SERIOUS ABOUT SOUND

Balanced Input and Output Boards

Introduction 

These boards are a simple cost effective way of converting existing equipment so that its inputs and outputs are balanced.  The balanced output boards will drive into 600R lines, ensuring full compatibility with all professional equipment.  If installed within an already existing piece of equipment, the boards can usually be powered from the equipment's internal supply.  They are small enough to fit into most equipment housings with a minimum of modification (balanced input board size  -  w36mm x d25mm x h18mm, balanced output board size  -  w46mm x d28mm x h18mm).  Connections for signal and power are via a 6 pin molex type connector.

As with all our products, quality and long term reliability are designed and built in:

  • All power rails decoupled on board to ensure audio isolation

  • 1% metal film resistors to ensure low noise, consistency and long term reliability

  • Polyester capacitors on input boards for high DC blocking and long term stability

  • Fibreglass PCBs with solder masks for added protection

  • Each unit soak tested before packing

Performance

Both boards perform to the highest standards, and once installed are transparent to the user.  The signal to noise ratio is high, and transformer based hysteresis crossover distortion is eliminated.  The common mode rejection ratio of the balanced input board is high, giving very good immunity to hum, noise and general pickup.

Either signal leg can be shorted to ground for interfacing to unbalanced European or USA standard equipment.  Maximum input and output levels will be determined by the supply voltage.

Installation Service

We have designed a very high quality PSU for powering our equipment.  Giving ±17V, it uses an adjustable regulator (LM317), giving better regulation than standard ICs (78/79 type), but with additional smoothing circuitry to enhance its performance still further.

We will house these units to your specification:  in your equipment, in free standing cases, wall boxes, stage boxes or rack cases in any finish or configuration.  Generating suitable artwork and having units silk screen printed or engraved is also part of our comprehensive customisation service.

Studio

In one studio we have balanced all the line inputs and the unbalanced outputs of a Soundcraft 800 series desk, as well as a lot of peripherals in the same Studio.  In another installation the between studio tie lines are balanced with our boards. 

Another studio has used these boards in two ways.  In the control room they have a number of wall boxes for plugging additional equipment into the system.  These have XLR connectors for balanced inputs.  Unbalanced inputs are balanced by our Balanced Output Boards.

Behind the rack containing the patch bays and effects units they have a box which holds a number of Balanced Input and Balanced Output  Boards and balances the Ins and Outs of the effects units that are not already balanced.

Stage / Live Work

One user asked us to build 8 Balanced Output boards into a 1U case with its own PSU and  2 jacks, 1 XLR, a volume control and earth lift switch for each channel.  This gave him a DI box for his keyboards that would drive balanced line inputs or microphone inputs and allowed him to adjust his outputs for optimum performance.

Another user mixes his keyboards on stage and asked us to balance the outputs of his keyboard desk for transmission to the main auditorium desk.  Two European and one UK tour have been completed without any hum or pickup problems.

In another case we have balanced 34 outputs from a Soundcraft desk and 34 inputs to Quad 405s and other amplifiers which are housed remotely from the mixer.

Specs

    Balanced Inputs:

  •     Distortion @ +22dB        <.0025% (20Hz - 22kHz)

  •     CMRR @ 1kHz               >58dB

    Balanced Outputs:

  •     Distortion @ +22dB         <.003%  (20Hz - 22kHz)