Home studio - Balanced or unbalanced patchbay?

Discussion in 'Patchbays' started by quesne, Nov 30, 2008.

  1. quesne

    quesne Active Member

    I am not new to recording, but I am just getting around to setting up my first semi-pro home studio. A few pieces of equipment that I have had for a while (compressor, interface, mixer) -- as well as a new headphone amp and effects box -- use balanced cables for some aux patches.

    Ninety percent of the time, I use unbalanced cables. But in some cases, it would be very nice to have the option to either split or combine a balanced pair into left and right mono signals.

    I have only ever used an unbalanced patchbay (and I recently ordered a new one from MF). My questions are: Will a balanced patchbay work exactly like an unbalanced one if I need it to? Does it just give me the added benefit of using balanced cables sometimes, or is there some more fundamental difference between them? In other words, if I definitely want the balanced patchbay, will I need to keep the unbalanced one?

    Thanks in advance for any help!
     
  2. Boswell

    Boswell Moderator Distinguished Member

    Some major misconception here. A mono signal can be balanced or unbalanced: unbalanced has a single signal wire and ground; balanced has a pair of signal wires and ground. The two signal wires of a balanced signal carry the same information, differing only in phase. There is no meaningful concept of splitting these two signals into left and right. A stereo channel has two separate signals; each of these separate signals could be balanced or unbalanced.

    A balanced patchbay will not act exactly the same as an unbalanced one for every case. However, if all your equipment were unbalanced, you would not notice any difference whether you used a balanced or unbalanced patchbay.

    As soon as you introduce balanced equipment, then the type of patchbay does matter. Most pieces of equipment with balanced inputs are happy to take unbalanced input signals as long as the -ve input is grounded. However, driving balanced outputs into unbalanced patchbays (and by default into unbalanced inputs of other gear) takes some care and understanding. Rather than repeat all the rules here, try using the search facility on this board, as it has been covered several times. For example, check out:
    (Dead Link Removed)
     
  3. quesne

    quesne Active Member

    Thanks very much for this information.

    I did a search for "balanced", "unbalanced" and "patchbay" and it has led me to a number of relevant posts.

    From reading some of the explanations, it appears to me that -- in cases where I am using only unbalanced connections with unbalanced cables -- I do not lose anything with a balanced patchbay.

    If, however, I throw balanced I/O and/or balanced cables into the mix, then I need to be conscious of the signal orientation (balanced vs unbalanced, mono vs stereo, etc.) that I am passing through a particular patch. This is because I can lose volume and/or a portion of the signal if I have not made the patch correctly.

    Is that an accurate statement?

    Thanks again for your help.
     
  4. AudioGeezer

    AudioGeezer Active Member

    You're on the right track. Most modern balanced outboard gear can be unbalanced without much concern. If the outboard gear has a transformer balanced output, things get a bit tricky. The down and dirty way to hook up transformer balanced gear to unbalanced gear is to tie the low audio side of the balanced output to ground(shield). Not doing this can make things sound weird.
     
  5. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Pretty close. You can use a balanced patchbay as an unbalanced, but not vice-versa. You have a TS cable, and a TRS cable. Look at the difference. Tip/sleeve is normally tip (+), sleeve (-). TRS is Tip and ring, signal (out of phase for noise cancellation), and sleeve (-). The cable doesn't make it out of phase...the equipment does. The cable doesn't really care.

    Since an unbalanced piece is likely to have only a tip/sleeve connection, the ring goes unused. The sleeve DOES hit the ring connector in a patchbay, but if it's patched out to another TS device...it shouldn't matter. It's just another path for (-).

    What you have to be careful about is connecting balanced to unbalanced stuff. Some things have no problem, and some things will not do well. You have to research your equipment, and know how they will interface. It's the circuitry that's in the device that matters.

    Also, as Boswell mentioned....get the idea of "stereo" out of your head. This is NOT stereo, and most normal people don't use patchbays for that. Patchbays are used for one signal each connector...balanced or unbalanced.

    Balanced will be quieter in many situations. The theory behind balanced is that the signal gets inverted going out of one of the two (+) wires in a balanced cable. It then get's inverted back into the proper phase at the input of the connected device. Noise (EMI, RFI, etc) that may have been picked up along the cable is cancelled out, leaving only the intended signal. Since some devices can't flip that phase back over, which also increases the signal level since they are "added" back together, you get a weaker signal, with possible noise...since it also couldn't cancel. If you try to make up for it by increasing gain soewhere...you'll likely bring any noise up, also.

    There are things you can do to make things work together. Stuff you can make or buy...but you have to understand how each piece of equipment will handle it.

    I even have a couple of Ebtech Line Level Shifters that come in handy, occasionally. DI boxes and many preamps will balance an unbalanced signal, but sometimes it's just as easy to stick one of those handy little boxes in there if I want to use one of my old unbalanced rack mount pieces in the middle of all the balanced stuff..(especially if everything else is already being used). These boxes will work either way...balance an unbalanced, or unbalance a balanced....to some degree.

    It gets REALLY confusing. Here's some more reading material that may help clear things...or confuse you even more:

    http://rane.com/note124.html

    http://www.tweakheadz.com/all_about_cables.htm

    http://members.ozemail.com.au/~tabbler/GndRule/GndRule.html

    http://www.rane.com/library.html#rnotes

    Kapt.Krunch :wink:
     

Share This Page