RE: [USR-TC] The Balanced vs. Unbalanced discussion/definition...
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum. I am "Artist Formerly known as Brian Becker" with Benson Music Group, Nashville, (Christian Rock) and spent many hours working with top studios in Nashville & Houston...they would laugh at the thought of combining ground and shield. Brian Becker President, Poplar Bluff Internet, Inc. http://semo.net Home of TotallyFabricated.com Software & Web Design http://TotalScrutinizer.com - Tech Support Just Got Easier! POBox 190 - Poplar Bluff, MO 63902 - 573.686.9114 -----Original Message----- From: usr-tc-admin@mailman.xmission.com [mailto:usr-tc-admin@mailman.xmission.com] On Behalf Of Jeff Mcadams Sent: Wednesday, July 03, 2002 6:31 PM To: usr-tc@lists.xmission.com 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
AHHHH!! So which one is it?? There has to be an EE on this list somewhere. Charles -- Charles Sprickman spork@inch.com On Thu, 4 Jul 2002, Brian Becker wrote:
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum.
I am "Artist Formerly known as Brian Becker" with Benson Music Group, Nashville, (Christian Rock) and spent many hours working with top studios in Nashville & Houston...they would laugh at the thought of combining ground and shield.
Brian Becker President, Poplar Bluff Internet, Inc. http://semo.net
Home of TotallyFabricated.com Software & Web Design http://TotalScrutinizer.com - Tech Support Just Got Easier!
POBox 190 - Poplar Bluff, MO 63902 - 573.686.9114
-----Original Message----- From: usr-tc-admin@mailman.xmission.com [mailto:usr-tc-admin@mailman.xmission.com] On Behalf Of Jeff Mcadams Sent: Wednesday, July 03, 2002 6:31 PM To: usr-tc@lists.xmission.com 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
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AHHHH!! So which one is it??
There has to be an EE on this list somewhere.
Guilty as charged. Balanced signalling transmits a signal over a pair of conductors (usually referred to as "+" and "-") with opposite polarity in order to eliminate "common mode" distortion from external electromagnetic sources. EMF is induced equally in each of the two conductors and is cancelled out (to the extent of the common-mode rejection offered) at the receiving end of cable. No shield is technically required (unshielded twisted-pair [UTP] ethernet cabling is one example), but is often used, especially on analog (e.g. audio) cabling.
Charles
-- Charles Sprickman spork@inch.com
On Thu, 4 Jul 2002, Brian Becker wrote:
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum.
I am "Artist Formerly known as Brian Becker" with Benson Music Group, Nashville, (Christian Rock) and spent many hours working with top studios in Nashville & Houston...they would laugh at the thought of combining ground and shield.
Brian Becker President, Poplar Bluff Internet, Inc. http://semo.net
Home of TotallyFabricated.com Software & Web Design http://TotalScrutinizer.com - Tech Support Just Got Easier!
POBox 190 - Poplar Bluff, MO 63902 - 573.686.9114
-----Original Message----- From: usr-tc-admin@mailman.xmission.com [mailto:usr-tc-admin@mailman.xmission.com] On Behalf Of Jeff Mcadams Sent: Wednesday, July 03, 2002 6:31 PM To: usr-tc@lists.xmission.com 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
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-- ------------------------------------------------------------------------ Dave Martin Netcetera, Inc. dpm@netcetera.com "May the Foo be with you" ------------------------------------------------------------------------
On Thu, 4 Jul 2002, Brian Becker wrote:
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum.
In the more abstract case "balanced" refers to forcing or guaranteeing the return current follows the same path as the forward current, but just in reverse. - one could use a coax line and still be electrically balanced (as long as the devices at each end do not share a common electrical return) - one could have a paired line with a shield and still be unbalanced (if one leg of the line is tied to a common electrical point) It's not so much the type of physical cable in use that determines whether a line is balanced but how that cable is used electrically and whether there is a common electrical point (usually ground) between devices that might possibly allow some return electrical current through a different cable or path than the forward current. Whenever that happens, the likelihood of noise being picked up through electrical induction is significantly increased. I'll leave the physics explanation out... :)
Also sprach Brian Becker
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum.
I'm still skeptical that ground and shield are required for a signal to be considered balanced, although I don't doubt that they are used pretty much without fail in analog audio work. I believe, however, that I misstated what my uncle said earlier (having gone back and re-read his messages to me). I think his point was that there are seperate ground and shield lines, but he said that the shield is at ground potential...I made the (erroneous) mental jump of thinking that ground and shield were the same line.
I am "Artist Formerly known as Brian Becker" with Benson Music Group, Nashville, (Christian Rock) and spent many hours working with top studios in Nashville & Houston...they would laugh at the thought of combining ground and shield.
Man...all these years, the name "Brian Becker" was tickling the back of my mind somewhere...but the lack of context prevented me from ever making the connection. -- Jeff McAdams Email: jeffm@iglou.com Head Network Administrator Voice: (502) 966-3848 IgLou Internet Services (800) 436-4456
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Im looking at having a play with some older edgeservers.. (the older 486 based models).. Ive got the edgeserver NAC, but no nic for it... can anyone tell me about them, or point me in the direction of some edgeserver reference areas ?? What do they normally come with ? are they normally pre-loaded with anything ? are there any usr flash upgrades or anything i need to know about ? regards Steve -----BEGIN PGP SIGNATURE----- Version: PGP 7.1.1 iQA/AwUBPSUNQLzZ2D1wrS2iEQJ88gCdGSO9lvrsSsN831Sq6kVWPqbNac8An3Bn +c4/6Jy0KZElfmA1tCqIBtzp =nEPl -----END PGP SIGNATURE-----
On Thursday 04 July 2002 10:27 am, Brian Becker wrote:
Just as a comment...balanced is required to have a ground and a shield to be defined as balanced. Of course much of the audio gear can survive if the ground and shield are the same signal, but it is not part of the spec and all major recording studios will utilize separate and distinct paths for the ground and the shield to reduce the level of noise to its minimum. I know when I used to deal in a ton of analog phone circuits they were commonly referred to as balanced. Of course these were common UTP phone cables without ground. We merely "balanced" them by adjusting the outbound voltage levels with the inbound voltage levels. This helped eliminate some signal to noise problems as well as assuring that the audio out was "as loud" as the audio in.
Maybe the confusion comes from crossing disciplines. Each industry has its own terms, some of which conflict with other fields. -- Lewis Bergman Texas Communications 4309 Maple St. Abilene, TX 79602-8044 915-695-6962 ext 115
participants (7)
-
Antonio Querubin -
Brian Becker -
Charles Sprickman -
Dave Martin -
Jeff Mcadams -
Lewis Bergman -
Steve Monkhouse