Why You Should Think Twice About Buying an Unbalanced miniDSP 2x4


For several years now, people wanting to add one or more subwoofers to their audio or AV system, along with the ability to apply EQ and individual delay to the subs, have been asking about the miniDSP 2x4 DSP devices in online forums. They offer three different models of 2x4 device as of this writing: the standard 2x4 unbalanced, 2x4 balanced, and 2x4 HD versions. Unfortunately, the standard 2x4 unbalanced version, which appears at first blush to be the best choice for most users, has a problem that will prevent proper system operation in many, but not all cases.

The Problem: Insufficient Maximum Output Voltage For Many Systems

The standard unbalanced miniDSP 2x4 has a maximum output voltage of 0.9 Volts RMS. This is the maximum amplitude of a sinusoidal voltage it can supply at its output without significant distortion or clipping. Why does this matter? The answer lies in an important power amplifier specification called input sensitivity. This specification refers to the power amplifier connected to the miniDSP that's used to drive its associated subwoofer. The input sensitivity of a power amplifier is the amplitude of a sinusoidal input voltage required to drive the amplifier to its rated continuous power into a specified load. The "sensitivity" terminology is misleading, and might actually be considered a measuire of insensitivity, as the larger the "sensitivity" number is, the less sensitive the amp is to changes in input voltage. At any rate, the important thing to remember is that in order to be able to drive the amplifier to its rated output power, the maximum output voltage of the device driving the amplifier (in this case the miniDSP 2x4) must be greater than or equal to the amplifier's input sensitivity rating. For an exhaustive discussion of amplifier input sensitivity and its relationship to amplifier gain and output power, see Understanding Input Sensitivity Specs.

Things You Can Do to Ensure Success