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
**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.
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
2) Ability to run a program in a DOS window.
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
*No problems should be encountered on
computer running Windows XP and Office
|ABC Dipole is now free!**
To download click here.