Hi all To my knowledge this isn't a question of ground or not. A twisted pair cable is for example a balanced cable but a coaxial cable is un-balanced. When a TP cable is subjected to interference both wires are affected equally which means that the interference doesn't effect the signal at the end. When a coax cable is subjected to interference the outer conductor will be more affected than the core which means that more of the interference will be affecting the signal at the end. Pls correct me if I'm mistaken or don't remember correctly :) Regards Johannes Rognvaldsson Electronic technician -----Original Message----- From: Jeff Mcadams [mailto:jeffm@iglou.com] Sent: mið. 3.7.2002 23:30 To: usr-tc@lists.xmission.com Cc: Subject: [USR-TC] The Balanced vs. Unbalanced discussion/definition... OK...this is probably rather off-topic, but there were a couple of different people participating, and it might be of interest to some, so feel free to delete if you're not interested. Talked (via email) to my uncle who works for Sweetwater Sound (http://www.sweetwater.com) and owns his own sound studio on the side, about the use of the term "balanced" in audio gear. He said that the term wasn't precisely defined (gee, sounds like the data world!), but that in his opinion it didn't require a ground line to be considered a balanced signal. He basically said that virtual every cable type that you'll run across in audio work *does* have a ground line (sometimes, its also the shield), so its kinda a moot point, but that its not strictly required. Indeed, he pointed out that it can be a *bad* thing to have ubiquitously connected ground lines in audio work. He pointed out that the local ground of one piece of equipment may not be the same as the local ground of another piece of equipment, so since they are both grounded through their AC line, connecting the ground line between the two pieces of equipment can result in a voltage and waveform across the ground line, which can result in a hum in the signal. He mentioned that the way they avoid this problem in his studio (plug: DSL Studios, http://www.dslstudios.com...hosted by IgLou ;) was to have every connection between different pieces of equipment run through patch bays. Each piece of equipment has its own ground (through the AC line), and the patch bay itself (a passive piece of equipment) is also ground, but that the ground line in the cable is *not* connected to the ground of the patch bay. This ensures that there is no continuous ground connection between two different pieces of equipment and avoiding a ground loop. FWIW, he pointed out the use of the balancing concept at http://www.equitech.com...specifically "balanced power", ie, rather than having a hot line at 120VAC and a ground, you have two hot lines at 60VAC, but in opposite phase. When the power supplies in the equipment run by this looks at the two lines, it still sees 120VAC, but the opposite polarity of the lines means that the "reactive currents" coming back out of the power supply end up cancelling each other out, resulting in a significant noise reduction. I found it interesting that there's a third field where balancing is used. Anyway...this is probably way more than most of you wanted to know, but I found the mental excursion interesting, hopefully others have found the discussion enlightening as well. Let me know if anyone has questions, if I can't answer them, I'll get better answers from my uncle...he's *quite* knowledgeable about audio production. :) -- Jeff McAdams Email: jeffm@iglou.com Head Network Administrator Voice: (502) 966-3848 IgLou Internet Services (800) 436-4456 _______________________________________________ USR-TC mailing list USR-TC@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/usr-tc