Hi All,
I'm going to take a tangent before getting to the point
<tangent>
I recently acquired a new [SnobFi - aka Classe DVD/SSP] system from ebay [for dirt cheap] and after hooking it up I got a really bad hum after turning on the amp. Strangely, the same interconnects were carrying signal from source components to my Class D AVR (and hooking the system back up to the AVR saw no hum).
After swapping a few cables out, the hum disappeared but that got me to thinking. All of my cables are > 15 years old and are probably due for retirement so I went out looking for new ones and nearly died when I saw the prices. It's impossible to get a decent cable for less than 20 quid, and they average 25+ (50+ quid for a 1.5m AES/UCB cable!?!?!?!)
So, the logical conclusion was that I could save myself a few hundred quid by DIY'ing my interconnects; naturally.
</tangent>
I've been googling interconnects quite a lot in my search for the perfect balance between performance, appearance [I'm shallow] and cost and I'm amazed by the prices that folks are charging for RCA and XLR plugs. What's got me wondering though all of the different platings that they put on these damned things.
Examples:
I get that they plate the conductors to prevent oxidization (of copper or silver) but doesn't that basically nullify any benefit (increased conductivity) of using the exotic materials in the first place?
If I'm understanding conductivity correctly, you can increase the amount of charge that you can pass through a conductor by increasing the mass of the conductor (thereby effectively matching the conductivity of a better conductor).
So, in the case of using rhodium over silver over brass, the brass has 10000x the mass of the plating so it's, by far, the best conductor in the chain. The silver is mega conductive and then we come to the rhodium, which is 1/3 as conductive as the silver.
Okay, rhodium is durable, I get that, but I don't get what the purpose of the silver plating under it is. It seems like an excuse to charge 10x the price for the plug and that's it.
And is all of this moot anyways because of the ultra low current signals that are expected to go through your interconnects?
What am I missing?
Cheers,
Dave.
I'm going to take a tangent before getting to the point
<tangent>
I recently acquired a new [SnobFi - aka Classe DVD/SSP] system from ebay [for dirt cheap] and after hooking it up I got a really bad hum after turning on the amp. Strangely, the same interconnects were carrying signal from source components to my Class D AVR (and hooking the system back up to the AVR saw no hum).
After swapping a few cables out, the hum disappeared but that got me to thinking. All of my cables are > 15 years old and are probably due for retirement so I went out looking for new ones and nearly died when I saw the prices. It's impossible to get a decent cable for less than 20 quid, and they average 25+ (50+ quid for a 1.5m AES/UCB cable!?!?!?!)
So, the logical conclusion was that I could save myself a few hundred quid by DIY'ing my interconnects; naturally.
</tangent>
I've been googling interconnects quite a lot in my search for the perfect balance between performance, appearance [I'm shallow] and cost and I'm amazed by the prices that folks are charging for RCA and XLR plugs. What's got me wondering though all of the different platings that they put on these damned things.
Examples:
- Solid brass, silver plated then rhodium plated
- Solid copper, silver plated then rhodium plated
- Solid silver conductor
- Solid Copper, lacquered to prevent oxidation
I get that they plate the conductors to prevent oxidization (of copper or silver) but doesn't that basically nullify any benefit (increased conductivity) of using the exotic materials in the first place?
If I'm understanding conductivity correctly, you can increase the amount of charge that you can pass through a conductor by increasing the mass of the conductor (thereby effectively matching the conductivity of a better conductor).
So, in the case of using rhodium over silver over brass, the brass has 10000x the mass of the plating so it's, by far, the best conductor in the chain. The silver is mega conductive and then we come to the rhodium, which is 1/3 as conductive as the silver.
Okay, rhodium is durable, I get that, but I don't get what the purpose of the silver plating under it is. It seems like an excuse to charge 10x the price for the plug and that's it.
And is all of this moot anyways because of the ultra low current signals that are expected to go through your interconnects?
What am I missing?
Cheers,
Dave.
Bad hum sounds like a bad or broken connection.
While the purists will suggest the most expensive leads I personally just stick with basic leads like a mains lead for speaker wires and this works just fine.
However a piece of wire is not just a piece of wire. I did some research many years ago for a project and i was amazed how much the even the resistance of a piece of wire varies from manufacturer to manufacturer.
It is worth buying short lengths and testing the wire for resistance over a metre.
Another problem in amplifiers is connectors and I prefer to ditch them for soldered connections where possible.
While the purists will suggest the most expensive leads I personally just stick with basic leads like a mains lead for speaker wires and this works just fine.
However a piece of wire is not just a piece of wire. I did some research many years ago for a project and i was amazed how much the even the resistance of a piece of wire varies from manufacturer to manufacturer.
It is worth buying short lengths and testing the wire for resistance over a metre.
Another problem in amplifiers is connectors and I prefer to ditch them for soldered connections where possible.
@nigel,
Interesting re: soldering, I've read that non-soldered connections are better; interesting.
Interesting re: soldering, I've read that non-soldered connections are better; interesting.
Yes but whoever wrote that has no clue! Crimp connections with proper tooling has advantages but not for audio. Solder is at least 200 time better by measurement.
Use an ohmmeter to be sure all the shields are actually carried to each end. Hum is usually a loose connector. Use deoxit on the connectors, be sure they are tight. Many prefer the sound of older cables.
Ah yes, many's the evening I like to sit in the garden shed and rub linseed oil from a rusty tin into some much-loved cotton covered silver wire that's been passed down through the family for generations. They say that when it was new it was a bit sibilant and had a narrow soundstage, but it's a deep chestnut colour now and sounds beautiful.
cables
hi,
Just from my own experiences,I have found the yellow cable that usually comes with 2 audio cables to work the best ,I have found 2 types one is thin about a 1/8 of a inch,don't like it,the other size is almost a 1/4 inch it does the best sound wise and it works for a spdif cable, The 1/4 inch was compared to some other costly cables and the owners of the cable that was more expensive chose the 1/4 yellow and I was the one that switch them on him twice ,just my 2 cents,I haven't listen to the hundred $ or so more cables or some of the made for audio types,I have tried gold ,silver,and plated copper cores and can't tell alot of difference,I have experamented with 4" wires between componets just to see what cables do, The best length I have found especially for spdif is a meter,for speakers to a amp short as you can get them I used zip cord,14 ga.
I haven't tried cramolin B-5 or deoxit but acetone and pure alchol I have used and does work,check before and after you use it with a ohms meter and you can see,Check a soldered and a unsoldered connection (like rca,bnc plug) too,Just my 2 Cents!
hi,
Just from my own experiences,I have found the yellow cable that usually comes with 2 audio cables to work the best ,I have found 2 types one is thin about a 1/8 of a inch,don't like it,the other size is almost a 1/4 inch it does the best sound wise and it works for a spdif cable, The 1/4 inch was compared to some other costly cables and the owners of the cable that was more expensive chose the 1/4 yellow and I was the one that switch them on him twice ,just my 2 cents,I haven't listen to the hundred $ or so more cables or some of the made for audio types,I have tried gold ,silver,and plated copper cores and can't tell alot of difference,I have experamented with 4" wires between componets just to see what cables do, The best length I have found especially for spdif is a meter,for speakers to a amp short as you can get them I used zip cord,14 ga.
I haven't tried cramolin B-5 or deoxit but acetone and pure alchol I have used and does work,check before and after you use it with a ohms meter and you can see,Check a soldered and a unsoldered connection (like rca,bnc plug) too,Just my 2 Cents!
I really don't know what "lacquered" means in this situation, it seems the contacts would have to scrape through the lacquer to actually touch metal to metal and make the connection.
Well, there's two things - there's the cross-section of the actual wire in the cable - resistance is inversely proportional to cross area (meaning a fatter wire is better), and directly proportional to length (meaning a shorter wire is better). But this is only important in very low-impedance connections, between an amplifier and a speaker. At line level, the resistance of even a thousand feet of wire is insignificant (but not its capacitance, but putting that aside...).
The other thing is the connector, specifically the mating between two connectors. This is critical in all cases, as the mechanical connection can be too weak (especially in RCA connectors) and/or too corroded to make a good electrical connection. That's partly what all these different platings are about.
It has nothing to do with the overall conductivity of the metal, but rather how easily it can get tarnished and how well it conducts when it touches the metal contact in the other connector.
I don't know about this specifically, but what I recall reading about material A (the base metal of the contact )plated with B and then with C (the metal chosen to make good contact with the other connector) is that there's some good technical/mechanical/chemical reason that A plated with C won't work well, however A and C both get along well with B. Maybe someone with metallurgy and plating knowledge could be more specific. It's not about "what sandwich of metals makes the best conductor."
Yes and no - I do recall XLR connectors can carry a good bit of current, but none of that matters if connector surfaces are corroded and conduct badly if at all.
OTOH, I just use cheap cables and connectors (any "good" stuff I have is made with Belden and Neutrix), and when needed I wipe/clean any crud off the contacts and use "tweak" or whatever other contact deoxidizer that's available.
Oh goody!! another cabling-type thread...just what DIY Audio needs!!
technically, the short answer to your plating ?'s is
Copper can be a good conductor, but it corrodes, and then has poor surface conductivity... ditto for brass... what to do auntie Bee???
Why, let's plate them with sumthin better... maybe gold?? naw too expensive, and unless you put some of that nasty ole nickel under it, the copper will jump right thru the gold over time (known in the trade as a diffusion barrier)... and we all know that nickel just plain sounds cheap and cheesey, right?
How bout silver??? well the military uses alot of it, 'cause the corrosion products can be conductive (but not always)... okay, let's put a teeny weeny bit-o-rhodium (an uber$$$$ precious metal, but it's hard as H^%l and resists corrosion to anything except boiling 85% sulfuric acid) like maybe .000010" maximum.. yeah that works (used in microwave plumbing when cost is no object)
Does this clear things up???
I myself use el-cheap-o gold plated whatever I can find... seem to work for years, I usually toss the equipment b4 the cables wear out...
John L.
technically, the short answer to your plating ?'s is
Copper can be a good conductor, but it corrodes, and then has poor surface conductivity... ditto for brass... what to do auntie Bee???
Why, let's plate them with sumthin better... maybe gold?? naw too expensive, and unless you put some of that nasty ole nickel under it, the copper will jump right thru the gold over time (known in the trade as a diffusion barrier)... and we all know that nickel just plain sounds cheap and cheesey, right?
How bout silver??? well the military uses alot of it, 'cause the corrosion products can be conductive (but not always)... okay, let's put a teeny weeny bit-o-rhodium (an uber$$$$ precious metal, but it's hard as H^%l and resists corrosion to anything except boiling 85% sulfuric acid) like maybe .000010" maximum.. yeah that works (used in microwave plumbing when cost is no object)
Does this clear things up???
I myself use el-cheap-o gold plated whatever I can find... seem to work for years, I usually toss the equipment b4 the cables wear out...
John L.
Keep in mind that the good 'ol RCA plug/socket is a hideously bad design, done way back in prehistoric times with low cost being the #1, #2 and #3 criteria. Plating it with gold is sorta polishing a turd, but it's better than nothing. I've used all sorts of connectors and frankly can't tell the difference between expensive gold and tinned brass as long as they're clean and have good tension. A shot of Caig DeOxit is a good idea too. BTW, never twist an RCA connector as you'll like as not twist off the center conductor of the wire if the pin turns. IMHO, the wire you use is more important than the connector, if the connector is at least halfway decent. Also, be absolutely sure to clean off all the flux after soldering. Rosin films will give you bad connections and water washable flux will corrode everything, giving you bad connections.
Last edited:
This isn't a cable thread, it's a materials thread. I couldn't find an thread that answered my question, ergo...
Yes, I get the point behind the plating.
Not really, it just added more detail to statements that I said that I already understood.
This thread isn't about cables. Even cheapo cables are 7quid a pop and 15quid for an XLR. Given that I'm looking at buyin around 14 cables, that still comes out to be a remarkable amount of money.
Ergo the question about materials... so I can understand the point behind the different platings and whether their chemical composition and/or layering should play a factor in my purchasing decisions for when I diy my own cables.
But again, this is not a cable thread.
Dfidler,
Auplater opened with a "cabling-type thread" comment. Get beyond that and his post is significantly only about materials.
Auplater opened with a "cabling-type thread" comment. Get beyond that and his post is significantly only about materials.
Thanks for the advice and I'll take it under advisement, but I'm more interested in the material properties for the plugs than the wire.
Hmm, reading it a second time, you're right. But only because of benb's claim that...
Because auplater didn't restate that in his post, I took his post to be a restatement of what I already knew... that plating prevents corrosion. I was still stuck on the conductivity of the materials and the justifications for them.
But now that I think on it a bit more, the "cross section" of material in the plug (aka the conductor) that touches both the cable and the terminal is pretty huge in terms of "wire gauge".
I guess my problem is that the way that I envision conductivity working alot like fluid dynamics, such that electrons are water molecules traveling through sponges of different densities (more dense = less conductive).
When the water molecules hit the 'silver' sponge (less dense/more conductive), it travels laterally through the sponge because it is the path of least resistance. But because that is so thin, it saturates very quickly and so the force behind the water (voltage) pushes the water into the denser medium which allows the water to soak through it more slowly, until it's forced back through the outer plating (again) once the entire 'conductor' is saturated.
That same image is what bothered me about rhodium, which is a very dense sponge, even though it's really thin, it would add an initial resistance to the water before it could get through to the more conductive (less dense) inner layers. So in my mind it acted like a barrier (resistance) to conducting the signal.
But the more I think about it, you're right, it doesn't matter. I was thinking of the start state of my sponges as being dry but that's wrong; they start off 'saturated' so applying more water (under force) and the thickness of outer 'rhodium' sponge is so thin (but with a very large cross section) means that it doesn't add a great deal of resistance to the overall system.
My apologies auplater. You were trying to answer my question, I just wasn't getting your drift.
In fact, the more I think about this, envisioning the fluid flows through my different sponges is making quite a lot of sense in how the electrons flow through the different materials, especially starting from a state of saturation.
I get it now, thanks.
Electons only travel at 8.4mm per hour, though the electrons are important for signals it is how the wave travels down the waveguide (bit of wire PCB track etc) and how it interacts with the dialectric. The conductance of materials (G) is the repricrical of resistance (If my memory serves me). The better the conductance the less resistance a given material will have to the flow of current.
The signal will travel at a speed determined by the Er of the dialectric sourounding the wire.
I will have a look at some of the stuff I've got on transmission lines as they use conductance, as it is not often considered normally, we tend to use resistance, and my interest is pipped. I have been looking at high speed digital signal transmission, but would presume the same basic principles apply.
The signal will travel at a speed determined by the Er of the dialectric sourounding the wire.
I will have a look at some of the stuff I've got on transmission lines as they use conductance, as it is not often considered normally, we tend to use resistance, and my interest is pipped. I have been looking at high speed digital signal transmission, but would presume the same basic principles apply.
would it be reasonable to expect the electrons in other atoms (metals) to travel at a similar speed?
Average speed of electron flow along a wire.
Average speed of the wave/impulse along the wire.
These are quite different question that deserve different analysis.
The "speed" of an electron in a stationary state has no relevance (as well as no real meaning- if I were dictator for a day, I'd clean every one of those planetary pictures of atoms out of science textbooks).
The main thing here is, as others have noted, contact integrity. With a low source impedance and a high load impedance, the differences in conductivity of the metals for 0.1% of the path is pretty insignificant to the transfer function (really, really close to 1). Contact resistance overwhelms it.
The main thing here is, as others have noted, contact integrity. With a low source impedance and a high load impedance, the differences in conductivity of the metals for 0.1% of the path is pretty insignificant to the transfer function (really, really close to 1). Contact resistance overwhelms it.
Andrew,:
electrons travel very slowly through wire when conducting signals, look it up.
speed of electrons
A signal travels down a wire or a PCB track at different velocitys depending on the dielectric, the structure of the cable etc, but ranges from 85%*C for some coaxial cables to approx 60%*C average for FR4 PCB's, tyhe speed depends on the velocity factro which depend on the Er of the dialectric.
Again thinking about this, I also thin k withing certain parameters and frequency range and differences in conductance will be more tha masked by other probolems such as contact resistance. When defining a system we work on a basic figure range of 15-30mOhms per contact, when we work out the influence on adding interconnects, and where we require a lower resistance figure we use more contacts.
When you do PCB design for high speed digital, these things are a part of your everyday life, as you are looking at a signal travelling down a wire/track, not a voltage at some point at some time.
Error I put 8.4mm per hour for average speed of electrons in a wire for signals I belive it should ahave been 8.4cm per hour.
electrons travel very slowly through wire when conducting signals, look it up.
speed of electrons
A signal travels down a wire or a PCB track at different velocitys depending on the dielectric, the structure of the cable etc, but ranges from 85%*C for some coaxial cables to approx 60%*C average for FR4 PCB's, tyhe speed depends on the velocity factro which depend on the Er of the dialectric.
Again thinking about this, I also thin k withing certain parameters and frequency range and differences in conductance will be more tha masked by other probolems such as contact resistance. When defining a system we work on a basic figure range of 15-30mOhms per contact, when we work out the influence on adding interconnects, and where we require a lower resistance figure we use more contacts.
When you do PCB design for high speed digital, these things are a part of your everyday life, as you are looking at a signal travelling down a wire/track, not a voltage at some point at some time.
Error I put 8.4mm per hour for average speed of electrons in a wire for signals I belive it should ahave been 8.4cm per hour.
Last edited:
I am currently going back to basics and reading Ralph Morrisons book, The Fields of Electronics, to get a different perspective on the transmission of signals. This is tied in to the re education we are going through due to the ever increasing speed of our digital sections.
I think looking at signals both from the 'electronics' point of view (electrons) and the physics point of view (waves and fields) is probably the way to go.
I think looking at signals both from the 'electronics' point of view (electrons) and the physics point of view (waves and fields) is probably the way to go.
- Status
- Not open for further replies.