- Written by John E. Johnson, Jr.
- Published on 29 April 2013
Having a fully-balanced circuit means essentially that there are two complete preamplifier circuits from input to output. The difference between the two circuits is that one is inverted with respect to the other. Each circuit is referenced to ground. At the output, the signal from one circuit is re-inverted and added to the other, giving you not only a 6 dB increase in output compared to a single-ended design, but common mode rejection, which means that any electrical interference that is picked up along the circuit is cancelled out when the two signals are added together.
The XSP-1 may be only $899, but it looks much more expensive, and let's face it, we like to have an expensive-looking rig on the A/V rack.
The front panel has a vertical set of buttons on the left hand side, which include an HT Bypass (signal goes direct from input to output), a buton for turning the Processor Loop (for recording) on or off, and buttons for activating high frequency tone control (± 3 dB) and low frequency tone control (± 3 dB) These are called the "Trims". There is a headphone output at the bottom of these buttons.
In the middle is a row of buttons that select the input, with the Standby Power On/Off button below them. On the right is a Mute button and the Volume Control.
The rear panel is shown below. It looks almost like an SSP rather than a stereo preamp, which is due to myriad connections. Inputs 1 and 2 are stereo XLR or RCA, a set of XLR or RCA Home Theater Inputs, which includes left and right, but also a subwoofer (line-level). This is the set of inputs that are bypassed by selecting HT Bypass on the front panel. If you use the RCA input jacks on the Input 1 pair, you select Input 1 on the front. If you use the XLR jacks on the Input 1 pair, then you select Bal 1 on the front. This eliminates the need for the often seen slider switch on the rear panel to select RCA unbalanced or XLR balanced inputs.
At the top left are Inputs 1 and 2, the Processor Loop inputs and outputs, and the inputs for the RIAA phono. Surprisingly, even at this low price, the phono preamp allows the selection of an impedance load value for MC cartridges. On the right hand side are the XLR and RCA outputs, which can be configured as full range, or using the small dials at the top, you can split the output signal for each channel so that there is high-pass and low-pass for each channel, with the crossover variable between 50 Hz and 250 Hz. Obviously, this would be used if you wanted to have one or two (stereo) subwoofers in the kit. This concept has good news and bad news. The good news is that setting up a subwoofer (or two) will make much more efficient use of the power amplifiers driving the mains, as the speakers will not be wasting energy on frequencies that they cannot reproduce. The bad news is that there will be some phase shift near the crossover frequency. Anyway, it's there. Try it out. I love stereo subs in a two-channel system. On the far right are the trigger ports, grounded AC receptacle, and main power toggle. Note that the trims and high-pass/low-pass features are performed totally in the analog domain. No A/D - D/A involved.
The inside of the chassis has the audio circuitry in the rear, near the inputs and outputs, and the power supply in the front, covered by a shield to protect the audio circuitry from any electromagnetic interference produced by the power supply transformer.
The remote control is metal, with the battery compartment accessible by removing six Phillips-Head screws. The buttons push in solidly with a click, almost like your PC keyboard. There is no backlighting though, and most of the buttons have the same shape, so you just need to learn where each of your most-used buttons are located.