[greenhorn]

Speaker wiring phase/polarity is one of the silent killers of a car stereo install. You install a car stereo, and it sounds fine, but over time, you find that it sounds weird, the bass reduces - and tweaking the settings don't really help.

Usually the culprit is the speaker phase. While done right at the ICE shop, the connections to the speakers are connected & disconnected multiple times during services, and mechanics really don't bother about speaker phase - all they care about is if the speaker is hooked up and working or not.

if one or more speakers are connected in the wrong polarity relative to the others, the sound can suffer. and you will not even know what is wrong. I usually do a quick diagnostic on those friends who are kind enough to let me mess around with their car HU settings, and for those of whom, the polarity is wrong, are usually surprised how much of a difference just swapping a pair of wires makes

so without further ado
http://www.audiocheck.net/audiotests_polaritycheck.php

listen to the various clips and figure out if you can spot the difference. If you can't spot the difference, You can ignore the rest of this guide - its not the end of the world, not everybody can hear every nuance of sound - I for one have not been able to figure out what this imagining business is which most audiophiles talk about, and even when i was demonstrated, i found it rather distracting. Familiarize yourself with how in phase and out of phase sounds on your headphone.

Back to the subject at hand, download the clips and play them on your car to spot the difference. My methodology (may not be the best, but it works for me) Will need a fair amount of setting your car HU settings
1. Set Fader to the front, so that you can hear only the front speakers. Play the in phase and out of phase sounds and make sure that the front speakers are in phase - with the correct phase, it should sound like the audio is coming from the middle of the dashboard. and the bass and mids should be more when playing the in phase track
2. Now that you have confirmed that the front speakers are in phase, the next step is another experiment - With the fader control sent to the front speakers only, change the balance from left to right and back. You will notice that the sound gradually increases and builds up, then progressively decreases as you move from left to right and vice versa. when the speakers are out of phase, you'll notice that the bass and mids are better when one speaker alone is playing, and the sound gets gradually thinner as you move from right to left. Also, the sound will sound as if it is coming from one speaker alone, until some point when it abruptly shits to the other speaker (when the speakers are in phase, the transition is gradual)

This is because when the speakers are out of phase, the speakers are effectively fighting each other to cancel each other out. It's like a tug of war. The winning speaker dominates, until you start moving the balance, and slowly the other one gets louder and louder, and at one point, it will suddenly shift the sound to its side. When the speakers are in phase, both are working together, so this issue does not happen.


Now the objective of this exercise is to figure out phase without using any special sound clips - once you figure this out, you can troubleshoot any speakers using just music.

Now, set the balance to Full right or full left (I would recommend right, as the differences are more pronounced), and start adjusting the fader forward and backward with the sound playing. if the speakers are wired correctly, then sound should build up gradually from front to back, If not, your rear speaker wiring needs to be reversed.

Once this is done. Set your fader to rear speakers only, and check the polarity of the back speakers. adjust the wiring as required.

Congratulations. Your speakers are all firing correctly!

Advanced phase -
1 Subwoofer - I have not been able to figure out this - It's more trial and error - Try both and settle for which sounds better for you
2 Component speakers - You can test component speakers by downloading test tones at high and low frequecies - the phase of one component may be wrong - generally the woofers - Happens if your woofer is fitted to the door pad like in some tata cars - and it is dismantled for working on the locks/power windows etc
3 Between the tweeter & woofer - this is tough, and hard to figure out by ear. I have no idea how only way I know is to actually check the wiring at the speakers and the crossovers

Thank you for your patience and good luck with the tuning

[navin]

Originally Posted by greenhorn

I for one have not been able to figure out what this imagining business is which most audiophiles talk about...

Advanced phase -
1 Subwoofer - I have not been able to figure out this - It's more trial and error - Try both and settle for which sounds better for you
2 Component speakers - You can test component speakers by downloading test tones at high and low frequecies - the phase of one component may be wrong - generally the woofers - Happens if your woofer is fitted to the door pad like in some tata cars - and it is dismantled for working on the locks/power windows etc
3 Between the tweeter & woofer - this is tough, and hard to figure out by ear. I have no idea how only way I know is to actually check the wiring at the speakers and the crossovers

Thank you for your patience and good luck with the tuning

Phase is relative. There is no way to hear absolute phase. The term "absolute phase" in my view is an oxymoron. It's like saying "smarter". Smarter than whom? Hope that clears the base concept of phase.

One way to test phase is to use a battery. This works for woofers and subwoofers (for car audio woofers are generally 4-6" and subwoofers 8-12"). If the +ve terminal of the battery is connected to the +ve terminal of the woofer the cone will move out and if the +ve terminal of the battery is connected to the -ve terminal of the woofer the cone will move in. This can allow you to ensure that your subwoofers and woofers are electrically in phase. However since your subwoofer is usually in the trunk and your woofer is generally in the front door (separated by distances of 1m or more) you may have to shift the phase of the subwoofer so that both woofer and subwoofer are acoustically in phase. I do this by ear. Using a piece of music I am familiar with I will have someone rotate the phase knob of the subwoofer amplifier till my ear tells me all is good. The best music for this is an isolated bass guitar that will cover the range from about 40Hz (Low E is 42hz) to 200hz. Stanley Clarke is a good option.

Testing the relative phase of a woofer and tweeter is a bit trickier. It involves understanding and recognizing overtones (since woofer-tweeter crossover frequencies are usually in the 2kHz+ range). Few instruments (pianos, violins, flutes, piccolos, etc.) have fundamental frequencies that go that high. You can refer to this chart, put up some time ago.
http://www.team-bhp.com/forum/car-en...struments.html

In any case other than a 180 phase shift few component speakers offer you an option to change the phase between the tweeter and woofer. If you are cursed enough to be troubled by this your best option is to get a DSP processor like the Audison Bit One, Alpine 800, RF 360.3, etc..

[drpullockaran]

Try this out in your free time. It might seem crude but this is what the professionals do when they do not have the sound calibration stuff working or lost in transit. Get a 9 volt rectangle box battery which outputs about 300 milliampere. Connect the positive of battery to the positive terminal of the speaker(red dot) and watch for the out movement of the speaker cone. All sub-woofer cones need to be moving out when connected in phase. For tweeters and mids the same rule applies. Tweeter movement though is very minuscule. Professionals though will calibrate with their electronic device.

I am extremely sensitive to sub-woofer and mid; phase out and get a severe head numbness and blunt pain and can instantly tell if the speakers are out of phase but as far as tweeters are concerned my ears are more forgiving.

I am no professional but used to design speakers 30 years ago.

Navin, sorry I just went through your post and you have mentioned the same thing.

[greenhorn]

One way to test phase is to use a battery. This works for woofers and subwoofers (for car audio woofers are generally 4-6" and subwoofers 8-12"). If the +ve terminal of the battery is connected to the +ve terminal of the woofer the cone will move out and if the +ve terminal of the battery is connected to the -ve terminal of the woofer the cone will move in. This can allow you to ensure that your subwoofers and woofers are electrically in phase.

When the drivers don't have the + and minus marked on them, that helps. in my case, the drivers are marked, but the wiring is a virtual birds nest with different sections connected and spliced together at different points. ( HU - > Stock speaker wiring up to dash, doors and rear) then add on wiring for the tweeter and add on wiring for the rear coaxes till the MDF Tray. Plus my comps come with split crossovers (seperate HPF and LPF), and I have jugaaded a mid in between the woofer and the tweeter, hence the confusion.

The wiring for the mids and the rears get disconnected almost every time there is a service, since one of my power windows is chronically ill, and the wheels need to be rotated = the MDF tray and sub needs to be taken out for convenience

[navin]

Originally Posted by greenhorn

in my case, the drivers are marked, but the wiring is a virtual birds nest with different sections connected and spliced together at different points.

If you are connecting wires it pays to do the following:

1. Add a heat shrink sleeve over the connection
2. Add RED/BLACK/BLUE/WHITE tubing over the heat shrink sleeve.

The heat shrink sleeve will ensure that the connection remains secure and does not short and the RED/BLACK/BLUE/WHITE tubing will ensure the wire for the FR/FL/RR/RL are easily traceable. The colour code is of my own creation (I created this some 30 odd years ago when I did my own installs). Something like this: http://www.aliexpress.com/item/5mm-T...713473443.html

For more complex wiring (like when I had to trace 20-30-100 connections) I use ferrules.

If you are frequently connecting and disconnecting a speaker, it might help to use a "SpeakOn" connector.
http://www.neutrik.com/en/speakon/

[ISO]

Battery method described above is the only reliable method of checking speaker phasing though it is not recommends for the tweeter.

Wrong phasing will only affect low bass frequency and not mid and high frequency.

[low_bass_makker]

Originally Posted by ISO

Wrong phasing will only affect low bass frequency and not mid and high frequency.

I disagree here. It affects the whole freq band. But the difference is more perceivable in lower freq.

[condor]

Can this problem happen due to a bad adapter (HU to Car's OE ) wiring kit ?

My ICE was not sounding good - pretty much as described by Greenie in Post #1. When I went to the installer saying I am not happy with the output, he swapped a couple of wires, and there seemed to be an improvement.

ICE setup is a HU + Components in front + CoAx in rear. No sub

[DerAlte]

Originally Posted by condor

Can this problem happen due to a bad adapter (HU to Car's OE ) wiring kit ? ...

It is unlikely that the installer made a mistake with the color coded wires. The usual mistake takes place at the speaker (mid-bass) terminals, if they are using wires without a stripe down one of the wires of the pair. In such case, the wiring guy simply connects without checking / maintaining phase relationship (+ from XO to + of the speaker). Good installers check first, and make a knot on the wire connected to the + terminal at the XO.

[keroo1099]

Originally Posted by drpullockaran

Try this out in your free time. It might seem crude but this is what the professionals do when they do not have the sound calibration stuff working or lost in transit. Get a 9 volt rectangle box battery which outputs about 300 milliampere. Connect the positive of battery to the positive terminal of the speaker(red dot) and watch for the out movement of the speaker cone. All sub-woofer cones need to be moving out when connected in phase. For tweeters and mids the same rule applies. Tweeter movement though is very minuscule. Professionals though will calibrate with their electronic device.

I am extremely sensitive to sub-woofer and mid; phase out and get a severe head numbness and blunt pain and can instantly tell if the speakers are out of phase but as far as tweeters are concerned my ears are more forgiving.

I am no professional but used to design speakers 30 years ago.

Navin, sorry I just went through your post and you have mentioned the same thing.

9V battery may be too much for some voice coils and you might just have it jump out of the magnet and end up cursing yourself. I find that a AA or AAA battery works just fine even for 12" drivers, and you only have to touch the terminals briefly.

I agree that this is the best method to check phase, and according to me it does make a huge difference to the sound. Comes from another casual speaker builder.

[gearbox]

OK, so i would like to pitch in here.

The output from a car stereo is NOT DC, but AC, i.e. a few mV, so the speakers are fed AC voltage, which is NOT polarity conscious.

Phase or out of Phase really matters when you have more than one speaker in one box, let's say a sound box, with more than one speaker, if those two speakers are wired out of phase, while one speaker' cone will tend to travel inward and the other would travel outward, creating an uneven pressure inside a (non ported) box, this will lead to unpleasant sound output, reason being, these cones due to their opposite movement will push air in a direction that will not let the other cone to move effortlessly, hence affecting some frequencies. An out of phase setup will only cancel the phase of the other speaker in a car situation, which may or may not affect the overall sound, depending on porting/space for the air to move behind the speaker.

[greenhorn]

Originally Posted by gearbox

An out of phase setup will only cancel the phase of the other speaker in a car situation, which may or may not affect the overall sound, depending on porting/space for the air to move behind the speaker.

um, speaker wired out of phase WILL impact the sound adversely
1. screwed up imaging (left vs right & front vs back)
2. reduced bass & possibly mids

[keroo1099]

Originally Posted by gearbox

An out of phase setup will only cancel the phase of the other speaker in a car situation, which may or may not affect the overall sound, depending on porting/space for the air to move behind the speaker.

1. If you have more than one speaker in a door (components) the door becomes the enclosure.

2. It's true that you mainly loose the lows with an out of phase setup, but that completely changes the balance of the sound which can then end up sounding thin.

3. What greenhorn posted.

[drpullockaran]

Originally Posted by keroo1099

9V battery may be too much for some voice coils and you might just have it jump out of the magnet and end up cursing yourself.

A million volts going through the coils is fine as long as the current is not high. It is current that kills wires and not voltage. H=I squared *R*T. Miliiamperes from the AA is far more than the 9Volt cell. I may be wrong though.

[keroo1099]

Originally Posted by drpullockaran

A million volts going through the coils is fine as long as the current is not high. It is current that kills wires and not voltage. H=I squared *R*T. Miliiamperes from the AA is far more than the 9Volt cell. I may be wrong though.

My apologies, you are right. Too much current is bad.