Instructions for System 2000 Polarity Chec ker
with Auto-Off Circuitry
Description: The Polarity Checker is a small hand-held
audio testing tool. It is powered by a 9-volt battery and
designed to determine the direction of cone movement
of a dynamic loudspeaker. The device features an internal microphone, a red LED, a green LED and a push-on
switch. A very low current circuit automatically turns
the Polarity Checker off after approximately five minutes of non-use.
Specialized Polarity pulses are provided on a test CD
that accompanies this device. The recorded pulses and
the hand-held detector feature a unique method of
self-authentication whereby the system actually checks
itself to insure proper readings. No other polarity checker
has this feature. This means that the Polarity Checker is
highly accurate, extremely reliable and very suitable
for hobbyists, audiophiles, car audio dealers, home audio listeners, studio and recording system engineers, and
pro-audio contractors
Background: When more than one speaker is used in a
system, it is important that the direction of cone movement of each and every speaker be the same. Any
speaker moving opposite to the rest will detract from
the effect in a manner not at all unlike a single boat
rower pulling opposite of the majority. Next, consider
the boat as a system with two rowers pulling when ten
rowers are pushing It is obvious that the boat will function much better with all twelve rowers pulling and pushing together.
Natural sound travels in chain-reaction type waves made
up of high-pressure and low-pressure fronts. In nature,
all sound waves emanating from a free radiating source
travel in the same direction - out and away from that
source.
INSTRUCTION MANUAL
electrical polarity. In most cases, a red dot or a + sign is
placed on or near the terminal of the voice coil known
as the positive terminal. By default, the other terminal
is known as the negative terminal. When a DC potential is applied to the voice coil so that the positive voice
coil terminal is connected to the + potential and the
negative voice coil terminal is connected to the potential, the cone of the speaker usually moves out and away
from the basket and magnet structure. However, this is
not always the case because some speaker manufacturers choose to label their terminals otherwise.
Another problem is that, due to phase shift the output of
a Passive crossover is delayed with respect to the input
at certain frequencies. The amount of delay depends on
the order of the filter network. For instance, the output
of a second order crossover (12 dB/octave) is shifted by
180 degrees near the crossover frequency. Some crossover manufacturers and some enclosed speaker manufacturers choose to reverse the electrical polarity of the
crossover’s output to minimize this effect Other manufacturers choose not to reverse the output. This means
that the end user of pre-assembled or “home-brew” passive crossovers cannot be sure of the final polarity without actually testing the system.
Many cars and homes are pre-wired for sound systems.
Making sure of the wire polarity can be a tedious task.
With car audio, removing factory door panels or lifting
a dashboard can be a difficult task. For these reasons,
we have seen many car audio systems with two or more
speakers working against the rest of the system. With
woofers, this problem manifests itself as a tremendous
lack of bass. With midrange and higher frequency speakers, the problem leads to flaws in the staging and overall poor performance.
A dynamic loudspeaker is a two terminal device that
features a voice coil of wire placed in a permanent
magnetic hole. The voice coil is fastened to a rigid
speaker cone that is capable of moving in only two directions, forwards and backwards. Basic physics tells us
that when an electric current flows in the voice coil, the
coil will either be pulled into the magnet or pushed away
from the magnet. The determining factor for the direction of coil (and cone) movement is the polarity of the
electric current flowing in the windings. T his means that
simply reversing the direction of current (polarity) will
reverse the direction of cone movement.
The Problem: When speakers are manufactured the voice
coil terminals are usually marked with respect to their
Contemporary car audio Often features OEM upgrades
and that typically leads to the use of devices known as
Line Output Converters, Floating Ground Adapters, and
Ground Loop Isolators. The problem here is that man y of
these inexpensive devices invert the audio signal. This
means that a positive signal entering the device becomes
a negative signal at the output. Likewise, there are many
active electronic components that invert the signal.
Although not necessarily a problem for that individual
component as soon as that component is added to a
system, the amplifiers and speakers fed by this component will be out of polarity with the rest of the system.
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SYSTEM 2000 POLARITY CHECKER
Many components cause a polarity inversion in the signal Power amplifiers are r arely specified for this attribute,
yet it can cause difficulty in multiple amplifier systems.
Large commercial systems that use hundreds of speakers and complex wiring schema can be easily checked
in minutes instead of hours aging the Polarity Checker.
Visibly checking speaker polarity with a small flashlight battery accomplishes little except verifying the
factory labels on the voice coil terminals. Proper polar ity verification requires checking the speaker wires, the
amplifier, the equalizer all the way to the deck.
Familiarization: T he operator should be familiar with the
Checker before testing systems. First you’ll need to place
a 9-volt battery inside your Polarity Checker and then
you’ll need a quiet room to make some tests. To understand the concept of speaker polarity, place the Polarity
Checker on a table or counter top with the Polarity
Checker’s microphone end slightly protruding over one
edge. Press the centered “on” button and notice that the
green and/or red LEDs may blink. If the LEDs are blinking, it means that the microphone is picking up too much
ambient noise to make valid measurements. Find a quieter location.
that the sound energy is insufficient to measure polarity .
Although you can slam the book harder to force the LEDs
to light, reflections from the floor , walls, tables and y our
body will begin to affect the measurements. It is best to
keep the microphone very close to the flat object and/or
the speaker’s cone.
Set the Polarity Checker do wn or the table and sing into
the microphone until the LEDs stop blinking. Notice
that approximately 5 minutes time has elapsed. This is
how the auto-off circuitry works.
Checking Polarity: Place the test software into a CD
player, set the repeat track and then use the balance
and fader controls so that only one speaker is playing at
a time. It is always best to test one speaker at a time.
The polarity pulses on the test softw are are recorded with
two consecutive positive pulses immediately followed
by a single, equal but opposite negative pulse. The software actually creates the electrical equivalent of the
book’s positive and negative directions of travel. The
timing and duration of the specially recorded pulses
makes it possible for the Polarity Checker to actually
checks itself so as to accurately verify its readings. Following is the order of the recorded software pulses:
Obtain a small flat object such as a book, magazine,
CD case, or a plate. Using one hand, hold the book
about 1 foot away from, and directly in front of, the
Polarity Checker’s microphone. Make sure that the Polarity checker’s microphone is the closest thing to the
book so that reflections will not be entering into this
test. With your other hand, sharply tap the book towards
the Polarity Checker’s microphone. T he green LED should
light. When the flat surface moves towards the microphone, we call it a positive direction of travel. Try this
experiment again and notice that each time you tap the
book toward the microphone the green LED lights, indicating that the Polarity Checker recei ved a positive pulse
from the book.
Now, tap the book away from the microphone, notice
that the red LED lights each time the book is tapped
away from the Polarity Checker’s microphone. When
the book moves away from the Polarity Checker’s microphone, we call it a negative direction of travel. Repeat the experiment and notice that each time the book
is tapped away from the microphone, the red LED lights,
indicating that the Polarity Checker received a negative pulse from the book.
Green Green Red
Green Green Red etc.
With that single speaker playing the test software, position the microphone of your activated Polarity Checker
directly in front of the speaker’s cone. Be sure to stay
away from ports, passive radiators, and reflective surfaces. Adjust the volume of the speaker until the LEDs
on the Polarity Checker synchronously blink with the
sound of the pulses- Notice that you cannot easily hear
the difference in polarity, but the Polarity Checker’s circuitry measures the difference. Watch the pattern repeat over and over.
Let’s say that your Polarity Checker’s LED’s are blinking
Red Red Green. Well, from your familiarization session,
the reason for the reversed pattern is that your sound
system is reproducing the exact opposite of the worded
pulses. Actually your system is creating a mirror image
reproduction of all software not just our test CD. We’ll
talk more about this later. The important aspect of this
test is the repeatable pattern of either Green Green Red,
indicating a faithful reproduction of the software or Red
Red Green, indicating a mirror image reproduction
Move the book out farther aw ay from the P olarity Checker
and repeat the experiment. Notice that as you get four
or more feet awa y, the LEDs no longer light. T his means
2
If the LEDs are blinking randomly or all Red or all Green,
then something is wrong with either the sound system,
the Polarity Checker, or the way in which you are per-
INSTRUCTION MANUAL
forming the measurements. Re-read the instructions. Install a fresh 9-volt battery, get out your flat book and
check out the Polarity Checker’s readings, and repeat
this section. Remember that the environment must be
quiet and the Polarity Checker must receive the most
direct energy from the speaker - no reflections!
Relative P olarity: When all the speakers in a system are
working together, we can say that the system is in relative polarity, This means that if all your speakers tested
either Green Green Red or Red Red Green, then your
system is in relative polarity. Congratulations. If one or
more of your speakers tests opposite to the rest, simply
reverse the wires on the speaker terminals and recheck
the system.
Absolute Polarity: When all the speakers in a System
are working together and the Polarity Chec ker indicates
the Green Green Red pattern, then your system is said to
be in absolute polarity with the software. This means
that a positive pulse on the software ends up in your
listening room as a positive pulse. With many
non-symmetrical waveforms - particularly male vocals,
trumpets, clarinets, etc., - there can be a perceived difference in the acoustic reproduction of the sound. Systems in absolute polarity tend to be more natural sounding.
Summary: Insuring at least relative system polarity is
one of the mat basic of audio tests. However, it has
been our experience that such a simple test is often over looked. Old methods utilized pulse generators, microphones, and oscilloscopes. The Polarity Checking system makes it possible to quickly and accurately get your
system into absolute polarity - from the software to the
listening environment.
CD Reference Material with most commonly Used CD
Tracks:
1 Polarity Pulses
These pulses are wide enough in duration to enable them
to be used with most makes of polarity checking devices. The pulses have been sequenced so as to eliminate invalid readings. A single negative pulse follows
each group of two positive pulses. The sequence is repeated for five minutes. The third pulse in each group
must show opposite polarity in order for the reading to
be considered valid.
2 20Hz to 20KHz Slow Sweep
This track contains a very flat low distortion 20-20kHz
sweep for testing the frequency response of electronic
components. It is not intended for acoustical evalua-
tions where reflections or standing waves may cause
interference. Such acoustical measurements are better
done with warble sweeps or noise tracks.
3 20 Hz to 20M Fast Sweep
Identical to track 2 except that the sweep occurs faster
This will result in less time for the measurement.
4 20Hz to 20kHz Pink Noise
Correlated pink noise. (The exact same noise information in each channel.)
5 200Hz to 5kHz Pink Noise
Correlated, band limited pink noise.
200Hz to 5kHz.
6 1 kHz @ Digital Zero
The tone represents the highest level signal that can be
recorded in the CD medium. This maximum signal is
useful for checking the output level of the other devices
interfaced to the CD player as well as for optimizing the
overall gain structure of a complete system.
7 Voice Counting
This is a recording of a person simply counting from 1 to
25. Although it maybe normal for some of us to evaluate
system by listening to musical instruments, others may
experience difficulty . W e all know what a person sounds
like. Although you may not know the person doing the
counting, your system should lead you to believe that
that he is real and in the room with you. Even though
the bandwidth of a human voice is not as wide as some
instruments, you’ll find that vocal realism is not trivial.
Choice of microphone type can certainly effect a demo
such as this. In order to minimise coloration, we used a
B & K instrumentation microphone placed close to the
announcer in a very diffuse room. The omni-pattern
helped minimize proximity effect. A great use for this
track is in systems designed to cover large areas such as
sound reinforcement systems, PA systems, etc. By putting this track on repeat and playing it as you walk around
the room, information regarding the evenness of coverage and the intelligibility of the speech can easily be
evaluated.
8-17 Acoustic Quick Check
The following tracks are intended for an evaluation of
the acoustical response of both headphones and loudspeakers Although the signals are sine waves, they have
been warbled and standing waves that would otherwise
occur with pure sine waves. Each track starts with a 1
kHz reference tone with a duration of one second. The
warble lasts for three seconds. In an ideal system, all of
the multi-frequency warbles should match the 1kHz
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SYSTEM 2000 POLARITY CHECKER
warbles in loudness. The complete sequence will allow
a generalized evaluation in less than 43 seconds. The
sequence is track 8: 20Hz, track 9: 62Hz, track 10:
125Hz, track 11: 250Hz, track 12: 500Hz, track 13:
2.5kHz, track 14: 5kHz, track 15: 10kHz, track 16:
15kHz, track 17: 19kHz.
18 Sound Stage Description
This track contains a recording of three people describing their location within the sound stageIf your system
==fulfill the descriptions defined by the voices then your
system is not reproducing a correct stereo image.
19 Sound Stage Description
This mad contains the same information as track 18
except that all three people are talking simultaneously. Just as if three people were talking at once,
your system should rot mix them together. Y ou should
be able to understand each individual and concentrate
on what each individual is saying while mentally
tuning out the other two announcers. This is a particularly difficult test for a sound system but is very
revealing. If you are unsure as to how well your
system handles this track, try comparing the real
thing. Have three friends stand across the front of your
listening room and repeat this test for yourself.
20-21 Percussion L-C-R
This track is used for evaluation of the Left, Center, and
Right balance and relative placement. The snare drum
beats should begin on the left side of the stage and
progress to the fight, with the fourth beat being center
stage.
22 Subwoofer Test
This trac k is a warble from 100Hz to 23W for the quick
subjective evaluation of subwoofer systems. Response
on a good system should be strong down to the lowest
frequencies (20Hz) which occur at the end of this track.
23 “Stranger In My Bed”
UPFRONT • The Po wer of Seven (10033-2-F)
You should be able to define many different levels of
percussion intermingled with the keyboard work. Note
the cowbells just behind and below the vocals at all
times. Listen to the back-up vocals as they sing “I got
trouble...” at 1:17 can you pick out all 6 voices? Remember all these vocals and different instruments were
recorded in real time - your system should deliver some
pretty intense SPL readings, so listen carefully!
24 “Dish Rag”
GOT THE MUSIC IN ME
THELMA HOUSTON & PRESSURE COOKER (I0002-2-M)
The 1975 original direct disc LP version of this project
sold more then a quarter million copies before exhausting the masters, and is widely credited with starting the
entire audiophile recording industry. During the opening 30 seconds notice how well you can distinguish the
individual voices of the two keyboards. Then notice the
vertical lift in the entire sound as the horns come in over
the keys. Can you bear the tambourine (panned far left)
from :29 to :42? See if your system does a good job of
property staging the trumpets (predominantly in the left
channel, e.g. 1:13), with the “fat” lower sound of the
trombone on the right (reference the trombone solo at
1:29)
25 “Dance Of The Knights- from Prokofiev’s Romeo &
Juliet THE LIENSDORF SESSIONS, VOL. 1 (10043-2-G)
Los Angeles Philharmonic, Erich Leinsdorf conducting.
Recorded at the legendary MGM Sound Stage One. You
should be able to recreate the orchestra sitting in a
semi-circle around you: the concert grand in the upper
left corner of the stage. The Violins and cellos in front
followed by the woodwinds further up towards the back
of the stage and on a higher elevation and in the very
back rows, the trombones, and percussion (including the
massive timpani drums) Notice in the first 20 seconds
how the sound “seesaws” front to back between the violins and cellos. Beginning at 8:27, in the upper left corner of the stage, notice the sharpness of the tight drum
rolls, punctuated by the raspy horns and strings.
26 “Dirty Blue” THE NAME IS MAKOWICZ
ADAM MAKO WICZ WITH PHIL WOODS
(10021 -2-V)
Notice the presence of the vibes even with the busy and
intricate piano work. Listen in the transition between
notes 1:07, as sax legend Phil Woods bites down and
charges the sound of the note. At to end of the track,
Woods steps back and swings around, points the horn
upstage and center to guide the band out.
27 “Wishing Well”
SPEAKING IN MELODIES
MICHAEL RUFF (10035-2-F)
Here’ s w hat Sheffield chairman and mastering engineer,
Doug Sax, has to say about the track: “Sheffield’s own
pre-amps and line level mics really shine through. Notice the clarity of the piano, the natural but extended
cymbals, the clarity and warmth of the vocals. Notice
the astonishing percussion presence, without artifact, a
combination of Coles ribbon mics into GML
transformerless pre-amp. I am extremely proud of the
sound we achieved on this project.”
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INSTRUCTION MANUAL
28 “Dock Of The Bay”
MA YORGA &
DISTINGUISHED COLLEAGUES,
VOL. III (10001-2-V)
This was actually a bonus track on the CD version:
During rehearsals for the original direct disc recording
sessions, the dynamics of Jim Keltner’s kick drum were
so extreme that groove excursions from the cutting
lathe became too wide to fit on the album side. The
song had to be eliminated! What you hear on this
track is an actual take with the band beginning to
block out parts and solos. When the guitar comes in at
:57 with fairly equal force in both channels, you
should really get a tremendous sense of stereo separation and “liveness” around the instruments. At 1:33 the
horn comes in on the right channel; if you are listening in your car, the hornplayer sounds like he is sitting
right about on top of your glove box. Notice the
somewhat crude-sounding fade at the end of the cut.
When recording in 1973, they mixed with fader knobs
the size of your steering wheel!
Channel Identification Tracks
This test CD also contains several audio tr acks for locating and identifying the separate channels in home theatre systems These tracks have been encoded for the
popular matrix systems used in film (or video) multichannel soundtracks. Track 29 through 33 are encoded
for 4 channel matrix systems. Tracks 34 through 39 are
coded for “Circle Surround” 5 channel matrix systems.
Each channel is announced and the sound should appear on the same speaker that is identified by the announcer . A tone will follo w each announcement to help
identify the channel.
37 Right Stage Speaker
38 Left Surround Channel
39 Right Surround Channel
29 4 Channel SurroundAnnouncement 40Hz Tone
30 Left Stage Speaker
31 Center Stage Speaker
32 Right Stage Speaker
33 Surround Channel
34 5 Channel Circle Surround Announcement 40Hz
tone
35 Left Stage Speaker
36 Center Stage Speaker
5
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