Speaker Wire

[biferi]

I have the Bose Acoustimass 3. and the Center Speaker as Well.
They are about 20 something Years Old and I had to Disconnect them.

I need help I Forgot does the Red Wires go to the Positive Terminals on the AV / Receiver and the Black Wires go to the Negative Terminals on the AV / Receiver?

[jagabo]

For speakers it doesn't really matter as long as you connect both speakers the same way. But with electronics red is usually positive. Black or white is negative.

[johnmeyer]

Just to add to jagabo's correct answer: if you wire one speaker the opposite way to the other, they will be "out of phase" which means one speaker will be going forward at the same moment in time that the other is going backwards. This makes a massive difference (i.e., it is NOT subtle) and you will find that you have poor bass, the audio that should sound like it is coming from the middle (between the two speakers) will instead have no obvious point of origin. You may also find that the audio sounds hollow.

If you have a modern receiver that uses a microphone to help set up your speakers, it will automatically check for this mis-wiring. Some will even correct it "in software" so that you don't have to re-wire.

One last thing: when you wire speakers TURN OFF THE AMPLIFIER. It is an all too common mistake to leave the system powered up, and it is very easy to short the terminals. I tried to rescue a friend's $1,000+ amplifier after he did this, but after I got past the two blown output transistors, I found many other components that got fried, and had to give up.

[jan5678]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards, so yes it is important to connect them right.
For the rest i agree with jagabo, red is positive, black negative

[jagabo]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards

But you can't hear that.

[johnmeyer]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards

But you can't hear that.

Did you see my explanation above? The difference between in-phase and out-of-phase speakers is massive. It is not subtle at all. It is caused by the speaker cones moving in the opposite direction to each other.

When I set up my first stereo, back in the 1960s using my dad's Altec 605 speakers (I still own both speakers and the amp), I built a phase inverter switch that I attached to one of the two speakers. I needed to do this because the speakers were almost thirty feet from the amplifier, and we were using 16 gauge lamp wire for connection, and the lamp wire did not have any markings to identify one wire from the other. We didn't have any additional wire to hook up our Simpson 260 VOM.

I turned on the speakers, put on some classical music, and worked the switch back and forth.

That is where I first realized that this REALLY MATTERS. The difference was immediately obvious. No way would you want to listen to out-of-phase speakers.

Fast forward to the early 1990s and I was setting up my second home theater. I purchased a TDK CD ("TDK's Ultimate Guide to Great Sound") that contains all sorts of "super Hi-Fi" test music, along with Dolby Surround Sound test tones (this was just before the introduction of Dolby 5.1). One of the tests was a phasing test, where they played test audio that was in phase and then out of phase. They had a guy with a deep, resonant "radio announcer's voice" that, when played out of phase sounded like he was speaking inside of a bathroom shower, with his voice seeming to come from everywhere. When the in-phase version was played, his voice was dead center between the speakers and full of fullness and bass.

[jagabo]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards

But you can't hear that.

Did you see my explanation above? The difference between in-phase and out-of-phase speakers is massive.

Of course. I interpreted jan5678's comment was in regard to when both speakers were connected "backward".

[johnmeyer]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards

But you can't hear that.

Did you see my explanation above? The difference between in-phase and out-of-phase speakers is massive.

Of course. I interpreted jan5678's comment was in regard to when both speakers were connected "backward".

I was pretty sure you understood phasing. My fault for not fully comprehending what you were saying.

Yes, if both sets of wires are backwards (black to red), then everything will be OK. It is one case where two wrongs DO make a right.

[Cornucopia]

Out of Phase is more pronounced when the signal is mono, because then you have "optimal" destructive interference. In stereo, it will sound spacy-but-stretched, but not truly "hollow".
And "weak" usually only occurs when the destructive interference occurs electronically (combined within the pre-amp or amp), not acoustically, as then there are intervening/moderating factors. Most of that weakness is due also to the bass (which is often mixed predominantly to the center) getting totally annihilated by the combination of signal + equal anti-signal (sounds more scifi to say it that way, but it's still accurate).

Scott

[cornemuse]

If you connect the speaker wires wrong the cone from the speaker will move backwards instead of forwards

But you can't hear that.

Set up stereo 'red pos' and listen to something (NOT video, you dont want distraction!), pay attention.
Now, change to 'red neg', without changing any settings on your stereo, (turn it off 1st!). Listen again, no difference?

My hearing is bad, yet I can tell the difference.

-c-

[Cornucopia]

That's not what he was saying.
If all your channels' positives are reds and all your channels' negatives/grounds are black, you would hear no difference if you changed it so that all your positives were black and your negatives red. That is about absolute speaker polarity (compression - forward, vs rarefaction - backward).
There is speculation that some people can hear the difference, and I believe that might be true, but don't know of anyone that actually CAN, consistently (and I've been around audio tech for decades).

Scott

[jagabo]

There is speculation that some people can hear the difference, and I believe that might be true, but don't know of anyone that actually CAN, consistently (and I've been around audio tech for decades).

I agree that nobody can tell the difference on "normal" audio. But I suspect one might be able to tell the difference with specially constructed test waveforms. For example, consider a continuous high frequency sine wave and a low frequency soliton. A doppler shift would cause the frequency of the high tone to increase on the rising side of the soliton, then to decrease on the falling side (assuming the same driver is producing both tones). If the wires were reversed you would hear the opposite -- the high frequency tone would first lower, then rise.

[Cornucopia]

Oohh, very good. Similar to how one can "hear" binaural/IAD differences when there is a change that would normally be higher freq./shorter wavelength than individual ears are supposed to hear.

Scott

[jan5678]

The direction of the sound wave is backwards if you connect the speakers wrongly. in other words the sound wave moves backwards instead of forwards, this changes the sound like johnmyer said.

If you can hear the difference is another matter. The influence in a real world scenario is to be seen off course

[hello_hello]

Reading this thread brought back some memories. Remember when one company's positive caused the speaker cone to move inwards while for everyone else it moved outwards? http://www.jblpro.com/pub/technote/tn_v1n12b.pdf

[johnmeyer]

I am really surprised by some of the posts. Let me provide proof of how important speaker phasing can be.

I mentioned the "TDK's Ultimate Guide to Great Sound" CD. I own two of them and have set up many stereo systems and home theaters using its test tones. However, you don't need, nor do you want to use, any special test tones. Instead, all you need is someone talking.

Here is a link to a tiny 1 MB MP3 that is one track from this CD where they provide audio that is recorded in-phase and then similar audio that is recorded out-of-phase. As you can clearly hear, even on your computer's speakers, the difference is not subtle and does not require trained ears. The difference is massive.

What's more, this is NOT the result of some trick done during recording. This is precisely the same effect, with no difference at all, that you will get if you wire one of your speakers backwards from the other.

Track 3 Speaker Phase Test from TDK CD

[hello_hello]

Here is a link to a tiny 1 MB MP3 that is one track from this CD where they provide audio that is recorded in-phase and then similar audio that is recorded out-of-phase. As you can clearly hear, even on your computer's speakers, the difference is not subtle and does not require trained ears. The difference is massive.

I'm not arguing about the need for speakers to be in phase with each other, but I'm wondering how easy it is to hear a difference when they're both phase reversed (but in phase with each other).

If you're still around jan5678, can you hear a difference between these two? One has been phase reversed (both channels). I don't think I can, but my speakers aren't great and my ears are old. It's easy to confirm they're out of phase if you have Audacity. Import both versions and play them together. You should hear silence.

[jan5678]

@hello_hello

Well to my ears number 2 seems to have a better forwarding sound feeling, but i have to agree that the difference (on my computer speakers) is not very big

i will later on test it with audacity if my first impression is correct

[johnmeyer]

I don't even know what it means to have both channels "phase reversed." If you change the polarity of both, it does absolutely nothing and it will work just as well as when you have "red-to-red, and black-to-black."

"Phase reversal" only happens when one speaker cone is pushing out at the same moment that the other speaker cone is pushing in. Thus, there is no such thing as having both channels phase reversed.

[hello_hello]

I don't even know what it means to have both channels "phase reversed." If you change the polarity of both, it does absolutely nothing and it will work just as well as when you have "red-to-red, and black-to-black."

That's because they're both phase reversed so they remain in phase with each other.

"Phase reversal" only happens when one speaker cone is pushing out at the same moment that the other speaker cone is pushing in. Thus, there is no such thing as having both channels phase reversed.

You can phase reverse one speaker, so it follows you can phase reverse two.
The question is, if you phase reverse both so a positive voltage moves the cones in the opposite direction, while it shouldn't cause sound cancellation as phase reversing only a single channel can, does it make a difference to the sound.

I suspect we're debating semantics to a certain degree. What you're referring to as phase reversal I'd describe as "out of phase" because you can phase reverse both and they'll be in phase again.

[HarpMaster]

If you reverse both speakers together they will be in phase. I agree with that, but I've tried to hear the difference with my hi-fi and when I've set up other peoples systems and there is a difference between both black wires plugged in to the positive terminals than the reds. The sound may still be in phase but it sounds thinner, in my experience and not as rich.

[hello_hello]

HarpMaster,

I meant to ask jan5678 if the samples I uploaded earlier sound different using headphones, but have you tried them with speakers or headphones yourself? The phase difference is exactly what you get by swapping the speaker wires on both cabinets, without having to move around the room or swap wires to hear it. I do have an open mind because I know I've heard the effect of phase reversal many times, more-so for low frequencies, but I'd arguing with my final breath that one phase doesn't always sound better than the other.

In a previous life I mixed bands for a living, and most mixing desks have a phase reversal switch on each channel. For something like a bass drum microphone you can often change the phase and hear a difference, but ignoring it also changes the phase in relation to other instruments, most of the difference is due to sound wave lengths of 3m or more reflecting off walls and interfering with themselves in different ways. At that sort of sound pressure level, a couple of steps to the left or right can be the difference between wondering where all the low frequencies are, to feeling the bass drum thumping against your chest. If you reverse the phase of the speakers, you might move the sweet spot to a different place in the room, but the sound coming directly from the speakers probably hasn't changed in an audible way.

The trouble with comparing sound is it interacts the environment so much that standing in a slightly different position could potentially change what you hear quite a bit. Sound moves through the air at around 340m/s, so a 1 kHz sine wave has a wavelength of roughly 3.4cm, if my brain is working. If you move your head 1.7 towards or away from the sound source, in theory at least, you've reversed the phase at 1 kHz.

I'm not saying you're not hearing something, but comparing the samples I uploaded earlier using headphones is probably as close as you'll get to hearing nothing but the difference phase reversal makes on it's own, or more likely the difference it doesn't make.

[jan5678]

I don't have a headphone so can't test that. I listened to the samples on my computer speakers (not the best quality but not the worst either)
I agree that headphones use is the best option to hear a or the difference

[HarpMaster]

My experience is based on my hi-fi. If the wires are reversed at one end, that is the speaker end, on one speaker, then the sound will be out of phase with the other speaker. If you do the same to the other speaker, I believe that although they will be in phase with each other, the sound will be thinner, at least to my old ears.
Of course, if the speaker wires on one speaker are reversed on one and also on both speakers, it will make no difference.
I don't have much experience with headphones. I dislike using them very much. Partly from having to use them in recording studios as a musician, when, playing on an album nearly 50years ago there was a problem with the wiring in the outlet and one side of my phones kept flickering on and off and I ended up with a terrible migraine. We did the whole album in one day but I had to be carried home in a van!