Preamplifiers

Emotiva USP-1 Stereo Preamplifier

ARTICLE INDEX

The Design

The front panel is very simple. Each function has its own button. Inputs include CD, Phono, Tuner, Aux 1, and Aux 2. You can also select Mono, the Tape Monitor, HT Bypass (lets you bypass the USP 1 and send the signal to your SSP instead), and Mute. The volume control is a rotary dial that operates a potentiometer.

Besides the standard full-range outputs, this preamp offers a split output where you can adjust the low-pass frequency for one (which goes to your subwoofer) and the high-pass frequency for the other (which goes to your main power amplifier). This allows you to essentially bi-amplify, and with the low frequencies removed from the high-passed output, your power amplifier will run more efficiantly, not having to waste power on low frequencies that your speakers cannot reproduce. And, they toss in a phono stage that has both MC and MM settings. This may mark the beginning of phono stages being a standard part of stereo preamplifiers, rather than having to purchase an outboard phono stage. Long live LP's! Oh, there's a headphone jack too.

You can see on the rear panel photo above that the full-range output jacks are situated next to the split-output jacks, and that the low-pass (for the subwoofer) offers both an RCA unbalanced as well as an XLR balanced output. The low-pass output combines both channels and comes from an op-amp, while the high-pass output is the main preamplifier output stage with a filter.

For the phono stage, there is a switch for using either an MC or an MM cartridge. MC cartridges have low output (often less than 1 millivolt), so the basic difference between the MM and MC circuits is an additional gain stage for the MC circuit. The MM input has an impedance of 47 kOhms, which is standard, while the MC input's impedance is 240 ohms. One advantage of outboard phono stages is that they have settings to vary the load impedance, which is for the purpose of matching the optimum load impedance for a specific cartridge.

The remote control is small, but has all the necessary controls, such as power on/off, input selection, and volume control.

The AC receptacle is two-pronged (not grounded). You have to power-on with a toggle on the rear panel, which puts the unit into standby, and you then turn the unit on for use by pressing the Standby/Power button on the front panel.