home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Shareware Overload
/
ShartewareOverload.cdr
/
games
/
alpha.zip
/
XMODEL.SCR
< prev
Wrap
Text File
|
1986-12-31
|
4KB
|
78 lines
Arnold B. Krueger
1600 Prestwick
Grosse Pointe Woods, MI
48236
313-881-4829 home
313-583-9610 business
October 29, 1985
Gentlemen:
Attached are the program listings and sample output for two programs that
assist persons designing multi-way loudspeaker systems. It is assumed that
the drivers are essentially linear and minimum phase However, non-minimum
phase systems can be modelled by adding fixed and frequency-dependent delay
equations. Delay due to non-coincident mounting of driver acoustic centers
is included.
The first program, line numbers 10-770 is named "Xover" and is the
modelling program. Crossover characteristics are defined on line 210, in
terms of corner frequency (FC) and Q (Q). This particular program is set up
for 2nd order crossovers. Driver characteristics for the low and high
frequency drivers are defined on lines 230-240 in terms of corner frequency
and Q. This particular program is set up for 4th order drivers, that is
systems with a 2nd order roll-on and a 2nd order roll-off. The distance of
displacement between the two drivers is set on line 260.
This program can be enhanced to handle higher-order driver and crossover
characteristics by modifying lines 420-450. Additional orders are handled
by adding additional phase shifts, and multiplying by additional gains.
The functions required for calculating these additional effects are defined
in lines 10-80. The functions are named as follows:
.e
name order type result
FNPHLP1 1 Low Pass phase in radians
FNPHHP1 1 High Pass phase in radians
FNAMLP1 1 Low Pass amplitude
FNAMHP1 1 High Pass amplitude
FNPHLP2 2 Low Pass phase in radians
FNPHHP2 2 High Pass phase in radians
FNAMLP2 2 Low Pass amplitude
FNAMHP2 2 High Pass amplitude
.e
The arguments are W (frequency of operation) WC (corner
frequency) and D (damping or 1/Q). They may be typed into the equations as
numbers or variables set elsewhere in the program.
The second program, named DRVCHR facilitates comparisons between tabulated
measured data about driver frequency response, and the results of the
equations used in the driver/crossover model, XOVER. Line 150 is user-
defined descriptive text. Line 170 contains the subscripts of the first
and last data points to be considered. Lines 180-470 are a work area for
inputting the results of the measurements. Lines 490-500 are for inputting
the trial driver model parameters. Lines 630-640 compute driver model
frequency response and phase response, and may be extended to handle
drivers with more complex characteristics in a like manner as described for
program XOVER, above. A common requirement would be for a 4th order low
end characteristic, accomplished by adding the results or another call to
FNPHLP2 in line 630 and multiplying in the results of another call to
FNAMLP2 in line 640.
To use this program, type the measured data in lines 180-470, and then
alter the data in lines 490-500 and rerun the program until the calculated
data most closely resembles the measured data. An error sum is calculated
and typed out at the end of the run as "Error". Try to minimize this
number. Once the desired match is obtained, transfer that information to
the XOVER program lines 230-240. Note that the data provided in the sample
program is for a driver with a second order roll-off and probable 4th order
roll-on. This driver will never be closely matched to the model until it
is extended to the 4th order at the low end.