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Di Box Question

Discussion in 'Sound, Music, and Intercom' started by stuart, May 19, 2007.

  1. stuart

    stuart Member

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    I just finished setting up my new gear rack, eq, gate, comp. and i wanted to take it home and hook it up to my home stereo, i have two Di boxes , and im used to running un balance into balanced, ie, instrument out into the board with an active DI, but what happens if i run it backwards, i want to run my stuff through the rack then switch to unbalanced at the end and go to the amp. will the di work both ways? or is it going to make bad noises, or no noise at all. Does anyone have any idea how to accomplish this, im sure there is a simple answer its just something ive never run across. (no getting a better balanced amp is not an option, lol)

    Thanks
    Stu
     
    Last edited: May 19, 2007
  2. SHARYNF

    SHARYNF Well-Known Member

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  3. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    One option to consider is the simple BALUN (BALanced to UNbalanced) lead, which can be easily made. There are two versions, one using a small 1:1 transformer and the other without. I have a couple of each because some amps (including some pro audio) reject the transformer (of course, this is when taking an unbalanced input into a balanced input - but could also be a problem for your application).

    The simpler of the two is constructed as follows, using balanced XLR to unbalanced RCA as an example:

    Using shielded cable, connect the Hot on the XLR (pin 2) to the signal on the RCA (centre pin) and the Cold on the XLR (pin 3) to the ground on the RCA (skirt). The ground on the XLR is not used.
     
  4. SHARYNF

    SHARYNF Well-Known Member

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    In my experience, if you have a problem with the amp "rejecting" the transformer it is usually because the amp has what is know as a Pin 1 problem (this has been covered on other threads) but basically it is where the shield has been connected to signal ground in the amp with the balanced input, with all sorts of noise problems

    If you use the simple cable connection, again in my experience make sure that both of the devices are connected to the same power source, as in power plug NOT merely the same electrical panel. Usually this is not practical since the reason for the balanced cable is typically due to the long length.

    Sharyn
     
  5. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    I think this got glossed over, but you do mention that you're using an active DI, in which case the answer is no, you can't use it backwards. Ignoring other discussions of better/worse ways to do things, and just speaking in general yes/no possibilities, passive DIs, which are basically just transformers, can be used backwards.

    This is sometimes used as a studio trick to re-amp a guitar that's been recorded directly; you take the line level output into the DI via an XLR turnaround, and then go from the 1/4" input into the guitar amp. I've used this trick in the shop to test a guitar head/speaker with a guitar track from an iPod.

    --Andy
     
  6. TimmyP1955

    TimmyP1955 Active Member

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    Depends on the topology of the balanced output circuit. If it is a transformer, you must do it as described. If it is an IC, you will be driving one side of the IC into a short, which may cause short term or long term problems. First try using pin 2 as RCA hot and pin 1 as RCA ground, and let pin 3 float. Only if this does not work should you switch to pin 3 as RCA ground.


    Why do you want to put all this stuff in your hi-fi's signal chain? All these gadgets are necessary evils in a PA, but if it's a good hi-fi system, just the extra connections and cable lengths will cause a noticeable degradation, let alone all the electronics you are adding.
     
    Last edited: May 26, 2007

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