At home, I am on one outlet at least. When talking about balanced circuits, it's easy to think about things in terms of polarity, or degrees worth of phase flip, but this isn't really how it works - if you look at any waveform, it's not simply a mirror image, and phase of course, is a time function - while polarity is a different thing.
The phase buttons on mixers for years carried the phase title and symbol, but were just polarity reversers! We gliby promote balanced systems as having noise reduction properties, and telephones for years ran on unshielded cables, that were balanced, referenced to something else, and the something usually being ground. It's difficult to detail all this in a forum, because the full story is very complex, but easily googleable.
The usual explanation, which is the mass market simplified one, is that any interference hits both conductors equally, and because the device they are driving is simply quantifying how far the signal pulls away from 0v the differential tag often used any input applied to both cancels out and that is that. Two conductors that differ in capture area won't cancel completely, so the noise will be added.
In practice, all this noise reduction is only important at low level inputs - microphones typically. The interference vs the wanted signal. In a line level signal case, the ratio between any noise and the wanted signal is much, much greater, and the importance of balanced connections is much less. On the ground loop issue, it's critical to understand that not every hum is a ground loop. If we are using the screen of a cable to be a protection from external interference, then it needs to be at the same potential as ground.
Depending on the type of power delivered to your premises, your actual ground can be the real ground potential at your location, by a metal rod being buried in the actual ground, and the electrical ground is the same potential as the 'real' ground.
However, some types of supply bond the neutral conductor to this real ground where the power enters the building, while others supply the neutral and the live as totally floating sources. If your electrical system is grounded a fair way away, the it's possible for the neutral to be a few volts different from the ground in the outlet.
Equally, something in the room can also be connected to the real ground, so you can have multiple versions of 'ground'.
This is quite normal. The first problem we have is when items are grounded at different places, and then audio cables connect pieces of kit together. At some point, the mains ground at one potential gets connected to a ground of a different potential by the building ground wires, AND the cable screens. This difference circulates in the two paths in a loop, and because there is voltage difference, there will also be current flowing, and because of the mains frequency, it's very easy to generate significant audio levels at 60Hz or 50Hz.
Breaking the loop solves the problem. In a balanced circuit, it's simple - just lift a screen, the loop is broken, current flow stops and the hum vanishes. The screening function still works fine, because one end is still attached to a ground. Lifting the mains ground does the same job at one of the pieces of kit - BUT, especially in the UK with our higher V mains power, this is considered both stupid and legally problematic. We used to do it, but now, listen ground wires mean a test fail - as most places now regularly test appliances.
In XLR circuits, a simple male-female barely connector with no Pin 1 connection often cures ground loop hum. Worth always trying, as are the switches on things like DI boxes and transformer splits - they do the same thing. The usual advice to run everything from a single local outlet simply makes sure that the ground potential is that same on all devices connected.
One very brief warning about another hum inducing problem. With mains powered equipment that is properly designed the mains ground will also be attached, for sensible safety reasons to the chassis and case, if it has a 3 conductor mains cable. In a two conductor cable, often the figure 8 shaped ones, the metal work is all floating and not connected to ground at all - in the UK, we term it double insulated. If kit has 3 pin XLRs for balanced connection, it's considered bad form to connect Pin 1 to the chassis or external metalwork because if you screw it into a rack, all the metal is joined into one big unit, so any ground currents circulating away can easily be induced to flow in the cable grounds.
To sum up - I personally don't really bother with balanced circuits for line level as a preference. Making up a balanced to unbalanced cable is a pain, so if both bits of kit will run unbalanced, I'll take that choice.
If we're talking about microphones, then everything balanced, and I even have a few Star Quad cables Google them for the explanation which I use if I know interference is likely. I just bought a Radial JDI passive direct box today.
It's got the Jensen transformer. Sounds great! That's why I finally broke down today and bought one brand new. Top Mentioned Manufacturers. Facebook Twitter Reddit LinkedIn. Subscribe to our Newsletter. By using this site, you agree to our use of cookies.
Code by Port Forward. Hosted by Nimbus Hosting. Connect with Facebook. Apemandan 18th March What vocal mic did you use today RightOnRome. Plush 3 days ago. Radial stops using Jensen transformer in JDI duplex? Hard balanced outputs cannot be shorted to ground, however each phase is referenced to the chassis pin 3 ground, so you can treat them as two unbalanced outputs, out of phase with each other.
All Crookwood balanced outputs are hard outputs for audio fidelity reasons. RF however gets into analogue electronics and messes it about, creating odd background noises, distortions and sometimes audible noise. For all situations however:. Do not remove any mains safety earths. Check that nobody has already done this. If so, add them back. Death is permanent, hums can be fixed! The unbalanced gear will either be truly floating from ground, or connected to ground by the mains power, or by an external connection.
Examples of floating gear are passive things like dynamic or electret mics, battery powered things like phones, or ipads, or mains powered gear with a two pin mains connector, that are not earthed to anything else — plastic case, no other connectors except those going to the balanced gear. This configuration maximises the RF protection.
Connect the screen at the unbalanced gear for maximum RF protection. Note: shorting together pin 1 an 3 together on the floating output forces the output to float properly. Note: leaving pin 3 floating lets the hard balanced circuit work properly, and by connecting the grounds at both ends, you maximise RF rejection and minimise hum. The grounding and cold wire connections vary depending on the type of gear you connect to and from. While in many cases it may seem to work OK, no matter what you do, the above gives you the maximum RF and hum loop protection.
Unbalanced is unbalanced, balanced is balanced. Balaced uses out of phase signal leads and a ground. The pre amp detects the difference between the phased signal to produced a result and ignores in phase signals from both signal leads.
A standard jack lead will work fine over short distances but check for grounding issues in some cases. Sep 15, 3.
Posts: 10, To add to the above: Unbalanced lines two conductors, like a guitar cable are high impedance or "high Z. The simplest way is to use an in-line impedance matcher, which contains a little transformer in it. The matcher you need depends on your hookup scheme.
The problem with all this is you basically have a long 'stick' protruding from your equipment, if the cable gets yanked it can easily break the plug or the jack.
Note that an adapter and an impedance matcher are two different things. Blue Bill and Bill Moore like this. Sep 15, 4. Lowerleftcoast , nedorama and tubegeek like this. Sep 15, 5. Age: 61 Posts: 3, The TS connector inside the mixer will short the 'cold' signal to ground which is what the Mackie will need up at the other end.
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