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RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum?

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In Reply to: RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? posted by greenamyer on September 19, 2012 at 21:08:11

I find it kind of surprising that nobody can write here and simply say....'they use 16ga solid Al'. or Maybe 'Magnepan uses 15ga tinned copper'......
or whatever.
Though aluminum, having no fatigue strength, will only take so many stress cycles if the crossover is worked on.
Too much is never enough

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RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - josh358 19:35:08 09/20/12 (19)
Probably because nobody had any reason to check. Why would they use aluminum? I don't think I've ever seen equipment wired with aluminum, other than speakers, where the mass/conductivity ratio is critical. Aluminum is hard to solder, its corrosion layer is non-conductive, it's susceptible to metal fatigue, and its bulky. I'm not sure why anyone would have a reason to check the gauge, either.
- Probably because nobody had any reason to check. - neolith 07:42:22 09/21/12 (3)
  Exactly. Right in keeping with the rest of the OP's posts.
  But for what it's worth, they use 16 stranded tin-coated copper. Check the "authentic" schematic for the MMG on the tweaks page.
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  - RE: Probably because nobody had any reason to check. - josh358 10:50:16 09/21/12 (2)
    Wendell apparently came across this thread because I just got an email from him that says "ALUMINUM wiring?????? Are you kidding me?" :-)
    - RE: Probably because nobody had any reason to check. - Emsquare 11:39:16 09/21/12 (1)
      ???
      
      I would have laughed at the notion and assumed you were trying to fool me. And it's nowhere even close to April fools. So is the inductor aluminum wound as well? Let me check to see something... Nope, the sky is still pretty much blue so there goes that theory.
      
      I got nothing.
      
      Tom Waits, Cooler than you for thirty years.
      - RE: Probably because nobody had any reason to check. - josh358 14:04:53 09/21/12 (0)
        
        In Reply to: RE: Probably because nobody had any reason to check. posted by Emsquare on September 21, 2012 at 11:39:16
        
        Nope, the inductor isn't aluminum wound, except in the ultra-low-mass model on the ISS.
- RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - pictureguy 20:59:33 09/20/12 (14)
  Josh, you're old enough to remember when, for a couple years, houses were wired with Aluminum. Of course, after a few fires due to wrong connectors....that nonsense stopped.
  Yep, as it turns out, aluminum has NO fatigue limit. Every stress cycle eats into its lifetime. Steel and Titanium....to name just 2 metals, have an infinite life as long as the fatigue limit is not exceeded.
  But that's not especially relavent to internal speaker wire. Internal wire is probably 2x sized to max anticipated current (8 to 10 amps in my 1.6s) and is as short as practical to keep resistance down..though in such short lengths, who cares?
  
  One day, when I do the big-rewire/crossover, I'll know internal wiring size and composition for sure.
  
  As for not having any reason to check? I find that a little un-extreme for this crowd who will go thru every aspect of the speakers in a effort to optimize or improve every facet of the electrical and mechanical aspects of the design.
  
  As usual.....cheers:
  
  Too much is never enough
  - Metal fatigue - neolith 19:07:24 09/21/12 (5)
    Copper has no fatigue limit either although its fatigue strength is a bit higher than aluminum. Fatigue strength is the stress level that causes failure at some fixed number of cycles (typically 10 million cycles). The stress applied on the speaker hookup wire (aluminum or copper) is so low that the endurance time is well beyond the reasonable lifetime of the speaker. Unlike steel, failure will eventually occur but this is not a factor in choosing aluminum v. copper. There are obviously other factors that go into this decision - mostly conductivity. Cost is also not a consideration as aluminum is cheaper than copper. For power transmission lines the lower weight and cheaper cost make aluminum preferrable to copper but again fatigue strength is not a factor.
    
    BTW, this thread has become much more erudite than the OP ever dreamed of.
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    - RE: Metal fatigue - pictureguy 12:29:31 09/22/12 (0)
      I wanted to add something...perhaps 'picky'.
      My understanding of fatigue limit it is that stress level under which the test piece has essentially no wear from the stress. ABove the fatigue limit, you being eating into the ultimate lifetime. In Bicycles, some riders complain of a bike going 'soft' after part of a season. This is nutty, given the high strenght steel they were talking about, the work hardened nature of same as well as the impossiblity of even the strongest rider exceeding the fatigue limits of the frame.
      The strength limit question is why an Aluminum structure can't take (full) advantage of the lower weight material. It's gotta be built stronger to make up for no fatigue strength. Aluminum bikes are also generally made with large diameter tubes (at least 6000 series) in order to minimize the 'soda straw' effect. Walls must be a certain %age of diameter to help in this factor......
      
      Too much is never enough
    - RE: Metal fatigue - pictureguy 20:07:04 09/21/12 (3)
      yes:
      My entrance to metalury was 25yrs as a semiconductor process guy in metals / thin films. I have a book on metalurgy for Bicycles here somewhere. That is in interesting read since it introduced me to some interesting insights about alloys.
      
      Now, back to Aluminum. I don't know offhand if Aluminum self-passivates. IOW, will the oxide 'crust' on the surfact propgate thru the entire piece or shell over and become impervious to further oxygen incursion?
      Silicon, for example, as used in semiconductors has a native oxide of 20 angstroms. That's IT at room temp. Steel...at least non-core10 alloys will simply eat all the way thru.....Look at that '56 Buick which spent a couple summers vacationing in Florida, for example...or a dozen winters in Chicago with salted roads.
      I don't know where Aluminum lies on this scale.
      The reason I bring this up is that The wires or ribbons of the panel itself are subject to lots of stress. I'd have to think thru whether it was mainly torsion or tension.....or as the ribbon flexes, it would be compressive on the bottom and tensile on the top? Anyway, Once you get micro flex cracks, is that IT, except for the time it takes to oxidize all the way thru? IF so, as the active conductor gets less and less cross sectional area, the current density goes UP as does the tendency to 'fuse' at very high levels......
      
      And this is WAY beyond this thread, but do you thank Magnepan has some SEMs of ribbons or wires after extensive use ot answer nutty questions like that?
      NOTE TO WENDEL::
      Too much is never enough
      - RE: Metal fatigue - neolith 07:01:18 09/22/12 (0)
        
        In Reply to: RE: Metal fatigue posted by pictureguy on September 21, 2012 at 20:07:04
        
        I agree with Andy, you bring up an interesting question. For sure, the aluminum wires corrode all the way through as this happened to a pair of MG-IIb's that I had. OTOH the ribbon's on my IIIa's were going on 30 yrs and would still be with me if I hadn't knocked over one of them causing it to rupture. I always thought that the aluminum oxide formed an impervious barrier to further oxidation but then why did the wire fall apart and why did the ribbons hold up? Ah, life's mysteries!
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      - Interesting point, pictureguy ... - andyr 01:15:01 09/22/12 (1)
        
        In Reply to: RE: Metal fatigue posted by pictureguy on September 21, 2012 at 20:07:04
        
        I assume the "QR foil" used on the latest models (and some previous models) is much thinner than the "round wire" which it replaced? (How else does it get approximately the same driver resistance, when it is 1/8" wide?)
        
        So will we get wire failure in these models in 10 years? (Whereas my 30-year old, 30g mid drivers would've been fine ... except the glue degraded. :-(( )
        
        Regards,
        
        Andy
        
        RE: Interesting point, pictureguy ... - josh358 13:16:01 09/22/12 (0)
        
        In Reply to: RE: Interesting point, pictureguy ... posted by andyr on September 22, 2012 at 01:15:01
        
        Not as far as I know. The quasi ribbon foil has been in use for many years -- it was first introduced in the midrange of the 20.1 -- and as far as I know, it hasn't deteriorated, though the adhesives used until ten years ago have. However, I haven't asked. In the case of the ribbons, the word is that they will eventually develop metal fatigue and fail if played at very high levels, but will last indefinitely if not. Judging by reports of levels and ribbon replacements on the forums, for most audiophiles, it will be forever. But Satie's would be at risk (though AFAIK, his haven't ever failed).
        
        You could figure out how the maximum deflection of the ribbons compares to that of the midrange and bass ribbons by looking at frequency and area, but I'm not sure the comparison would tell you anything, since the ribbons are pleated and tacked down. I gather from what people report that failures tend to occur at the points where they're attached and experience the most stress, though again, it's not something I've confirmed.
  - RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - josh358 05:45:02 09/21/12 (5)
    I think a few people have replaced the internal wiring, but if you did that, you probably wouldn't be interested in what's already there, since your goal would be to replace it with something made from the smoked tongues of Albanian cherry bats.
    
    Anyway, in my opinion, checking for aluminum crossover wiring would be like checking a condom to see if it's made of cheesecloth: one hopes that it isn't, but doesn't generally have cause to suspect that it is.
    - RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - Roger Gustavsson 07:36:26 09/21/12 (4)
      Aluminium is not such a bad conductor (except it will be easily brooken). The short length of wire inside a Magnepan speaker does not really make a difference. I think the many connections in the signal path are of more concern. All these push-on tabs and crimp connections of various materials (aluminium, copper and steel). In the long term, some galvanic reactions can become a problem. I removed the connecting plates of my speakers (MG 3.6), http://twin-x.com/groupdiy/albums/userpics/2~6.jpg I will make new ones in the future with a reduced number of connections. Most of them will be soldered, even the fuses, the rest will be gold plated ones (high quality bananas from Multi Contact). The external crossover will not be used, it will be replaced with an active filter (slopes identical to the passive filter).
      - RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - josh358 10:48:13 09/21/12 (3)
        
        In Reply to: RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? posted by Roger Gustavsson on September 21, 2012 at 07:36:26
        
        I used to have trouble with the jumpers that connected the panels on my 1-D's. They'd get crackly. Of course, I used to move the panels around so they flexed, not to mention that in those days a lot of people smoked.
        
        Flexing shouldn't be a problem inside the speakers but as you say galvanic reactions could occur where dissimilar metals are in contact, particularly in humid and salt air environments. Still, crimp connections seem to be reliable even where dissimilar metals are involved as they almost always are. I assume that this is because the crimps are gas tight, and keep out moisture -- no electrolyte, no reaction.
        
        That wouldn't be true of the slip-on pressure connectors, but those would use the same plating. I imagine they're tight enough to prevent surface oxidation too, but once removed, it seems to me that they should be cleaned with Deoxit since they won't seat again in exactly the same place. I've often seen clean and oxidized areas in disassembled connectors, depending on where they mated.
        
        Crimp connections aside, I always try to avoid mating dissimilar metals. I used to use Cramolin when I did, as far as I know that isn't available anymore but there's another corrosion prevention product whose name I can't remember that does the same thing.
        
        RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - pictureguy 11:45:53 09/21/12 (2)
        
        In Reply to: RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? posted by josh358 on September 21, 2012 at 10:48:13
        
        Galvanic or BiMetalic? BiMetalic junctions form thermocouples which produce a voltage in relation to temperature differences within the circuit. VeryVery tiny voltages to be sure, but cumulative?
        Does galvanic produce a voltage at the junction? I know copper oxide is a diode.
        I'm just thinking about the same thing as above....great number of connections, crimped and of dissimilar metals in a different way.
        
        Now, one other question. Al is used on the panel itself for very good reason. However, Aluminum has no fatigue limit so when being bent, even the tiny amount on a moving mylar diaphragm, what is the lifetime you can expect? Is / are microcracks the source of some corrosion which will eventually take the panel 'out'?
        Too much is never enough
        
        RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - josh358 14:02:22 09/21/12 (1)
        
        In Reply to: RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? posted by pictureguy on September 21, 2012 at 11:45:53
        
        Yes, dissimilar metals will produce a voltage at the junction in the presence of an electrolyte like moisture in the air. So as a general rule, you don't want to mate dissimilar metals. If you must, there are tables that let you choose metals with similar potentials.
        
        As you say, oxides (and just plain dirt) are semiconductors and corrosion will cause contact rectification that in small amounts produces a measurable increase in harmonic distortion and in high amounts is to my ears practically unlistenable.
        
        In practice, the aluminum wires do seem to break down after many, many years -- maybe three decades? That's just a very rough inference from some of the posts I've seen. However, I'm not sure how much of that has to do with metal fatigue and how much of it has to do with deep corrosion. Aluminum ribbons will eventually fail from metal fatigue if driven hard, if driven at typical levels they'll last indefinitely. I assume that last means they're being used within the linear portion of the stress/strain curve, at that point fatigue shouldn't occur.
        
        This is a practical problem with midrange ribbons as in the Apogees, they have higher excursion than tweeter ribbons so are prone to fatigue. The cost of servicing high in-warranty ribbon failures apparently contributed to Apogee's demise. The guys on DIY audio who have built midrange ribbons say they have to replace them periodically.
        
        RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? - pictureguy 17:10:41 09/21/12 (0)
        
        In Reply to: RE: What kind of hookup wire does Magnepan use in Crossover, stranded copper or stranded aluminum? posted by josh358 on September 21, 2012 at 14:02:22
        
        Doesn't even have to be moisture>
        For a thermocouple to work, the junctions just must be at a different temperature.
        Will this effect sound? Doubtful, considering that even at low levels, you are at a couple volts. While TCs vary by composition, only a few combinations work at room temp and produce more than a few MV.
        I just picked type 'J' at random. Other types will be more useful at lower temps......And indeed, they ALL, when properly calibrated against a reference 'cold junction' will read temps to within 'tenths' of a degree.
        Too much is never enough
        http://www.omega.com/temperature/Z/pdf/z203.pdf (Open in New Window)
  - "will go thru every aspect of the speakers in a effort to optimize or improve every facet of ..." .... - andyr 01:44:16 09/21/12 (1)
    I find it bizarre that anyone would think that Magnepan uses aluminium wire, and not copper wire, behind the backplate (from terminals through XO components to drivers). I can only assume that they must assume that, because there is good reason for Magnepan to use aluminium wire on the mylar, they must think Magnepan would continue its use off the mylar?
    
    (I would have posted against the OP's initial post but, because he refuses to register like us plebs ... I refuse to consider he's anything else than a troll ... and I don't answer trolls.)
    
    Given that we know Magnepan is extremely frugal with its manufacturing costs and given that Cu wire is the norm - and therefore very cheap - I'm wondering why someone would believe Magnepan would use esoteric (aluminium) wire, over standard Cu?
    
    It just doesn't make any sense - and, of course, aluminium has a higher resistance than Cu - so why would you use it? On the mylar, the situation is different: Magnepan wants:
    a) low mass, and
    b) relatively high resistance
    
    ... so aluminium is the right stuff. But for hookup - absoloootely not! :-))
    
    Regards,
    
    Andy
    - he's anything else than a troll ... and I don't answer trolls.) - neolith 07:57:00 09/21/12 (0)
      In principle, I agree wholeheartedly with you. However I don't think he's a troll, I think he is f*cking idiot. I define an idiot as someone with normal intelligence that refuses to think. People who have low IQ's should be treated with respect, kindness and tolerance; people who fail to put their brains in gear deserve contempt. A troll is someone who gets perverse pleasure out of annoying others and again deserves contempt. A fine line to be sure.
      
      "Men are the only animals that devote themselves, day in and day out, to making one another unhappy. It is an art like any other. Its virtuosi are called altruists."
      H. L. Mencken
      �
      
      �

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