Mix Magazine (July 2000)
By Michael Cooper
Snapshot Product dealers: Demeter HDI-1 Stereo Tube Direct/Line Driver
Part of Demeter's H Series line of studio tube equipment, the HDI-1 is a 2-channel, rackmount unit serving both as a DI box and a line-level driver, ostensibly for "warming up" digital audio tracks. One 12AX7LPS tube is in the audio path for each channel; ICs drive the outputs.
Each channel has an unbalanced 11/44-inch front-panel input that accepts either instrument or line-level sources. For an extra $35, Demeter will provide an extra pair of unbalanced inputs on the rear panel-an attractive option for those who wish to tie the HDI-1 into a patchbay for processing line-level signals.
Separate volume control knobs provide as much as 24 dB of boost for each channel. Independent "unity gain" switches disable corresponding volume controls but nevertheless provide 6 dB of boost for the XLR and TRS balanced outputs on the rear panel. Each channel also features a low-impedance, tube-buffered, unbalanced aux output for splitting an instrument's signal to route to an amplifier. Ground lift and phase inversion switches round out the channel controls.
My only functional complaint with the unit is that pressing its unity gain switch produces a loud pop. This is not an issue as long as you turn down your monitors beforehand.
The HDI-1's 27-megaohm input impedance prevents instrument pickup loading, making the unit an outstanding DI box for bass and electric guitars. Bass sounded lush, yet fully endowed with presence and definition. And my '62 Strat never sounded better, delivering gorgeously rounded, bell-like tones. The HDI-1 can also add nice coloration to line-level signals, although I would not say this is its greatest strength. Running entire mixes through the box, the stereo imaging became a little ghosty. But as a DI box, the HDI-1 offers the perfect marriage of warmth and clarity. At $899 for two channels, the HDI-1 is an attractive buy for the engineer looking to transform dry, flat DI tracks into lush, fat tones.