Back-loaded-horn speaker design for FE103En-S [トールボーイスワンⅡ]
2010-10-01
Enclosure design for FE103En-S
Tall boy swan 2
Outline
1. The form of enclosure was assumed to be a back loaded horn speaker/BLH of the Swan type. However, an open mouth of the horn was made the front side.
The reason assumed to be a Swan type is to have the presence and the power of expression of the space to which the speaker of the Swan type is peculiar.
The reason for this power of expression is that it is thought that not only including surroundings of the sound from the air chamber of the speaker but the air chamber panel vibration extends up and down and before and behind and right and left.
2. Tall boy Swan2 designed the entire enclosure from the aspect of the panel vibration by thinking.
The board around the speaker is sure to vibrate even if it is said that Swan is a point sound source. I want to challenge enclosure that artificially uses the panel vibration this time.
The part that vibrates easily most becomes a front board.
It is thought that a front board is a part of vibration board, and after it produces it, I want to test the bass region by changing the difference about a front board.
3. The material and board thickness were selected.
I want to select board thickness from study from Tall Boy Swan according to the speaker unit diameter and the area of the room.
Concretely, it was assumed 12mm(Cedar plywood) and 18mm(Plyawood).
Moreover, the part where it wanted to vibrate the board was assumed to be 12mm thickness, and the part that fixed as much as possible was assumed to be 18mm thickness. Two kinds of boards were used properly and the design was advanced.
4. It wants to aim at the speaker of the small volume type with a good response and to earn a bass region.
It became 2.5m from the restriction of constructional though the length of the back loaded horn wanted to take about 2.6m.
The horn was approximated to the exponential curve as much as possible.
In the simulation, because the error margin in the vicinity of S0 (Throat area) went out easily, the vicinity was assumed to be a design that did a detailed correction.
Specifications
Unit FE103En-S (10cm full range), so close to the swan and root parameters.
*FE103En-S Unit
*Va (air chamber volume) = 1.9 ℓ
*S0 (Throat area) = 42c m
*Fx (Cut-off frequency)
fx = 10 × So / Va 221 ≒ (Hz)
*Horn aperture ratio of the expression
S = S0 × 1.103 ^ (0.1 × distance (cm))···(1)
*Horn length ≒ 2.5m (front opened)
*Plate thickness is 12mm (Cedar plywood) & 18mm (Plywood)
*Hight 1.0m Width: 32.0 cm Depth - 30.3 cm
More information on how to design, “FE88ES-R design Tallboy Swan” please look.
Design
First of all, adjusting the parameters of the horn in a 42 sq cm as S0, approximately 490 sq cm, with an opening (1) the aperture angle of the expression parameters was 1.103.
Exponential curves made in Excel, it was approximated cross section.
To improve the accuracy of this horn as possible, took the technique to make a plate angle.
If the board diagonally, overlapping plates raised more accurate. However, when making the effort it takes.
Moreover, folding of the 5 and 7, the error out easily.
To reduce the load resistance, designed around the throat as much as possible as close to square.
Please refer to the following graph numeric data.
Exponential curve & Fitting(numeric data)
Others
Naturally, when a certain signal is input to the speaker, energy from the vibration board of the speaker is discharged in air.
Besides, the enclosure is transmitted to the transmitting floor and the wall. Moreover, the vibration of the enclosure is discharged in the air again. Additionally, it changes into heat as an internal loss of the board.
Such a convenient material is not in the world though the ideal of the speaker is written that only the vibration board of the unit only has to vibrate well, and enclosure vibrates without fail.
The board of enclosure is made to resonate, and it is very a point whether the sound from enclosure and the speaker harmonizes.
This design was ended but "Go ahead!" not applied yet.
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