Unbalanced to Balanced Desk XLR Outputs

[picky]

Hi, I have an old Allen Heath S2 Studio Desk which I want to use for live work. I plan to use one of the 2 Track outputs for main left and right. However the problem is that this is unbalanced.

 

Does anyone have a circuit diagram for a suitable mixer output level unbalanced to balanced circuit that I can build inside and add a couple of XLR outputs from this?

 

Alternatively does anyone know of a suitable stand alone external mixer output level unbalance input to balanced line output unit that would be suitable to use for this? All the ones I have seen are DI box types (mostly battery only which worries me) with an instrument / line inputs. Also I do not want to affect the frequency response of the mixer output or alter the gain between in and out; it needs to remain the same at both input and output and the spec sheets on the units I have seen do not really go into much detail so it’s difficult to know.

 

Thanks for your help, Phil :)

[Ben Langfeld]

Behringer do a low cost balancing transformer. List is £20 but it can be had for £17 from Dolphin Music.

[Jivemaster]

Maplin items

N81CC Audio Tx 1+1:2+2 11 in Stock £10.67

N82CC Audio Tx 1+1:1+1 6 in Stock £10.67

N83CC Audio Tx Screen Can 10 in Stock £5.22

 

N84CC Min Audio 600ohm 1:1 17 in Stock £7.66

 

The same transformers come out of RSwww.com and no doubt other suppliers.

 

Transformer balancing has the advantage of breaking ground loops and they can elinate hums and buzzes.

 

Active electronic balancing would be a pair of op amps configured as invert for one and non-invert for the other, - may be better according to the op-amp will take more making and will not isolate.