![]() ![]() This improved to 101dB when the measurement bandwidth was restricted to the audioband, and to 104dB when A-weighted. Taken with the input shorted but the volume control set to its maximumvery much the worst case for a preamplifierthe wideband, unweighted ratio was 80dB ref. The line-input signal/noise ratio was also respectable. These are shown in fig.3 the filter slopes appear to be second-order.įig.3 Parasound Halo P 5, subwoofer output response with low-passfiltered output set (from left to right), 20≡40Hz (5dB/vertical div.).Ĭhannel separation via the line inputs was excellent, at 110dB below 1kHz, and still 88dB RL and 91dB LR at 20kHz (not shown). The P 5's subwoofer output can be set to have low-pass frequencies ranging from the same 20Hz to 140Hz, as well as none. The high-pass filter can be set to frequencies between 20Hz (left trace) and 140Hz (right trace), or can be switched off altogether if the user wants to use the main speakers full-range, which provides the maximum flexibility in marrying those speakers to a subwoofer. The blue traces in fig.2 show the response at the main outputs when the subwoofer switch is activated. Note that the level drops by an audible 0.43dB when the tone-control button is pressed but the controls are set to their detented, zero-action positions. The top and bottom blue and red traces in fig.2 show the effect of the tone controls set to their maximum and minimum positions. This imbalance disappeared with the volume control set to unity gain commendably, the preamplifier's frequency response was identical to that in fig.1.įig.1 Parasound Halo P 5, frequency response with volume control set to maximum at 1V, into: 100k ohms (left channel blue, right red), 600 ohms (left cyan, right magenta) (0.5dB/vertical div.). This graph was generated with the volume set to its maximum, when there was a very slight channel imbalance of 0.05dB. Reducing the load impedance to 600 ohms increased the low-frequency rolloff to ≠.85dB at 20Hz (cyan and magenta traces), but it's unlikely the P 5 will see such a low impedance in practice. The P 5's line inputs have a very wide frequency response into high impedances (fig.1, blue and red traces), with no sign of any rolloff at the 200kHz limit of this graph, and a low-frequency output down by just 0.25dB at 20Hz. The balanced output impedance was 897 ohms at 20Hz, 850 ohms at 1 and 20kHz the unbalanced output impedance was a low 41.5 ohms at 20Hz, dropping to a very low 2.5 ohms in the midrange and treble. ![]() The line input impedance was constant with frequency, at 41k ohms balanced and 23k ohms unbalanced. Both sets of outputs preserve absolute polarity ( ie, are non-inverting), with the XLR jacks wired with pin 2 hot. The unity-gain setting of the volume control for unbalanced operation was 1:00. Looking first at the P 5's behavior as a conventional line preamplifier, the maximum gain is specified as 10dB for balanced input and balanced output I measured 12.3dB for unbalanced input and output, the maximum gain was 10.6dB. Unless stated otherwise, all of my measurements were taken from the unbalanced main outputs. Not only is the P 5 a full-function preamplifier with a phono stage, tone controls, and the ability to provide the necessary high- and low-pass crossover functions to enable the use of a subwoofer it has digital inputs, including USB. I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see and the January 2008 " As We See It") to measure the Parasound Halo P 5. ![]()
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