1. Register NOW and become part of this fantastic knowledge base forum! This message will go away once you have registered.

Questions about soldering cables

Discussion in 'Accessories / Connections' started by Death addeR, Dec 19, 2003.

  1. Death addeR

    Death addeR Guest

    Hi everyone,

    I am getting ready (and practicing) soldering my own cables... I am using Neutrik balanced TRS connectors and Mogami balanced cable... anyway, my questions are:

    1) Should the ground/shield be soldered only to one connector? ... if so, why is it like this for balanced cables and not unbalanced? .. I heard it's something to do with the loop, but I still don't quite understand...

    2) Does it matter how much shield you solder to the connector? ... for example, if you cut off more than half of the copper(?) associated with the shield, will it make things different at all in the sound?

    3) Does it matter what type of solder you use? ...

    4) Is there any big soldering threads on this or another forum? ... I thought I saw one before, but couldn't find it when I looked again recently...

    Thanks a lot for anyone's help, I really appreciate it!
     
  2. Gary Gidak

    Gary Gidak Member

    As far as the balanced/unbalanced question is concerned - you can do a search on this site and find the information to help you out. I had similar questions a few months ago, and got a lot of good information from some of the members.

    For the soldering part, you'll want to use the best you can find. Stay away from "resin core" solder if possible, and if it's all you can find make sure you clean each connection with alcohol and a stiff brush. The resin core will leave behind a residue which is corrosive, and will eventually weaken the connection.

    I use liquid flux to prepare my connections before applying the solder. It's much cleaner than resin core, and makes the solder flow evenly around the connection. I don't know the name of the manufacturer of the flux, but it's a clear, blue liquid, and can be purchased at electronic supply stores. You should still clean the soldered connection with alcohol, regardless of which type you use. The liquid is just a bit cleaner, and makes for a nicer connection.

    Oh, one more piece of advice - when it comes to soldering do not adopt the moto: "The bigger the glob, the better the job." Use just enough to cover the wire, and the connector. You should be able to see the wrap of the wire beneath the solder. It should form a light coating upon whatever you apply it to.

    Do yourself a favor and "tin" the wires before you solder them to the connector. All you have to do is strip them down enough to reach the connector, and apply solder to the stripped end. This will also help the solder flow evenly.

    As far as the shield is concerned, don't worry if you strip an inch or so more of it than the conductor. Such small differences will not cause any problems. Good Luck.
     
  3. Death addeR

    Death addeR Guest

    Thanks for the help, this is useful information... luckily I have a soldering quasi-expert helping me, he has just never worked with balanced audio cables...

    if I may, though, I do have a couple of clarifications to make.. mostly about the shield talk...

    first off, what I meant by #2 is cutting off more strands, not length (sorry I stated that in such an abstract way)... for example, if there are 100 strands of copper on the shield (for sake of argument and ease), will it make any difference if you only attach 10 strands to the plug? ... or should you try to connect all 100 strands to the plug?

    Secondly I know a fair amount about balanced vs. unbalanced, just not the answer to that specific question... but, perhaps I haven't searched correctly :) ...but, to be more specific... what I understand is that an unbalanced cable needs the shield attached at both ends to make a ground loop ("send" and "return")... but, a balanced cable only needs the shield attached at one end, if at all, since the + and - signal creates the loop itself... my confusion is: how can two sends create a loop?? ... wouldn't, if anything, both the + and - need seperate shields attached at both ends? ... I do know, by diagrams I've found on this and other forums, that I am wrong here... but I don't know the why of it all...

    at any rate, thanks again for the information... even with my two slightly abstract questions, this is very useful and appreciated stuff...! :D
     
  4. audiotech

    audiotech Guest

    OK now
    Do not worry about the rosin thing. The oxigen free is the key as, oxigen creates a form of rust.
    I have been working on pro audio tube gear since the 60's and tho it maybe site-full, the rosin acts as a rust/deterioration preservative.
    NOTE: Buy and keep a "WET" sponge or cloth close by and clean your soldering tip and re-tin before each solder joint. The dehyderated flux/rosins create an insulation between the iron and your work. This is key. #2. Get your self some heat shrink. Your cables will frey and inter conect before the connection goes bad. Use the shrink any time that you can. It also makes for a good Strain releaf.
    #3.The sheild is always the cumbersom part. NO, you do not need all 100 strands, but, A lot of times we will use a single solid wire soldered into the sheild to make for easier work. Also it will still work if you do not, but I prefer taking the single solid and connecting it to pin and ground ... just to make sure. #4. When in Emorald studios with Glen Meadow's, he had several gals who did his soldering.
    They had this mechanical connection wrap that they did when ever possible. NOTE: They used a 20% silver solder that takes only a little more heat.
    Emarold was Glens answer to Reba's Star struck Studio on music row. Glen spend over 3,000,000. in just the design of this studio. He could not have a woman in Nashville with a larger studio than him. There are pictures of it on the net.(try and find them) It was like being in an 18,000. sq foot space ship.
    I hope that this helps you in understanding the connection.
     
  5. Death addeR

    Death addeR Guest

    Thanks!

    ...and for anyone interested, I finally found this:
    http://acapella.harmony-central.com/forums/showthread.php?s=111e50d97f08b6359e27851e27908d84&threadid=501771&highlight=solder
     
  6. ruffrecords

    ruffrecords Guest

  7. ruffrecords

    ruffrecords Guest

    There are three types of connection used in audio - unbalanced, balanced and balanced floating. In unbalanced the signal flows down the centre conductor and returns via the screen so the screen normaly needs to be connected at both ends to achieve this. However, where you have a lot of unbalanced connections between two pieces of equipment e.g a mixer and a multitrack recorder you have a lot of screens connected in parallel. These form ground loops which can induce hum and noise. In such cases it is common to cut the screen at one end of some, but not all, the connections to solve the problem.

    In a balanced connection there are two signal wires which carry equal but opposite polarity signals. These are subtracted at the receiving end and as a result any noise induced equally in the two signal wires is cancelled. In a normal balanced output the two signals are refered to a local ground (the screen) and similarly at the receive end. If the screen is connected at both ends there should in theory be no signal flow along the screen. This is because the return signal would be made up of two equal but opposite polarity signals which therefore cancel out. This means hum and noise due to ground loops (which are still present) is much less likely. Electronic balancing is never perfect so a small screen signal is present but it is normaly small enough not to cause problems. Since there is little or no screen current it is possible to disconnect the screen from one end of the cable. I would not recommend this because there is no way of knowing what is the relative dc potential between the two pieces of equipment and a large dc potential offset could damage the electonics.

    In a balanced floating connection a transformer is used at both ends of the connection. The signal from the sending transformer's secondary winding goes down one signal wire, through the receiving transformer's primary winding and back via the other signal wire to the other side of the sending secondary. There is therefore zero screen current and hence no need for a screen /return connection and the screen is there solely to reduce interference and so can be connected at one or both ends. Ground loops cannot occur because the screen (ground) connection never carries signal.

    HTH

    Ian
     

Share This Page