OFC or CCA speaker cable?

[Doodski]

Aluminium for all the 275kV lines here- imagine the cost/weight if they used copper. There was a situation here where thieves were cutting down new HT lines from towers before they were connected with giant cherry pickers and concrete saws. Thieves even steal the 15-20ft of neutral-ground ties (solid copper) that run down our power poles. A energy bloke I spoke to told me there are 30-50 replacements they do every week just those alone.

Now I make a habit of looking at power poles and it's incredible how many earthed neutrals have been stolen- and keep getting stolen.

In Calgary copper thieves have been found dead in underground vaults where the conductor runs. They accessed the vault(s) and progressed to cut conductors and voila... fried.

 

[Mnyb]

Aluminium for all the 275kV lines here- imagine the cost/weight if they used copper. There was a situation here where thieves were cutting down new HT lines from towers before they were connected with giant cherry pickers and concrete saws. Thieves even steal the 15-20ft of neutral-ground ties (solid copper) that run down our power poles. A energy bloke I spoke to told me there are 30-50 replacements they do every week just those alone.

Now I make a habit of looking at power poles and it's incredible how many earthed neutrals have been stolen- and keep getting stolen.

Copper thieves has always been an issue , when i was young I worked at a energy company.

And we have to use our backhoe/digger ( what are those machines called in English) to actually bury the reels of grounding wire we lay in parallel with the power cables in the ground every evening and dig up the reel in the morning to continue the work .

And when we took down old copper power lines for recycling ( they where a thing for 6 and 10kV historically and low voltage 380v 3 phase ) 10 square mm was a common gauge and put them in our recycling bins , at several occasions when we had a couple of tons of it we get a break in and got It stolen . Sometimes they stole a pickup truck to haul it with

 

[DanielT]

Copper thieves has always been an issue , when i was young I worked at a energy company.

And we have to use our backhoe/digger ( what are those machines called in English) to actually bury the reels of grounding wire we lay in parallel with the power cables in the ground every evening and dig up the reel in the morning to continue the work .

And when we took down old copper power lines for recycling ( they where a thing for 6 and 10kV historically and low voltage 380v 3 phase ) 10 square mm was a common gauge and put them in our recycling bins , at several occasions when we had a couple of tons of it we get a break in and got It stolen . Sometimes they stole a pickup truck to haul it with

That's right. An example:

"The copper thefts on the country's railways are rampant - especially in southern Sweden.

The Swedish Transport Administration believes that the thieves dress up as track workers when they steal thousands of meters of cable.

- It is very cheeky, says Ola Malmberg, maintenance manager in the south.

- There, 27,000 meters of copper pipe have been stolen from this summer until the end of October, says Ola Malmberg."

Kopparstölder skenar: ”Ökar lavinartat” | SvD

Kopparstölderna på landets järnvägar skenar – framför allt i södra Sverige. Trafikverket tror att tjuvarna klär ut sig till banarbetare när de stjäl tusentals meter av kabel. – Det är väldigt fräckt, säger Ola Malmberg, underhållschef i syd.

www.svd.se

Excuse me, 27,000 meters?! How the hell do thieves manage to take so much?!

 

[restorer-john]

Excuse me, 27,000 meters?! How the hell do thieves manage to take so much?!

Maybe they stole a goods train to transport all this loot. Stored it all in a disused tunnel someplace until they could send it via ocean going freighter overseas when copper prices were heading towards a peak. Anyway, that's how the heist movie in my mind plays out.

 

[Berwhale]

It's not just copper or aluminium, we've had cast iron drain and manhole covers disappearing from the roads around here. The council has been replacing them with very chunky ones made from (presumably recycled) plastic.

 

[toddsdonald]

12 Gauge copper wire only has around 1.6 ohms resistance per thousand feet at DC, so short lengths clearly present a measurement challenge - as already pointed out by others. Don't even bother trying to accurately measure a short 10 or so foot length with a multimeter and alligator clips.

IME the advantage(s) of copper cladding another type of metal wire has more to do with taking advantage of skin effect to reduce cost and/or increase strength and/or reduce stretch and/or reduce corrosion.

Skin effect is a much more complex AC discussion that has to do with AC's changing magnetic fields within a conductor and most folks will simplify this discussion by stating it doesn't matter at AC audio frequencies (20 Hz to 20 KHz), and only pertains to applications at higher AC radio frequencies (over 500 KHz). That is probably the easiest way to deal with a speaker cable skin effect discussion from a practical standpoint since the AC frequency is rather low and the conductors are rather small in diameter. Nevertheless skin effect does actually pertain to some extent at lower AC frequencies where larger conductors are used. As an example, I have a couple of friends that have made their careers engineering 60 Hz Transmission Lines for Electrical Power Utilities (the big ones you see from aircraft), and they do actually engineer skin effect in their work using these large conductors in order to use a steel core in the conductors for lower stretch (simple physical and also thermal) and for greater strength. Sometimes they even use several "smaller" conductors in a "bundle configuration" where the several conductors are insulated from one another by a ceramic spacer and air, to reduce the skin effect loss that would be experienced when carrying 60 Hz current in one single larger conductor, and also for more efficient surface area air cooling of the conductors. Skin effect is indeed engineered for 60 Hz transmission line conductors, the transmission lines that bring electric power long distances to where the electric power is then distributed to vast numbers of customers.

In the middle of the audio frequency band (10 KHz) using 12 gauge copper conductors (81 mil diameter) the skin effect is around 1/3rd of the way into the conductor (26 mil deep), meaning that the 1/3rd or so in diameter core part of the conductor (29 mil diameter) carries much less current than the outer "skin" part of the conductor, and other complicated things like eddy currents exist in the core part of the conductor. Again, this particular analysis is for 10 KHz, right in the middle of the audio frequency band, and done considering solid conductors because stranded conductors are typically a little larger in diameter based on the stranding implementation (how many strands and their gauge) and would thus be another variable. The skin effect runs shallower into the conductor as you go higher in frequency (thus more significant), and runs deeper into the conductor as you go lower in frequency (thus less significant). For this reason I typically suggest using 14 gauge or 16 gauge speaker cables for sending the full audio frequency range over the typical short distances within a room, as all you're really accomplishing with larger conductors is spending more of your money for copper than you probably need to. Using 12 gauge conductors at treble frequencies brings with it some more complex variables related to skin effect and core eddy currents. These variables theoretically "might" account for some different listening experiences between different size conductors, or at least the physics says it "might". OK, for long speaker cable runs at lower subwoofer frequencies 12 gauge may well possibly make sense when the current flow is high enough, so long as all you're sending through the 12 gauge cable is the subwoofer frequencies.

Personally I would not use copper clad aluminum conductors for speaker cable due to the many new variables it introduces, many of them simply physical shortcomings.

In the end, please refer back to my post number 25 suggesting making speaker cables from cable that is engineered specifically for speaker cable by one of the largest cable manufacturers in the world, with actual cable engineers doing their engineering.

Aren't speakers / transducers DC?

 

[JSmith]

Aren't speakers / transducers DC?

No, all speakers work using AC provided by the amplifier. Basically, although the amp runs on DC internally (after being rectified to DC from the AC source), DC is not supplied to the speakers... audio is an AC signal.


JSmith

 

[toddsdonald]

No, all speakers work using AC provided by the amplifier. Basically, although the amp runs on DC internally (after being rectified to DC from the AC source), DC is not supplied to the speakers... audio is an AC signal.


JSmith

Thx and I learned something new. Pretty good article covering it here:

Are Speakers AC or DC? Here's The Truth - Stamp Sound

Alternating current (AC) and direct current (DC) are differentiated by the direction that the electric charge flows. When using speakers, it’s important to

stampsound.com