Frugel Horn v1 Maps 130307

8/3/2019 Frugel Horn v1 Maps 130307

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The Frugel-Horn (cross between flugel horn & frugal) is an open-source DIYproject to develop a small, inexpensive corner horn. It is not a commercialproduct*. We started with a modified-Buschorn, then made changes to makethe design more rational & more versatile for the DIY community. With the

involvement of the entire community sonics can rival & exceed any speaker inits niche.

Your Feedback helps improve this design and spurs continued development.

The web site:

Design History

1.0.0/A modified Buschhorn 1-- enlarged to accomodate the larger driversused in this design.

1.2.1/ Refolding of1.0.0. This was our 1st Frugel-Horn build.

1.3.0= version 1.0 Level 0/ Simplifications & minor change of some detailsto ease building (drawings for this were in limited release)

1.4.0= version 1.0/Increases cabinet width, adds a curved rear mouth, anddeflector to improve bass extension by 10-12 Hz and reduce reflections off the"supporting" corner back into the horn mouth thus reducing the ripple in the LFresponse.

Compression Chamber Size

The design accomodates a large range of compression chamber sizes to(hopefully) help allow a wide range of drivers. The internal partitions naturallydefine 3 possibilities -- small, medium, & large. These can be further refined byadding fill-in material. The smaller the CC size the higher the acoustic low-passfilter to the rear-loaded horn. For the initially targeted FE126e & FE108e, thesmall CC is a good starting point.

Drivers with similar parameters to the 2 target drivers are likely to work best,but like every other horn i have seen, people will want to try many drivers, and

the variable CC is there to aid in that endeavor.

supraBaffle

The purpose of the supraBaffle is to push roll-off due to baffle step down to thepoint where the horn action takes over flattening the speaker's frequencyresponse. The smaller the compression chamber the smaller the supraBafflerequired. Since the supraBaffle is applicable to any skinny speaker anotherdocument covering it in more detail is in the works.

Build Levels

The Frugel-Horn can be built to a number of levels. Although a full-on Level 3 isbest,even at Level o the horn is good. With each additional level the sonics areimproved but the build moves away from a rectangular box which may or maynot be a WAF issue (my wife prefers the Level 3 looks :^)

Voids

Unused voids in a folded horn are quite common. The voids in the Frugel-Horncan be left as is, filled (sand, lead shot, kitty litter....) or as illustrated in manyof the renderings and examples, opened up so that they are no longer void. Thisalso adds an aesthetic touch and gives a visual indication that this is indeed ahorn.

Adding your own creative touch

The Frugel-Horn design intentially leaves a lot of scope for your own creativeaesthetic. Even on the few builds to-date there are examples of a wide range ofartistic interpretation.

The Frugel-Horn Open Source Corner Horn Project

Version 1.0.3 Plan Set(updated 13-march-07)

Drawings/Contents

Sheet i0/ OverviewSheet i1/ Build Levels

Sheet FH0/Horn Path & NotesSheet FH1/Parts placement detailSheet FH2 Internal parts detailSheet FH3/DeflectorSheet FH4/Side pattern (imperial)Sheet FH5/Side pattern (metric)Sheet FH6/Compression Chamber

Sheet A0-W0/Wedgie DetailsSheet A0-W1/Wedgie PlanSheet A0-W2/Wedgie PlacementSheet A0-W3/Wedgie PartsSheet A0-W4/Side pattern (imperial)

Sheet A0-W5/Side pattern (metric)

Sheet A1-S0/SupraBaffleSheet A1-S1/SupraBaffle Shapes

Sheet A2-B0/Modified Buschhorn

please email me withcorrections & suggestions to make this documentmore useful


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The Frugel-HornOpen Source Corner HornProject V1.0 sheet i1Build Levelsdrawn by dld09-october-2006

Level 0/The horn in a rectangular box. Instead of thecurved rear the sides are made straight down from the backof the top panel.

Level 1/Just the horn but with curved mouth

Level 2a /Add the deflector to Level 1 Level 2b/Add a supraBaffle to Level 1

Level 3/Full Build. Horn with supraBaffle & deflector

Level 0 to Level 1 upgrade once built isa bit tricky, but upgrades from otherlevels to higher levels can beaccomplished step-by-step just byadding to the current build.


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250

123.7

291

44.643.9

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41.141.1

461.7

20.8

31

31.9

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48.2

48.2

98.2

739

126

18.619.9

47

63.5

43.2

160.6

1/This alpha is (mostly) consistent with theHornShoppe expansion.

2/Internal width is 140mm, internalpartitions drawn are 12mm, front, top,bottom, sides are 18mm (feel free to uselarger or smaller material for the outerpanels)

3/optional ~300 mm wide/diametersupra-baffle not shown. Its purpose is tomove the baffle-step drop off to where thehorn action starts flattening lowermidrange FR

4/Has up to 5.4 litre compression chamberusing all of the upper void -- this should

give some latitude for other drivers. Thedesign has partitions which lend themselvesto small, medium & large CCs. Choose onelarger than needed and add "fill" to decreaseit as required

5/intended for Fostex FE126 or FE108e,horn action from ~50-200(250) Hz

6/Deflector and curved mouth are optional,but recommended. In conjunction theyincrease mouth size and give 10-12 Hz moreextension in the bottom.

The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH0Horn Path & Notesdrawn by dldupdated 05-october-2006

These partitions can be removed, changed, modified toaccomodate different size compression chambers to

allow some driver versatility. See Sheet 7(page 8)

10

30

11.3

3.1

Cut side walls at this line for aLevel 0 build

1262.1 cm^2 x 14 cm width

=17669 cm^3

=17.67 litre

Area of thisshape is

1262.1 cm^2


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415/16[125]

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52"(1321mm) radius

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[285]

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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH1Panel Placement Detailsdrawn by dldupdated 02-february-2007

615/16

[176]

51/2[140]


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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH2Internal Panel Detailsdrawn by dld17-june-2006

A

B

C

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EF

G

11[280.2]

121/8[307.9]

3060

11[279.2]

11[279.7]

3

4[102.1]

41/8[104.2]

10

201/4[515.7]

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1010

13/[35.

1[3

11

167/8[428.3]

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10.7 11.3

43/4[122]

41/2[113.8]

4511


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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH3Deflectordrawn by dldupdated 5-october-2006

755.2

37.7

41/4[108.5]

52" radius

213/8[542.3]

101/4[261.9]

65/8[169.7]

any deflector above this isbonus ... an angle as drawnwill provide a bit extra aswell as potentially higheraesthetic

55

45

23/8[61]

101/4[261.9]

115/8[294.9]

66

projection of top surface ofenclosure hieght deflector

147/8[379.2]

5/8[14.3]

221/2[573.1]

91/2[241.6]

Notes:

0/The deflector serves 2 tasks, first it actsto reduce the reflection back up the horn,and second, it increases the mouth size.Without the mouth are is the opening onthe back of the horn (1,060 cm^2). Withthe deflector it is the 2 surfaces on the sidesdefined by the verticle edge of the rear ofthe horn, and the outer, back edge of thedeflector (2,080 cm^2 for a full heightdeflector) The shape of the mouth is alsobetter with the deflecto (1:5.4 Vrs 1:1.5)

1/The minimum deflector is a triangularprism up to 2/3 height. Everything abovethat helps a bit but is mostly cosmetic.

2/angled tops with an angle greater than45 will be more of a challenge to build.

3/material for this is not critical -- a goodchance to use up that MDF. should be filledwith sand, kitty litter, lead shot ...something to keep it from ringing.


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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH4Side Pattern(1/2" grid)drawn by dld17-june-2006

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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH5Side Pattern(1 cm grid)drawn by dld17-june-2006

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=

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The Frugel-HornOpen Source Corner HornProject V1.0 sheet FH6Compression Chamberdrawn by dldupdated 13-march-2007

small(2.356 litre/143.7 in^3)

medium(4.067 litre/248.1 in^3)

large(5.854 litre/357.3 in^3)

0/internal partitions readily allow 3major sizes of compression chamber.Volumes indicated do not subtractvolume of the back of the driver orany braces added

1/the volume of the CC along with thethroat size & the driver parameterscreate a low pass filter for outputfrom the horn. The larger the CCvolume the lower the filter's cut-off. Itis important that this is not so high as

to allow significant midrange to get tothe horn (ie not too small), but not solow that the horn action isn't beingused to ease the job of the driver inproducing bass (not too big). Thelower this high pass is set the largerthe supraBaffle required

2/choose a CC larger than you thinkyou need and then add solid fill -- anopportunity to make inside quiteirregular -- to tune the CC size. A set ofwooden blocks or such would allowchange in fixed steps

3/as a generalization drivers withgreater Vas & Qt will require a largerCC and will vary depending onatmospheric pressure.

4/please report back your findings forthe driver you use, these will helpfellow builders fine tune theirenclosures

5/The small CC is a good starting pointfor the FE126e & FE108e

6/The 1st approximation is 2.2 litre forthe FE126e & 1.8 litre for the FE108e

7/If you do the wedgie version youstart out with a slightly larger CC

extra CC area inWedgie Version

extra volume added by wedgie version

(0.186 litre/11.36 in^3)


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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W0Wedgie Detailsdrawn by dldupdated 13-march-2007

B

C

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E

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18[46

125/32[45]

21/16[52]

123/32[44]1.63

2.78

517/32[140.5]

17/32[31]

17/32[31]

17/32[31]

A

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A

1613/16[426.8]

167/8[428.9]

43/32[103.6]

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10

Notes:

0/the "wedgie" comes from the useof2 wedge shaped pieces to makethe taper. The 1st 2 passages arefixed at 31mm wide and the wedgein the niddle of each passage isused to taper the line. This allows aless severe cross-section ratio (2channels with 1.4:1 aspect vrs 1with an aspect of7.5:1) and bracesthe high pressure panels.

1/the increase in the height of the1st section requires a slightly tallerbox and a slightly deeper top.

2/all the angles in pieces A, B, C, D,& E are now 10,45 or 90

3/top, baffle, A, B, C, & D aredifferent sizes. A & C aren'tdifferent by much.

1/16[1.5]


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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W1Wedgie Detailsdrawn by dldupdated 13-march-2007

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65/8[167.9]

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31/2[89]

21/2[63.5]

207/16[519.3]

17/32[31.2]

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115/16[48.9]

6[152.5]

45/32[105.8]

123/32[307.5]

43/8[110.8]

1515/32[392.8]

52" radius

119/32[286.7]

45/32[105.8]

3015/16[786]

10

17/32[31]


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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W2Wedgie Placementdrawn by dld04-october-2006

Notes:

0/red bits are the 2 wedgies


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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W3Internal Panel (Wedgie)drawn by dld14-august-2006

A

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203/4[527.2]

163/4[426.8]

43/8[111.8]

4[103.1]

45

11/2[37.8]

Notes:

1/all miters are 10 except for the one 90 cut &

the marked 45

2/only panels that differ from the non-wedgieversion shown

163/4[426.8]

13/8[35.7]

203/4

[527.2]


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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W4Wedgie Side Pattern(1/2" grid)drawn by dld09-october-2006

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The Frugel-HornOpen Source Corner HornProject V1.0w sheet A0-W5Wedgie Sidedrawn by dld09-october-2006

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The Frugel-HornOpen Source Corner HornProject V1.0 sheet A1-S0supraBafflesdrawn by dld04-october-2006

Notes:

The supraBaffle serves a specific purpose. Any speaker mounted on a baffle will see 2steri-radians at high frequencies & 4 steri-radians at low frequencies. Ignoring any otherinfluences this means an on-axis drop in level of6 dB in the low frequencies. This is calledbaffle step loss*. With the narrow baffle of the Frugel-Horn this would start ~650-700Hz. The output from the horn is high enough to compensate but only up to 250-300 Hz.The purpose of the supraBaffle is to push the baffle-step down in frquency until it meetsup with the output from the horn. This depends on compression chamber size (ie theacoustic XO between the horn & the direct driver radiation), Exact values await actualmeasurements of units in the field.

*(for more info http://www.t-linespeakers.org/tech/bafflestep/intro-bds.html)

A 1st order approximation is that the supraBaffle needs to have an average minimum dimension of111/2'--13"(292-330mm). The actual shape

leaves a lot of room for creativity.

On the next sheet i have reproduced Page 23 of Olson's Acoustics and some shapes suggested or implemented already. This graphically illustratesthe diffraction behaviour of a number of standard shapes. One can see that a sphere is smoothest, a truncated pyramid is close, and that anyshape requires a trailing edge. From this, and ease of construction, a truncated pyramid will be designated as "the standard supraBaffle".

Considering work done since Olson, the shape that B&W uses on their top-of-range speakers for their midrange probably represents a close toideal shape.

The supraBaffle can be flush with the front baffle, stand completely proud, or somewhere in-between. The standard sB will fit over the front, withmost of the sB behind the plane of the front -- this because it is easiest to execute. Keep in mind that a supraBaffle proud of the front is going toincrease the size of the suprabaffle.

This "standard supraBaffle" is comprised of4 layers of~3/4"(19mm) material, and then passed thru a table saw with the blade set at 45 toachieve the bevel.

11 1/2

[292.1]

1 1/2

[38.1]

6 3/4

[170]

11 1/2

[292.1]

3 pieces1 piece

shown at 50% of the scale of the other drawings on the page


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The Frugel-HornOpen Source Corner HornProject V1.0 sheet A1-S1supraBaffle shapesdrawn by dld04-october-2006

The most thumbed page in my copy of Olson's Acoustics -- everybodyshould have a copy of this book (available from audioXpress).

It shows the baffle step diffraction on various shape baffles. It can be veryhelpful deciding what not to do.

John in Costa Rica provided thesesketchs of possible supraBaffle shapes.

Josh's star shaped supraBaffle &the Nautalus midrange pod


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0/Internal width is 51/8"(130mm)

1/internal partitions are 5/8"(15mm))

2/this was what we built as proof of concept,ie Version Zero. All subsequent builds havebeen superior, so this is only here for historic

interest.

281/4[718]

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Modified Buschhornsheet A2-B0a Buschhorn 1 stretched to fit a 4"(100mm) driverdrawn by dld15-february-2006

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Frugel Horn v1 Maps 130307