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I'm just about to DIY a balanced cable, and I'm not sure if I should use the same material and length for the ground wire.
My guess is that it does not matter. Without ground connection, there is terrible noise coming from the speakers (despite both the amp and premp being fully balanced), so I need to add a ground wire.Thanks in advance
Zozo
Follow Ups:
Check out this post:
http://www.AudioAsylum.com/audio/tweaks/messages/25544.htmlIf you need the pin 1 connection, then a simple 16 ga. wire will do the job OUTSIDE the shield braid, and doing it this way will avoid the residual leakage of ground line noise into the signal pair.
As for making any chassis connections, this should not be necessary with a balanced cable with pin 1 to pin 1 connected.
You mnetion you have two prong plugs on all your equipment, but are they all polarized, that is, is one plug a larger width than the other? If not, see:
http://www.AudioAsylum.com/audio/tweaks/messages/25544.htmlThis will help you minimize the AC leakage currents in your set-up, in so much as it is possible to do so.
Jon Risch
NT
By balanced connection I'm assuming that you mean the connection between the pre and the power amp. Is your interconnect shielded? If not you will get noise. Do you have a ground loop? If so you will get noise. For a very through examination of the cable thing with no hype go to the Rane site and check out RaneNotes 110 and 151. Contrary to specious claims by snakeoil purveyors/adherents the most important thing about your interconnects is how you build them, not what you build them from- see RaneNote 126.
Thank you for the reply, it was very useful indeed. Reading Rane's notes it seems that I have to connect the shield to the chassis at both end near the enty point, but how do I do that? Also pin 1 has to be connected to the chassis, too. How can I do that easily?
(There is no ground loop in my system, as none of my mains have a ground/earth wire).Thanks
Zozo
What are you using for connectors? Normally a balanced system would use either 3pin cannons or TRS phone plugs/jacks. In either case there are connections for two signal paths and one ground path. Which do you have? RaneNote 110 covers just about every possible scenario of different connectors and how to wire them.
Some of your problems could be arising from the fact that you have,apparantly, no chassis grounds. If your components were factory equipped with 2 prong AC supply plugs they probably have internal RF bypass caps, but if there are 3 prong plugs and the ground prong is simply not connected that could be problematic. Also, even if all your components have 2 prong AC mains the presence of ground loops is still possible. Once you get your interconnects made up you may find that the system has less noise/hum with the shield connected at one end only- try it both ways to be sure. If you have two cables connecting the pre and amp (for left/right) you may find it works best with one interconnect shield connected at both ends and one connected at one end only- again, try it both ways.
Thank you for your advice, I'll try to connect the shield in all possible ways.
The only thing I'm still not sure about is how to connect it to the chassis physically. Connecting the shield to pin 1 (on an XLR connector) seems difficult enough compared to a small wire, but I haven't got much idea how I can make the physical contact between the shield and the chassis (and pin 1 as suggested in Rane's notes).
I undestand the theory, just cannot see how it can be implemented in practice.As for the AC mains ground, I don't know if there is an RF bypass cap in the amps, but here in Japan wall sockets can only take two pronge plugs, so I suppose all equipment is design for these circumstances. (I have Accuphase and Luxman by the way).
Thanks in advance
Zozo
On the interior side of the XLR jack there is a lug which connects to the shell of the jack. Assuming that the shell is not isolated electrically from the chassis a jumper from pin 1 to that lug will ground pin 1 to the chassis- if there is not one there already, which is likely the case. There is a like arrangement on the XLR plug to connect pin 1 to the XLR shell. Soldering the shield to pin 1 of the plug should be no problem- strip the insulation back a couple of centimeters to allow you enough material to work with. You'd only have a problem with the shield if it is not tinned copper- if it is aluminum or foil with no associated wire then you might want to consider a different cable. Or check out solderless XLR plugs- Neutrik Easycon is one choice.
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