each driver




                                        6 3/32
                                       [154.7]                                                                     6 11/16
                                                                                                                   [170]
                                                                     2 3/4
                                                                    [69.8]
                 2 3/4                                                                                              5 1/2
                [69.8]                                                                                             [140]



        2 3/4
       [69.9]




                4.9°




                                                                                                 34
                                                                                               [863.8]

                                                                                     35 3/16
                                                                                     [893.9]
1753 mm
radius (69")




                45° cut on the end
                of end piece. Round
                over top edge join
                with back partition
                using sand paper
                after assembly. This
                point is subject to
                high pressures, glue
                very well.


                                                          85.2°
                    1 1/2
                   [38.1]

                                                           5 1/2
                                                          [139.7]




                                         17
                                       [431.8]
                         17 11/16
                         [449.1]
                                         Notes:
                                                                                                           Frugel-Horn Mk3 0v8
                                         1/ drawn with 15mm material
                                         2/ optional ~300 mm wide/diameter supra-baffle not                sheet FH3-0 – 18mm Plan
                                         shown. Its purpose is to move the baffle-step drop off to
                                         where the horn action starts flattening lower midrange FR         designed by S Lindgren | drawn by dld
                                         3/ intended for Fostex FE126En, CHR-70, Alpair 7, EL70            06-sept-2010
                                         4/ damping will differ for each driver

                                          7 5/8
                                         [193.8]

                                         6 7/32
                                         [157.7]                                                                     6 15/16
                                                                                                                     [175.9]
                                                                       2 3/4
                                                                      [69.8]
                    2 3/4                                                                                             5 1/2
                   [69.9]                                                                                            [140]



         2 3/4
        [69.9]




                    4.9°




                                                                                                   34
                                                                                                 [863.8]

                                                                                       35 7/16
                                                                                       [899.8]
1753 mm
radius (69")




                 36mm half round piece
                 defines choke point


                                                            85.2°
                        1 1/2
                       [38.1]

                                                             5 1/2
                                                            [139.7]




                                         17 9/32
                                         [438.9]
                            18 1/16
                            [458.5]
          Note: example uses 15mm material




 5 3/4    As originally designed
[146.6]
          A difficult piece to cut




          Modified for easier build

          Adds an additional piece, not all that tolerent
          of thicker material




          Alternateeasier build

          Overcomes material thickness issues.
          Requires extra material – 1/2 round with
          radius of build material




                Frugel-Horn Mk3 0v8
                FH3-x Alternate Choke Point
                Execution
                design by S Lindgren | drawn by dld
                01-sept-2010
                                             The Frugel-Horn Mk 3
                                             Side Curve Chord & Height
                                             designed by S Lindgren | drawn by dld
                                             02-sept-2010
                              B

                                            To fabricating a side panel template by
                                            hand, the curve can easily be drawn
                                            using a narrow flexible board (1/4" MDF
                                            works great) and the 4 points as
                                            dimensioned.

                                            Mark points A,B (chord ends), C (chord
                                            centre line) and D (segment height)
               17 11/16                     on the work-piece. Use a square to draw a
               [449.4]                      perpendicular line (C-D)

                                            Clamp or screw a wood block straddling the
                                            centreline at D, clamp the
                                            flexible board to this block and each end of
                                            the chord ( A & B) then draw
                                            the curve.

                                            Cut to the outside with jig or band saw, and
                                            carefully sand to line

                                  2 13/32
                                   [61]

      35 3/8
     [898.8]



                C
                          D




17 11/16
[449.4]




    A
           1/2" (12mm) cotton or wool felt
                                                                             Frugel-Horn Mk3 0v82
           poly-fluff (BAF, acoustistuff, pillow stuffing -- different       Ax – Damping Plan
           colours represent different "zones" to add stuffing too)          designed by S Lindgren | drawn by dld
                                                                             26-oct-2010
1/ FE126En blue + orange
2/ CHR70 blue + orange + more           increasing density as you approach
3/ EL70 blue + orange + more            the point. Take the equal density
4/ A7 blue + orange + more              fluff on the right and squeeze it
                                        into the point (actual amounts to         walls lined around driver to
                                        be determined)                            minimize reflections




                                                                                   this is the area
                                                                                   subject to additional
                                                                                   poly-fluff damping,
                                                                                   depends on driver

                                                                                   see notes page ix for
                                                                                   driver-by-driver
                               32 3/32
                               [815.1]
                                                                                  5 1/2
                                                                                 [140]
                                 29 5/32
                                 [740.9]




                                                               top

                                                                        top
                               internal                                               6 3/4
                                                                                     [171.5]


                                internal




                                                               bottom

                                                                        bottom
                               back                                                  17 3/32
                                                                                     [434.3]

     5 1/2
    [140]                      back




                                                                                     35 3/8
                                                               baffle

                                                                        baffle      [898.4]




                                Frugel-Horn Mk3 0v8
                                CHR-70/EL70
                                Sheet 4 – 5x5 15mm cut sheet
                                designed by Scott Lindgren
                                drawn by dld / 01-sept-2010
Notes:
1/ 5mm kerf & trim allowance
2/ very tight cut plan
                                            top

                                                     top
                                                                     6 3/4
                                                                    [171.5]
                5 1/2
               [140]




                                            bottom

                                                     bottom
                                 internal
                                                                    17 3/32
                                                                    [434.3]




                         5 1/2
                        [140]




                                                                    35 3/8
                                 internal

                                            baffle

                                                     baffle
                                                                   [898.4]
               back

                        back




32 3/32
[815.1]


     29 5/32
     [740.9]




                                                               Frugel-Horn Mk3 0v8
                                                               CHR-70/EL70
                                                               Sheet 4 – 4x8' 15mm cut sheet
                                                               designed by Scott Lindgren
                                                               drawn by dld / 02-sept-2010


                                                              Notes:
                                                              1/ 5mm kerf & trim allowance
                                                              2/ room to increase kerf for CNC
                                                              3/ works for 1220x2440mm sheets

				
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