💾 Archived View for gemini.spam.works › mirrors › textfiles › computers › DOCUMENTATION › perfect.tx… captured on 2022-06-12 at 06:36:33.
-=-=-=-=-=-=-
* PERFECT BOX *
Loudspeaker Enclosure Simulation
using the
Neville Thiele - Richard Small Model
Version 4.5
January 1, 1990
Warren A. Merkel
2851 Newcomb Ct.
Orlando, FL 32826
Program registration is required.
See final page of this document for details.
***** PERFECT BOX ***** Version 4.5 ******
* Program and documentation written by *
* Warren A. Merkel *
******************************************
I. INTRODUCTION:
PERFECT BOX is a Computer Aided Design (CAD) program for the
simulation of loudspeaker performance. PERFECT BOX is a very
powerful tool for the amateur or professional speaker builder.
Loudspeaker design is a balance of compromises involving
enclosure size, low frequency cutoff, and transient response.
This program will allow you to model the loudspeaker-enclosure
combination entirely on your PC. With proper use, you can be
assured of the best (lowest in frequency) bass response in the
smallest enclosure. You can then build the enclosure with full
confidence that the final result will not become the new dog
house for Fido, but an accurate, natural sounding system.
PERFECT BOX does not deal with midrange or tweeter drivers. It
only considers the low frequency driver in a multi-way system (or
the only driver in a full-range system.) Since enclosure
alignments, such as box size, box type, and box frequency (now on
referred to as Alignments), effect the woofer response, PERFECT
BOX models systems covering low frequencies from 10 to 200 Hertz.
The mathematical model will hold for higher frequencies, but I
have optimized the program for the most useful range.
II. REQUIREMENTS:
PERFECT BOX requires certain parameters that uniquely define the
driver's characteristics. Some of these parameters have been
coined as the Thiele/Small (or T/S) parameters. If you are new
to loudspeaker design, it isn't important that you understand
what each value represents, only that you are able to obtain
these values from the driver manufacturer, or measure them
yourself (the preferred method.)
PARAMETER UNITS
Free air resonance (Fs) Hertz
Electrical (Qes)
Q Mechanical (Qms)
Q Total (Qts)
Volume Equivalent Compliance(Vas) Ft^3
D.C. Voice Coil Resistance (Re) Ohms
Peak Cone Displacement (Xmax) Inch
Effective Piston Diameter Inch
Thermal Power (P) Watts, RMS
PERFECT BOX allows you to store these driver parameters in a data
file ("BOXDATA4"). This file can store characteristics for
thousands of different drivers. A few sample drivers have been
included so that you can experiment with PERFECT BOX. These
samples represent "real life" units which are currently available
at this time.
III. DEFINITIONS:
***SYSTEM ORDER***
PERFECT BOX uses a classical high-pass filter model to simulate a
loudspeaker mounted in an enclosure. The order of a loudspeaker
system represents the same characteristic roll off as that of an
electrical filter. The roll off rate (or slope) is:
roll off rate = (6 * system order) dB/frequency octave
or roll off rate = (20 * system order) dB/frequency decade.
PERFECT BOX can simulate both infinite baffle (sealed box), and
vented (ported) systems. Each of these systems have a natural
order in which they resemble an electrical high pass circuit.
For infinite baffle, order=2, or that is to say that they are of
2nd order. And for vented systems, order=4. It seems that each
kind of enclosure has pros and cons associated with them.
In general, both systems, if properly aligned, perform with the
same low frequency response. In practice, an infinite baffle
system is easier to build, and possibly has better transient
response. The vented system offers slightly higher efficiency
(2.9 dB), and good cone dampening near the vent frequency (but
less below Fb.) My preference is for 4th and 6th order systems.
The sixth order system involves the use of a 4th order system
tuned slightly lower than the 4th order ideal, and an 2nd order
active equalizer circuit in the amplifier path.
***SYSTEM CUTOFF FREQUENCY***
This is the frequency at which the system amplitude response is
exactly 3.0 dB less than at a mid-band reference frequency (where
response is basically flat at 0 dB.) This is a standard point of
interest that can be used to compare with another system's low
frequency response data. This point on the frequency plot
represents the "half-power" amplitude, as compared to the
amplitude at a mid-band reference frequency.
***OTHER SYSTEM ORDERS***
As you are probably aware, a Graphic Equalizer can make a
tremendous effect on the way your speaker system sounds. The
bad news is that an equalizer (EQ) usually doesn't have a control
exactly centered on the proper frequency to properly extend low
frequency cutoff, and thus will typically make matters worst.
PERFECT BOX can incorporate the effects of either a 1st or
2nd order, ACTIVE EQ (that you must build) into the loudspeaker
model. The affects of which are easily depicted in the PB Graphic
Plots.
This mini EQ consists of a simple active high-pass filter, having
a low turn-over (cutoff) frequency (typically 20-60 Hz), which
actually has a slight boost (peak) in its amplitude response
above its cutoff frequency. If the amount of boost and cutoff
frequency are suitably chosen, the total system response
typically is extended a half-octave or more, while
providing infrasonic (rumble) filtering to boot. In
2nd-order EQ's, the boost is controlled by the "D" parameter
(D=1/filter Q, for you filter buffs.) Typical values of
"D" range from 0.3 to 1.414, giving most to least amount of
amplitude boost. A "D" of 0.52 gives approximately 6 dB of
boost, a typical starting value. The EQ frequency and the
"D" factor should be juggled for the flattest, most extended low
frequency response. Use the "EQ2.EXE" program to calculate
components to implement the 2nd order EQ.
A word of caution. Using large amounts of boost may tax small
power amplifiers (less than 50 Watts,RMS) beyond their
limits. A properly designed 3, 3.5, 5, or 6th order system will
not over tax your amplifier unless you listen to music either :
1. at extremely high SPL levels,
2. with heavy (double fortissimo) organ pedal notes, or
3. use other signal modification equipment such as an
extremely low-end boosted Graphic Equalizer
(quite stupid!), or Sub-Sonic Synthesizer (Harmonizer.)
The EQ can be inserted into the signal path of your system at
either a "Preamp-out/Amp-in" loop, or "tape monitor" connection.
A simple design for a 2nd order EQ is provided with PERFECT BOX.
Type EQ2 at the DOS prompt to execute this option. You must
have (at least) a CGA graphics card in order to run EQ2 because
the electrical schematic is drawn on the screen after all of the
circuit values are calculated.
IV. RUNNING PERFECT BOX - PROGRAM EXECUTION:
If you have an IBM, Epson or HP LaserJet compatible printer,
you can print the graphic plots generated by PERFECT BOX. Perfect
Box 4.5 has built-in support for Graphic printing for these
printers in CGA and EGA modes. You no longer have to use
the DOS GRAPHICS.COM or PERFGRAF.COM included with previous
releases of Perfect Box. You might have to set your printer
switches to DEFEAT "automatic" Linefeed [LF] after a Carriage
Return [CR], (see your printer manual.)
I have included a simple batch file called GO.BAT,
which will execute Perfect Box for you. You may change this
batch file to suit your particular needs. The actual program
file is BOX4_5.EXE. You will not have to change the program
file name until you receive a future upgrade of PERFECT BOX.
Insert the PERFECT BOX program disk into your default disk
drive, and type GO <Return>. You should see the PERFECT BOX
opening screen. Take the time to read this screen and remember
that many, many hundreds of hours of effort have been put into
this program. If you use this program more than five times, you
must be understanding the purpose so don't forget your obligation
to this author!
If you see an error message stating "Bad Command or
Filename", check to see if you are in the same directory as the
PERFECT BOX files. After about 5 seconds, you may press RETURN
to continue.
If all is well, you should see the following screen.
PERFECT BOX - Version 4.5 Current Time:
??? Boxdata Choices ?????????????? ???????????????????????????????
? ? ? Drivers on file : 1573 ?
? (B) Browse the database ? ? Boxdata path : G:\perfect\ ?
? (L) Load a driver by # ? ? Graphics mode : EGA ?
? (S) Store New Driver data ? ???????????????????????????????
? (E) Edit the database ? Quick Mode
? (B) Boxdata Reports ???????????????????????? Utility ???
? ? ?
????????????????????????????? (C) Change Boxdata path ?
? (P) Sort/Pack Boxdata file ?
?????????????????????? ? (A) Append new records ?
? REGISTERED TO: ? ? (W) Write defaults ?
? Trial copy. ? ? (D) DOS Shell ?
? Your name or ? ? (Q) Quit to DOS ?
? company name should? ????????????????????????????????????
? be listed here. ?
? ?
??????????????????????
Use PgUp - PgDn - Home - End - - - <RETURN>= Select - or HotKey
Output Menu
Each of the menu choices may be executed by either pressing the
"key letter" or by using the cursor arrow keys to highlight the
choice and then pressing RETURN. If you have a mouse, you can
choose by clicking the left button on any of the options
BOXDATA CHOICES:
(B) Browse. This option will allow you to view the drivers
currently in the BOXDATA file. You can move through the list
using the arrow, Home, End, Page Up, and Page Down Keys. The end
key takes you to the bottom of the list, and Home will return you
to the first listing. Use these keys to point the "flashing
arrows" at your driver choice. If you have sorted your Boxdata
file using the Sort/Pack option, you can press any of the Alpha
keys (A-Z) to jump to that corresponding Manufacturer name. If
you have a mouse installed, you can move the highlight arrows
straight to the driver of interest with the left button. The
right button will load the currently selected line.
Browse-Choose the driver with the arrow keys and press RETURN.
?106 ?PR 38 XM 150 ?POLYDAX ?15",PRO,MONITOR,96dB ?
107 PR 38 XT 150 POLYDAX 15",PRO,FOAM EDGE,MONITOR
108 PR 38 XT 250 POLYDAX 15",PRO,99dB
109 PR 38 XT 350 POLYDAX 15",PRO,HI-POWER,100dB
110 TA-305 FSW PRECISION DUAL V.C. SUBWOOFER
111 TA-305F PRECISION OMEGA
112 TD-125F PRECISION ALPHA
113 TD-255F PRECISION EPSILON
114 TD-255F-SW PRECISION 10",Alum Dual VC,90.7dB
115 TO-205F PRECISION INFINITE BAFFLE 8"
(** Only ten drivers are listed here for clarity. **)
<Esc>=Quit - <F2>=Edit - <F3>=Load defaults.
PgUp-PgDn-Home-End - <INS>=Get # < <? >= Get Record 106
Perfect Box Browse function.
After pointing to a particular driver, you may LOAD the driver
parameters by pressing RETURN. You can EDIT the driver
parameters by pressing the <F2> function key. The <F3> function
key will load any previous Box Volume, Vent Frequency, Order, D
factor, and EQ frequency information saved in a previous
execution of PERFECT BOX, and initiate the calculation loop. You
still can bypass the current selected driver and load any other
driver by pressing <INSERT> and entering the record number. The
<F3> function key will take you back out to the opening menu.
When you return to the BROWSE function, the BOXDATA list will be
on the same page as the last time you were there.
(L) LOAD:
This option allows you to LOAD driver data directly from the
BOXDATA file using the record number. On Floppy based systems,
this option might save you time by skipping the Browse feature.
(S) STORE:
This option allows you to enter new driver data into the
BOXDATA file. ALL parameters listed are required, so don't skip
any unless you are told you may enter a Zero. If you don't have
all of the correct T/S parameters, you should try to obtain them
from the manufacturer. In a pinch, you can approximate values
from other drivers in the BOXDATA file. Don't forget to add the
correct values when you get them. Of course, the accuracy of
this loudspeaker model is DIRECTLY proportional to the T/S
parameter accuracy! Which brings me to say this:
I claim no responsibility for the completeness or accuracy
of the T/S parameters included with your copy of PERFECT
BOX. Many (very many!) of the current drivers listed have
been appended from files sent to me by Registered users of
PERFECT BOX. If you are unsure of any data, it is your
responsibility to verify the T/S parameters with
the manufacturer or test them yourself!
(Soapbox off.)
The new entries are placed at the bottom of the BOXDATA file
and once entered, can be LOADED immediately.
(E) EDIT:
You can edit any of the T/S parameters in the BOXDATA file. Use
the current driver record number to call up the driver and
follow the screen prompts for instructions. You can also edit a
driver directly from the BROWSE function.
(B) REPORTS:
You can print the full BOXDATA file on your printer in two
forms. The first form contains ALL of the driver parameters
including comments. The second form will print the driver's
basic T/S parameters, Fs, Vas, and Qts, and use them to calculate
the "Ideal" 4th order Box volume, Vent frequency, and F3 cutoff
point. This form is very handy to compare driver performance.
UTILITY
(C) Change Boxdata Path:
The BOXDATA file containing all driver parameters, can be
located on a different drive/directory than the current DOS
default. Choose this option if you want to change the path to
the data file. Note: The path is saved for future executions of
PERFECT BOX using the Write Defaults option. You could use this
feature to maintain more than one BOXDATA4 file.
(P) Sort/Pack
Each new driver that you enter into the BOXDATA file is placed
at the bottom of the file. You can use the Sort/Pack option to
sort the file alphabetically by Manufacturer. If you have
marked a driver for deletion in the EDIT driver menu, the Sort /
Pack routine will purge it from the BOXDATA file. This routine
is the an updated version of the sort program that was included
with earlier versions of PERFECT BOX, and thus (if you have
them) you should delete the old BSORT.BAT and BOXSORT3.EXE
program files.
(A) Append new records
This option is used to combine other BOXDATA files into the
current, active BOXDATA file. If you are upgrading from Version
3.xx, rename the OLD data file to "DATAUP.DAT". Start PERFECT
BOX and choose the Append option. If you are upgrading from
Version 2.xx, you must run the 2to4.exe program first. Version 3
uses a slightly different file structure, and thus the 2to4.exe
program will convert you old BOXDATA file into the new structure,
leaving a new file called "BOXDATA4".
Since this is the current name of the Version 4.0 data file, YOU
MUST DO THIS CONVERSION IN ANOTHER DIRECTORY THAN THE ONE
CONTAINING THE NEW BOXDATA4 FILE INCLUDED IN THE VERSION 4.5
ARCHIVE! Either use a different directory or copy the NEW,
original BOXDATA4 to another directory for safe keeping. I
suggest that you make backup copies of EVERYTHING, OLD AND NEW,
before attempting the conversion process. After running the
2to4.exe program, rename the resulting file from BOXDATA4 to
"DATAUP.DAT". Copy "DATAUP.DAT" file into the PERFECT BOX
directory, choose the APPEND function, and watch it fly!
(W) Write defaults.
Each time PERFECT BOX is loaded, a file named PERFECT.CTL is read
for startup defaults. There are many default values kept in
this file including: 1. Boxdata4 data file directory: 2.
Graphics mode: CGA, EGA, or HERC; 3. "Quick mode" toggle; 4.
Printer Port assignment, mouse calibration values and other
variables.
The first two values have obvious purposes. The third parameter
is used to hold the default mode for the calculation loop end
point. In normal mode, the loop counts up to 200 Hz. In Quick
mode, the loop counts up to 100 Hz. This is useful for making
quick estimates on the slower "XT" type machines. You can toggle
this mode within PERFECT BOX with the <F9> function key. The
write defaults option will over-write the configuration file with
current values for BOXDATA file path, Graphics and Quick
Modes. PERFECT BOX 4.5 uses a different format for this control
file than earlier releases. You should delete you old
perfect.ctl file and restart PERFECT BOX.
(D) DOS Shell
You can spawn another copy of COMMAND.COM from within PERFECT BOX
using this option. Use this option to check directories or
file space. Type EXIT at the DOS prompt to return to PERFECT
BOX. This option actually executes a batch file called "SH.BAT".
You could modify this batch file to run another program instead
of loading Command.com.
(Q) Quit to DOS
Just like it says! This choice will halt execution of PERFECT
BOX and immediately return you to the DOS.
OK, OK!, enough talk. Let's see some action!
Now that you know what all of that stuff does on the opening
menu, choose a driver from the BOXDATA file. Use the BROWSE
option, point at an interesting driver, and press RETURN. The
parameters listed are the minimum that you will need to know
about any driver simulated with PERFECT BOX. For this example,
answer "Y" to the question "Do you want this driver?" Now choose
"1" for a single driver simulation.
Record # ?????????> 106
Manufacturer ?????> POLYDAX
Model Number ?????> PR 38 XM 150
Comment ??????????> 15",PRO,MONITOR,96dB
Free air resonance= 19.5 hz.
Vas = 24.37 ft^3.
Qts = .27
Qes = .3
Qms = 2.7
Re = 5.8 ?
Xmax= .1377953
Piston Diameter= 14 in.
Power= 150 Watts.
DO YOU WANT TO USE THIS DRIVER (Y)?
Now, PERFECT BOX will calculate the "Ideal" 4th Order Box volume,
the port frequency for that ideal box volume, and the cutoff
frequency (-3dB point.) The ideal box volume is the smallest
enclosure that provides the flattest, deepest low frequency
response. The cutoff point will give you a general idea of how
low the driver will perform in any box design (best case.) The
port frequency (box frequency) must be set as calculated to
obtain the cutoff predicted.
In a 4th order system: Ideal vented volume is 8.53 Ft^3.
System cut-off (-3dB) is 32.54 Hz.
If the Vent frequency is 26.61 Hz.
?????????????????????????????????????????????????????????
? ORDER ? SYSTEM DESCRIPTION ?
?????????????????????????????????????????????????????????
? 2. ? CLOSED BOX???without Active Equalizer ?
? 3. ? ??with 1st Order Active Equalizer ?
? 3.5 ? ??with 2nd Order Active Equalizer ?
? ? 4. ? VENTED BOX???without Active Equalizer ?
? 5. ? ??with 1st Order Active Equalizer ?
? 6. ? ??with 2nd Order Active Equalizer ?
?????????????????????????????????????????????????????????
Efficiency Bandwidth Product..(Fs/Qes).. is 64 , which suggests a
4th order system.
Enter System Order [ 4 =default] ?
Enter BOX VOLUME (Ft^3) [ 8.53 =default] ?
Enter BOX VENT FR. (Hz.) [ 26.61 =default] ?
Now you must decide what type of enclosure to use. If the driver
has a Qts of 0.5 or greater, I would try infinite baffle
(order=2) systems first, otherwise, use Order=4, with the ideal
box size and frequency. Save the other Order options for later.
Since PERFECT BOX will recommend the Order for you, use it as a
default. Press RETURN to accept the default Order.
Enter the Box volume in cubic feet. I suggest that you use the
ideal box size as a starting point. Then, on the next pass,
change one of the box alignments and check how the response was
affected. Again, press RETURN to accept the default Box volume,
or change it if you prefer to do so.
Enter the Vent Frequency in Hertz. Again, since this is your
first time through, press RETURN to accept the default value.
PERFECT BOX will now calculate :
1. Amplitude response in decibels;
2. Maximum Power in Watts;
and 3. Maximum Sound Pressure Level, at each frequency cycle
between 10 and 200 Hertz. (100 Hz in Quick mode.)
Please wait ... Calculating data for the frequency of xx Hz.
Be patient here. PERFECT BOX is running through a healthy chunk
of floating point calculations, just sit back, watch the counter
change and reminisce about the good old slide rule days. When the
calculations are complete, an Output/Changes Menu will be
presented. A math coprocessor chip makes this loop fly by in
about 2 seconds (if you have one installed!)
PERFECT BOX - Version 4.5
??? Output Choices ?????????????? ??????????????????????????????????
? ? ? Record # : 106 ?
? (F) Frequency vs. Amplitude ? ? Driver : PR 38 XM 150 ?
? (L) Excursion Limit plot ? ? Manufacturer: POLYDAX ?
? (V) View data points ? ??????????????????????????????????
? (U) QUAD-Plot Set-Up [ OFF ] ?
? (D) Print Data points ? Quick mode
? (P) Calculate Ports ????????????? Changes ????????????????
? (W) Driver Worksheet ? ?
? ? (B) Change Box Volume or Vent freq.? ?=2.857
???????????????????????? (E) Change EQ. Frequency or D ? h=1.365
? (A) Change All parameters ?
? (T) Toggle graphics mode (EGA) ?
? (C) Change QLoss ????????????????? Done??
? (Qloss = 7 ) ? ?
??????????????????????? (S) Load/Save Align. ?
? (R) Retrieve another ?
? (Q) Quit to DOS ?
? ?
????????????????????????
Use PgUp-PgDn-Home-End- - - <RETURN>= Select - or HotKey
Output/Changes Menu
OUTPUT CHOICES:
(F) Amplitude vs. Frequency Plot
This choice will plot the classical Bode (pronounced BO-DEE) or
Amplitude Response plot. If the Quick mode was on during
calculations, the plot will stop a 100 Hz. You may print a copy
of the plot on your graphics printer by pressing a "P". This
pops up a nice time-date stamp, dumps the plot to your printer.
After the printer is finished, you can send a Form Feed (FF) to
your printer by pressing the <F10> function key.
(L) Excursion Limit Plot
This graph of SPL & Power vs. Frequency, will give you an picture
of the system driven at maximum power. This plot gives the
Sound Pressure Level (in dB) and the input power required to
reach the excursion limit (Xmax) of the driver. See the Design
Notes chapter of this document for more discussion of this
important graph.
(U) QUAD-Plot Setup (New to Version 4.5)
??????????????
?Current Data?
? in RAM. ?
??????????????
?Trace toggle Model#: Filename: Load Data:
???> F1 On ????
?
F2 Off ????< --- ?Empty <? F6??
? ?
Press F1-F4 F3 Off ????< --- ?Empty <? F7??
to enable ? ?
that trace #. F4 Off ????< --- ?Empty <? F8??
? ?
? ?
?????????????????
?From Disk file.?
?????????????????
Press F10 to Exit
Save driver data in the Output Menu with the F7 key.
You may load up to three data files for display
in the QUAD Plot mode.
QUAD-Plot Setup Menu
For EGA users, the QUAD-Plot function will allow you to compare
Amplitude Plots from the current run with up to three other runs
previously saved from the Output Menu with the F7 option.
Once in the QUAD-Plot Setup menu, you load the data files with
function keys F6, F7 and F8. The function keys F1-F4 will toggle
each trace off and on, allowing printout of fewer traces than the
loaded number. Once you have loaded your comparison files, press
F10 to return to the Output Menu. You should notice that the
prompt beside the QUAD-Plot Setup function should say
"[ ON ]" This is automatically set to ON after leaving the QUAD-
Plot Setup Menu. You can toggle the QUAD-Plot OFF/ON with the F4
key in the Output Menu. Turning OFF the QUAD-Plot will not erase
the currently loaded data, and will allow you to bounce back and
forth between the usual plot modes and QUAD-Plot.
The QUAD-Plot function is available only in the EGA graphics
mode. If your machine cannot support EGA 43 line mode, you
cannot use QUAD-Plot. Also, your mouse becomes useful tool
during the QUAD-Plot display. Without a mouse, some features
will be unavailable to you, but you still can view up to four
graphs at once.
Perfect Box (4.5) ? QUAD-Plot
| Fb
??????????????????????????????????????????????????????????????????
?Registered to:?+6 ? ?
? ? 5 ? ?
?Your name or ? 4 ? ?
?Company should? 3 ? ?
?be listed ? 2 ? ?
?here. ? 1 ? ?
? ? 0?????????????????????????????????????? ?
? ?-1 ? ?
? ?-2 ? ?
? ?-3 ? ?
? ?-4 ? ?
? ?-5 ? ?
? ?-6 ? ?
? ?-7 ? ?
? ?-8 ? ?
? ?-9 ? ?
? ?-10? ?
? PERFECT BOX ?-11? ?
? ?-12? ?
? by ?-13? ?
? Warren ?-14? ?
? A. ?-15??????????????????????????????????????????? ?
? Merkel ? ?
? ? 20 30 40 50 60 7 8 9 100 200 Hz ?
??????????????????????????????????????????????????????????????????
? ? ? ? ? ?
? ?Trace 1 ? Trace 2 ? Trace 3 ? Trace 4 ?
?At Magnifier: ? 3124 ? Mod: ? Mod: ? Mod: ?
?Amp = ? ALTEC ? Man: ? Man: ? Man: ?
?Freq= ? From RAM ? File: ? File: ? File: ?
?At Ruler: ? Vb : 2.79 CF ? Vb : ? Vb : ? Vb : ?
?Amp = ? Fb : 33.44 Hz? Fb : ? Fb : ? Fb : ?
?Freq= ? Ord : 4 ? Ord : ? Ord : ? Ord : ?
? ? Feq : ? Feq : ? Feq : ? Feq : ?
? ? D : ? D : ? D : ? D : ?
? ? Single ? ? ? ?
??????????????????????????????????????????????????????????????????
Press P to Print ? <?? to continue
The QUAD-Plot Screen (not to scale)
Each trace is plotted in a different color and can be temporally
erased with function keys F1-F4 or with a left click in the data
area for that particular trace. If you have a mouse, you can use
the cursor as a magnifier to determine which Trace is where. As
you pass over a particular trace, a asterisk will flash beside
that Trace's number.
You can also set a ruler line at any point on the graph with the
left mouse button. This will allow quick measurements of any
point on the plot. The ruler will be drawn from the center of
the magnifier to each axis, and the values for the ruler will be
locked at the "At Ruler" area. To erase the ruler, click the
right mouse button. The "At Magnifier" values are constantly
updated to the cursor magnifier position.
You may have to calibrate your mouse to read the plot correctly.
If the magnifier values do not reflect the actual point on the
plot, move the magnifier to the words "At Magnifier" and click
both buttons. You will be asked to move the magnifier to the
20Hz-0dB point an click the left button. Then you will be asked
to move the magnifier to adjust the "At Magnifier" values to
reflect exactly 0dB at 20 Hz. Then click left again. Then, if
you are satisfied that you correctly positioned the mouse, press
the right button to save these new calibrated values in the
Perfect.ctl file. You can abort by pressing the right button.
As with the other Plot screens in PERFECT BOX, you can press a
"P" to print the screen on your graphics printer. The F10 key
will cause a Form Feed command to be sent to your printer.
At this time, only the Amplitude Plots can be compared. If
sufficent user interest dictates the addition of the SPL-Power
plots into the QUAD-Plot function, I will work that mode into the
next release. (Registered users first though...)
(V) View data points
This option will list on the screen, all calculated data,
between the frequency limits of your choice.
(D) Print data points
This option will print on your printer, all calculated data,
between the frequency limits of your choice.
(W) Driver Worksheet
This option produces on your printer, a worksheet which
gives you a handy reference table to use as you change the
different alignments about your system. Each block can be filled
from data printed on the Frequency vs. Amplitude plot option. I
suggest that you do this option first (only if you have a printer
on-line.) and log each repetition of your progress.
(B) Change Box Volume or Vent Frequency
(E) Change EQ. Frequency or D
(A) Change ALL parameters
At this point you may choose what parameter to change in an
attempt to optimize the frequency plot, or what ever else you are
trying to achieve (maximum power for instance.) If you are
currently working on a 2nd or 4th order system, the "Change
EQUALIZER Frequency or D." choice will not be allowed. Thus if
you want to change to an "equalized" order, you must use the
"Change ALL Parameters" option. Remember that the previous value
for each prompt in the CHANGE menu, there will be the default
value (just press RETURN.)
(T) Toggle graphics mode
This choice toggles you between EGA and CGA modes. This is
really not needed anymore. I left it in for those of you whom
can't get the build-in graphics dump program to function properly
with your printer. You could for example, have the DOS
GRAPHICS.COM loaded before PB, and switch to CGA for printing.
(C) Change Qloss
This option allows you to account for box leakage losses. Normal
vented cabinets are modeled at Ql=7. If you do not have the
means to accurately measure Qloss, then leave Ql=7.
(S) Load/Save Alignment
This choice allows you to save your current design parameters to
the BOXDATA file for future use. This becomes very handy if you
want to keep track of your best designs for each driver.
(R) Retrieve another driver
This choice will dump all calculated data, and return you to the
opening menu.
(P) Calculate Ports
After you are satisfied with the current design parameters,
PERFECT BOX will calculate the port lengths required to tune the
cabinet to the frequency currently chosen. A column for two
identical length ports is also given. Dual ports are useful when
the box volume or the MACH speed is too large for a single port.
The MACH number is the percent of the speed of sound that will
occur at the largest port output.
POLYDAX PR 38 XM 150
BOX VOLUME= 8.53 Ft^3 BOX FREQUENCY= 26.61 Hz. ORDER : 4
HEIGHT= 39.72 in. WIDTH= 24.52 in. DEPTH= 15.2 in.
VENT LENGTHS FOR TYPICAL INTERNAL DIAMETERS OF PVC PIPE
(Inches)
DIAMETER LENGTH MACH DUAL VENTS MACH
------- ------ ---- ---------- ----
1 -.38 1.243 NO ! | -.03 .311 NO!
1.5 -.31 .553 NO ! | .48 .138
2 -.06 .311 NO ! | 1.35 .078 Best
2.5 .37 .199 Use Dual| 2.57 .05 Best
3 .97 .138 O.K. | 4.13 .035 Best
3.5 1.75 .101 O.K. | 6.05 .025 Best
4 2.7 .078 Best | 8.32 .019 Best
4.5 3.83 .061 Best | 10.95 .015 Best
5 5.13 .05 Best | 13.92 .012
Vent Calculations.
Stay away from large (speed> 0.2) port MACH speeds as they
will cause unmusical whistle noises from the port. Ports that
are longer than the box depth, can be curved inside the enclosure
with PVC swept elbows.
V. DESIGN HINTS:
If the ideal box volume is too large to be realistically built,
PERFECT BOX will allow you to see just how the loudspeaker
performance will suffer, as you down size box volume. It is do to
this iterative design process that PERFECT BOX accels other
modeling programs. By changing either box volume, port
frequency, or in EQ cases, EQ frequency and boost, a "perfect"
frequency curve should be obtainable. At this point you can tell
how good a driver really is because sometimes one driver will
out perform others in half the enclosure volume.
The port frequency is set by the area and length of the vent.
PERFECT BOX will calculate the port for you, but the length is
typically 10% off, so add an half-inch to the calculated value,
and measure the box frequency for yourself. The system will not
perform as calculated if you miss the port frequency by as little
as 1 Hz, so try to hit it as close at possible. Also, after you
have reached a final box size, increase the box volume by as much
as required to account for volume used by the drivers, bracing,
and crossover network. It is much better to error on the high
side of Box Volume. I typically add 10% to the final size as a
fudge factor. You can always add braces to account for any
overage.
To find box dimensions from the box volume, take the volume
in cubic feet, multiply by 1728 cubic in/ft^3, to get in^3. Then
take the cube root (or raise it to the 0.3333334 th power.) Now
this number is the width in inches. Multiply the width by 1.62
for the height, and multiply the width by 0.62 for the depth.
volume (in^3) = volume (ft^3) * 1728
width (in.) = (volume (in^3) )^0.3333334
height (in.) = width * 1.62
depth (in.) = width * 0.62
NOTE: All dimensions are internal, not external!
This will give the box a typical speaker "look" and also set the
dimensions up for minimum internal reflections. PERFECT BOX
calculates these dimensions for you and prints them in the port
length table.
VI. COMMAND LINE SWITCHES
There are a few command switches which will override the settings
in the PERFECT.CTL file.
/CGA = Sets graphics mode to CGA.
/EGA = Sets graphics mode to EGA.
/HERC = Sets graphics mode to Hercules.
/LPT1 = Sets the active printer port to LPT1:
/LPT2 = Sets the active printer port to LPT2:
/LPT3 = Sets the active printer port to LPT3:
/QUICK = Runs PB in the fast mode (10-100 Hz).
/RESETMOUSE = Clears previous mouse calibrations.
/NOMOUSE = Defeats all mouse functions.
/PTF = Reroutes all text printing to a file called
"Printer.out". All text output is APPENDED to this file.
/NOPAPER = Defeats the printer error checking.
This might be useful if you are using a "Print-TO-File" TSR to
grab output. As it stands now, the Novell "SPOOL" command is
supported for LPT1: if your workstation has an active local
printer attached. The /NOPAPER option bypasses local printer
checking and allows SPOOL to capture LPT1 correctly without a
local printer attached to LPT1:.
All values affected by the Command line switches except /PTF can
be made the current default by the "W" Write Defaults command in
the opening menu.
NOTE: The /NOTEST switch is no longer supported (or required.)
If you have a 8087/80287 coprocessor installed, PB will
automatically use it for all Floating Point calculations. If for
some reason, you would like to defeat the coprocessor from
functioning, set an Environment variable in your CONFIG.SYS file
NO87=Coprocessor is Defeated
and reboot, before executing Perfect Box. You may also use the
DOS "SET" command to create the NO87 variable.
VII. REFERENCES:
This document and the program PERFECT BOX are only tools for
the speaker designer. One must know how to use these tools
properly before judging the usefulness of PERFECT BOX. I suggest
that you read or subscribe to any of the following publications
on the finer art of speaker building.
SPEAKER BUILDER MAGAZINE (6 times a year)
Edward T. Dell, Jr., Publisher
PO Box 494 Peterborough, NH 03458
An excellent publication. Articles vary from the most basic
"cookbook" projects, to the exotic mathematical theories used in
PERFECT BOX. Electronic projects and crossover designs are
covered in depth. Many of the systems discussed are years before
the designs hit the market. Articles are written by
knowledgeable authors well known in the field, ideas of which
have been mimicked by the major Speaker Manufacturers. Now with
full color layouts, software and book reviews, Speaker Builder is
an absolute must.
"The Loudspeaker Design Cookbook"
by Vance Dickason
Distributed by:
Old Colony Sound Lab
PO Box 243
Peterborough, NH 03458-0243
Hats Off! to Dickason for handy reference to all design formulas
required by the speaker designer. Covers explanations of many
types of crossover designs and enclosure systems, including Push-
Pull, and Isobaric.
"How to Design, Build, & Test Complete Speaker Systems"
by David B. Weems
Library of Congress #TK9968.W43
Published by:
TAB Books
Blue Ridge Summit, PA 17214
No. 1064
The perfect starter book in speaker design. Written in a down to
earth style, Weems covers the T/S theories with just enough math
to get the job done correctly without being overbearing to the
beginner. Many complete projects and testing methods are
covered. A beginners standard for the past decade!
VIII. ERRATA:
Your support helps! PERFECT BOX is supported by YOU, the user.
Without user support, Shareware such as PERFECT BOX cannot
continue to exist! Use this program!, give a copy of PERFECT BOX
to your friends (the BBS Archive file is the best way to make
sure all the PERFECT BOX files are present.) Above all, don't
forget your part in the deal! If you are using PERFECT BOX on a
trial basis, that's fine. Determine its usefulness in accurately
designing your new speaker system, then REGISTER! The money that
you save by building your own system can easily cover the
registration fee.
If you are using PERFECT BOX in a business or commercial
environment, you MUST Register, PERIOD. IF YOU ARE MAKING A
COMMERCIAL PROFIT USING PERFECT BOX WITHOUT REGISTRATION, YOU ARE
IN VIOLATION OF YOUR SHAREWARE AGREEMENT WITH THIS AUTHOR. Your
job is easy with PERFECT BOX in your tool kit. Don't forget who
bought you that tool!
Many registered users are using PERFECT BOX for professional
sound reinforcement or automotive sound applications. If this is
true for you, just don't forget the concepts under which
shareware functions. Perfect Box can easily pay for itself with
ONE SALE.
PERFECT BOX is under constant scrutiny for improvement. If you
have any ideas for new features/functions, or problems in program
operation, send them to me at the address on the next page.
Your suggestion could be included in the next revision of PERFECT
BOX. By registering your copy, you will be sent (if requested) a
disk with the current Version installed in your name. You will
also receive a copy of the next MAJOR PERFECT BOX revision, and
new BOXDATA file parameters. Registered users can have their
current copy updated at any time. Also, Registered users can
download the future releases of PERFECT BOX directly from my 24
hour BBS at FIDONET 363/507 (407-281-5522 : 2400-N-8-1),
including unlimited "Online support" through BBS E-Mail.
If you want to others to share in your BOXDATA resources, please
send a COPY of your BOXDATA file on disk (5.25" or 3.5") to me
in a U.S. Post Office approved disk envelope (or safe
equivalent.) Or, upload your BOXDATA file to my BBS.
TO REGISTER:
Send $40.00 in U.S. funds (personal checks accepted) to cover
registration and return postage. IT'S THAT SIMPLE.
The un-registered copy is NOT "crippled" in any way. All PERFECT
BOX functions are available on the un-registered program.
Please make checks payable to:
>>> WARREN A. MERKEL <<
and send your contribution to:
Warren A. Merkel
2851 Newcomb Ct.
Orlando, FL 32826
(PERFECT BOX 4.5) *** End of Document *** (PERFECT.DOC)