How to test speaker polarity?

I had a long suspicion that my Mach 460 stereo (2K GT) might not be
properly wired to the speakers. It seems like a major pain to remove
the covers and look at the wiring. Is there a test CD that can be used
to verify polarity?
My issues are mainly with missing or muted instrument tracks on songs I
know pretty well. Someone has suggested that if the speakers were not
wired correctly, this type of filtering may occur.
Thanks
ROn

wrote:

> I had a long suspicion that my Mach 460 stereo (2K GT) might not be
> properly wired to the speakers. It seems like a major pain to remove
> the covers and look at the wiring. Is there a test CD that can be used
> to verify polarity?

Whether it's the best idea or not, the trick I read in a really old Radio
Shack (so consider the source) book on speakers was to hook up a very small
battery, something no bigger than AA size, to the wires of the speaker
and note the direction in which the cone travels. If it moves out, the
polarity is correct. If it moves in, it is reversed. You can then mark
the leads accordingly. The book also cautioned to do this VERY briefly,
not for any extended period of time at all. Basically, just a fraction of
a second to see what direction the cone moves. Any longer than that can
supposedly damage the speaker.

Again, it was a Radio Shack suggestion, but in theory it seems valid. I'm
sure others will chime in about it, although if someone does have an
argument against it I'd like to hear an actual bit of evidence as to why
as proof. Something like a comparison of voltages, amperages, and duration
against what a normal amplifier produces, etc. It's not like the things
are made out of butterfly wings and are so delicate that a quick spike of
that sort would kill them. Still, solid evidence in one direction or the
other would help resolve my perpetual query as to whether or not it really
is a truly bad idea or it it's actually a pretty good one.

wrote:

> I had a long suspicion that my Mach 460 stereo (2K GT) might not be
> properly wired to the speakers. It seems like a major pain to remove
> the covers and look at the wiring. Is there a test CD that can be used
> to verify polarity?
> My issues are mainly with missing or muted instrument tracks on songs I
> know pretty well. Someone has suggested that if the speakers were not
> wired correctly, this type of filtering may occur.
> Thanks
> ROn
>

You are correct that there will be a cancelling effect of sorts,
although I've never noticed it personally.

Check to see if the speakers are labeled for polarity, and then tune to
an FM frequency with just steady static, at a nominally loud level, and
check with an analog voltmeter(set to under 10 volts scale) to see that
each speaker is receiving the same polarity. The terminal brackets, and
the cones/coil wires, should both be marked in some fashion as to polarity.

Ideally, it would be grand if the speaker expresses (pushes out) with
higher positive input levels, but this can be very hard to discern.

On a sort of related note, good friend of mine from high school
frequently drove his father's 1976 Grand Marquis... a real boat for
sure... and fairly anemic at that weight with a smog-era 400M V-8 2bbl.
His father insisted the factory stereo was wired backwards by F-L-M,
as the strings were on the "wrong side" in the orchestral numbers he was
tuning in to. I couldn't convince them that the perceived switch L-to-R
could have been anywhere from the mics, the board(s), mixing, mastering,
or radio station source, board, pre-amp, EQ..., ... well you get the idea.

Another simple explanation could be that the system is not set up with
band equalization as you are familiar with, resulting in the different
sound reproduction.

Rob

> wrote in message
ups.com...
> I had a long suspicion that my Mach 460 stereo (2K GT) might not be
> properly wired to the speakers. It seems like a major pain to remove
> the covers and look at the wiring. Is there a test CD that can be used
> to verify polarity?
> My issues are mainly with missing or muted instrument tracks on songs I
> know pretty well. Someone has suggested that if the speakers were not
> wired correctly, this type of filtering may occur.
> Thanks
> ROn
>

The 1.5V battery test (mentioned in another reply) is the best way. However,
if you can't get to, and separate the speakers from the amp, then the
easiest way is to get a cd that has monaural music/vocals on it. Play it,
then get your head exactly between the left and right speakers. If the sound
seems to be coming from the middle of your head then the speaker polarity is
correct. If the sound is spread out -- sounding like it's coming from the
left and from the right, then (most likely) the speakers are out-of-phase
with each other.

Bob
'03 Cobra coupe

"Joe" > wrote in message
...
> "Bob" > wrote in
> hlink.net:
>
> >
> > > wrote in message
> > ups.com...
> >> I had a long suspicion that my Mach 460 stereo (2K GT) might not be
> >> properly wired to the speakers. It seems like a major pain to
> >> remove the covers and look at the wiring. Is there a test CD that
> >> can be used to verify polarity?
> >> My issues are mainly with missing or muted instrument tracks on
> >> songs I know pretty well. Someone has suggested that if the
> >> speakers were not wired correctly, this type of filtering may
> >> occur. Thanks
> >> ROn
> >>
> >
> > The 1.5V battery test (mentioned in another reply) is the best way.
> > However, if you can't get to, and separate the speakers from the
> > amp, then the easiest way is to get a cd that has monaural
> > music/vocals on it. Play it, then get your head exactly between the
> > left and right speakers. If the sound seems to be coming from the
> > middle of your head then the speaker polarity is correct. If the
> > sound is spread out -- sounding like it's coming from the left and
> > from the right, then (most likely) the speakers are out-of-phase
> > with each other.
> >
> > Bob
> > '03 Cobra coupe
>
> Additionally, you should do the same between front and rear. It's
> entirely possible to have the L + R fronts be in phase with each other
> and the L + R rears to be in phase with each other, but the front pair
> and rear pair to be out of phase with each other.
>
> Best way to check is with the 1.5 V battery, but you can always do
> what Bob described with the fader instead of the balance control.
> Position yourself sideways in the car (looking out the side window)
> directly between the front and rear speakers, then roll the balance to
> the side you're facing. Then perform Bob's test "sideways". HTH.
>
> Joe
> Calypso Green '93 5.0 LX AOD hatch with a few goodies
> Black '03 Dakota 5.9 R/T CC


Great points, Joe.

There is a test CD put out by Stereophile magazine. It has monaural tracks
that are in-phase, and the same stuff but out-of-phase. Using this type of
signal, it's really obvious if the speakers' phase is correct.

Bob

An interesting problem with the older Mustangs was that the ground returns
for the right and left front speakers were swapped. This caused a real
headache when wiring in a new head unit. The test for this you used the
aforementioned battery test and jumped across the speaker lead and its
return. If they were wired correctly you would hear a "scratchy" noise
coming from the speaker. If they were miss wired, as in my case, no sound
would be heard. To find the correct return you held one side of the battery
on the speaker lead you were testing and tried each return line in sequence
until you heard the noise.

Note, at some point in time the factory became aware of this problem and
"fixed it" by swapping the speaker power leads around. I found this out by
installing a newer factory amplified stereo into my older (and already
properly wrung out) factory stereo wiring. This caused the front balance
not to work, thinking it was the same old problem I swapped the ground wires
on the amplifiers output, which caused the right and left speakers to
switch, so I had to put the returns back where they were and swap the power
leads instead. So while you are doing your testing make sure the noise you
hear is coming from the correct side of the car.


"Joe" > wrote in message
...
> "Bob" > wrote in
> link.net:
>
> >
> > "Joe" > wrote in message
> > ...
> >> "Bob" > wrote in
> >> hlink.net:
> >>
> >> >
> >> > > wrote in message
> >> > ups.com...
> >> >> I had a long suspicion that my Mach 460 stereo (2K GT) might not
> >> >> be properly wired to the speakers. It seems like a major pain to
> >> >> remove the covers and look at the wiring. Is there a test CD
> >> >> that can be used to verify polarity?
> >> >> My issues are mainly with missing or muted instrument tracks on
> >> >> songs I know pretty well. Someone has suggested that if the
> >> >> speakers were not wired correctly, this type of filtering may
> >> >> occur. Thanks
> >> >> ROn
> >> >>
> >> >
> >> > The 1.5V battery test (mentioned in another reply) is the best
> >> > way. However, if you can't get to, and separate the speakers from
> >> > the amp, then the easiest way is to get a cd that has monaural
> >> > music/vocals on it. Play it, then get your head exactly between
> >> > the left and right speakers. If the sound seems to be coming from
> >> > the middle of your head then the speaker polarity is correct. If
> >> > the sound is spread out -- sounding like it's coming from the
> >> > left and from the right, then (most likely) the speakers are
> >> > out-of-phase with each other.
> >> >
> >> > Bob
> >> > '03 Cobra coupe
> >>
> >> Additionally, you should do the same between front and rear. It's
> >> entirely possible to have the L + R fronts be in phase with each
> >> other and the L + R rears to be in phase with each other, but the
> >> front pair and rear pair to be out of phase with each other.
> >>
> >> Best way to check is with the 1.5 V battery, but you can always do
> >> what Bob described with the fader instead of the balance control.
> >> Position yourself sideways in the car (looking out the side window)
> >> directly between the front and rear speakers, then roll the balance
> >> to the side you're facing. Then perform Bob's test "sideways".
> >> HTH.
> >>
> >> Joe
> >> Calypso Green '93 5.0 LX AOD hatch with a few goodies
> >> Black '03 Dakota 5.9 R/T CC
> >
> >
> > Great points, Joe.
> >
> > There is a test CD put out by Stereophile magazine. It has monaural
> > tracks that are in-phase, and the same stuff but out-of-phase. Using
> > this type of signal, it's really obvious if the speakers' phase is
> > correct.
> >
> > Bob
>
> That CD is a real good test source. However, for those looking for a
> mono source, good ol' AM radio works pretty well.
>
> Joe
> Calypso Green '93 5.0 LX AOD hatch with a few goodies
> Black '03 Dakota 5.9 R/T CC

This is the way to do it. Works perfectly.

LJH
95GT


"The Hurdy Gurdy Man" > wrote in message
news:4o%Ad.16194$2X6.14845@trnddc07...
> wrote:
>
> > I had a long suspicion that my Mach 460 stereo (2K GT) might not be
> > properly wired to the speakers. It seems like a major pain to remove
> > the covers and look at the wiring. Is there a test CD that can be used
> > to verify polarity?
>
> Whether it's the best idea or not, the trick I read in a really old Radio
> Shack (so consider the source) book on speakers was to hook up a very
small
> battery, something no bigger than AA size, to the wires of the speaker
> and note the direction in which the cone travels. If it moves out, the
> polarity is correct. If it moves in, it is reversed. You can then mark
> the leads accordingly. The book also cautioned to do this VERY briefly,
> not for any extended period of time at all. Basically, just a fraction of
> a second to see what direction the cone moves. Any longer than that can
> supposedly damage the speaker.
>
> Again, it was a Radio Shack suggestion, but in theory it seems valid. I'm
> sure others will chime in about it, although if someone does have an
> argument against it I'd like to hear an actual bit of evidence as to why
> as proof. Something like a comparison of voltages, amperages, and
duration
> against what a normal amplifier produces, etc. It's not like the things
> are made out of butterfly wings and are so delicate that a quick spike of
> that sort would kill them. Still, solid evidence in one direction or the
> other would help resolve my perpetual query as to whether or not it really
> is a truly bad idea or it it's actually a pretty good one.