With the miniDSP balanced kit or balanced 2x4 being used in a wide range of applications (balanced/unbalanced connectivity), a clarification is in order on the expected levels depending on the jumper configuration and type of signal. The following application note will assume that you understand what is a balanced/unbalanced signal and understand the difference. If you don't, please take the time to have a look online.
miniDSP balanced kit/balanced 2x4 Input/Output circuity
- An operational amplifier turns a balanced signal to a unbalanced signal for processing by the DSP.
- To allow higher input level before saturation, an input padding network attenuates the signal based on the jumper position. The two jumper positions (0.9/2Vrms) refer to the maximum value of a balanced input signal before reaching 0dBFS. Note however that these values are for a balanced signal (it's a balanced board after all.. :-) so please see more about unbalanced inputs below.
- DSP does its processing on the signal in digital domain and outputs an unbalanced signal from the DAC. It's the task of an operational amplifier to turn this unbalanced signal to a balanced signal along with amplifying the signal up to a stronger level (up to 2Vrms).
Hoping we didn't loose you so far in this electronic mumbo-jumbo... In case we did, don't worry about it, all the information you need to know is summarized in the following tables.
Balanced input signal
|Jumper position||Unbalanced max output||
Balanced max output
Note that the miniDSP Balanced 2x4 and Balanced Kit are by default configured for the 2Vrms setting.
Unbalanced input signal
Now when it comes to feeding an unbalanced signal to any balanced input, only one leg of the operational amplifier is driven, i.e. half of the typical of a balanced signal configuration. The 0.9V/2Vrms settings therefore have a different meaning:
- In the 0.9Vrms, the board can actually accept up to 1.8Vrms with an unbalanced signal before reaching saturation (0dBFs).
- In the 2Vrms position, the board can accept up to 4Vrms unbalanced before reaching saturation (0dBFS).
The below table summarizes it all for you:
|Jumper position||Max unbalanced Level||Unbalanced max output||
Balanced max output