Abstract:
A self diagnostic loudspeaker load impedance testing system, or Push Here Diagnostic (PHD) system, located within a mixer/amplifier for testing loudspeaker connections to the mixer amplifier during installation and maintenance. The system includes a test signal source that replaces the normal audio input to the amplifier during test. A PHD analyzer within the mixer amplifier analyzes the response of the loudspeakers and related wiring to the test signal to detect a total system impedance that exceeds the amplifier rating and to detect short circuits in the wiring. The PHD analyzer illuminates an indicator when a fault occurs. The test is initiated by depressing a momentary contact switch within the mixer amplifier housing by inserting a tool through an opening in the mixer amplifier housing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 62/012,300 filed 14 Jun. 2014 to the same inventor, the contents of which are incorporated herein in its entirety. 
    
    
     FIELD OF ART 
     The present invention relates to a built-in test system for distributed audio systems, such as 70.7 volt and 100 volt systems, with multiple speakers, such as public address systems. The present invention more particularly relates to a built in test system used during installation of an audio system to test speaker connections to the amplifier. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     None. 
     SUMMARY OF THE INVENTION 
     The Atlas Sound AAPHD Mixer Amplifier Series and other future Atlas Sound Products that feature a mixer amplifier Self Diagnostic Speaker load Impedance Testing System, also known as a Push Here Diagnostic (PHD) system. The PHD feature of the AAPHD Series mixer amplifiers is simple to use and is very effective for running a self-diagnostic system test to assure the amplifier of the mixer amplifier has the proper speaker load/impedance applied. This test requires no external diagnostic tools to run the test. The PHD circuit is incorporated in the Atlas Sound AA Series Mixer Amplifiers. Many amplifiers fail because an incorrect load is applied to the amplifier. This is especially true when using the amplifier in a 70.7V or 100V distributed audio speaker system. 
    
    
     
       DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
       The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and self diagnostic speaker load impedance testing system 
         FIG. 1  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 2A  is a rear elevation view illustrating an exemplary embodiment of the self diagnostic speaker load testing system in a mixer amplifier, according to a preferred embodiment of the present invention; 
         FIG. 2B  is a front elevation view illustrating an exemplary embodiment of the self diagnostic speaker load testing system in a mixer amplifier, according to a preferred embodiment of the present invention; 
         FIG. 3  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system in a mixer amplifier, according to a preferred embodiment of the present invention; 
         FIG. 4  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 5  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 6  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 7A  is a schematic view illustrating a first portion of a first exemplary embodiment of a PHD analyzer of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 7B  is a schematic view illustrating a second portion of the first exemplary embodiment of a PHD analyzer of the self diagnostic speaker load testing system of  FIG. 7A , according to a preferred embodiment of the present invention; 
         FIG. 8A  is a schematic view illustrating a first portion of a second exemplary embodiment of a PHD analyzer of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 8B  is a schematic view illustrating a second portion of the second exemplary embodiment of a PHD analyzer of the self diagnostic speaker load testing system of  FIG. 8A , according to a preferred embodiment of the present invention; 
         FIG. 8C  is a schematic view illustrating a third portion of the second exemplary embodiment of a PHD analyzer of the self diagnostic speaker load testing system of  FIG. 8A , according to a preferred embodiment of the present invention; 
         FIG. 9A  is a schematic view illustrating a first portion of an exemplary embodiment of a PHD testing signal source of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 9B  is a schematic view illustrating a second portion of an exemplary embodiment of the PHD testing signal source of  FIG. 9A  of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; 
         FIG. 9C  is a schematic view illustrating an exemplary embodiment of a filter of the PHD testing signal source of  FIG. 9A , according to a preferred embodiment of the present invention; 
         FIG. 9D  is a schematic view illustrating an exemplary second embodiment an oscillator of the exemplary PHD testing signal source of  FIG. 9A  of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention; and 
         FIG. 10  is a process diagram illustrating a method of use of an exemplary embodiment of the self diagnostic speaker load testing system, according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. The AAPHD Series PHD Self Diagnostic Test System  100  is divided into five sections  102 ,  106 ,  112 ,  16  and  120 . Each section  102 ,  106 ,  112 ,  16  or  120  is described below but all are required for a complete PHD self-diagnostic speaker load testing system  100 . A commercial audio mixer amplifier  200  (see  FIG. 2A-2B ) consists of two main segments that make up the specific product category called mixer amplifier  200 . The first section  102  includes mixer  104  that comprises an interface assembly that accepts analog audio signals from multiple sources such as microphones and CD players, combines them into a mono signal, and delivers them through the second section  106  to the amplifier  114  in the third section  112 . The second section  106  includes PHD test enable switch  108  and the testing signal source  110 . The third segment of the mixer amplifier  200  is the amplifier  114  that receives the mono signal from the audio mixer  104 , via the PHD test enable switch  108 , and amplifies the low level audio signal into a much higher power level. Speakers  302  (see  FIG. 3 , one of six labeled) (collectively, speaker system  300 ) connect directly to the amplifier analog output  126 , collectively creating speaker load  124 . 
     Various embodiments of AAPHD Series Mixer Amplifiers  200  (see  FIG. 2A-2B ) vary in mixer  104  features and vary in output power to the speakers  302 . All AAPHD Series Mixer Amplifiers  200  have the same method of operation.  FIG. 1  is the block diagram of the AA Series PHD self diagnostic speaker load testing system  100  circuit. The first section  102  includes the analog input mixer  104  that sums all of the analog inputs into one signal to feed the amplifying power stage  112 . The second section  106 , which precedes the amplifying power stage  112 , includes the PHD testing signal source  110  and PHD test enable switch  108 . On the front panel  206  (see  FIG. 2A ) of the AAPHD Series mixer amplifier  200 , a recessed momentary switch  108  is used to activate the PHD testing signal source  110 . The third section  112  amplifies the signal from mixer section  102 . The amplifier stage  112  is susceptible to failure if an incorrect speaker load  124  is applied. The purpose of the PHD self diagnostic speaker load testing system  100  is to prevent the system from failure during installation and customer use. The fourth section  116  includes the PHD diagnostic analyzer  118 , which, when implemented, determines if the impedance of the speaker load  124  applied to the AA PHD mixer amplifier  200  meets the safe operating area specification of the amplifier  114 . The PHD diagnostic analyzer  118  calculates the impedance of the speaker load  124  applied to the amplifier  114 , determines if the current required has exceeded the safe operating limits of the amplifier  114 , and sends a fault command with an indicator  122  to inform the installer to inspect the installation of the speaker system. The fifth section  120  includes the PHD limit fault indicator  122 , which is exemplified as an LED. If the impedance of the speaker load  124  applied to the AA PHD mixer amplifier  200  does not meet the safe operating area for amplifier  114 , the PHD limit fault indicator  122  will illuminate, informing the installer there is an installation issue or fault within the speaker system. 
       FIG. 10  is a process diagram illustrating a method  1000  of use of an exemplary embodiment of the PHD self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. In operation, the PHD self diagnostic load testing system  100  is preferably used via a six-step process  1000 . In step  1002 , install the AAPHD mixer amplifier  200 , connect the input signals and turn all levels to minimum. Do not attach the speaker system  300  to the mixer amplifier  200  while connecting inputs and setting levels. In step  1004 , install the speaker system  300  per the design, double check speaker tap settings. The sum total power for all the speakers  302  should not exceed the maximum power rating of the amplifier  114  installed. If  1006  the sum total power for all the speakers  302  does exceed the maximum power rating of the amplifier  114 , correct the installation in step  1204 . In step  1008 , connect the speaker system  300  to the mixer amplifier  200 . Pay special attention when connecting the speaker leads to the proper terminals on the mixer amplifier  200 . In step  1010 , turn the mixer amplifier  200  on. In step  1012 , make sure no people are present or near the speakers  302  during the diagnostic test without taking proper hearing precautions. A one-half watt test tone will be present at each speaker  302 . The audible sound pressure level (SPL) will be based on the power tap setting at each speaker  302  and sensitivity specification of the speaker  302 . The audible SPL level may be alarming to some people. Wear proper hearing protection before starting the test. In step  1014 , activate the PHD circuit by inserting a small, pointed tool through the hole  212  on the front panel  208  labeled PHD. Press and hold the momentary switch  108  for  1 - 2  seconds, then release. A test tone will be audible through the speakers  302 . If the limit fault LED  122  does not illuminate yellow, the system is properly set up and no errors in the system were found  1018 . Continue or complete the installation. If  1016  the limit fault indicator  122  does turn yellow, STOP and inspect the speaker system  300  for one of the faults listed above and repair the fault  1020 . Re-run the test after the fault condition has been fixed. Continue until the limit fault indicator LED  122  does not illuminate. 
       FIG. 2A  is a rear elevation view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100  in a mixer amplifier  200 , according to a preferred embodiment of the present invention. Rear panel  204  in case  202  provides power, audio input, and speaker output connections, as shown. 
       FIG. 2B  is a front elevation view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100  in a mixer amplifier  200 , according to a preferred embodiment of the present invention. Front panel  206  provides user interface devices and the PHD test display  208 , as shown. Included in the test display  208  is a window  210  to the limit fault indicator  122  and a labeled hole  212  for activating the system. Additional test indicators are also provided. 
       FIG. 3  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100  in a mixer amplifier  200 , according to a preferred embodiment of the present invention. Without running a distributed audio impedance diagnostic test during installation, failure may occur to the amplifier if a fault is in the speaker system. There are a few common failure points that can occur during speaker system installation. The PHD feature runs a series of tests to diagnose and identify if the speaker system has a fault condition or if the impedance of the speaker load  124  matches the selected mixer amplifier  200 . The following product diagrams describe the possible fault conditions that are common. The illustrations in these diagrams feature the Atlas Sound AA30PHD Mixer Amplifier  200 . Note: The PHD circuit operates in the identical manor for the complete AAPHD Series.  FIG. 3  illustrates proper 70V amplifier loading. Each speaker  302  (one of six labeled) is connected to mixer amplifier  200  via 70 volt power line  304  and an audio signal, or com, line  306 . In  FIG. 3 , the installation is correct, as the sum of the power required by all speakers  302  is less than the power rating of the mixer amplifier  200 . The illustrations showing six speakers  302  is not intended to suggest that only six speakers can be connected at any given time: the number is limited only by the power of the mixer amplifier  200  and the power requirements of the speakers  302 . 
       FIG. 4  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. In the example of  FIG. 4 , the tap setting  402  on speaker  404  has been set incorrectly, resulting in a wrong impedance being detected by the self diagnostic speaker load testing system  100 . A tap setting involves the selection of a particular tap on a transformer integral to the speaker  302  (one of six labeled) to determine the power drawn by the speaker  302 . In the configuration of  FIG. 4 , the power (wattage) required by the speaker load  124  would exceed the power rating of the mixer amplifier  200 . Improper load selection or power tap setting on 70V speaker systems generates a fault. It is very common when using many speakers to have one of the speakers tapped accidently at 8Ω. This error will definitely be very hard on a 70V amp and in most situations cause the mixer amplifier  200  to fail within a few days. This kind of error is easy to make, time consuming to find and costly to fix. 
       FIG. 5  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. In the example of  FIG. 5 , the tap setting  504  on speakers  506  and  508  have been set incorrectly, resulting in a wrong impedance being detected by the self diagnostic speaker load testing system  100 . In the configuration of  FIG. 5 , the power (wattage) required by the speaker load  124  would exceed the power rating of the mixer amplifier  200 . A fault is generated when too many speakers  302  are attached or the wrong power taps are selected. For non-limiting example, if a 50 watt mixer amplifier  200  is used in a 70V system and it has six speakers  302  all tapped at eight watts, but two of the speakers are accidently tapped at sixteen watts, the total power demand is fifty-six watts of power required to drive the system properly, which exceeds the power rating of the mixer amplifier  200 . While it may work at low levels, as soon as the system needs to be louder the mixer amplifier  200  will be strained and fail over time. Most amplifier  114  failures are caused by improper installation on the speaker  302  side. 
       FIG. 6  is a diagrammatic view illustrating an exemplary embodiment of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. Short circuits  602  or  604  will generate a fault. Short circuit  602  is a conduit short, in which the insulation on the wire is degraded and the wire shorts to the conduit. Short circuit  604  to speaker  606  is caused by a staple, intended to secure wires to environmental surfaces, penetrating the wire insulation and shorting out the power line  304  to the audio signal line  306 . The self diagnostic speaker load testing system  100  detects these shorts as a fault and illuminates the fault indicator  122 . 
       FIG. 7A  is a schematic view illustrating a first portion of a first exemplary embodiment of a PHD analyzer  118  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. The second half of the schematic is in  FIG. 7B , where the numbered connectors indicate corresponding lines on both  FIG. 7A  and  FIG. 7B . The entire schematic is in the file wrapper of US provisional patent application number  62 / 012 , 300 . The schematic is presented here for purposes of enablement. A person of skill in the art, enlightened by the present disclosure, would be able to make the first embodiment of the PHD analyzer  118  based on the schematic of  FIG. 7A  and  FIG. 7B . 
       FIG. 7B  is a schematic view illustrating a second portion of the first exemplary embodiment of a PHD analyzer  118  of the self diagnostic speaker load testing system  100  of  FIG. 7A , according to a preferred embodiment of the present invention, as discussed above. 
       FIG. 8A  is a schematic view illustrating a first portion of a second exemplary embodiment of a PHD analyzer  818  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. PHD analyzer  818  is second embodiment of PHD analyzer  118 . The second and third portions of the schematic are in  FIG. 8B and 8C , where the numbered connectors indicate corresponding lines on  FIG. 8A  and FIG.  8 B. The entire schematic is in the file wrapper of U.S. provisional patent application No. 62/012,300. The schematic is presented here for purposes of enablement. A person of skill in the art, enlightened by the present disclosure, would be able to make the second embodiment of the PHD analyzer  818  based on the schematic of  FIGS. 8A, 8B, and 8C . 
       FIG. 8B  is a schematic view illustrating a second portion of the second exemplary embodiment of a PHD analyzer  818  of the self diagnostic speaker load testing system  100  of  FIG. 8A , according to a preferred embodiment of the present invention. The numbered connectors indicate corresponding lines on  FIGS. 8A and 8C . The numbered connectors indicate corresponding lines on  FIG. 8B . 
       FIG. 8C  is a schematic view illustrating a third portion of the second exemplary embodiment of a PHD analyzer  818  of the self diagnostic speaker load testing system  100  of  FIG. 8A , according to a preferred embodiment of the present invention; 
       FIG. 9A  is a schematic view illustrating a first portion of an exemplary embodiment of a PHD testing signal source  110  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention.  FIG. 9A  illustrates the oscillator portion of the PHD testing signal source  110 . Switch SW 1 A connects contacts  2  and  3  during operation of the self diagnostic speaker load testing system  100 . Contact  3  is coupled to a clock signal or similarly varying signal to operate the Schmidt trigger oscillator. The output of the oscillator is the raw test signal. The embodiment of  FIG. 9A  is merely exemplary, and the exact parts illustrated need not be used where functional substitutes are available. A second portion of the schematic is in  FIG. 9B , where the numbered connectors indicate corresponding lines on both  FIG. 9A  and  FIG. 9B . The entire schematic illustrated in  FIGS. 9A and 9B  is in the file wrapper of U.S. provisional patent application No. 62/012,300. The schematic is presented here for purposes of enablement. A person of skill in the art, enlightened by the present disclosure, would be able to make the PHD testing signal source  110  based on the schematic of  FIG. 9A and 9B . 
       FIG. 9B  is a schematic view illustrating a second portion of an exemplary embodiment of the PHD testing signal source  110  of  FIG. 9A  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention.  FIG. 9B  illustrates a resistive attenuation network  902  with an optional trimmer resistor receiving the raw test signal and providing it to switch SW 1 B which, when activated, conducts the testing signal to the amplifier  114 . A direct current isolator  904  may be provided before switch SW 1 B. Switches SW 1 A and SW 1 B are preferably both contained in switch  108  or, in another embodiment, may be commonly controlled by switch  108 . 
       FIG. 9C  is a schematic view illustrating an exemplary embodiment of a filter of the PHD testing signal source  110  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. The schematic is presented here for purposes of enablement. A person of skill in the art, enlightened by the present disclosure, would be able to make the filter, based on the schematic of  FIG. 9C . 
       FIG. 9D  is a schematic view illustrating an exemplary embodiment of a second embodiment an oscillator of the exemplary PHD testing signal source  910  of the self diagnostic speaker load testing system  100 , according to a preferred embodiment of the present invention. The schematic is presented here for purposes of enablement. Exemplary PHD testing signal source  910  may replace PHD testing signal source  110 . A person of skill in the art, enlightened by the present disclosure, would be able to make the oscillator based on the schematic of  FIG. 9D .