1. BK-12m for Fostex FE126En
Designed by planet10-hifi team, drawn by dld, 16-sept-2011
© 2011 Madisound Speaker Components
Back loaded horn for the Fostex
FE126En in the style of the classic
BK16, BK20.
1]
2]
3]
4]
5]
6-10]
11-12]
3/4” plans
3/4” details
5/8” plans
5/8” details
damping plan
3/4” cut plans
5/8” cut plans
Drawings:

2. 32
[812.8]
15
[381]
7 1/2
[190.5]
4 1/2
[114.1]
4 1/2
[114.1]
4 1/2
[114.3]
13 1/2
[342.9]
5
[127]
7 1/2
[190.5]
3
[76.2]
2
[50.4]
1
[25.4]
7
[177.8]
3
[76.2]
3
[76.2]
Notes
1/ drawn with 3/4” material
2/ driver chamber damped with 1.5 oz (42 g) evenly
distributed Acousta-Stuf
6
[152.4]
56.3°
12.1°
45°
3 1/2
[88.9]
i1
i2
i3
i4 i4
i5
17 3/4
[450.9] 15 1/4
[387.4]
13 1/2
[342.9]
14 1/4
[362]
BK-12m Back Loaded Horn
for Fostex FE126En
Plans 1v0 3/4”
16-sept-11 | design p10-hifi | drawing dld
© 2010, 2011 Madisound Speaker Components
15
32

3. 12°
45°45°
12°
12.0°
33.7°
56.3°
4 1/4
[107.8]
12 1/8
[309.2]
6 1/2
[165.1]
9
[229]
i2
i3
i4
i5
Notes:
1/ for 3/4” material
2/ all pieces 6” “deep”
Simulated low frequency response
BK-12m Back Loaded Horn
for Fostex FE126En
Angled parts detail 3/4”
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

4. 4 1/2
31 5/8
14 1/27 1/4
4 1/2 4 1/2
13 1/2
5
7 1/2
3
2
1
7
3
3
Notes
1/ drawn with 5/8” material
2/ driver chamber damped with 1.5 oz (42 g) evenly
distributed Acousta-Stuf
3/ additional stuffing to reduce bass up around the
deflectors
6
56.3°
12°
45°
3 1/2
i1
i2
i3
i4 i4
i5
17 1/2
15 1/4
13 1/4
14
BK-12m Back Loaded Horn
for Fostex FE126En
Plans 1v0 5/8”
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components
13 7/8
31 5/8

5. 45°45°
12.0°
12.0°
33.7°
56.3°
4 1/4
[107.8]
12 5/32
[308.5]
6 1/4
[158.7]
9
[229]
i2
i3
i4
i5
Notes:
1/ for 3/4” material
2/ all pieces 6” “deep”
Simulated low frequency response
BK-12m Back Loaded Horn
for Fostex FE126En
Angled parts detail 5/8”
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components
12°

6. BK-12m Back Loaded Horn
for Fostex FE126En
damping
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components
DriverChamber
driver chamber damped with 1.5
oz (42 g) evenly distributed
Acousta-Stuf
additional stuffing to reduce
bass up around the deflectors

7. bottom
internal 2
top
int 4internal 5 internal 3
backbaffle
internal 1
side
6
6
6
15
32
15 1/46 23/3212 3/164 1/49
14 1/4 13 1/2
17 3/4 32
BK-12m Back Loaded Horn
for Fostex FE126En
panel extents 3/4”
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

8. baffle
bottom
back
internal1
internal2top
internal3int4
internal5
int4
int4int4
internal5
internal3
back
internal2
bottom
baffle
internal1
top
Notes:
1/ for 3/4” material
2/ drawn with 5mm kerf & 8mm edge trim
3/ 2 sides out of a 2nd sheet
side
side
side
side
BK-12m Back Loaded Horn
for Fostex FE126En
5’x5’ 3/4” suggested cut
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

9. baffle
bottom
back
internal1
internal2
top
internal3
internal5
internal5
internal3
back
internal2
bottom
baffle
internal1
top
Notes:
1/ for 3/4” material
2/ drawn with 5mm kerf & 8mm edge trim (kerf
a touch less on le+ side of i4 pieces)
3/ 2 sides out of a 2nd sheet
side
side
side
side
int 4
int 4
int 4
int 4
BK-12m Back Loaded Horn
for Fostex FE126En
5’x5’ 3/4” alternate cut
09-sept-11| design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

10. Notes:
1/ for 3/4” material
2/ drawn with 5mm kerf & 8mm
edge trim
bafflebottom
backinternal1
internal2
top
internal3int4
internal5
int4
int4
int4internal5
internal3
back
internal2
bottombaffle
internal1
top
side
side
side
side
BK-12m Back Loaded Horn
for Fostex FE126En
4’x8’ 3/4” suggested cut
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

11. bafflebottom
backinternal1
internal2
top
internal3
int 4
internal5
int 4
int 4
int 4
internal5
internal3
back
internal2bottom
baffle
internal1
top
side
side
side
side
Notes:
1/ for 3/4” material
2/ drawn with 5mm kerf & 8mm
edge trim
BK-12m Back Loaded Horn
for Fostex FE126En
4’x8’ 3/4” alternative cut
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

12. bottom
internal 2
top
int 4internal 5 internal 3
backbaffle
internal 1
side
6
6
6
14 1/2
31 5/8
15 1/46 1/412 5/324 1/49
13 7/8 13 1/4
17 1/2 31 5/8
BK-12m Back Loaded Horn
for Fostex FE126En
panel extents 5/8”
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components

13. Notes:
1/ for 5/8“ material
2/ drawn with 5mm kerf & 8mm
edge trim
BK-12m Back Loaded Horn
for Fostex FE126En
4’x8’ 5/8” suggested cut
09-sept-11 | design p10-hifi | drawing dld
© 2011 Madisound Speaker Components
bottom
internal2
top
int4internal5
internal3
backbaffle
internal1
side
side
side
side
backbottom
baffletopinternal1int4
internal5
internal3internal3
6 3/16
internal2
int4
internal3
int4
with some conservation of
kerf & trim this strip becomes
wide enough for internal
pieces