© 2007
If you can design a passive or active 2-way speaker system, with the introduction of A, B, C, Dipole you can build a dipole
speaker system using conventional drivers.
A, B, C, Dipole  is a full featured hypertext "How to" design guide with
accompanying Excel based tool kit, that walks you through the complete design of a 3 - way, dipole speaker system.  The system
can be designed as either a hybrid, bi-amplified system using an active crossover between the woofer and midrange/tweeter
panel, and a passive midrange/tweeter crossover, or as a fully active, 3-way system requiring tri-amplification. However, even if
you desire to build a fully passive dipole speaker there is a wealth of information in the Guide to assist you. The guide includes a
proprietary dipole baffle simulation tool, accessed through the Excel tool. The Excel tool kit allows evaluation of midrange and
low frequency drivers for dipole use, estimation of the baffled driver response, H and U - frame woofer evaluation, and the
complete design of the active circuits required for dipole equalization and the woofer to midrange active crossover, including
component value calculation for a standardize circuit topology. With the guide, the Excel tool kit, your favorite speaker design
CAD  and measurement software all that remains is to design the passive or active midrange to tweeter crossover as would be
done for any conventional 2-ways speaker system. The guide provides  background on dipole operation and theory as well as a
step by step design example. Even if you have only passing interest in dipole speaker based on conventional drivers, you
shouldn't be without
A, B, C, Dipole.

A complete table of contents, several screen shots, and system requirements are presented below. Due to continued updates to
the MicroSoft Office suite and the introduction of newer operating systems the complete dipole design guide with Excel tool kit
and baffle simulation tool is available from
Music and Design  free of charge. However, it is possible that the Excel tool may
not operate properly on newer versions of Excel.

**If you encounter problems displaying content of ABC Dipole, open the folder containing the CHM file.
Right click on the file and open the Properties dialog. In the properties dialog look for and choose Unblock.
Above is a screen shot of the driver/baffle evaluation tool. Values shown in red are user specified. Driver parameters are entered at the upper right
along with the intended listening distance. Below that the baffle type is set and the baffle size and driver position are specified. At the bottom left the
type of simulation,  dipole or standard baffle diffractions, is specified. The run simulation button is then clicked to execute the baffle simulation
program. When completed, the update results button is clicked to display the result in the main plot screen. The driver Xmax and the cut off
frequency of the  high pass crossover  (for a midrange) or rumble filter (for a woofer) can be altered to aid in evaluation of the maximum SPL the
driver can produce at a give frequency. Calculators above the main display are used to convert inches to centimeters and to provide an estimation
of the maximum length of an H or U - frame woofer system.
Above is a screen shot of the midrange equalization and high pass filter design tool. The measured midrange response is imported to the
tool and displayed in the center plot (light blue trace). As with the driver/baffle evaluation worksheet, the parameters in red are entered by
the user. These consist of the driver Fs and Qts. The high pass target level is adjusted and crossover frequency specified. Circuit
parameters are then adjusted to optimize the imported driver response to match the target LR4 high pass acoustic response (a 4th order
Linkwitz/Riley acoustic crossover is implemented between the midrange and woofer). The circuit topology and component calculators have
been obscured for proprietary reasons. However, sufficient information is provided that the active circuits could easily be constructed or
emulated with a digital crossover such as the Behringer DCX2496. Full instruction of how obtain the measured midrange response and how
to match the target response are provided in the guide. It should be apparent that once the optimization is completed the midrange
response is flat and all that remains is to develop the passive or active low pass crossover filter to manage the midrange response above
the dipole region as would be done for a conventional speaker system.
Here the active woofer equalization and low pass filter are designed. Since the a woofers low frequency response is determined by Fs and Qts
the woofer equalization and low pass filter can be designed without SPL measurements. Once the circuit is designed, near field measurements
of the woofer performance can be made and a notch filter can be added if required to tame any significant deviations form the target resulting
from a 1/4 wave resonance in the H or U -frame. This is discussed in detail in the guide. The guide also address the required acoustical
damping of a U -frame woofer system in detail. As with the midrange worksheet, circuit topology and other details have been obscured for
proprietary reasons.
The figure to the left shows the
complete system simulation, as
presented as an example in
the guide,  made using Sound
Easy. The woofer and
midrange active circuits were
designed using the Excel tool
kit. Sound Easy was used to
design the passive midrange to
tweeter crossover, shown to
the right. While SoundEasy
was used as the CAD program
featured in the guide, any CAD
software capable of simulating
active and passive circuits can
be used.
System Requirements*:

1) Ability to run an Excel worksheet
developed under Excel 2002. You must
have the Analysis Tool Pack and the
Analysis Tool Pack, VBA add-ins activated
with macro security set to medium.

2) Ability to run a program in a DOS

3) A measurement system capable of
making SPL and impedance measurements
and T/S parameter extraction
(manufactures T/S data can be used but
accuracy may suffer).

4) CAD design software capable of passive
and active filter design.
(The active circuits designed using the
Excel tools will need to be set up in your
CAD program.)

*No problems should be encountered on  
computer running Windows XP and Office
ABC Dipole is now free!**

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