The applet referenced via this page is copyrighted
and comes with no warranty. It is intended for demonstration purposes only.
There is no warranty express or implied for this applet. Use of the applet
is granted for personal use only. Designs produced by the applet may not
be sold commercially without permission from the authors.
The speaker design program which you can access via this page uses
Thiele-Smallparameters for a speaker, and allows you to
calculate various designs. The two primary style of speaker designs handled
by the program are horn-loaded cabinets and vented cabinets.
The designs produced may be used to construct high efficiency horn-loaded
cabinets for PA and sound-reinforcement use. Horn flares may be conical
or exponential. Exponential flares have the best efficiency/distortion
tradeoff of all flares. However, conical flares are easy to build. A conical
flare is commonly seen as the mid-range cabinet in large PA systems (a
Roy box perhaps?). Other flare types (hyperbolic, parabolic) are not implemented.
Hi-fi cabinets would most likely be designed using vented cabinets. As
a social consideration, we do not include any design ability for band-pass
designs used for cars that go thump-thump-thump. Similarly, closed cabinets
are almost always outperformed by vented cabinets, so they have been omitted
N.B.All units used by the program are metric.
To use the program, first enter the speaker parameters using the 'Choose
Speaker' option. Next, choose either 'Vented Design' or 'Horn
Design' to select features for your design.
If you are doing a horn-loaded design, you then go to the 'Horn Response'
section to plot speaker capabilities, horn impedances, and system response.
Note, that for horn designs, the compliance volume (the air volume between
the diaphragm and the throat of the horn) affects the high frequency response
of the horn. Hence, a real design will show high-end rolloff unless a 'phase-plug'
is used. If you specify a compliance volume, you will see high frequency
roll-off when plotting the frequency response of horn designs. The compliance
volume is specified in cubic metres, so, for example, with a typical 15"
driver, the volume displaced by the driver is approximately 4 litres, and
the compliance volume is roughly 3 litres, or 0.003 cubic metres.
When doing a horn design, the 'Speaker Limits' graph shows what
the defined loudspeaker is capable of when different diaphragm to throat
ratios (Sd/St) are used.
Fmin is the frequency of simultaneous thermal and displacement
Nt is the maximum attainable efficiency
fH is the upper half-power frequency
(3db point at the high-end)
par is the 50Hz displacement limited
acoustic power rating
Per is the 50Hz displacement limited electrical power rating
Pa is the thermally limited maximum
acoustic power rating
Pin is the thermally limited maximum
electrical power rating
When doing a vented design, the following definitions are used:
VB is the volume of the box in litres
FB is the resonant frequency of the box
F3 is the low frequency 3 dB point for the response of the speaker
in the box
Dv is the diameter of the vent (port) in millimetres
Lv is the length of the vent in millimetres
PAR is the peak acoustic power that may be produced at the speaker
displacement limit (Xmax)
PER is the electrical power to produce PAR (note, this can be
greater or smaller than the speakers thermal capability
RG is the system impedance which affects damping (the closer
to 0 the better)