OT - Speaker Wire, Crackling Speakers

[DerbyDad03]

A few weeks ago I picked up a surround sound system on Craigslist. It came with some pretty thin speaker wire, (24 gauge I think) but the guy said it worked fine for him. I had enough of my own 16g wire to connect the front and center speakers, but not enough to connect the rears.

With what I had left after wiring the front and center speakers, I ran

2 lengths of 16g down into the basement, across the ceiling and back up into the living room, where I attached them (securely) to the 24g for the rear speakers. I'd guess 15' of 24g for the right rear speaker and 25' for the left. The wires ran next to each through the basement, up into the living room, along one wall and then parted ways in a corner, with one going up to the right rear and the other continuing along the floor to the other side of the room and then up to the left rear speaker.

What I found was that both rear speakers would sort of crackel if I turned the volume up too high. Low volumes were fine, but I couldn't crank it up. It wasn't really distortion of the sound itself, as much as a high pitched tick-tick-tick on top of the sound. I actually narrowed it down to the left rear speaker wire as the root cause, the one with the longest wire run of 24g wire. As long as that length of wire was hooked up, both rear speakers would crackle at high volume. If I plugged one of the 16g wires to the front speakers into the left rear jack on the system, there was no crackling. If I unplugged the left rear and ran just the right rear, there was no crackling. That tells me that the noise was definitely related to that run of wire.

This weekend I bought enough 16g wire to rewire both rear speakers, each with it's own single run of wire from the system to the speaker. No more crackling even when cranked up loud enough to send the cat running from the room.

So, to all you would be sound engineers, I ask this simple question:

Why would a small gauge wire running to that one speaker cause both rear speakers to crackel? Yes, originally there was small gauge wire running to both rear speakers, but as I said, when I unplugged the longest length of 24g to the left speaker, the right speaker stopped crackling.

What would cause that type of problem?

[Han]

DerbyDad03 wrote in news:2964af91-c524-4a98-90d8- [e-mail]:

Since 24 g is rather thin, and probably was NOT a stranded wire, could there have been a separation that occasional was sufficient to interrupt the signal?

[DerbyDad03]

It was stranded wire. This stuff...

Besides, there was no "interruption" of the sound from either speaker. The crackling was in addition to the regular sound and happened at the peaks of volume.

[Han]

DerbyDad03 wrote in news: [e-mail]:

So these were 24 gauge strands of wire, still if the strands were partially broken, with high volum of the speakers, I could see intermittent contacts that would cause crackling. Definitely, your replacing the wires did eliminate the problem, so a defect in the wire is highly likely. But this is a biochemist talking, not an EEE.

[Tony Hwang]

Hi, Is it eally a multi idependent channel amp. HT Amp? Not El Cheapo stuff? You phased all the speakers?

[gregz]

One possibility is the channel becomes unstable due to some capacitive or inductive effects, or both.

Greg

[harry]

Crackling is usually caused by a loose connection or corrosion somewhere. You sometimes get a break inside the insulation of the wire that is not visible..

[trader4]

On this rare occasion, I'd have to say I agree. IMO, something like that, at one of the connection points is more likely the cause. I don't see how the wiring change could cause crackling sounds. The biggest difference would be in the resistance of the wire and that would result in less sound. There are differences in capacitance too, but would not expect that to be huge, nor would you expect it to result in cracking type sound.

[DerbyDad03]

I'm not doubting anyone's assessment of the situation, but I have to at least question the loose connection/broken wire as the root cause.

How would a loose connection cause this to happen:

Environment:

- Volume is up high. - Left rear speaker is crackling - Right rear speaker is crackling

Action:

- Unplug the left rear speaker wire from the back the surround sound system.

Result:

- Left rear speaker goes dead (of course) - Right rear speaker stops crackling

Why would the right rear speaker stop crackling when the left rear speaker wire is unplugged? Could the loose connection cause feedback through the system (maybe through the ground?) and back out to the rear speaker?

If the noise was ending up on the ground, wouldn't it also be present at the front speakers, center speaker and sub-woofer? It never is.

[Arthur Shapiro]

I'd guess that trying to drive long lengths of preposterously-undersized cable caused a clipping problem. Even 16 guage was enough of an improvement that the amplifier wasn't being pushed beyond its capability.

Art

[Bill]

Try leaving the first speaker connected and disconnect the other speaker.

Then a test is to run a different wire or wires along the floor and see if those different wires eliminate the problem.

Or try different speakers.

Or try a different amplifier.

Note: Wires which are run in a house can have nicks or shorts if they have scraped something metal. Or a wire staple holding the wire might be shorting it or shorting to a metal object in the wall (grounding it).

Wires run close together for a long distance can "induce" electricity in the other wire. Try using "shielded" wire. This wire has foil around the wires like this...

[trader4]

The connections for both speakers are right next to each other, no? It would seem you could have pulled, moved, etc the other wire too, no?

I don't think you have a noise problem. As others have said, I crackling that goes away after fiddling with wires sure sounds like an intermittent connection.

[DerbyDad03]

...

I'm not sure what you mean by the "first" speaker. Right rear, Left rear, etc. is a better way to refer to them.

In any case, disconnecting speakers one at a time is how I narrowed it down to the left rear channel as the problem.

That's how I found that the 16g eliminated the problem.

That's one of the very first things I tried by swapping the speakers that came with the system. The problem stayed with the rear channels regardless of which speakers I connected.

The only other amp I have is too powerful for the small surround sound speakers and I didn't want to chance blowing them.

All of that was checked early on in the troubling shooting process.

That's one of the things I considered but I didn't know if going from

24g to 16g would eliminate the induction effect. It may have, since the problem went away when I increased the wire size.

[trader4]

You can't blow out speakers regardless of amp size unless you turn it up loud enough to do so. It's better to have a 100W amp on speakers that can only handle

50W, than it is to have a 50W amp on speakers that can handle 100W and turn the volume all the way up. Very often the damage is not done to the woofers, which take the most power, but to the tweeters or midrange because when you overload an amp, it clips. And the clipping produces harmonics that are high frequency.

[Sjouke Burry]

DerbyDad03 wrote in news: [e-mail]:

This sounds like you have(at high volume) a High freq. oscillation, swithcing on and off with sound level. The thin wiring just acts as a filter and avoids oscillation. Removing one speaker removes the feedback path. Try putting a ferrite filter block around the speaker wires, like the ones you find on the mains input lead on a lot of computer equipment. This HF oscillation can sound like crackeling, when going on/off on speaker wiring.

[DerbyDad03]

"You can't blow out speakers regardless of amp size unless you turn it up loud enough to do so"

Right...and since the issue occurs at high volumes, which is where my testing needed to be done, I did not want to hook the speakers to an amp that had the capability to blow the speakers at high volume.

Besides, my other amp is not a surround sound, so I couldn't test the same set up.

Besides, besides, I was able to narrow down the problem, and eliminate it, with the exact system and speakers I will be using. Once that was done, there was no need to introduce another variable.

[DerbyDad03]

re: "It's better to have a 100W amp on speakers that can only handle

50W"

From a sound perspective, yes. However, unless you are the only one that uses the system, you run the danger of kids/neighbors/drunken buddies cranking the volume without knowing the limitation of the speakers.

[clare]

We do not know enough about your system to say with any certainty - but a bad onnection on one output CAN cause noise on the other channel of the same amplifier - so if you have a "bi-amped" system, where the front and rear use separate amps, the interference would not affect the front speakers.

[clare]

Sheilding is not usually required - but twisted pair cable is DEFINITEY recommended. It eliminates "common mode" noise.

[gregz]

Twisted is not going to be better than close pairs. Close pairs eliminates common mode noise. Twisted brings it up in higher frequency rejection, and when run with other close pairs in close proximity.

Along with my unstable comment, that would include oscillations as mentioned by another poster.

Bigger amp, less prone to stability problems.

Ferrite core, may or may not help. Adding series resistor may help.

Seems like you best need to stay with larger gauge wire.

Greg