Apogee speakertest Brochure

SPEAKER TEST PROCEDURE

A PROCEDURE, EQUIPMENT REQUIRED AND A TEST SET-UP ARE GIVEN FOR EACH TEST
REQUIRED.

BEAR IN MIND THAT SOME SET-UPS ARE REPETITIVE AND SO THE SET-UP AND
PROCEDURE WILL BE SOMEWHAT SIMILAR.

EQUIPMENT REQUIRED FOR ALL TESTS A THROUGH D:

(1) DVM (Digital Volt Meter)
(2) OSCILLATOR ADJUSTABLE
(3) NEUTRIK
(4) POWER AMPLIFIER AUDIO/ WITH PRE AMP IF REQUIRED
(5) FREQUENCY COUNTER
(6) MICROPHONE AND PRE AMP /POWER SUPPLY
(7) ALL INTERCONNECTING WIRE
(8) IMPEDANCE MEASUREMENT CIRCUIT (APOGEE)
(9) MARKING STICK OR SCALE
(10) OSCILLOSCOPE

THE SEQUENCE OF TESTS IS LISTED BELOW AND THE PROCEDURES WILL BE PREFIXED
UNDER THE LETTER GIVEN.

EQUIPMENT SET-UP FOR TEST:
A - WOOFER TUNING
B - RESONANCE
C - MRT/WOOFER PHASE TEST
D - ONE METER RESPONSE
E - IMPEDANCE OF SYSTEM

(SOME SEQUENCE VARIATION CAN OCCUR. THIS IS ONLY RECOMMENDED SEQUENCE.)

TEST A - WOOFER TUNING

FOR TEST A, WOOFER TUNING SET UP THE FOLLOWING TEST EQUIPMENT

FROM TIDE LIST ON THE FRONT COVER:

(1)DVM
(3)NEUTRIK
(4)POWER AND (PRE AMP)
(5)FREQUENCY COUNTER
(6)MICROPHONE/POWER SUPPLY
(7)CONNECTING WIRE
(9)MARKING STICK

BEFORE WE PROCEED WITH THE TEST, SOME PRELIMINARY SET-UP IS REQUIRED.

MARK SPEAKER FOR MEASUREMENT POINTS (FIG. I)

SET UP MICROPHONE CLOSE TO SPEAKER (FIG. 2)

EQUIPMENT SET-UP THEN WE CAN GO ON AND TUNE SPEAKER

MICROPH0NE PLACEMENT

MICROPHONE SHOULD BE SQUARE AND PARALLEL TO THE FACE OF THE SPEAKER.

MICROPHONE SHOULD BE APPROXIMATELY 1" FROM FACE OF SPEAKER.

MICROPHONE SHOULD BE CONNECTED TO THE B AND K PRE AMP AND POWER SUPPLY.

MAKE SURE THAT IT IS "ON" AND IN THE FIRST CLICK POSITION.

OBSERVE THE BATTERY INDICATOR AND MAKE SURE THAT NEEDLE IS

IN THE GREEN PORTION OF THE SCALE - IF NOT, CHANGE BATTERIES.

THE OUTPUT OF MICROPHONE PRE AMP/POWER SUPPLY SHOULD BE CONNECTED TO
THE NEUTRIK INPUT. (SEE FIG. 3.2)

SET UP NEUTRIK AS FOLLOWS:

PAPER SPEED - 3 mm/s FOR RESPONSE CURVES
PLOT MODE/SINGLE
INPUT IMPEDANCE/GOO
INPUT/UNBALANCED
INPUT RANGE/-20db OR -40db
VERNIER/CALIBRATE
0 db REFERENCE/DBM (0.775V)
HP FILTER/--- (FLAT)
DISPLAY SCALE/50db
WRITING SPEED -- 20 mm/s FOR RESPONSE CURVES
OUTPUT RANGE/ANYWHERE FROM - 20db TO -l0db DEPENDING ON WHAT IS TO BE
MEASURED: MOST LIKELY SETTING IS -l0db.
VERNIER/WHATEVER ADJUSTMENT FOR LEVEL DESIRED AT

SPEAKER INPUT TERMINALS.
0 db Ref/DBM (0.775V)
MUTE/ON OR OFF (ON SOUND OUT, OFF NO SOUND)
START FREQUENCY/WHATEVER YOU WANT FOR FREQUENCY OUTPUT TO START. AT, BUT
SHOULD BE 20Hz FOR TEST.
SWEEP FUNCTION/CONTINUOUS WARBLE 1/3 Oct.

SET UP DVM AS FOLLOWS:

AC VOLTS
VOLTS
20 VOLT RANGE
RELATIVE OFF

CONNECT NEUTRIK OUTPUT TO POWER AMPLIFIER INPUT, CONNECT MICROPHONE OUTPUT
TO NEUTRIK INPUT. CONNECT POWER AMP OUTPUT TO WOOFER INPUT ON SPEAKER.
(FIG,3 AND 3.2)

FREQUENCY CAN BE MEASURED AT THE OUTPUT OF THE NEUTRIK AND THE VOLTAGE CAN
BE MEASURED AT THE OUTPUT OF THE AMPLIFIER OR THE INPUT TO THE SPEAKER
WHICH EVER IS EASIER TO DO.

NOTE: CONNECT POWER AMP OUTPUT TO WOOFER TERMINALS ON SPEAKER.

FIGURE No.3

TEST A EQUIPMENT CONFIGURATION

STARTING OUT WITH THE NEUTRIK IN THE LOWEST FREQUENCY OUTPUT (20 Hz) AND
THE MICROPHONE POSITIONED AT THE BOTTOMMOST MARK, APPLY AN AUDIO SIGNAL TO
THE SPEAKER. MEASURE WITH THE DVM AN OUTPUT LEVEL OF 2.3 VOLTS A.C. AT THE
TERMINALS OF THE SPEAKER. THIS IS NOT A CRITICAL VOLTAGE; IT'S JUST A LEVEL
THAT WILL GIVE A WORKABLE AMOUNT OF SOUND OUTPUT FROM THE SPEAKER.

ON THE STRAIGHT SIDE OF THE SPEAKER THERE ARE A NUMBER OF HEX HEAD SCREWS
SET INTO HOLES (THIS IS THE EDGE OF THE SPEAKER). THESE ARE THE ONES THAT
ARE TIGHTENED OR LOOSENED TO MAKE THE RESPONSE THAT IS WANTED.

THIS BASIC PROCEDURE IS REPEATED FOR EACH MARK; TOP, MIDDLE AND BOTTOM.

IN TUNING THE SPEAKER, WE ARE AIMING AT HAVING THE BOTTOM PEAK IN AMPLITUDE
AT THE LOWEST FREQUENCY, THE MIDDLE THE NEXT HIGHEST FREQUENCY, AND THE TOP
AT THE HIGHEST FREQUENCY, THE BOTTOM SHOULD BE 33Hz TO 37Hz. THE MIDDLE
SHOULD BE 38Hz TO 42Hz AND THE TOP SHOULD BE 43Hz TO 47Hz.

TO PERFORM THE TUNING PROCEDURE WITH MICROPHONE IN THE POSITION PREVIOUSLY
STATED, PUSH THE START. ALLOW THE NEUTRIK TO GO TO ABOUT 100Hz OR SO.
YOU CAN THEN EITHER PRESS FAST FORWARD OR STOP. YOU WILL SEE THE AMPLITUDE
TRACE FROM A LOW AMPLITUDE TO A PEAK AND THEN FALL OFF AGAIN TO A LOWER
AMPLITUDE.

THE POINT WHERE THE AMPLITUDE DISPLAY PEAKS IS THE RESONANCE FREQUENCY.
THIS IS THE POINT YOU ADJUST WITH THE SCREWS ON THE SPEAKER TO CHANGE IT'S
FREQUENCY. THE BOTTOM SCREWS ARE FOR THE LOWER PART OF THE SPEAKER AND THE
MIDDLE SCREWS FOR THE MIDDLE PORTION OF THE SPEAKER AND SO ON. CARE MUST BE
TAKEN NOT TO TIGHTEN THE TENSIONING SCREWS TOO MUCH. BY NO MEANS SHOULD YOU
TURN IN THE SCREWS SO MUCH THAT YOU COMPRESS THE SPRING COMPLETELY.

RESONANCE TEST - TEST "B"

EQUIPMENT REQUIRED
(1)DVM
(3)NEUTRIK
(4)POWER AMP (PRE AMP)
(5)FREQUENCY COUNTER
(6)MICROPHONE/POWER SUPPLY
(7)CONNECTING WIRE
(10)OSCILLOSCOPE

BEFORE THIS TEST CAN BE PERFORMED, THE WOOFER MUST BE TUNED AND AN MRT
MATED TO IT.

SPEAKER SHOULD BE IN THE GENERAL LOCATION OF THE NORMAL, OPERATING POSITION
IN THE ROOM.

MICROPHONE SHOULD BE PLACED CLOSE TO THE SPEAKER AS IN TEST "A". SETTING UP
THE MICROPHONE CLOSE TO SPEAKER, SAME PRECAUTIONS TO APPLY.

THE MICROPHONE SHOULD BE POSITIONED IN THE CENTER OF THE WOOFER.

INTER CONNECT EQUIPMENT

SET UP OF NEUTRIK:

MAINFRAME:
PAPER SPEED/0.3mm/S, PLOT MODE/SINGLE
INPUT MODILE:
INPUT IMPEDANCE/600Ω, INPUT/UNBALANCED
INPUT RANGE/-20db or -10db (USE ENOUGH GAIN TO PLACE DISPLAY ON GRAPH
PAPER)
VERNIER/CALIBRATE
0db REFERENCE/DBM (0.775v)
HP FILTER/ - (FLAT)
DISPLAY SCALE/50db
WRITING SPEED/20mm/S
OUTPUT MODULE:
OUTPUT RANGE/ -10db to 0db (DEPENDS ON THE GAIN OF
AMP/PRE AMP)
VERNIER/POSITION DEPENDS ON GAIN OF PRE AMP/AMP AND VOLTAGE DESIRED AT
OUTPUT OF AMP.
START FREQUENCY/300Hz
SWEEP FUNCTION/CONTINOUS SINE NO WARBLE

SET UP OF FREQUENCY COUNTER

SELECT Hz
FILTER IN
POWER ON

SET UP OF OSCILLOSCOPE:

SET DISPLAY SO THAT YOU JUST ABOUT FILL THE SCREEN ON THE LARGEST RECEIVED
SIGNAL FROM THE MICROPHONE AND THAT YOU CAN OBSERVE 4 OR 5 COMPLETE CYCLES
OR THE WAVE SHAPES.

BE CERTAIN THAT NEUTRIK IS ON MUTE. (TURN ON NEUTRIK, POWER AMP,
OSCILLOSCOPE MICROPHONE (ONE CLICK FROM OFF). WHEN YOU TURN NEUTRIK OUTPUT
ON (MUTE OFF) ADJUST VERNIER OUT AND/OR OUTPUT RANGE TO PRODUCE 2.3 VOLTS
A.C. AT SPEAKER TERMINALS OR AMPLIFIER OUTPUT.

NOTE: FOLLOW SAME SPEAKER WIRING PROCEDURES THAT ARE SET OUT IN THE "C"
TEST (RESPONSE 1 METER).

YOU SHOULD HAVE SOUND COMING FROM THE SPEAKER AND 2.3 VOLTS REGISTERING ON
THE DVM.

YOU CAN NOW START NEUTRIK (TRACE SHOULD START AT 300 Hz)LET THE NEUTRIK
RECORD OUTPUT UNTIL YOU HAVE PASSED 500 Hz DISPLAY ON FREQUENCY COUNTER.
YOU CAN NOW STOP OR FAST FORWARD THE PAPER OUT OF THE MACHINE. YOUWILL HAVE
TO LOOK AT THE TRACING PRODUCED AND THE: OSCILLOSCOPE DURING THE TIME THAT
THE NEUTRIK IS GLIDING THROUGH THE FREQUENCY RANGE. WHAT YOU ARE LOOKING
FOR IS A DIP OR PEAK IN THE TRACE PRODUCED BY THE NEUTRIK AND/OR A
DISTORTION OF THE WAVE SHAPE DISPLAYED ON THE OSCILLOSCOPE.

DURING THIS TIME YOU SHOULD ALSO HAVE AN "EAR" LISTENING TO THE SOUND
PRODUCED. IT MAY SOUND CLEAN (NO DISTORTION) "RASPY" OR HAVE A "WHA WHA"
SOUND TO IT. YOU SHOULD TRY TO NOTE WHAT FREQUENCY THESE LAST TWO SOUNDS
OCCUR AT SO YOU CAN "GO BACK" TO IT AND MAKE FURTHER DETERMINATIONS AS TO
THE SERIOUSNESS OF IT.
YOU MAY NOT HEAR ANYTHING DURING THE FREQUENCY SWEEP BUT YOU MAY SEE A
DISTORTION ON THE OSCILLOSCOPE. THIS FREQUENCY SHOULD BE NOTED FOR THE SAME
REASONS AS ABOVE. THIRDLY, YOU WILL OBSERVE ON THE GRAPH PRODUCED BY THE
NEUTRIK SOME LEVELS OF OUTPUT WHICH ARE MARKEDLY HIGHER OR LOWER THAN THE
AVERAGE OF THE REST OF THE TRACE. ALL OF THESE CONDITIONS ARE POSSIBLE
RESONANCE PROBLEMS. THE CHANCES ARE THAT MOST OF THE INDICATORS NOTED WILL
BE THE SAME FREQUENCY OR VERY CLOSE TO EITHER. THE BEST ONES TO START AT
ARE THE ONES ON THE NEUTRIK TRACE. THE INDICATIONS WHICH GO BELOW THE
AVERAGE ARE THE ONES MOST LIKELY TO CAUSE PROBLEMS.

WITH THE NEUTRIK IN THE "REST" MODE YOU CAN CONTROL THE OUTPUT FREQUENCY BY
THE FREQUENCY START KNOB. TURN THE KNOB UNTIL THE FREQUENCY METER READS THE
SAME AS THE "NOTED" FREQUENCY. AT THIS TIME YOU SHOULD OBSERVE THE
OSCILLOSCOPE TRACE LOOK AT WAVE SHAPE AND CHECK TO SEE DISTORTION. YOU MAY
HAVE TO "HUNT" WITH THE FREQUENCY KNOB TO SEE EFFECTS ON THE OSCILLOSCOPE.
IF YOU SEE ANY DISTORTION OR AN ABRUPT CHANGE IN LEVEL. SEE IF YOU CAN
INDUCE A "WHA WHA" FROM THE SPEAKER BY INCREASING THE OUTPUT LEVEL OF THE
AMPLIFIER (TURN UP THE VOLUME). DO NOT GO ABOVE 20 VOLTS INPUT TO THE
SPEAKER. IF IT DOES GO INTO THE "WHA WHA" MODE DETERMINE THE LOWEST VOLTAGE
INPUT THAT MAKES IT "GO". YOU MAY HAVE TO "HUNT" AROUND WITH THE FREQUENCY
KNOB SOME MINOR AMOUNT TO GET THE ABSOLUTE LOWEST VOLTAGE. A SPEAKER MAY
HAVE MORE THAN ONE RESONATE POINT AND A DIFFERENT VOLTAGE FREQUENCY ET
CETERA.
A SEPARATION OF 1 OR 2 Hz IS PROBABLY THE SAME POINT. ANYTHING MORE THAN A
FEW Hz SEPARATION IS PROBABLY A NEW POINT.

NOTE: NOT ALL INDICATIONS WILL RESULT IN A "WHA WHA" SO USE DISCRETION WHEN
INVESTIGATING THESE POINTS. DON’T SPEND A LOT OF TIME ON EACH POINT.
THE DEPTH OF TRACE ANOMALY OR SEVERITY OF DISTORTION IS DIRECTLY RELATED TO
THE PROBABILITY OF FINDING A POINT AT WHICH THE SPEAKER "BREAKS UP”

RECORD THE LEVEL (VOLTS) AND THE FREQUENCY AT WHICH YOU COULD MAKE IT
"BREAK UP" ON THE NEUTRIK GRAPH PAPER. A PASSABLE OR ACCEPTABLE LOWEST
VOLTAGE IS 11 VOLTS.