Lake District Design Series for CSS EL70 & planet10-hifi EL70eN
Lake District Design Series
for CSS EL70 & planet10-hifi EL70eN by Scott Lindgren (design) & David Dlugos (drawing & design detail) Key to drawings
0-1/ Introduction/Descriptions 0-2/ Notes & comments 1-1/ Derwent single mouth MBVR for EL70 2-1/ Thirlmere single mouth MBVR bipole for 2xEL70 2-2/ Thirlmere-R single mouth MBVR bipole for 2xEL70 3-1/ Coniston double mouth MBVR for EL70 3-2/ Coniston^2 double mouth MBVR for 2xEL70 4-1/ Windermere twin pipe resonant air coupler for EL70 4-2/ Windermere^2 twin pipe resonant air coupler for 2xEL70 4-3/ Alternate heads for Windermere^2 4-4/ Suggested Bracing for Windermere 1-2/ suggested cut plan for Derwent 5x5' 1-3/ suggested cut plan for Derwent 4x8' 2-3/ suggested cut plan for Thirlmere 5x5' 2-4/ suggested cut plan for Thirlmere 4x8' 3-3/ suggested cut plan for Coniston 5x5' 3-4/ suggested cut plan for Coniston 4x8' 2-5/ suggested cut plan for Coniston 4x8' minimal build 4-5/ suggested cut plan for Windermere 5x5' 4-6/ suggested cut plan for Windermere 4x8'
Derwent Thirlmere
Windermere Coniston
Lake District Design Series
for CSS EL70 & planet10-hifi EL70eN
"The Lake series of cabinets for the new CSS EL70 driver, developed by Mark Audio, offers a range of high performance designs, from a compact BVR style horn, to a highly characterful resonance tube design that attempts to extract as much bass extension from the driver as possible. Minimalism is key to all of the Lake enclosures, which draw their names from haunting stretches of water in Britian's Lake District. As well being an essential design philosopy, this also ensures they are relatively easy for any DIYer to build, from the most experienced to someone planning their very first speaker project. The Lake range comprises of the following designs: Derwent: A compact BVR horn for general listening use when space is at a premium, or for when a larger cabinet cannot be employed for aesthetic reasons. 50Hz - 20Khz.
Coniston: A tall but slender BVR double horn for use in modest spaces, or for when a larger soundstage with greater height and depth perspective is desired. 55Hz - 20KHz.
Coniston^2: A twin driver, semi-omni version of Coniston, offering greater power-handling and dynamic range for those with larger spaces, but who prefer to retain an elegantly sized cabinet. 55Hz - 20KHz.
Thirlmere: A modestly sized bipole BVR horn with a narrow front baffle. Twin drivers per channel offer greater power-handling and dynamic range. For use in slightly larger rooms, or for those who favour a more spacious soundstage. 50Hz - 20KHz.
Thirlmere-R: A modestly sized bipole BVR horn with a wide front baffle, and sideways firing horns. Twin drivers per channel offer greater power-handling and dynamic range. For use in slightly larger rooms, or for those who favour a more spacious soundstage. 50Hz - 20KHz.
Windermere: A characterful high gain twin pipe resonance tube / back horn for those who favour more unusual aesthetics, and are willing to sacrifice a little midrange finesse in order to extract the maximum bass extension from the EL70 driver. 35Hz - 20KHz.
Windermere^2: A twin driver version of Windermere with several different head-styles for those who require greater power handling and dynamic range, or have a larger space. 35Hz - 20KHz."
Lake District Design Series Notes
10-august-09
Recommended materials | Baltic Birch or other near void-free plywood is highly recommended. The more plys the better – 18mm Baltic Birch has 13 plys. Plywood has been selected for the combination of its higher stiffness to weight ratio, well demonstrated advantages of speed of dissipation of resonances when compared to denser materials such as MDF or HDF, as well as its lower mass. The latter can be of significant benefit both during the construction and finishing of some of larger designs, such as Coniston double mouth BVR/Horn, and in their placement and movement in listening rooms.
Driver wiring | For the twin driver versions, series wiring is recommended; however parallel is possible providing the amp can cope with the very low impedance. Of course you can use 2 amplifiers as well. Locations and type of input terminals not shown, use your favorite.
Alternate material thicknesses | All these designs have been drawn with nominal 3/4" (19mm) material. As noted above,
typical 13 ply Baltic Birch is 18mm. We have achieved excellent results on several of these and other designs utilizing 15mm (5/8") Baltic Birch plywood, with additional bracing. Also note that material thickness can vary from sheet to sheet within a lift of material, so it is important to check and to vary lengths of panels to avoid surprises. Maintain internal chamber sizes, vent depth & length, "horn" heights as a priority. If you have no alternative but to use MDF or particleboard, it is strongly suggested that the side panels have additional pieces laminated to achieve 1 1/8" - 1 1/4" to increase the stiffness to ~equal that of BB ply.
Holey Braces 1) Critical to the function of the driver holey brace is for it to transmit driver energy away from the baffle. It should fit tight against driver, but not so tight as to stress the frame. 2) Braces are placed just off-centre – ie on one side of the cabinet or driver centre line. 3) Dimensions & placement of holes in bracing panels are only suggestive. Goal is 30-40% holes, leaving a solid path between back of driver to back of cab (or other driver). More bracing than shown or interlocked braces is OK. Avoid braces that are parallel to the back of the driver in the vicinity of the driver.
Cut Plans 1) 1/8" (3mm) kerf allowed – none of the cut plans should be so tight as to not allow a larger kerf (such as in 5mm commercial production beam saws), or trim cuts to remove damaged factory edges. 2) Cut plans oriented for combination of yield efficiency and integrity of grain direction, but not optimized for contiguous grain wrap matching. If Post-veneering with highly figured grain patterns, higher waste factors can be anticipated.
Other drivers | Inevitably, people ask if they can use alternate drivers. These boxes were designed specifically for the T/S
parameters and physical dimensions of the EL70. Drivers with very similar Theile/Small parameters may work, but you are on your own.
Driver Cutouts | Although all drawings show a bevel on the back of the driver cutout, our work with several initial
prototypes using CHR & EL70 drivers suggest that due to the width and thickness of the mounting flange, beveling the back side of the driver cut out may not be appropriate with thinner baffle materials (ie 15mm), or if the driver is rebated for flush mounting
Damping Materials | Damping in the MBVRs: damp these as you would a bass reflex – line at least 3 sides with suitable
damping to reduce standing waves and reflections. Use wool or cotton felt (1/4-1/2"), acoustic fiberglass (1") or polyester bats (1"). The centre side of the holey brace is a good place to attach some damping as at the middle between 2 walls is the most effective place to kill standing waves. Optimal damping locations specified for Windermere. Amounts of material and location on other designs may be subject to experimentation to fine-tune individual system synergy – ie room, amplifier used, materials used, taste.
Tightening driver mounting screws | The polymer material used in the Mark Audio once piece moulded basket/flange
requires the use of caution when tightening the mounting screws – preferably by hand not with cordless drill. Sonically just the right amount of torque on the screws has an effect. Screws should be just tight enough to hold a real or imaginary washer from being turned.
Rights to Designs Lake District Design Series cabinets copyright 2009 Woden Design. All rights reserved. Provided for non-commercial use only. Commercial enquires please contact Woden Design / Creative Sound Solutions Designs all pass through Martin J. King MathCAD worksheets Any commercial licensees will be required to have a separate commercial license to this software. Of course feel free to exercise personal taste in both the finishing of cabinets and use of mounting spikes, bases, etc. Note that taller slim designs such as the Coniston and Windermere can be tippy, and definitely benefit from mass loaded base plates or ballast fill to lower void cavities.
Derwent MBVR
6 [153.1]
for CSS EL70 0v96
designed by Scott Lindgren drawn by dld | 01-august-2009 © 2009 Woden Design
8 3/4 [222.3] 30°
Notes: 0/ drawn using 19mm (3/4") material 1/ minimal bracing shown 2/ damp as you would a bass reflex (ie top, back & 1 sidewall lined with 1/2in wool felt or similar as a start) 9 1/2 [241.3]
7 1/2 [190.5]
8 [203.2]
6 [152.4]
3 [76.2]
24 [609.6]
36 1/4 [920.8]
1 [25.4] 3 [76.2] 2 1/2 [63.5]
10 5/8 [269.4]
10 [254]
45°
1 1/4 [31.8]
Derwent Damping Plan designed by Scott Lindgren drawn by dld | 07-september-2009 © 2009 Woden Design
Notes: Damping sheets shown for 5/8" (15mm) recycled cotton/denim felt damping material. Wool felt or 1" acoustic fiberglass may be substituted
Additional damping well tufted polyfuff0 may be needed if the bass is found excessive in room. Start above the driver.
48 [1219.2] 50 3/16 [1275.4]
8 [203.2] 4 3/4 [120.7]
4 1/4 [108]
Thirlmere Bipole MBVR for 2 x CSS EL70 1v01
designed by Scott Lindgren drawn by dld | 05-sep-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ damp as you would a bass reflex (ie top, back & 1 sidewall lined with 1/2in wool felt or similar as a start) 3/ holey braces could extend & interlock 4/ optimum driver position shown, 8" or 4.75" Zd are alternatives but will require some polyfluff damping thruout the reflex box. Bracing will need adjustment.
6 [152.4]
7 1/2 [190.5]
11 1/2 [292.1]
11 1/2 [292.1]
10 [254]
8 1/4 [209.6] 10 [254]
24 [609.6]
1 [25.4]
2 1/2 [63.5]
25 1/2 [647.7] 36 1/4 [920.8]
10 [254] 12 1/8 [307.4] 38.3°
Thirlmere-R Bipole MBVR for 2 x CSS EL70 0v99
designed by Scott Lindgren drawn by dld | 05-september-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ damp as you would a bass reflex (ie top, back & 1 sidewall lined with 1/2in wool felt or similar as a start) 3/ Driver shown at golden-ratio, could be centred 4/ mirror image the pair
7 1/2 [190.5]
11 1/2 [292.1]
6 [152.4]
10 [254]
3 [76.2]
20 1/8 [509.6] 24 [609.6]
36 1/4 [920.8] 3 15/16 [100] 1 [25.4]
2 [50.8]
3 7/8 [100]
2 1/2 [63.5]
10 [254] 1 1/4 [31.8]
38.3°
12 1/8 [307.4]
Thirlmere alternate driver placement designed by Scott Lindgren drawn by dld | 06-sep-2009 © 2009 Woden Design
Notes: Some will find the optimal driver position (figure A) too low. To this end alternate positions are possible (note that the original design was figure D). These alternate driver positions require a different damping strategy, and may have a bit less bass quantity. Although shown for Thirlmere, they also apply to Thirlmere-R. 0/ damp B, C, D with 0.5 pounds/ft^3 of well teased polyfluff (or acoustistuff, wool, miraflex). Volume = 0.833 ft^3 -> 0.42 pounds = 190 g per box 2/ driver bracing will require adjustment (cut plans show the braces for D as an aside) 3/ as these could use a stabalizing base to make them less tippy, do account for the height it adds when choosing driver position
3 [76.2]
4 3/4 [120.7] 8 [203.2]
10 [254]
25 1/2 [647.7]
27 1/2 [698.5]
30 3/4 [781.1]
32 1/2 [825.5]
A
B
C
D
6 [152.4]
Thirlmere
8 3/4 [222.3]
Damping Plan designed by Scott Lindgren drawn by dld | 05-sep-2009 © 2009 Woden Design
Notes: Damping sheets shown for 5/8" (15mm) recycled cotton/denim felt damping material. Wool felt or 1" acoustic fiberglass may be substituted
47 1/8 [1197]
Additional damping well tufted polyfuff0 may be needed if the bass is found excessive in room. Start above the driver.
45 1/2 [1155.7]
Coniston
Twin Vent MBVR for CSS EL70 0v96 designed by Scott Lindgren drawn by dld | 01-august-2009 © 2009 Woden Design
7 1/4 [183.5] 12 1/2 [318.9]
Notes: 0/ drawn using 19mm (3/4") material 1/ damp as you would a bass reflex (ie top, back & 1 sidewall lined with 1/2in wool felt or similar as a start)
14 [354.5]
7 1/2 [190.5]
7 3/4 [196.9]
6 [152.4]
3 1/4 [82.6] 1 15/16 [49.1]
8 [203.2] 60 [1524] 27 [685.8] 12 1/2 [318.9]
1 [25.4] 3 [76.2] 30 [762]
4 [101.6] 15 [381]
Coniston^2
Twin Vent MBVR for CSS EL70 0v96 designed by Scott Lindgren drawn by dld | 01-august-2009 © 2009 Woden Design
7 1/4 [183.5]
12 1/2 [318.9]
Notes: 0/ drawn using 19mm (3/4") material 1/ damp as you would a bass reflex (ie top, back & 1 sidewall lined with 1/2in wool felt or similar as a start) 2/ mirror image pair
14 [354.5]
6 [152.4] 7 1/2 [190.5]
7 3/4 [196.9]
3 1/4 [82.6] 1 15/16 [49.1]
8 [203.2] 60 [1524] 27 [685.8] 12 1/2 [318.9]
3 7/8 [98.4]
1 [25.4]
3 [76.2]
32 1/2 [824] 27 1/2 [700]
4 [101.6] 15 [381]
Coniston Damping Plan designed by Scott Lindgren drawn by dld | 07-september-2009 © 2009 Woden Design
Notes: Damping sheets shown for 5/8" (15mm) recycled cotton/denim felt damping material. Wool felt or 1" acoustic fiberglass may be substituted
Additional damping well tufted polyfuff0 may be needed if the bass is found excessive in room. Start above the driver.
8 [203.2] 4 3/4 [120.7]
27 [685.8]
47 1/2 [1207.7]
54 [1371.6]
Windermere
twin pipe resonant air coupler for CSS EL70 0v99 designed by Scott Lindgren drawn by dld | 07-september-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ Bracing not shown – see Bracing sheet for suggested bracing
54 1/2 [1384.3]
3 [76.2]
6 1/2 [165.1]
53 3/4 [1365.3]
4 [101.6]
33 1/4 [844.6] 34 3/4 [882.7]
5 [127]
5 [127]
12 [304.8] 6 1/2 [165.1]
13 9/16 [344.2]
Windermere^2
twin pipe resonant air coupler for 2x EL70 0v99 designed by Scott Lindgren drawn by dld | 07-september-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ no bracing shown, a holey driver brace recommended at minimum 2/ lower driver can be rolled off 1st order at 400-700Hz, top or side mounted (see alternate head drawings)
54 1/2 [1384.3]
3 [76.2]
8 3/8 [212.9]
6 1/2 [165.1]
53 3/4 [1365.3]
4 [101.6]
33 1/4 [844.6] 34 3/4 [882.7]
5 [127]
5 [127]
12 [304.8] 6 1/2 [165.1]
13 9/16 [344.2]
Back panel for this part of the line will need notching to make room for the magnet
Windermere^2 for 2 x CSS EL70 0v95 Alternate Heads designed by Scott Lindgren drawn by dld / 01-august-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ damping shown in orange is 1/2" (12mm) wool felt or 1" fiberglass 2/ no bracing shown
Windermere
for CSS EL70 0v92 Bracing designed by Scott Lindgren drawn by dld / 01-augusr-2009 © 2009 Woden Design
Notes: 0/ drawn using 19mm (3/4") material 1/ an example bracing strategy – feel free to modify 2/ holey braces could extend & interlock 3/ braces oriented vertically to not restrict air flow, and to create subpanels that have greater aspect ratio. Braces offset from centre so that subpanels are dissimilat shape
9 1/4 [235.6]
9 1/4 [235.6] 37 1/2 [951.8]
Longer driver braces for Windermere^2
14 1/2 [367.6]
7 [177.8]
Windermere Damping Plan designed by Scott Lindgren drawn by dld | 07-september-2009 © 2009 Woden Design
Notes: Damping sheets shown for 5/8" (15mm) recycled cotton/denim felt damping material. Wool felt or 1" acoustic fiberglass may be substituted
12 [304.8]
40 1/4 [1022.4]
50 5/8 [1285.9]
3 3/4 [95.1]
Derwent 5'x5' cut plan drawn by dld / 26-july-2009
side
side
side
side
back
back
baffle
bottom
bottom baffle
inner deflect bottom vent inner bottom deflect vent
top
top
side
side
side
side
back
back
bottom
bottom
top
top
baffle
baffle
Derwent 4'x8' cut plan drawn by dld / 26-july-2009
inner bottom
inner bottom
deflect
deflect
vent
vent
Thirlmere 5'x5' cut plan drawn by dld / 05-sep-2009
side
top
side
top
side
side baffle
baffle
baffle
baffle
inner inner bottom bottom
bottom bottom deflect deflect
Thirlmere-R 5'x5' cut plan
baffle
top
top
baffle
baffle
side
side
side
side
baffle
inner inner bottom bottom
bottom bottom deflect deflect
drawn by dld / 05-sep-2009
inner bottom
inner bottom side
Thirlmere-R
side
4'x8' cut plan baffle
baffle drawn by dld / 05-sep-2009
inner bottom
inner bottom
baffle side
side
side
side
side
top
top
baffle
side baffle
baffle
top
top
bottom bottom
deflect deflect
baffle
baffle
Thirlmere 4'x8' cut plan drawn by dld / 05-sep-2009
bottom bottom
deflect deflect
side
side
side
side
back
back
Coniston 5'x5' cut plan drawn by dld / 25-july-2009
baffle
baffle
bottom deflect deflect
top
bottom
deflect deflect
top
vent
vent
inner top
inner top
inner inner bottom bottom vent
vent
triangle triangle
vent side
side
side
side
inner top
Coniston 4'x8' cut plan
inner bottom
drawn by dld / 25-july-2009
vent triangle vent inner top inner bottom
back
back
vent triangle
bottom
top
bottom
baffle
baffle
top deflect deflect
deflect deflect
Coniston 4'x8' cut plan Alternate drawn by dld / 25-july-2009
Notes: 0/ with the minimal build it is possible to get a pair out of a single 4x8 sheet
side
side
side
side
back
deflect deflect
vent
vent
inner top
inner top
back
deflect deflect
inner inner bottom bottom vent
vent
triangle triangle
baffle
baffle
top
top
bottom
bottom
baffle
baffle
inner front
inner front
end front
end front
back
back
side
side
side
side
Windermere
5'x5' cut plan
drawn by dld / 30-july-2009
Windermere 4'x8' cut plan drawn by dld / 25-july-2009
side
side
baffle side baffle
side
end front
inner front
end front
inner front
back back
bottom bottom
top top