E-27 Enclosure for Alpine DLX-Z17W


Monument Valley, Arizona, USA (Photo by Yuichi)


E-27 Specifications
(This enclosure was designed and made for Alpine DLX-Z17W woofer and DLX-Z30T tweeter)

DLX-Z17W catalogue data
= 17cm diameter diaphragm with Neodymium magnet
= Frequency range: 28Hz-12Khz
= SPL: 89dB/Wm = Input(RMS) : 50W, (Peak) : 200W, = Imp : 6 ohms
= Major TS Parameters Fs : 67Hz, Qts : 0.73, Vas : 8.9Liters

DLX-Z30T catalogue data
= 3cm ring tweeter construction
= Frequency range: 3.5KHz-60KHz
= SPL : 89dB/Wm = Input(RMS) : 20W, (Peak) : 60W, Imp : 4 ohms

Enclosure data
= Volume : 27 liters
= Size : Odd size (Please refer to the drawings in the download page)
= Type : Vented
= F(B) : 50Hz
= Frequency range : 50Hz to 20KHz
= Material : Cherry plywoods (21mm thickness) and a Chinese quince
laminated lumber for corners and the tweeter stand (30mm thickness).
= Finish : Oil based clear polyurethane
= Coloring : Oak

.July 2008 issue, MJ Magazine.

Design of E27 Enclosure
TS Parameters

TS parameters were measured by the CLIO system.
In this case, small signal measurement was adopted.
When larger signal is applied to the driver, TS
parameters such as Fs, Qts and Vas may be shifted a
little. However in this case, following major TS parameters were obtained in this environment.

Fs=61Hz , Qts=0.53 and Vas=10.9 Liters

WinSpeakerz software is used for low frequency simulation of the vented type enclosure. Since
EBP=(Fs/Qes)=Approx.100, rule of thumb tells us that
the vented enclosure is adequate choice for this
woofer driver.
Above TS parameter value were
applied. Simulation curve in the
left chart is one of the optimization.
Since the simulation software only
simulates low frequency properties,
small up and down property can not
be seen.

In this case, you can see the Vent
Area and the Length to obtain proper
F(B) which is 50Hz. The
recommended Vent Area is much
larger than the data used here. If you
use larger output from the driver,
you better follow recommendation.
Otherwise vent effect will be
de-gradated or air flow from the
vent will make some noise.
If you use in normal sound level, the
Vent Area can be a little smaller. So,
you can have shorter Vent Length.

The impedance curve is also seen.
Bottom of two peaks is approx. 50Hz.
Beyond this point, gain gets smaller.
Through this simulation, I obtained
following enclosure size.

Box Volume=V(B)=27 Litters
Vents Area=S(v)=20cm^2
Vent Length=L(v)=5.2cm


Building and assembly process


Please refer to the enclosure drawings and the frequency dividing circuit in the download page with .pdf file.

Cutting the top and the
bottom plates
Assembly of bracings by
adhesive and screws
Assembly of wall plate by
fixing clamps and corner
clumps
Putting of bracings for
frot and rear plates
The corner decoration
woods are assembled.
Driver mounting hole is
made by a jig saw.
By using 5cm dia. hole
saw, tweeter stand is
build..
Replaceable vents
are assembled.
Primary purpose of the
grass wool application is
to control Box Q.
Therefore, grass wool
will affect the effective
volume of the enclosure.
This must be carefully
considered.
Grass wool is applied for
acoustic absorption.

Upper side view of a
tweeter and a woofer.
Rear side view of a
adjustable tweeter stand.


Measurements

Impedance and Phase properties Frequency Response (Near field property)
Base Frequency response (red), 2nd (black) and 4th (blue)
harmonic distortion curves
Base Frequency response (red), 3nd (black) and 5th (blue)
harmonic Distortion curves
.
Please refer to the experiment of the Alpine system
configuration shown in the experiment page. This
enclosure is the final version based upon the result.


As a bottom line, this system reproduces the sound
very clearly without any distortion.


Special thanks

(For E-27 Enclosure craft, I used the WinSpeakerz
simulation software and the CLIO measurement system.
Thank you for both excellent products.)
Water fall property looks pretty smooth especially in
mid / high frequency space.

Enclosure Page...... ......Top Page

Monument Valley, Arizona, USA (Photo by Yuichi)