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Loudspeaker Enclosure Designer
version 2.00
10 March 1993
by David Kakenmaster
890 N. Tabor Ct.
Castle Rock, CO 80104-9715
Page 1
TABLE OF CONTENTS
page
OVERVIEW ................................................ 3
DISCLAIMER .............................................. 4
SHAREWARE ............................................... 4
ORDERING INFORMATION .................................... 4
HARDWARE & SOFTWARE REQUIREMENTS ........................ 5
WHY A SPREADSHEET? ...................................... 5
INSTALLING LED .......................................... 6
CONVENTIONS ............................................. 7
STARTING LED ............................................ 7
USING LED ............................................... 8
FAST CABINET ............................................ 9
DESIGN AREAS ............................................ 9
VIEWING AND PRINTING GRAPHS ............................. 11
VIEWING DESIGN AREAS .................................... 12
SCRATCH PAD ............................................. 12
QUITTING LED ............................................ 13
APPENDIX A
BUILDING A DRIVER DATABASE WITH LED2DRVR.WKS ............ 13
APPENDIX B
LED-XOM - CROSSOVER DESIGN MODULE ....................... 14
APPENDIX C
LED-EDM - ENCLOSURE DESIGN MODULE ....................... 15
APPENDIX D
HINTS AND TIPS .......................................... 16
APPENDIX E
LED AND A FAST COMPUTER (BENCHMARKS) .................... 19
THANKS .................................................. 20
Page 2
OVERVIEW
Loudspeaker Enclosure Designer (LED) is a very powerful, easy to use
tool for designing bass and midbass hi-fi loudspeaker systems. Using
widely available speaker driver performance parameters (known as the
Thiele-Small parameters), LED can generate sophisticated mathematical
models of any driver's behavior when mounted in a vented or sealed
enclosure. LED creates 4 different graphical models for each driver/
enclosure design:
1) Amplitude vs frequency response ('frequency response')
2) Maximum sound pressure level (half-space, or in-room)
3) Driver cone excursion at any drive level, in watts
4) Maximum power handling, based on the driver's thermal power rating.
All of LED's functions can be accessed via menus, making the program
very simple to operate. And, LED's menu functions can be activated with
a mouse, if one is connected.
Additionally, up to three driver/enclosure combinations can be modeled
at the same time, so LED provides for summing the frequency response of
any combination of active models. This is especially handy for designing
multi-way systems.
LED can also import up to three filters into each design. There are 50
pre-designed filters included now, with more planned. LED uses filters
which are pre-defined in external files. They can be used to simulate
the effects of passive or active crossovers/filters, or to simulate
the loading effects of a car's environment. This flexibility makes LED
much more powerful than many competing enclosure design programs.
LED includes Fast Cabinet, a quick alignment approximator for up to seven
sealed and four vented alignments. By supplying only a few of the Thiele-
Small parameters, LED can determine up to 11 designs virtually instantly!
LED also includes Scratch Pad, a simple calculation area in which you
can determine optimum port diameters, and lengths. You can also deter-
mine an existing enclosure/port combination's tuning frequency.
LED can manage a database of up to 250 different speaker drivers at a
time. More driver data files may be kept off-line on diskettes, etc.
All models are represented graphically, with highly detailed and richly
colored graphs. All graphs may be printed in any of four styles.
Two external utilities are also provided:
1) Crossover Design Module (XOM) calculates parts values for 1st, 2nd,
3rd and 4th order passive high- and low-pass crossovers, including up
to five different filter alignment families for each order. XOM can
also draw basic schematics for 1st, 2nd, 3rd and fourh order high- and
low-pass passive crossovers.
2) Enclosure Design Module (EDM) is simply an enclosure volume calculator.
You can determine internal net or gross volumes from dimensions or
known net volume. This is handy for determining the needed gross
volume of a design you created in LED v2.00 (knowing net needed), or
Page 3
for determining the gross and net internal volume of an existing
enclosure.
DISCLAIMER
As powerful as it is, LED is only a tool to help you design loudspeaker
systems. I accept no responsibility for the results of using this tool.
When used properly, though, LED will be immensely helpful in helping you
design speaker systems. And as with anything, the more you use LED the
better you'll be at utilizing it's abilities.
LED v2.0 comes with no warranties of any kind. As distributed it func-
tions as claimed. Please contact me if you've received a defective copy.
SHAREWARE
The shareware distribution method relies on the honor system. You have
a fully functional copy of the program for evaluation purposes. If,
after a specified time you decide that you'll keep using it, you are
obligated to register the program with the author. Shareware opens
itself to all types of abuse, but those who play by the rules find a
wealth of high-quality and low cost software available.
ORDERING INFORMATION
If you use LED for more than 30 days you are obligated to send for a
registered copy. You'll receive the most current registered version of
LED with your name and address branded in it. It also will not display
the shareware startup screen. I do not believe in 'crippleware' or
shareware with excessive nag notices. Shareware works on the honor
system, and I've put my cards on the table. Please send for a registered
copy if you use LED.
For your registered copy, send $39.00 in check or money order to me:
David Kakenmaster
890 N. Tabor Ct.
Castle Rock, CO 80104-9715
In return you'll receive the latest registered version of LED (specify
3.5" DD or 5.25" DD diskette). Please include your name, return address,
any comments you may have and where you got your shareware copy of
LED v2.0.
If you have any questions, please direct them to me in writing at the
address above. I'll try to answer all questions, with registered users
getting top priority.
Page 4
HARDWARE & SOFTWARE REQUIREMENTS
-DOS or Windows based PC, the faster the better! (See Appendix E).
-Math coprocessor optional for faster speed. (See Appendix E).
-512k AVAILABLE expanded memory (optional, use for fastest speed). (See
Appendix E).
-Hard disk with 1.5 Mb free, if all 250 drivers are loaded in the driver
directory on the hard disk.
-CGA or better graphics, with EGA or better needed for LED-EDM and
LED-XOM.
-As Easy As spreadsheet, version 5.50 C or newer, as published by
Trius, Inc. This product is distributed as shareware. As Easy As MUST
be installed on your system and configured properly for your printer
before you install LED.
-625k RAM available AFTER As Easy As is loaded. Expanded memory is
supported in As Easy As. If no or not enough expanded memory is
available, As Easy As can create virtual memory on your hard disk. Note
that this will be much, MUCH slower than expanded memory. (See Appen-
dix E).
-LED v2.00 is designed to be as intuitive as possible, and it automates
many of As Easy As' features. But, you should still have (at least) a
little knowledge of spreadsheet usage. Within As Easy As, pressing the
F1 key will present you with a detailed help screen, grouped by topic.
NOTE: LED and all it's files are fully compatible with disk compression
programs like Stacker (tm), SuperStor (tm) and DoubleDisk (tm).
In fact, I suspect you'll get better than 2:1 compression with
all of LED's files.
WHY A SPREADSHEET?
Most, if not all other speaker design programs are standalone products.
That is, they include their own executable files as well as other neces-
sary data files. LED is comprised of a series of spreadsheet files and
other data files, and is designed to work within As Easy As spreadsheet,
version 5.50C or newer. Spreadsheets, by their nature are incredibly
versatile packages: they perform math functions, have database capa-
bilities, have powerful graphing features, can print text and graphics
and they each have their own internal programming language. If you think
of a spreadsheet as an operating environment or platform, (like Windows,
sort of...), you can see that it is possible to create a vast array of
programs for that environment. With a spreadsheet you can create pro-
grams to balance and manage your checkbook, find and sort data, perform
statistical analysis, create sales presentations, store addresses and
phone numbers... and on and on. The possibilities are nearly endless!
Why, you may even create a program to design loudspeaker enclosures!
I'd like to believe that anybody who spends time with a computer can find
some new use for a spreadsheet. Plus, LED does not waste hard disk space
with it's own, single-use executable files.
Page 5
INSTALLING LED v2.00
First, you must have As Easy As installed in it's default directory,
z:\ASEASY\, with z representing the drive where the program resides.
If you've received LED v2.00 in it's zipped archive form, you must first
unzip all the files in the archive LEDV200.ZIP to your hard disk (or to
a floppy disk - a 5.25" 360k has enough room) using Pkunzip version 2.
Then you MUST execute the INSTALL.BAT program to properly set up LED on
your hard disk. You will be prompted for the drive name where As Easy As
is installed.
If you've received an LED source diskette, you should insert the diskette
into the proper drive, log to that drive and execute the INSTALL program.
When INSTALL.BAT is finished, LED installation is complete.
You should create a startup batch file for LED v2.00, too, using the
included MAKEBAT utility. I recommend you create this file because:
1) MAKEBAT creates a batch file LED2.BAT which will start up both
As Easy As and LED with your own customized startup parameters.
2) This greatly simplifies starting LED v2.00, since you will only need
to type LED2 to start LED from anywhere in your system.
MAKEBAT should only need to be run once, unless you want to change any
startup parameters and create a new LED2.BAT file. To create a startup
file for LED, type MAKEBAT followed by the startup parameters you want:
MAKEBAT z: c: VGA MONO VM x:\
| | | | | |
| | | | | |----Optional path for virtual memory. Omit this
| | | | | if expanded memory is available. You should
| | | | | direct this file to a 550k or larger RAM disk
| | | | | for best speed, if you can.
| | | | |
| | | | |----Use virtual memory. Omit if you have
| | | | expanded memory available.
| | | |
| | | |----Select COLOR or MONO screens. You must select one.
| | |
| | |----Set the graphics type your machine supports, options are
| | CGA, EGA, VGA or AUTO for autodetect. You must select one.
| |
| |----Location for the startup file, i.e. C:\BATCH This
| should be on your DOS path. You must specify a location.
|
|----Drive where As Easy As & LED are located, i.e. C: You must
specify this drive name.
Page 6
If you want monochrome graphics, you MUST start As Easy As itself FIRST,
specifying mono on the command line. Then you must save the configura-
tion using /User /Install /Save Config. At this point you may either
load LED or restart As Easy As & LED at a later time.
CONVENTIONS
This user manual is written primarily as a tutorial and program compan-
ion. You will benefit most by printing this manual and having it handy
as you use LED v2.00 the first few times. To be sure, there will be
information you'll need for reference purposes later. But many people
will want to get started right away, and this seemed the best way to
allow for that while also maximizing the learning curve.
Throughout you'll see many points of special interest, preceded by NOTE:.
Typically these notes detail aspects of LED's operation which may not be
obvoius or straightforward.
STARTING LED v2.00
If you created the LED2.BAT file with MAKEBAT, just type LED2 from the
DOS prompt. As Easy As and LED v2.00 will load automatically. If you
have not created LED2.BAT, please read the rest of this section.
For easiest use, run MAKEBAT and save yourself a lot of bother...
To use LED you must first start As Easy As. Change to your As Easy As
directory and type ASEASY. If you need any special startup parameters,
many are listed below. Refer to As Easy As documentation for further
descriptions.
Common As Easy As command line switches:
/EV Utilize VGA graphics if available and As Easy As did not detect.
/MONO Set screen colors to monochrome.
/VM=130 Utilize virtual memory if no expanded memory is available.
/VP=Path Set drive and path for virtual memory temporary file.
After As Easy As is loaded and you've confirmed that there is at least
625k of free memory, you can now load LED v2.00 into As Easy As. Type
/FR (forward slash, then F, then R), then use the highlight bar and
ENTER key to go to the LED directory and locate the file LEDV200.WKS.
Highlight this file and press the ENTER key. The file will load, and
you'll be on your way.
Page 7
USING LED v2.00
NOTE: If you receive an out-of-memory error while LED v2.00 is loading
into As Easy As, you must exit both LED and As Easy As. Before
restarting, confirm that you have at least 512k of expanded memory
AVAILABLE for the program to use. If you don't, you must specify
that LED use virtual memory. See the section describing MAKEBAT
above for more information about simplifying all this.
After LED loads, the first screen you'll see asks you to register your
copy of LED. A lot of work, time and energy has gone into developing
LED v2.00. I expect that if you use LED regularly, you'll send for your
registered copy. You should register As Easy As with it's authors,
Trius, Inc, too. As Easy As is a terrific and award-winning product.
I do not have any connection with Trius... I just believe that As Easy As
is one of the best values around.
Continue by pressing ENTER to clear the shareware screen.
Now you'll see LED v2.00's Main Menu. From here you can access ALL of
LED's features, by highlighting the selection you want and pressing ENTER.
NOTE: For all menus, any item which is followed by an ellipsis (...)
leads you to a sub-menu. If no ellipsis exists, LED takes you
straight to a function. You can also press the highlighted letter
of any menu item to select it. While any menu is active, pressing
the . (period) key will toggle the menu position between the upper
left and upper right corners.
At the top of the screen, you'll see a detailed description of the
highlighted menu item. Let's start with the first one now: LOAD DRIVER
PARAMETERS... Highlight this item and press ENTER (or press L, the
highlighted letter). This takes us to a menu which allows us to load
a speaker driver to model.
NOTE: From any menu, pressing the ESC key returns you to the Main Menu.
The next menu lets you select between loading a driver from a database
file or entering driver parameters manually. Select LIBRARY DRIVER DATA
FILE and press ENTER. Next, a list of all drivers currently in the
database (library) will appear. Highlight the driver you wish to model
and press ENTER. LED will load that driver's parameters into it's own
driver data area, and the Main Menu will reappear. FYI, LED's driver
data screen displays the driver's parameters, as well as it's calculated
free-air sensitivity and the mass of the moving assembly. The driver we
just loaded is now considered the CURRENT driver.
NOTE: By selecting MANUAL DRIVER DATA ENTRY you can either enter a new
driver, or change the current driver's parameters.
Now that a driver is loaded we can proceed with designing enclosures for
it. Select FAST CABINET from the Main Menu, if you do not already know
what size and type of enclosure you'll use. Fast Cabinet can suggest up
to 7 sealed and 4 vented alignments for you, as well as display frequency
Page 8
response graphs for up to 3 alignments of each enclosure type.
FAST CABINET
Fast Cabinet's main function is to make the enclosure design process
simpler by providing you with a number of suggested sealed and vented
alignments. Fast Cabinet can plot frequency responses for 3 sealed align-
ments (Qtc 0.577-Bessel, 0.707-Butterworth and 1.000-Chebchev) as well as
for 3 vented alignments (Maximally flat response, extended response and
user-defined F-3dB).
NOTE: Fast Cabinet assumes NO stuffing is in the enclosure. Fast Cabi-
net also assumes vented box Q losses as follows: Ql=7 for box
volumes up to 2x Vas, Ql=5 for box volumes between 2x and 3x Vas
and Ql=3 for box volumes greater than 3x Vas. All calculated
enclosure volumes are NET internal.
Fast Cabinet allows you to compare alignments for two drivers, too. From
the Fast Cabinet menu, you can select either the current or a specified
alternate driver. Viewing the different alignments is as easy as switch-
ing back and forth between the current and alternate driver menu selec-
tions. To load an alternate driver entry from the existing driver data-
base, select IMPORT DRIVER DATA FILE. To enter a driver's parameters
manually in the alternate entry field, first select the MANUAL DRIVER
ENTRY from the menu. Then select ENTER FAST CABINET DATA. You can now
enter the Fs, Vas and Qts parameters for the driver, as well as enter the
number of drivers to use and the mounting style (normal or compound/Iso-
barik). The number of drivers and mounting style remain constant for
both the current and alternate drivers.
When you're through entering Fast Cabinet data, press ALT-F to return to
the FAST CABINET menu.
If you see an alignment you'd like to model, make note of the enclosure
volume and tuning frequency, if applicable. Now we can step through the
enclosure design process.
Press ALT-M to return to the MAIN MENU.
ENCLOSURE DESIGN AREAS
From the main menu select DESIGN ENCLOSURES.... The following menu al-
lows you to select which design area you'd like to work in. There are
three available, and all are completely independent of each other. That
is, you can have different drivers, mounting styles, enclosure types,
sizes and tunings for each area. You have full flexibility to work in
any of the areas without affecting others.
NOTE: If you selected an enclosure design function without first loading
a driver, LED will take you right to the LOAD DRIVER PARAMETERS...
Page 9
menu.
The enclosure design menu also allows you to reselect filters for
existing designs.
Select ENCLOSURE DESIGN 1 for now. Press ENTER when prompted to confirm
the choice. LED then proceeds to initialize the design area by STORING
the CURRENT driver. In the upper right portion of the screen you'll see
a display for the CURRENT driver name, as well as the STORED driver name.
The CURRENT driver is the one that is loaded in the main Driver Data area,
while the STORED driver is loaded into the design area's memory. Each
design area can store one driver.
NOTE: When RE-designing an enclosure, LED will prompt you for use of
the CURRENT driver or the design's STORED driver. This saves a
lot of trouble if you've changed the current driver status.
Now you'll be prompted for each parameter required to model the enclo-
sure. Each parameter prompt has a description of the required parameter.
NOTE: Use the NET internal enclosure volume when prompted.
When you get to the number of ports, enter 0 if the enclosure is to be a
sealed system. Use an integer greater than 0 for vented enclosures.
If you're designing a vented enclosure, you'll be prompted to enter the
desired port diameter (not critical at this stage), the desired port
tuning frequency and the assumed enclosure losses (Ql).
When you've entered all the parameters correctly, press ENTER. In a few
seconds, you'll be prompted for the types of filters you wish to model.
At startup, LED defaults to no filters (straight-line, bypass). If you
wish to STORE a different filter in your design, press 1 when prompted.
Then you'll be asked whether you want to change filter 1 (A). Press 1
to acknowledge that you wish to change it. The CURRENT and STORED con-
ventions apply the same way for filters as for drivers: the CURRENT
filters are those that are active for the designs, and the STORED filters
are those you've stored for each design.
Next you'll have a menu of filters from which to select. Since the fil-
ter names are all short, they are labeled as follows:
HPB1-020
The first two letters indicate the type of filter - HP or LP, indi-
cating high- or low-pass filter characteristics.
The third letter indicates the alignment family - B for Butterworth,
C for Chebychev and L for Linkwitz-Riley.
The fourth character (the first digit) indicates the order (roll-off
characteristic, or slope) of the filter - 1 for 1st-order (6dB/octave),
2 for 2nd-order (12 dB/octave), 3 for 3rd-order (18 dB/octave) and
4 for 4th-order (24 dB/octave).
The remaining three digits indicate the -3 dB point of the filter.
Page 10
In the above example we have a high-pass, 1st-order Butterworth filter
with a -3dB point of 20 Hz. The labeling scheme is actually very simple!
NOTE: There are two additional special-purpose filters:
00BYPASS - This is the straight-line filter, used to reset the
design areas to the default NO FILTER status (set gain
to 0). You can also specify this filter WITH gain to
simulate each driver's gain.
AUTOSOUN - This is an in-car corrective filter, used to simulate
the loading effect of a vehicle. Use this filter once
in each design area if you're modeling a multi-way
system for a vehicle. If you're modeling individual
and distinct systems, use the autosound filter as
necessary in each design area. Always specify gain as
0 dB with this filter, or the results won't be valid!
Highlight the filter you wish to include and press ENTER. LED will load
the filter's characteristics. Next you'll need to specify the gain of
the filter - use 0 dB for passive crossovers.
You'll be asked to repeat these steps for filters 2 (B) and 3 (C) also.
Each works in the same way as the first. In total, you have the option
to add up to three corrective filters to your model.
After you finish entering any filter information LED will complete the
current design model and return you to the main menu.
You can repeat the design process for design areas 2 and 3 using the
current driver. You may specify a new driver for either design, too
via the LOAD DRIVER PARAMETERS menu.
VIEWING AND PRINTING GRAPHS
After you've run through at least one design process, you can view the
graphic results of your work.
From the main menu select GRAPH VIEW/PRINT....
The first five items on the following menu indicate the graph types
available for viewing and/or printing.
NOTE: Each graph type selection has a sub-menu attached so you can pick
the correct display range.
The CURVE SELECTION... option allows you to customize the graphs so they
display only the information you want. The attached sub-menu has an
option which allows you to select the curves you want to view or print
for all graphs. There is also an option to set the frequency range for
all graphs.
The GRAPH PRINT MENU... option allows you to print the graph you last
Page 11
viewed in any of 4 styles. To use this option, you must have As Easy
As configured for your printer.
Following is a listing of the information each graph displays:
1) FREQUENCY RESPONSE: This is a representation of the system's calcu-
lated output in dB at any frequency (in Hertz) between 1 Hz and
1000 Hz, and is displayed in actual dB.
2) MAXIMUM SPL: This is a representation of the system's calculated
maximum sound pressure level in dB at a 1 meter distance. Maximum SPL
is defined as the loudest the system will play - as limited by the
driver's maximum rated power or maximum cone excursion - whichever
limit is reached first at any frequency.
3) EXCURSION: This graph represents the distance (in millimeters) that
each driver's cone must travel in order to produce the output
represented in the FREQUENCY RESPONSE graph.
4) POWER HANDLING: This graph represents the maximum power (in watts)
that the system should handle, as limited by excursion ONLY. What you
see here is really the short-term PEAK power handling of the system
for any frequency.
5) SUMMED RESPONSE GRAPHS: These graphs represent the combined frequency
response of your designs. If you're developing a multi-way system,
this will approximate the response of the entire system! Note that
these graphs do not account for phase response differences.
NOTE: The SUMMED FREQUENCY RESPONSE... menu displays the combined
response of multiple designs. If you've only modeled one design,
this selection has no value.
NOTE: The FREQUENCY RESPONSE and SUMMED FREQUENCY RESPONSE graphs are
the ONLY graphs which display the effects of any added filters.
VIEWING DESIGN AREAS
After you've worked out a few designs, you might want to go back and
look over your work. From the Main Menu select VIEW DESIGNS... in order
to do just that. This function is really quite simple: it displays any
of the design areas as well as the current driver data area. It's an
easy way to check everything you've done in LED.
SCRATCH PAD
Scratch Pad is used to perform all the calculations necessary for
designing ports in a vented system. Once you've worked out a design
that you like, you can select SCRATCH PAD from the main menu. You'll
notice first that there is no menu here. It's a free-form data entry
Page 12
area for performing many types of port calculations.
Next you'll notice that LED has already entered the necessary enclosure
parameters from your designs. There is another field for each design
which must be considered: Baffle Depth. This is simply the thickness of
the panel upon which the drivers are mounted. LED defaults to 0.75", but
you may reselect this parameter if needed.
Below the enclosure information, you'll see the CALCULATED MINIMUM PORT
DIAMETER area. Based on the driver, enclosure and baffle thickness LED
will calculate the minimum diameter for any number of ports you'd like to
use. In a vented system, it's important to ensure you have enough port
area to minimize wind noise as the system plays. You can select the
number of ports to use and LED will recalculate the minimum inside
diameter necessary for each port.
NOTE: ALL port diameters referred to in LED are measured by the INSIDE
DIAMETER.
Below the minimum diameter information you'll see the CALCULATED PORT
LENGTH area. If you enter the number of ports and the desired inside
diameter for each port, LED will calculate the required length to achieve
the tuning frequency specified in the enclosure information above. For
multiple ports, each port is assumed to be the same size. It's a good
idea to use (at least) the number of ports and minimum diameter from the
minimum port area so you know that your ports won't cause any sonic
problems.
To the right of the port length section is the PORT CALCULATOR. This
feature is used to determine the tuning frequency of a known enclosure.
If you enter the information for Vab (net internal volume), stuffing
(fill), number of ports and their dimensions LED will calculate the
tuning frequency of the enclosure for you.
QUITTING LED
After you've completed your work, you can quit LED in two ways: back
to DOS or back to As Easy As if you'd like to work with another template.
From any menu, hit the ESCAPE key to return to the main menu. Then
select QUIT LED.... The following sub-menu offers you choices about
quitting. Select the appropriate option and press ENTER.
APPENDIX A: BUILDING A DRIVER DATABASE WITH LED2DRVR.WKS
You may add as many drivers as you like to the driver database. The only
limit is that As Easy As will only recognize 250 at any one time. If you
build up a large database, store less frequently used drivers on floppy
diskettes or in another directory.
Page 13
To add more drivers to the database, you must first start As Easy As.
While each system is different, the startup commands will be similar.
Log to the drive where As Easy As is installed and type:
CD \ASEASY
ASEASY [any_switches___see as_easy_as_instructions]
When As Easy As has finished initializing, type:
/ F R (type the forward slash key, then F, then R)
Use the cursor keys to go to the LED directory. Then highlight the
LED2DRVR.WKS file and press ENTER. This is the blank template you'll
use for storing driver information.
Enter all the driver parameters in the appropriate spaces. If you have
parameters which are specified in different units of measure, use the
WORK AREA to the right to perform the necessary conversions. You can
use the comment area to enter any other information or notes about the
driver.
When you're through, press ALT-S (hold down the ALT key and press S) to
save the information. You'll need to name the file, and in only eight
letters or characters. The file extension should always be WKS.
As for the name, I suggest that you use the first two or three letters to
describe the brand name and the last five or six letters to describe the
driver model or size. It's really pretty easy if you work out a
consistent naming system for the files. I doubt you'll have trouble
recognizing them.
NOTE: If you're entering information for more than one driver, you can
type over the old information AFTER you've saved the previous
file. This will save having to reload the blank template for each
driver you want to enter.
When you're through entering drivers, press ALT-D to exit to DOS, or
ALT-Q to exit to As Easy As.
APPENDIX B: LED-XOM, CROSSOVER DESIGN MODULE
NOTE: You must have EGA or better graphics capability in order to
display LED-XOM correctly.
LED-XOM is a small utility which calculates the parts values needed to
construct many types of passive crossovers.
You must first start As Easy As in order to use LED-XOM. While each
system is different, the startup commands will be similar. Log to the
drive where As Easy As is installed and type:
CD \ASEASY
Page 14
ASEASY [any_switches___see as_easy_as_instructions]
When As Easy As has finished initializing, type:
/ F R (type the forward slash key, then F, then R)
Use the cursor keys to go to the LED directory. Then highlight the
LED-XOM.WKS file and press ENTER.
The first area you'll see is the high-pass design area. If you enter
the desired -3dB cut-off frequency and the tweeter's impedance at this
frequency, LED will calculate the necessary parts values to construct
passive crossovers of many different alignment families.
Press ALT-L to go to the low-pass filter design area. It functions
identically to the high-pass design area, except that you'll enter the
desired cut-off frequency and impedance for the mid-range or woofer
driver.
Press ALT-P if you'd like to print these parts values for future
reference.
Press ALT-S to draw schematics for 1st-, 2nd-, 3rd- or 4th-order cros-
sovers. You can enter the desired filter order seperately for the high-
low-pass sections, and LED-XOM will draw the appropriate schematic.
There is no print function for the schematic.
To quit LED-XOM, press ALT-Q to quit to As Easy As, or press ALT-D to
quit to DOS.
APPENDIX C: LED-EDM, ENCLOSURE DESIGN MODULE
NOTE: You must have EGA or better graphics capability in order to
display LED-EDM correctly.
LED_EDM is a utility which will help you determine the gross enclosure
volume needed for a design after all parts are added in. LED-EDM can
also determine the net internal volume of an existing enclosure for you.
You must first start As Easy As in order to use LED-EDM. While each
system is different, the startup commands will be similar. Log to the
drive where As Easy As is installed and type:
CD \ASEASY
ASEASY [any_switches___see as_easy_as_instructions]
When As Easy As has finished initializing, type:
/ F R (type the forward slash key, then F, then R)
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Use the cursor keys to go to the LED directory. Then highlight the
LED-EDM.WKS file and press ENTER.
The first area you'll see is the GROSS INTERNAL VOLUME calculation
area. After you've worked out a design in LED, use this part of LED-EDM
to calculate the total (gross) internal volume necessary for your enclo-
sure as well as the optimum dimensions for the enclosure.
Start by entering the net volume you'll need in the enclosure. Then
enter the dimensions and quantities for the port(s), followed by the
driver(s') dimensions. Measure the diameter of the driver from edge to
edge of the SURROUND material. If you do not know the front to back
depth of each driver, then make an educated estimate. Many drivers are
between 3 and 5 inches deep. This is important, but not hyper-critical:
estimating the driver depth will probably put your total enclosure volume
estimate within 97% of actual volume. Finally, enter the estimated
amount of bracing your enclosure will contain. This figure should be a
percentage based on the net volume. 5% is often a good estimate.
To the right you'll see information regarding just how much space each
of these items takes up... this is really just for your own information.
Near the bottom of this screen you'll see the calculated optimum dimen-
sions for both the gross enclosure volume and for the net enclosure vol-
ume. The net volume dimensions are just for your own information, too.
Press ALT-I to go to the INTERNAL VOLUME calculation area. This area
is used primarily for determining the net and gross internal volume of
an existing enclosure.
Start working in this area by entering the EXTERNAL enclosure dimensions.
There are seperate figures for top/bottom and front/back dimensions.
Sometimes enclosures are not shaped as rectangles! This allows you to
account for many of those situations by treating each enclosure side as a
parallelogram. You MUST enter top and bottom AND front and back dimen-
sions for any enclosure! Because each side is treated as a parallelogram
you must enter ALL dimensions. Next, enter the port, driver and bracing
volumes as you did above.
In the top right of this screen you'll see the calculated gross and net
volumes for your enclosure.
To quit LED-EDM, press ALT-Q to quit to As Easy As or ALT-D to quit to
DOS.
APPENDIX D: HINTS AND TIPS
It is not my intention to tell you what boxes to design, but rather to
give you some guidelines regarding the modeling process. In this way
you can maximize the potential of LED and design the best enclosures for
your needs.
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1) The most predictable and accurate modeling results will be obtained
if the selected driver's Qts value falls between 0.200 and 0.700.
While results for values outside that range are useful, they are not
necessarily as accurate as those falling within that range. Don't
worry... most drivers fall comfortably within the range of best
accuracy. Remember also that LED is only a tool which can help you
design loudspeaker systems. It can provide only the mathematical
models of your designs. Often, real world results will differ. If
you build a system and do not like the way it performs... well, that's
part of learning the art of designing loudspeaker systems! It is
hoped that LED will encourage you to develop and improve your speaker
designing skills. With some practice you'll be able to fully inter-
pret and utilize the wealth of information LED can provide.
2) The value for Ql (vented box loss) is a fairly 'gray' area. Without
actually measuring an existing design's losses, you'll have to guess
the loss value. My own rule of thumb is this: Use Ql=7 if the enclo-
sure size does not exceed two times the total Vas. Use Ql=5 if the
enclosure volume is between two and three times the total Vas. Final-
ly, use Ql=3 if the enclosure volume exceeds three times the total Vas.
3) LED allows you to select the mounting style for the drivers in an
enclosure: normal or compound. Normal mount is simple; the driver(s)
are mounted near one another on the same baffle. If you're going to
use more than one driver and you're using them in multiples of two,
you can select compound mounting. This mounting style allows you to
achieve the same -3dB point of a system with the same number of
drivers mounted normally - only in an enclosure HALF as large!
There are three basic mounting schemes used in compound style mounts.
They are depicted below using two drivers, but multiple pairs may be
used. These enclosures may be sealed or vented, and the any port
should affect the main enclosure portion ONLY. The seal between the
driver pairs should be as airtight as possible.
╔═══════════════════════╗
║ /╨\ This compound mounting style is often
║ |-|/ \|-| referred to as 'clamshell'. This push-
║ | | | | pull mounting style also reduces driver
║ MAIN |-|\ /|-| distortions. It is popular among car
║ ENCLOSURE \╥/ audio system designers.
╚═══════════════════════╝
╔════════════════╦══════╗
║ /╝ /╝ This compound mounting style is often
║ |-|/ |-|/ referred to as 'Isobarik', and is true
║ | | | | to the original idea first proposed by
║ MAIN |-|\ |-|\ Harry Olsen in the 1950's.
║ ENCLOSURE \╗ \╗
╚════════════════╩══════╝
╔═════════╦═════════════╗
║ ╚\ /╝ This compound mounting style is a combi-
║ MAIN \|-| |-|/ nation of 'clamshell' and 'Isobarik'
║ ENCLOSURE | | | | mounting styles. It offers the aesthe-
║ /|-| |-|\ tics of a conventional enclosure, but
║ ╔/ \╗ has the size and distortion reducing ad-
╚═════════╩═════════════╝ vantages od the 'clamshell' style.
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4) Much note is made of the relevance of Qtc value in sealed boxes. This
value can be used to describe the sealed alignments, and one can
generalize their overall effect on sound:
Qtc ALIGNMENT EFFECT ON SOUND
0.500 `critically Light bass, though with great extension. Used in
damped' many British speaker systems.
0.577 Bessel Lightish bass with very good extension. Optimum
transient response. 'Fast bass'
0.707 Butterworth Maximally flat amplitude vs frequency response.
Good transient characteristics and well balanced
bass.
>=0.800 Chebychev Bass peak which increases with Qtc value. F-3 dB
(cutoff) point increases as Qtc also increases.
These alignments are used in many mini speakers
to give the impression of more bass.
1.000 - A preferred Qtc value for many car subwoofer ap-
plications. Since the car environment will boost
bass output, a very low half-space cutoff point
is not always needed or desirable.
1.200 - Little bass extension and a bass peak of about
2.4 dB. Used in some mini-speakers with small
drivers. This gives the impression of more bass
than they really have.
5) Many accept that, as far as human hearing is concerned, the F-10 dB
point is that at which bass response becomes significantly less audi-
ble. While you will perceive a dropoff in bass before that point,
you'll still have useable (as far as our hearing is concerned) out-
put down to the frequency at which bass response is down by 10 dB.
So, if a driver/enclosure combination exhibits an F-3 dB point of
47 Hz and an F-10 dB point of 26 Hz, you'll have diminished but per-
ceptable bass down to the lower frequency.
6) Stuffing material (like dacron or fiberglass) is used inside an enclo-
sure to help damp unwanted midrange frequencies AND to 'fool' the
driver into behaving as though it's in a larger enclosure. LED asks
you to specify the amount you want to use as a percentage of cabinet
volume. For example, 50 0.000000ill indicates that you'll be using enough
UNCOMPRESSED stuffing material to fill half the cabinet.
7) To lessen chances of standing waves arising inside the enclosure, do
not locate the driver in the center of any one enclosure surface.
8) In vented enclosures, you should attempt to keep the port(s) at least
4" to 6" away from the edge of any driver. You may also locate the
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port(s) on the back of the box. Doing this can also help minimize
radiated noises from the port(s), with only a minimum decrease in
direct radiated output.
9) For all design types, there should be no air leaks. This means that
you must make sure there are no leaks in cabinet seams or in the
seam between the driver frame and the baffle. A good material to use
for sealing all these areas is Mortite (tm) rope caulk. It is widely
available at virtually all hardware or home-improvement stores.
10) To learn more you should read some of the published documents about
speaker design. One of the best is 'The Loudspeaker Design Cookbook'
by Vance Dickason. It is available from Old Colony Sound Lab in
Peterborough, NH. Their phone number is: (603)-924-6371.
The more you know about the world of speaker design, the better your
design results will be...
There are also many periodicals, too: Speaker Builder Magazine, Audio
Magazine, AES Journal, etc.
APPENDIX E: LED AND A FAST COMPUTER
LED must perform many operations in order to generate a design model.
I've run some casual speed benchmarks for the modeling process on two
different computers. As you can see, a fast computer with expanded
memory makes a HUGE difference in speed!
Total time to
complete one model NOTES
i486/33DX: 23 seconds with EMS, Math co-processor ENABLED.
(0.38 minutes)
i486/33DX: 69 seconds with EMS, Math co-processor DISABLED.
(1.15 minutes)
i486/33DX: 434 seconds NO EMS (virtual memory used), Math co-
(7.23 ! minutes) processor ENABLED.
80286/12: 117 seconds with EMS, Math co-processor ENABLED.
(1.95 minutes)
80286/12: 308 seconds with EMS, Math co-processor DISABLED.
(5.13 minutes)
80286/12: 990 seconds NO EMS (virtual memory used), Math co-
(16.5 ! minutes) processor ENABLED.
The total time is the sum of all calculation times, and does not include
the time taken by the user to input information. All design areas were
unused prior to test.
Each computer had a software disk cache in use for all tests.
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I guess the moral of this story is that you should have enough expanded
memory first, and then a really fast computer!
THANKS
LED is the result of many hundreds of late night and weekend hours. My
goal is to provide a high-quality speaker design program which is so-
phisticated enough for experienced designers, but is also intuitive
enough that the casual user does not get lost.
Thanks to beta testers SJ, TS and WTC. These guys not only found many
of the bugs (they've been fixed!), but they also helped shape the way
LED looks and works.
*DK*
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