# Purpose of copper chassis headunits?



## Sarthos (Oct 29, 2010)

Okay, I guess this is more of a "theoretical" thread, but I know that some high-end headunits use copper plated chassis. Now, the stated purpose is to block magnetic interference by acting as a Faraday cage, but I'm just thinking, couldn't one get the same result by putting a copper sleeve around the headunit? (ie that sleeve that the headunit slides into in your DIN slot, just have one made with copper rather than aluminum/steel)? In which case, why is this not commonly done?

Also, if this is useful on headunits, why is it not done to amplifiers? Is it because the thicker aluminum case on an amplifier acts as a Faraday cage, whereas the chassis on a headunit is too thin to act as a cage unless it's copper plated? Or it it because the copper would be problematic as a heatsink? I'd think the copper chassis on an amp would make a better ground, and would fight interference so I'm not sure why they don't use copper in the chassis (perhaps due to copper corroding worse than aluminum?) Or is it just that the nature of an amplifier's internals don't pick up the same interference as that of a headunit?

And finally, in order to completely stop interference in your car's signal, why don't people use more Faraday cages? I've seen so many systems where background noise and humming ruins the overall experience it's sickening. Couldn't someone easily modify a system so that speaker wires, RCA cables, headunit, amps, etc. are all caged and stop most interference?

Anyway, end rant.


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## Baada (Nov 28, 2010)

I also wonder about this. Is it just one of the latest marketing techniques? If so it's an expensive one because copper isn't cheap right now. Does it make a measurable difference...in the real world or just a lab? 

Like Sarthos said, if it is a huge benefit it seems like would be pretty simple to get some copper foil to wrap a HU in before inserting it into the supplied steel sleeve? This could be the next aftermarket part for the SQ crowd if it really works? 

If I had to guess I would assume that most of the noise in a typical system is picked up/transmitted through the wires coming into and out of the HU and not so much into the HU from nearby sources?


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## TrickyRicky (Apr 5, 2009)

There are some car audio amplifiers that use copper chassis but very very few (can't even remember but am sure there is a few out there). But most likely copper traces. Also I've seen a bunch of Marantz home audio receivers that have copper chassis w/copper screws.


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## dragonrage (Feb 14, 2007)

Copper is the best conductor of all the metals that are cheap. Silver and gold are better, for example, but they cost much more. But, still, it's mainly marketing.


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## Sarthos (Oct 29, 2010)

> I also wonder about this. Is it just one of the latest marketing techniques? If so it's an expensive one because copper isn't cheap right now. Does it make a measurable difference...in the real world or just a lab?


Price of a pound of copper? Like 5 bucks. Amount of copper required to plate a headunit? A couple ounces. So it shouldn't be that expensive.



> If I had to guess I would assume that most of the noise in a typical system is picked up/transmitted through the wires coming into and out of the HU and not so much into the HU from nearby sources?


Yah, that'd sorta be my assumption. Particularly the antenna wire if you're listening to the radio, but also in the RCA cables. But the fact that headunits have more parts that are sensitive to magnetic waves than the wires and cables might make that untrue.



> Copper is the best conductor of all the metals that are cheap. Silver and gold are better, for example, but they cost much more. But, still, it's mainly marketing.


Gold isn't a better conductor, just silver. Gold is more resistant to corrosion which is why it is used to plate terminals and such.


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## minbari (Mar 3, 2011)

more than likely they use copper on the chasis for heat sinking properties since copper sinks away heat MUCH more efficiently than aluminum does.



> Gold isn't a better conductor, just silver. Gold is more resistant to corrosion which is why it is used to plate terminals and such.


exactly right, gold is not a great conductor, but it does not corrode, so it is used for plating conductors that are exposed to the elements.


here is a chart of the first few metals we use:


```
TIBTECH innovations logoTIBTECH 	Electrical conductivity
(10.E6 Siemens/m) 	Electrical resistivity
(10.E-8 Ohm.m) 	Thermal Conductivity
(W/m.k) 	Thermal expansion coef.
10E-6(k-1) from 0 to 100°C 	Density
(g/cm3) 	Melting point or degradation
(°C)
Silver 	62,1 	1,6 	420 	19,1 	10,5 	961
copper 	58,5 	1,7 	401 	17 	8,9 	1083
Gold 	44,2 	2,3 	317 	14,1 	19,4 	1064
Aluminium 	36,9 	2,7 	237 	23,5 	2,7 	660
```
Conductive Materials or Metal Conductivity - TIBTECH innovations -


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## Commissionmip (Jan 27, 2011)

TrickyRicky said:


> There are some car audio amplifiers that use copper chassis but very very few (can't even remember but am sure there is a few out there). But most likely copper traces. Also I've seen a bunch of Marantz home audio receivers that have copper chassis w/copper screws.



Pioneer stage 4 uses copper chassis.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

suckerbait for those that care to spend money... 

If someone cares to measure the difference between using a copper chassis and a "tin" one and show me a difference, I'll print and eat these words... I'll post that **** on YouTube...


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## minbari (Mar 3, 2011)

Aaron'z 2.5RS/WRX said:


> If someone cares to measure the difference between using a copper chassis and a "tin" one and show me a difference, I'll print and eat these words... I'll post that **** on YouTube...


ROFL, I really wish I had the test gear for this. copper has thermal conductivity of 420 watts/m K. tin is 67. no doubt copper will win then hands down.

now that said, if you are not producing much heat to begin with, the argument becomes moot


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## spl152db (Dec 20, 2007)

only heatsinks I've ever seen on a head unit are at the rear. They're aluminum and have a paste on them. Dont believe the copper chassis units have copper heat sinks at the rear. If the radio gets hot enough to need the thermal dissipation of a copper chassis, they've installed a fan to keep it cooler. There is no question that a copper chassis COULD move heat away more efficiently but without somewhere for the heat to go the unit would still have the same heat soak. 

does it do the magic voodoo that yoodoo? no. probably not. BUT, it comes with the high end units that are produced by the manufacturer. Can you ever measure the difference between the copper chassis and that of the radio without? NO. They don't have the same internals. Now, go get a sheet of copper, some basic tools and make your own. Then you can have a real test!


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## sqshoestring (Jun 19, 2007)

Copper is different with heat, alum actually conducts heat faster but copper can hold more heat or hold it more evenly I forget. Or maybe copper absorbs it better and alum dissipates better I'm sure its on the net someplace. The better CPU coolers would cast a copper coin (a blank) into the bottom of the sink. The copper would be against the CPU but the finned part was all alum. This was better than just alum, however I never saw a common one that was all copper.

My guess is marketing mostly why a HU case would be copper, it is a higher quality material to use for corrosion issues and it looks cooler. My 880 HU has a little fan in the back to cool it.

Once I worked on an expensive old house, it had a real slate roof. All the gutters and flashing were copper. It was built to last.

Here you go....
Amazon.com: Copper GlueFoil 8.5" x 11" Sheets, 2 Sheet Pack: Arts, Crafts & Sewing

If it were a matter of catching radio waves, just look at what most antenna are made of its not copper.


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## minbari (Mar 3, 2011)

it is simple thermal conduction. metal does not "store" heat. the higher the thermal conduction coefficient, the faster it conducts heat.

take a peice of aluminum rod and a piece of copper rod. apply a blow torch and see how long you can hold on to either one. the copper will get hot much faster. (it will also cool off much faster)

more than likely the difference in those uprocs was for cost savings. copper is about 5-6x as expencive. also, copper corrodes much fast than aluminum does.


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## spl152db (Dec 20, 2007)

sqshoe, you have the best ideas! I wonder if that would work on my 8443...


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## minbari (Mar 3, 2011)

what kind of antenna? most of the high gain antenna I use have a copper core and all the traces are copper. when you are talking uV of RF signal. loses in resistance is not a good thing.


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## narvarr (Jan 20, 2009)

copper does indeed help with stray magnetic fields, hence the use of it in speakers as shorting rings. Same principle applies. As far as proving it, I had a Sony HU back in the mid 90's that was picking up noise from somewhere. I read in a car audio mag about SQ competitor wrapping his HU in copper gauze to get rid of noise. I worked at a plastic injection plan at the time and we used copper gauze to clean burnt plastic off of our molds because it was soft enough not to scratch the tooling. I took about a foot of it home to try out and BINGO! Noise was gone. Three weeks of trying to trace down the problem and this method fixed it.

Sent from my X10i using Tapatalk


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## spl152db (Dec 20, 2007)

narvarr said:


> copper does indeed help with stray magnetic fields, hence the use of it in speakers as shorting rings. Same principle applies. As far as proving it, I had a Sony HU back in the mid 90's that was picking up noise from somewhere. I read in a car audio mag about SQ competitor wrapping his HU in copper gauze to get rid of noise. I worked at a plastic injection plan at the time and we used copper gauze to clean burnt plastic off of our molds because it was soft enough not to scratch the tooling. I took about a foot of it home to try out and BINGO! Noise was gone. Three weeks of trying to trace down the problem and this method fixed it.
> 
> Sent from my X10i using Tapatalk


ah, but sonically there was no difference in the sound. so it rejects external noise but if your car has none then its pointless.


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## narvarr (Jan 20, 2009)

narvarr said:


> copper does indeed help with stray magnetic fields, hence the use of it in speakers as shorting rings. Same principle applies. As far as proving it, I had a Sony HU back in the mid 90's that was picking up noise from somewhere. I read in a car audio mag about SQ competitor wrapping his HU in copper gauze to get rid of noise. I worked at a plastic injection plan at the time and we used copper gauze to clean burnt plastic off of our molds because it was soft enough not to scratch the tooling. I took about a foot of it home to try out and BINGO! Noise was gone. Three weeks of trying to trace down the problem and this method fixed it.
> 
> Sent from my X10i using Tapatalk


For those wondering what copper gauze is, here's a link to what I used:
Copper Gauze


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## narvarr (Jan 20, 2009)

spl152db said:


> ah, but sonically there was no difference in the sound. so it rejects external noise but if your car has none then its pointless.


Exactly. So as far as noise prevention, it works. Heat dissipation, I can't comment on...


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## minbari (Mar 3, 2011)

narvarr said:


> copper does indeed help with stray magnetic fields, hence the use of it in speakers as shorting rings. Same principle applies. As far as proving it, I had a Sony HU back in the mid 90's that was picking up noise from somewhere. I read in a car audio mag about SQ competitor wrapping his HU in copper gauze to get rid of noise. I worked at a plastic injection plan at the time and we used copper gauze to clean burnt plastic off of our molds because it was soft enough not to scratch the tooling. I took about a foot of it home to try out and BINGO! Noise was gone. Three weeks of trying to trace down the problem and this method fixed it.
> 
> Sent from my X10i using Tapatalk


basically built yourself a faraday cage


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## narvarr (Jan 20, 2009)

minbari said:


> basically built yourself a faraday cage


Lol, basically yes.


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## Orion525iT (Mar 6, 2011)

Aaron'z 2.5RS/WRX said:


> suckerbait for those that care to spend money...
> 
> If someone cares to measure the difference between using a copper chassis and a "tin" one and show me a difference, I'll print and eat these words... I'll post that **** on YouTube...


_That_ ****, did you mean _the_ ****. As in, the toilet after shot?

I wonder if it could magnetically shield the head unit. Like if you just happen to have 80oz subwoofer magnet sitting directly above you head unit. It is an issue I may have to deal with.


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## minbari (Mar 3, 2011)

Orion525iT said:


> I wonder if it could magnetically shield the head unit. Like if you just happen to have 80oz subwoofer magnet sitting directly above you head unit. It is an issue I may have to deal with.


wouldnt do a thing. you cant "suck" the noise out of the air with a magnet, lol.


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## WLDock (Sep 27, 2005)

I am sure that a tin cage does the jobs of shielding a deck. But I bet copper does a slightly better job. I know that copper makes a better antenna than cheap metals. So.....

From a marketing standpoint...it just makes sense to use more expensive materials to sell your more expensive deck... I really don't think it is much more than that.


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## sqshoestring (Jun 19, 2007)

I've seen the guts of a PCS antenna and it was not copper. The connector might have been but the element was not. And those things are not cheap at all.

Heat sink - Wikipedia, the free encyclopedia
There it is, copper conducts better but is quite heavy and alum is much easier to shape/form into heat sinks and is cheaper. So you can just make it larger with alum to get the same performance. Also on a cpu weight can be an issue.


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## Sarthos (Oct 29, 2010)

spl152db said:


> only heatsinks I've ever seen on a head unit are at the rear. They're aluminum and have a paste on them. Dont believe the copper chassis units have copper heat sinks at the rear. If the radio gets hot enough to need the thermal dissipation of a copper chassis, they've installed a fan to keep it cooler. There is no question that a copper chassis COULD move heat away more efficiently but without somewhere for the heat to go the unit would still have the same heat soak.
> 
> does it do the magic voodoo that yoodoo? no. probably not. BUT, it comes with the high end units that are produced by the manufacturer. Can you ever measure the difference between the copper chassis and that of the radio without? NO. They don't have the same internals. Now, go get a sheet of copper, some basic tools and make your own. Then you can have a real test!


I didn't realize that copper has the higher thermal coefficients, now I'm really interested to see what a copper chassis to an amp (or at least a copper skeleton to the chassis) would do.



sqshoestring said:


> Copper is different with heat, alum actually conducts heat faster but copper can hold more heat or hold it more evenly I forget. Or maybe copper absorbs it better and alum dissipates better I'm sure its on the net someplace. The better CPU coolers would cast a copper coin (a blank) into the bottom of the sink. The copper would be against the CPU but the finned part was all alum. This was better than just alum, however I never saw a common one that was all copper.
> 
> My guess is marketing mostly why a HU case would be copper, it is a higher quality material to use for corrosion issues and it looks cooler. My 880 HU has a little fan in the back to cool it.
> 
> ...


Except copper corrodes pretty badly. Although now that you mention it I have seen the copper slugs in computer heatsinks. I wonder if that might be worthwhile to try with an amp, actually open up the case and add copper slugs against the heatsinks and the chassis, just use either a high heat resin or solder them on there.

And it's not a matter of "catching" radio waves exactly, it's the matter of blocking them.



spl152db said:


> ah, but sonically there was no difference in the sound. so it rejects external noise but if your car has none then its pointless.


Yes, but how many cars actually do have NO external noise? It seems if the car has the volume all the way down you can almost always hear SOME noise. Now, whether the noise is internal or external is another question. Also, whether the noise can be heard or not is yet another.



minbari said:


> basically built yourself a faraday cage


That's what my OP was sorta about, is it really effective to do a copper chassis to act as a faraday cage?


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## Baada (Nov 28, 2010)

Sarthos said:


> Price of a pound of copper? Like 5 bucks. Amount of copper required to plate a headunit? A couple ounces. So it shouldn't be that expensive.


Well for a marketing tool to work it has to generate more income than it costs. And while copper is actually less than $5 per pound right now its significantly more expensive than more commonly used metals, which is what I was trying to say. And it's worth enough all these idiots keep electrocuting themselves trying to steal copper wire out of street lights.


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## Darth SQ (Sep 17, 2010)

minbari said:


> basically built yourself a faraday cage


That's that guy on LOST right?
Damn was he smart.
I don't remember him messing with copper though.
Just time travel.

Bret
PPI-ART COLLECTOR


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## Sarthos (Oct 29, 2010)

Baada said:


> Well for a marketing tool to work it has to generate more income than it costs. And while copper is actually less than $5 per pound right now its significantly more expensive than more commonly used metals, which is what I was trying to say. And it's worth enough all these idiots keep electrocuting themselves trying to steal copper wire out of street lights.


True, but when people steal copper wire they generally get very large amounts. To copper plate a chassis, I dunno what that takes, a couple ounces? I'm sure it's a maximum of 2 bucks of copper to plate the thing, when people steal wire they end up getting hundreds of pounds sometimes and that's why it's worth it to them to do something so dangerous


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## TrickyRicky (Apr 5, 2009)

Sarthos said:


> True, but when people steal copper wire they generally get very large amounts. To copper plate a chassis, I dunno what that takes, a couple ounces? I'm sure it's a maximum of 2 bucks of copper to plate the thing, when people steal wire they end up getting hundreds of pounds sometimes and that's why it's worth it to them to do something so dangerous


That reminds me when I worked with this one guy, he always go picking up scrap wire left over by the electricians. Those electricians just cut wire and leave long strands of wire laying everywhere. Oh and when they can't do a run with the left over wire they just throw it away (those guys make too much money to scrap it up). But the guy I work with would do this during break, lunch, second break and even after work.

He mention the pain in the butt part is that he has to remove the insulator jacket (this is 12gauge solid copper wires). But I've seen him haul away a few pounds everyday. Said how he gets good money for it but I never bother to ask how much a pound.


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## ReloadedSS (Aug 26, 2008)

Having had a couple of decks with a copper chassis, they were better decks even without the magic copper shielding than other decks. So it's hard to make apples to apples comparison. Probably mostly marketing mumbo jumbo.

But if you've had one, it's pretty cool to look at it. Then you install it and don't see it again unless you un-install it. :laugh:


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## Sarthos (Oct 29, 2010)

Hmm, now that I think about it, this topic is somewhat hard to apply to my current system, my headunit has nothing to do with the actual sound of the system . Old school Eclipse flip-out, uses a "brain" unit under the seat, the headunit is just a controller, doesn't do anything with the sound. But I suppose it would be easy to wrap the brain in copper, should have the same effect.


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## minbari (Mar 3, 2011)

PPI-ART COLLECTOR said:


> That's that guy on LOST right?
> Damn was he smart.
> I don't remember him messing with copper though.
> Just time travel.
> ...


no no no, I think that was jonny cage!


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## sqshoestring (Jun 19, 2007)

Lol, a friend of mine puts in HVAC and keeps the extra line from the line set to the AC. Lately the company says bring that back to us, we are keeping it, ha ha. He says screw you I still keep part of it anyway. So he had like 3 55gal barrels full. He cuts it into short lengths the price is better. Takes them in when it was up and got over $800 out of it. The AC tubing is high pressure and thicker wall. Who is going to laugh about an $800 bonus over maybe a year. He used to get around 300.


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## chad (Jun 30, 2005)

I find it ironic that the people that shoot for these copper chassis headunits use unshielded signal cable.


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## minbari (Mar 3, 2011)

chad said:


> I find it ironic that the people that shoot for these copper chassis headunits use unshielded signal cable.


how do you know that?

besides shielding is just a format for noise rejection. for the distance a car goes, twisted pair works just fine. (or balanced line)


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## SoundJunkie (Dec 3, 2008)

Because its PURTY!!!

No one said it yet so I had to!

Sent from my DROIDX using Tapatalk


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## chad (Jun 30, 2005)

minbari said:


> how do you know that?
> 
> besides shielding is just a format for noise rejection. for the distance a car goes, twisted pair works just fine. (*for* balanced line)


Fixed that for ya


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## spl152db (Dec 20, 2007)

almost always got noise and crosstalk with just twisted pair. too many other factors. and yes it would work fine for balanced line.


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## Jonny Hotnuts (Mar 15, 2011)

I own a few of these amps that use a copper shield around the toroidal. Note that this is NOT for heat dissipation the copper doesnt even make contact with the transformers. 










BTW:

Copper sheet at 1/32" (*I think thats the thickness of deck chassis) would cost retail 50-75$ for enough to do a copper sleeve. One guy mentioned 5$ per pound....thats scrap price.


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## Sarthos (Oct 29, 2010)

> Copper sheet at 1/32" (*I think thats the thickness of deck chassis) would cost retail 50-75$ for enough to do a copper sleeve. One guy mentioned 5$ per pound....thats scrap price.


Except the copper plated chassis have plating much thinner than the thickness of the chassis. Luckily for a company that buys things in bulk, things like copper can be obtained for MUCH cheaper than that. A consumer buying copper foil like that in small amounts is the most expensive way to get the stuff.


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## ReloadedSS (Aug 26, 2008)

Jonny Hotnuts said:


> I own a few of these amps that use a copper shield around the toroidal. Note that this is NOT for heat dissipation the copper doesnt even make contact with the transformers.
> 
> 
> 
> ...


Lies! Copper totally doesn't make a difference. In fact, you should give me that amp. 

Kidding, of course, that's a sweet amp.

Veering back on topic (sort of) -- it seems like copper of the quality needed for "audiophile" grade shielding raises the cost of materials beyond where they are viable for all but the high end decks (or equipment, otherwise). So by targeting the high end customer, who is more likely to want the copper shielded unit and see "value" for such a feature, so they can increase the price per unit to make up for the additional cost. Thus, the rarity, and why there's but a couple of units for sale currently with such a feature. Would that be fair to say?


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## Sarthos (Oct 29, 2010)

Well how high does it actually raise the price?

And just a quick calculation about that copper sheet
0.005 inch thick sheet * 18" wide by 4' long = 0.005" * 18" * 48"=4.32 in^3 of copper

A copper wire with 0.35" diameter by 4' long = (.35/2 ")^2 *pi * 48" = 4.62 in^3 of copper. And I know you can get that much wire for cheaper than the cost of the copper sheets, copper sheets just happen to be very overpriced from a retail standpoint.


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## The Baron Groog (Mar 15, 2010)

Sarthos said:


> I didn't realize that copper has the higher thermal coefficients, now I'm really interested to see what a copper chassis to an amp (or at least a copper skeleton to the chassis) would do.


Nothing, other then allow you to make a thinner more costly chassis. A copper skeleton would be pretty pointless if then mated to aluminium: copper may pull the heat away quicker, but if it then mates with alu the fastest rate it would be able to draw it away would be the rate at which the alu would be able to disperse it





Sarthos said:


> Although now that you mention it I have seen the copper slugs in computer heatsinks. I wonder if that might be worthwhile to try with an amp, actually open up the case and add copper slugs against the heatsinks and the chassis, just use either a high heat resin or solder them on there.


Again, if the alu can only disapate heat at one rate speeding the disapation into the alu would make no difference



Sarthos said:


> And it's not a matter of "catching" radio waves exactly, it's the matter of blocking them.
> 
> Yes, but how many cars actually do have NO external noise? It seems if the car has the volume all the way down you can almost always hear SOME noise. Now, whether the noise is internal or external is another question. Also, whether the noise can be heard or not is yet another.
> 
> That's what my OP was sorta about, is it really effective to do a copper chassis to act as a faraday cage?


The chassis of the radio will already act as a faraday cage-it conducts electricity and wraps around your radio...to that end your car is a faraday cage-unless it's a Vette/Lotus or something else primarily made of plastic/fibreglass.

Electroplating copper can leave a layer less than 0.1micrometer thick, so the actual amount of copper used will probably be less than a few grammes so cost will be low and perceived gain quite high-DEH-P88RS £600 and 3-way, DEX-P99RS £1400 and 4-way with a PURE COPPER coated CHASSIS

Marketing and looking hi-end, nothing more IMO.

Not an attack on yourself, your post just happened to encompass most of the discussion. I had, in the past, thought about copper plating my chassis on my 88RS-but after thinking over it for a while realised it'd be a lot of effort for no gain-except looking cool!


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## narvarr (Jan 20, 2009)

> Again, if the alu can only disapate heat at one rate speeding the disapation into the alu would make no difference


If I'm not mistaken, copper and aluminum draw heat at the same rate but aluminum dissipates it faster.

Sent from my X10i using Tapatalk


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## minbari (Mar 3, 2011)

The Baron Groog said:


> The chassis of the radio will already act as a faraday cage-it conducts electricity and wraps around your radio...*to that end your car is a faraday cage*-unless it's a Vette/Lotus or something else primarily made of plastic/fibreglass.


not true at all.  if that were true then your GPS, cellphone, etc wouldnt work. take a real faraday cage and put your cell phone in it. zero signal! trust me on this . we had a faraday cage the size of most people houses. when you went in there , you got no signal from anything!


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## narvarr (Jan 20, 2009)

Ok, my mistake, copper is more heat conductive than aluminum:
Thermal conductivity - the thermal conductivity of cop 394W/mK, is about twice that of aluminium and thirty times that of stainless steel. This means that copper is used in components where rapid heat transfer is essential. Exam include saucepan bottoms, heat exchangers, car and vehicle radiators and heat sinks in computers, disk drives an sets.

Sent from my X10i using Tapatalk


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## minbari (Mar 3, 2011)

narvarr said:


> If I'm not mistaken, copper and aluminum draw heat at the same rate but aluminum dissipates it faster.
> 
> Sent from my X10i using Tapatalk


you are mistaken. by alot  copper is 420 W/m.K aluminum is 267 W/m.K


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## narvarr (Jan 20, 2009)

minbari said:


> you are mistaken. by alot  copper is 420 W/m.K aluminum is 267 W/m.K


Umm, yeah, I just corrected myself.

Sent from my X10i using Tapatalk


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## The Baron Groog (Mar 15, 2010)

minbari said:


> not true at all. if that were true then your GPS, cellphone, etc wouldnt work. take a real faraday cage and put your cell phone in it. zero signal! trust me on this . we had a faraday cage the size of most people houses. when you went in there , you got no signal from anything!


Fortunately it works as one if your car is struck by lightening, or similar:

Top Gear - Richard Hammond struck by lightning in car - BBC - YouTube


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## minbari (Mar 3, 2011)

The Baron Groog said:


> Fortunately it works as one if your car is struck by lightening, or similar:
> 
> Top Gear - Richard Hammond struck by lightning in car - BBC - YouTube


not exactly true either. lightning will take the path of least resistance to ground. if it strikes your car it will instantly "arc" is way to ground around the metal chassis. if you are touching something metal at that second you will feel it. ( and probably be killed) for a car, it is still only a partial faraday cage. if you had a window open, for example. the lightning could enter your car with no issues what so ever.

Vehicles and Lightning - National Lightning Safety Institute


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## stalintc (Dec 6, 2007)

minbari said:


> not true at all. if that were true then your GPS, cellphone, etc wouldnt work. take a real faraday cage and put your cell phone in it. zero signal! trust me on this . we had a faraday cage the size of most people houses. when you went in there , you got no signal from anything!


Minbari: I agree technically with your point. Since there is glass, the cage is not complete, therefore making it either a really poor Faraday cage, or technically not one at all. However, I want to add that if you replace the glass with something like a conductive metal foil (or wrap the glass portions with it and ground it to the chassis) you will find that reception is nearly impossible for GPS, cell phone, etc. This is because it "completes" the cage. 

I have done this experiment in a lab and in the parking lot outside of the lab. While the results found that covering the glass as I said above does increase the ability to block radiated electric fields, it did not perform as well as placing the car in an actual copper mesh Faraday cage.

-Stalintc


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## minbari (Mar 3, 2011)

stalintc said:


> Minbari: I agree technically with your point. Since there is glass, the cage is not complete, therefore making it either a really poor Faraday cage, or technically not one at all. However, I want to add that if you replace the glass with something like a conductive metal foil (or wrap the glass portions with it and ground it to the chassis) you will find that reception is nearly impossible for GPS, cell phone, etc. This is because it "completes" the cage.
> 
> I have done this experiment in a lab and in the parking lot outside of the lab. While the results found that covering the glass as I said above does increase the ability to block radiated electric fields, it did not perform as well as placing the car in an actual copper mesh Faraday cage.
> 
> -Stalintc


complettely agree. its the glass that allows communication. it is also what lets in other RF interfereance.


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## chad (Jun 30, 2005)

there's so much **** RF-wise in a car that the car body is just doing a fantastic job of protecting the outside world.

Toss a RF spectrum analyzer in a car and prepare to shart. OR peruse e-ham or any other RF based forum. or even google ford fuel pump RFI, my Honda is incredibly noisy too. not only fuel pump but ECU.


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## UNBROKEN (Sep 25, 2009)

You want fuel pump noise...I'll send you the 200 gph race pump I use on my truck. It doesn't induce noise...it friggin makes it. Damned thing sounds like a leaf blower when it's running. lol


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## mullenmullen (May 1, 2010)

Not exactly head units,but for knowledge purposes.i have a few pioneer prs-a900 amps. in the closet that implement the use of copper plating covers on the bottom,and also to section off areas internally.theoretically, "to block r.f. noise".i know all of the o.d.r. pieces use copper plating bottom covers as well. i don't know how effective they actually are.i'd love to see test results?just my .02,

scott.


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## Sarthos (Oct 29, 2010)

A car does indeed act as a faraday cage, but definitely not a perfect one. It's sorta like how a piece of paper will work to block sound, just not much.

I'm curious, since aluminum is much cheaper than copper, how effective might it be to enclose a things like a signal processor or my HU brain in a thick aluminum case? The thick aluminum would act as a better faraday cage than thin copper I would assume, also be easier to work with and cheaper.


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## Orion525iT (Mar 6, 2011)

minbari said:


> wouldnt do a thing. you cant "suck" the noise out of the air with a magnet, lol.


Not what I was getting at. Its a question of a having a large magnetic field (the sub magnet and coil) inches away from the head unit. Then, would this cause a problem? Would a copper jacket be a solution?


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## Sarthos (Oct 29, 2010)

I dunno how close or how big of a magnet, but you might need to make a pretty good one if it's a large magnet and very close. I'm not sure about the LCD screens on headunits, but I know that large magnets can destroy something like a TV screen.


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## minbari (Mar 3, 2011)

Orion525iT said:


> Not what I was getting at. Its a question of a having a large magnetic field (the sub magnet and coil) inches away from the head unit. Then, would this cause a problem? Would a copper jacket be a solution?


wont make any difference. any magnetism of the coil is contained by the permanent magnet. permanent magnets dont have enough gause to effect thier surroundings very far. ( and TBO, most HU are already well shielded by the chassis. just because it isnt copper doesnt mean it isnt shielded.)



> I dunno how close or how big of a magnet, but you might need to make a pretty good one if it's a large magnet and very close. I'm not sure about the LCD screens on headunits, but I know that large magnets can destroy something like a TV screen.


that is because CRTs use an electron gun to shoot electrons to strike a phosphorus screen. when you put a magnet near the tube, you pull the electrons off target and you get that nice distorted picture. (most TVs auto de-gause and will fix that by itself after you remove the offending magnet)

LCD is totally different. just turns little light valves on and off electronically. only way a magnet could effect those is if the gause was strong enough to stop the electrons in the wire  (BTW, that is like particle accelerator style gause)


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## Sarthos (Oct 29, 2010)

Hmm, I've seen tvs permanently damaged by the magnet. And I totally forgot about the tubes, even though I learned that quite specifically in Physics before. 

I don't know how close or how big of a magnet we're talking here though, that's where my concern was. If it's a GIANT magnet and a few inches from the thing I'd think it could be problematic.


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## Navy Chief (Jun 14, 2010)

I see there is alot of conversation in here about copper plating on amps. So here is my question. I am looking at getting my PPI A1200 and 2350DM chrome plated. Since chrome plating requires copper plating first would that provide some sonic improvement potentially. Also what do you guys think of just having my amps copper plated and then clear coated to prevent corrosion. The chrome plater said it would be cheaper to just do the copper dip. I have never seen an all copper PPI, what do you guys think.


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## Darth SQ (Sep 17, 2010)

Navy Chief said:


> I see there is alot of conversation in here about copper plating on amps. So here is my question. I am looking at getting my PPI A1200 and 2350DM chrome plated. Since chrome plating requires copper plating first would that provide some sonic improvement potentially. Also what do you guys think of just having my amps copper plated and then clear coated to prevent corrosion. The chrome plater said it would be cheaper to just do the copper dip. I have never seen an all copper PPI, what do you guys think.


That would be....AWESOME!

What does the plater say about longevity with clear coating over copper?

Bret
PPI-ART COLLECTOR


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## Navy Chief (Jun 14, 2010)

I haven't asked him But I looked up a product called Incralac. It is a clear coat specifically for copper. It has studies that after 10 years it is still holding up. I only have $100 in the A1200 so I figure even if it's a few hundred dollars I can break even. I loaded both amps in the truck to take to the plater hopefully tomorrow to get an estimate.


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## Darth SQ (Sep 17, 2010)

Navy Chief said:


> I haven't asked him But I looked up a product called Incralac. It is a clear coat specifically for copper. It has studies that after 10 years it is still holding up. I only have $100 in the A1200 so I figure even if it's a few hundred dollars I can break even. I loaded both amps in the truck to take to the plater hopefully tomorrow to get an estimate.


Definitely need pics when it's done. 

Bret
PPI-ART COLLECTOR


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## Navy Chief (Jun 14, 2010)

So I went to see the Plater today. $250 to do the 2350DM and $300 to do the A1200. Even though the 2350DM is a bit bigger it will cost less because it has a steel shroud where the A1200 has an aluminum heat sink aluminum apparently is much harder to plate then steel. This is a bit more than I wanted to spend, I would have $400 into the A1200 and $750 into the 2350DM, what do you guys think is it worth it. For a comparison its about $150 per amp for powdercoating.


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## fisc2307 (Oct 29, 2011)

Sarthos said:


> Also, if this is useful on headunits, why is it not done to amplifiers? Is it because the thicker aluminum case on an amplifier acts as a Faraday cage, whereas the chassis on a headunit is too thin to act as a cage unless it's copper plated? Or it it because the copper would be problematic as a heatsink? I'd think the copper chassis on an amp would make a better ground, and would fight interference so I'm not sure why they don't use copper in the chassis (perhaps due to copper corroding worse than aluminum?) Or is it just that the nature of an amplifier's internals don't pick up the same interference as that of a headunit?
> 
> And finally, in order to completely stop interference in your car's signal, why don't people use more Faraday cages? I've seen so many systems where background noise and humming ruins the overall experience it's sickening. Couldn't someone easily modify a system so that speaker wires, RCA cables, headunit, amps, etc. are all caged and stop most interference?
> 
> Anyway, end rant.


Let me see if I can help. The reason it is not important for amplifiers but done for head units are two fold. First the primary decoding and processing are done on board the head unit, because of this any interferense or noise that is introduced here will be aplified by the amplifier, making it far worse. Secondly, the amplifier is generall installed in the rear of the vehcile, away from most of the wires and elextronics that would produce a magnetic filed. The head unit is installed in the front, where all of the wires and electronics have to pass through. Think about how many wires you could see when you pulled the dash apart. There are cables that are magnetically shielded via a copper sheath between the insulation, additionally RCA cables are twisted in such a way to cause opposing interference the the magnetic field essentially negating it. Power cables do not need insualtion usually, and speaker cable already has an aplified current so interference added at this point is negligible. Lastly you can actually put a magnetic ring around your cable to filter out noise and clean up the signal. You sometimes see this as black plastic cylinders on USB cables or power cables for small electronics.


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## envisionelec (Dec 14, 2005)

Long-ass thread with no real answers - again.

The copper plating is bogus. It means nothing for a standard headunit with a steel chassis. If a magnet sticks to the chassis, the electrically beneficial effect of copper is absolutely nil! 

Now, let's make it out of copper. Non-ferrous metals perform RF shielding better than ferrous metals because of their inability to 'store' a magnetic field. This is critical because you don't want to change the shielding characteristics of the chassis at any given time. Say a big current collapses through some wiring in the dash (turning off the A/C clutch...yeah, probably not _these days_, but play along), the chassis becomes slightly magnetically charged and its ability to reject noise has changed somewhat. But really - in what way and _is it measureable? Is it even important?_ Probably not. The steel sleeve of a car stereo is sufficient to reject most noise found in vehicle dashboards. Note that old cassette players often had bad sheilding to the heads and picked up all kinds of noise. Thus, using a copper gauze or mu metal often reduced noise because the aperture size was reduced. Slots in any shield can permit certain wavelengths. Depending on the type of circuit, these high frequencies can be demodulated and end up making noise in your system.

When a manufacturer shields their RF sections/preamps with copper, it's because a change in an external magnetic field won't change the characteristics of the circuit and it improves measurement repeatability. When they shield a toroid or transformer, they are reducing the amount of EMI 'spray' from the windings. The copper cans on the toroids in the Sony amplifier (pics above) are almost certainly grounded, otherwise they'd serve no purpose.


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## GypsyLette (May 27, 2020)

TrickyRicky said:


> There are some car audio amplifiers that use copper chassis but very very few (can't even remember but am sure there is a few out there). But most likely copper traces. Also I've seen a bunch of Marantz home audio receivers that have copper chassis w/copper screws.



_ The Eclipse model 55060 has a copper chassis plus all the features of AM/FM radio, cd player, USB & bluetooth capabilities, plus a built-in crossover. It's a SUPER NICE car stereo to have and although a little older model, is still widely popular & their best the best-selling Eclipse model to this day. 🎶•Highly Recommended• if you're considered purchasing a copper chassis unit!_🎶


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## K-pop sucks (May 28, 2018)

GypsyLette said:


> _ The Eclipse model 55060 has a copper chassis plus all the features of AM/FM radio, cd player, USB & bluetooth capabilities, plus a built-in crossover. It's a SUPER NICE car stereo to have and although a little older model, is still widely popular & their best the best-selling Eclipse model to this day. 🎶•Highly Recommended• if you're considered purchasing a copper chassis unit!_🎶


Why would you revive a 9 year old thread?


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## Holmz (Jul 12, 2017)

At least it is interesting, I am just not sure there are many facts in the thread.

Does a faraday cage work against electric fields or magnetic?

And Mu Metals were not even mentioned.


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## carlthess40 (Aug 21, 2018)

I use Cooper sleeves for making power cables and when I make custom rca snakes for car audio.


























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## Holmz (Jul 12, 2017)

Where do you get ^that^ from?
I'll probably use stainless just to prevent damage, and a friend has a dog that likes to chew his cables at home, so he may use stainless and a 12V DC transformer into the stainless to stimulate the dog's gums.


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## carlthess40 (Aug 21, 2018)

That’s funny


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## Holmz (Jul 12, 2017)

His dogs are named after Norse Gods.
I told him we fight fire with fire, like fire fighters do back burns.
(I am pretty sure that the dog in question is the one named Thor.)


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## carlthess40 (Aug 21, 2018)

Back in the 90’s I had a dog named Thor, he was a crazy dog for sure


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