frugel horn mk3
TRANSCRIPT
A development of the original Frugel-Horn with emphasis on easier build, more driver versatility, and a bit taller.
Topologically a tapped hypex horn (approximated with 2 conical sections), a choke point to act as a low pass filter, followed by a eapidly flaring terminus. The curve on 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 horn.
Testing with Fostex FE126En, Mark Audio CHR-70, Alpair7, and CSS EL70, shows a tolerance for a wide range of drivers. Suitable drivers should fall into, or be near the envelope of parameters defined by this set of drivers. Additional drivers will be added as tested.
Adjustment & tuning is accomplished with varying amounts of damping, and proximity to wall/corner.
Use of deflectors & supraBaffles yet to be explored.
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: www.frugal-horn.com/use.html
Frugel-Horn Mk3
sponsors & cheerleaders
beta document 25-october-2010
Drawings/Contents (provisional)
i0/ Introi1/ Notes
FHx/ Plan 15mmFHx/ Plan 12mmFHx/ Plan 18mmFHx/ Plan 5/8"FHx/ Plan 3/4"FHx/ Alternate Choke Point ExecutionFHx/ Side pattern creation
A0/ Damping
A1/ SupraBaffleA2/ SupraBaffle Shapes
A3/Deflector
C1/ 5x5 cut 15mmC2/ 4x8 cut 15mm (1220x2440mm)Cxxx/ more cuts
please email me <[email protected]> with corrections & suggestions to make this document more useful
Notes:
1/ drawn with 15mm material2/ optional ~300 mm wide/diameter supra-baffle not shown. Its purpose is to move the baffle-step drop off to where the horn action starts flattening lower midrange FR3/ intended for Fostex FE126En, CHR-70, Alpair 7, EL704/ damping will differ for each driver
Frugel-Horn Mk3 0v8sheet FH3-0 – 15mm Plandesigned by S Lindgren | drawn by dld30-august-2010
1753 mm radius (69")
34[863.8]
5 1/2[139.7]
6 3/32[154.7]
2 3/4[69.8]
2 3/4[69.8]
85.2°1 1/2[38.1]
2 3/4[69.9]
4.9°
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.
35 3/16[893.9]
17[431.8]
17 11/16[449.1]
5 1/2[140]
6 11/16[170]
Notes:
1/ drawn with 15mm material2/ optional ~300 mm wide/diameter supra-baffle not shown. Its purpose is to move the baffle-step drop off to where the horn action starts flattening lower midrange FR3/ intended for Fostex FE126En, CHR-70, Alpair 7, EL704/ damping will differ for each driver
Frugel-Horn Mk3 0v8sheet FH3-0 – 18mm Plandesigned by S Lindgren | drawn by dld06-sept-2010
1753 mm radius (69")
34[863.8]
5 1/2[139.7]
6 7/32[157.7]
2 3/4[69.8]
2 3/4[69.9]
85.2°
36mm half round piece defines choke point
35 7/16[899.8]
18 1/16[458.5]
5 1/2[140]
6 15/16[175.9]
17 9/32[438.9]
1 1/2[38.1]
4.9°
2 3/4[69.9]
7 5/8[193.8]
5 3/4[146.6]
Frugel-Horn Mk3 0v8FH3-x Alternate Choke Point Execution
design by S Lindgren | drawn by dld01-sept-2010
As originally designed
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
Note: example uses 15mm material
The Frugel-Horn Mk 3Side Curve Chord & Heightdesigned by S Lindgren | drawn by dld02-sept-2010
35 3/8[898.8]
2 13/32[61]
To fabricating a side panel template by hand, the curve can easily be drawnusing a narrow flexible board (1/4" MDF works great) and the 4 points asdimensioned.
Mark points A,B (chord ends), C (chord centre line) and D (segment height)on the work-piece. Use a square to draw a perpendicular line (C-D)
Clamp or screw a wood block straddling the centreline at D, clamp theflexible board to this block and each end of the chord ( A & B) then drawthe curve.
Cut to the outside with jig or band saw, and carefully sand to line
17 11/16[449.4]
17 11/16[449.4]
A
B
CD
Frugel-Horn Mk3 0v82Ax – Damping Plandesigned by S Lindgren | drawn by dld26-oct-2010
1/2" (12mm) cotton or wool felt
increasing density as you approach the point. Take the equal density fluff on the right and squeeze it into the point (actual amounts to be determined)
walls lined around driver to minimize reflections
this is the area subject to additional poly-fluff damping, depends on driver
see notes page ix for driver-by-driver
1/ FE126En blue + orange2/ CHR70 blue + orange + more3/ EL70 blue + orange + more4/ A7 blue + orange + more
poly-fluff (BAF, acoustistuff, pillow stuffing -- different colours represent different "zones" to add stuffing too)
baf f
le
Frugel-Horn Mk3 0v8CHR-70/EL70Sheet 4 – 5x5 15mm cut sheetdesigned by Scott Lindgrendrawn by dld / 01-sept-2010
bott
om
back
internal top
back
internal
baff
le
bott
omto
p
Notes:1/ 5mm kerf & trim allowance2/ very tight cut plan
6 3/4[171.5]
17 3/32[434.3]
35 3/8[898.4]
5 1/2[140]
29 5/32[740.9]
32 3/32[815.1]
5 1/2[140]
baf f
le
Frugel-Horn Mk3 0v8CHR-70/EL70Sheet 4 – 4x8' 15mm cut sheetdesigned by Scott Lindgrendrawn by dld / 02-sept-2010
bott
om
inte
rnal
inte
r nal
baff
le
bott
om
Notes:1/ 5mm kerf & trim allowance2/ room to increase kerf for CNC3/ works for 1220x2440mm sheets
top
top
17 3/32[434.3]
35 3/8[898.4]
5 1/2[140]
6 3/4[171.5]
32 3/32[815.1]
29 5/32[740.9]
back
back
5 1/2[140]