The Orange Acoustic Pre is incredibly full-bodied, clear, warm, harmonically rich, organic and with natural compression – unlike many other acoustic preamps that color your sound or add some type of ‘enhanced’ processing.
Focusing on Channel 1 (designed for active and passive instruments), the Gain and Heat knobs work well together by increasing sharpness and vigor in the signal, which is ideal for finger-pickers… or you can dial back these controls to warm up the signal if you’re a flat-picker. The EQ is quite excellent, in that the entire spectrum is not exaggerated, but tailored to work with an acoustic guitar (as well as other instruments) so that a lot of bass, midrange or treble does not sound out of place. Besides indicating how much midrange you want, there is a midrange emphasis or sweep knob that ranges from 180Hz to 1.8kHz for more of a tailored sound. Regardless of where you establish your EQ, the tone is very real and not artificial sounding. Channel B is super clean and clear, with an uncolored and flat frequency (it is not driven by the internal tube). It is meant for a secondary instrument, mic (for singing) or to run a guitar with two internal pickups, all of which can have a mono or a stereo output. In one part of the demo I hooked up a Kiesel guitar that has two such outputs… one for the humbucker pickups and the other for the bridge piezo pickup. Because each channel has its own FX Loop, you can add different effects into each channel, run it in stereo and produce some very unique tones and results (I added the ZVEX Vibrophase to Channel B/Piezo pickup). One other thing I should mention is that the manual suggests running a patch-cable from Channel A’s Send to Channel B’s Return (and then go out in stereo via the two XLRs) to achieve Reverb in stereo, a built-in effect. The demo shows me doing this, although I recorded in Mono. Interestingly enough, the signal not only sounded louder with that patch-cable trick, but the tone sounded fuller and of a higher quality. I’m unsure why that is, but I’m not complaining. I very much like the Heat knob, as increasing ‘heat’ drives the valve a bit harder to add some subtle, fatness, harmonics and modest compression (ideal for finger-style picking, to make the notes pop better, but also to add a punch to flat-picking).
OVERALL IMPRESSION: I could not get the sound I wanted in my acoustic recordings, and so, I didn’t bother with the medium much… until now. Although I still need some engineering/mixing experience in that regard, the Orange Acoustic Pre, the world’s first stereo valve acoustic preamp/active DI, produces an outcome that is both realistic and encouraging. With its tube-driven technology (12AX7/ECC83), this preamp produces warm and natural sounds that can be boosted via its HEAT knob, to drive the tube gain even harder. What this does is produce a sharper attack for finger-pickers, or simply dial back the preamp’s Heat for a warmer attack and for flat-pickers. Moreover, the valve circuitry was designed to amplify a much wider frequency range in order to project those subtle details inherent in acoustic instruments. Beyond its great sound, you can add a mic or second instrument to Channel B (which does not have a heat knob and produces a flatter response) or run your guitar in stereo (ideal for instruments with two pickup sources). The Orange Acoustic Pre also includes a built-in Reverb, which sounds very natural and ambient, and if you run a patch cable from Channel A’s Send to Channel B’s Return (fx loops) you can run the Reverb in stereo. There are several other features, including regular lines in/out, but also balanced XLR in/outs (for that stereo effect), Phase Inversion switches for both channels, ground lifts and a Mute switch (a separate on/off foot switch can be included via the rear of the unit). Although the Orange Acoustic Pre has a few short-comings, such as Channel A having an 18dB boost, whereas Channel B has +/- 12dB, no notch filter, boost switch or tuner output, this unit still delivers in sound quality that will match what can be found in quality studios. In fact, the Orange Acoustic Pre was designed for live and in-studio use with the assistance of Harpejji and fingerstyle jazz guitarist Martin Taylor (guitarist for Stevie Wonder).
GENERAL USE: Somewhat easy to use, depending on the complexity of your setup, the Orange Acoustic Pre takes little time to get to know. To look at it from a simple perspective, there is a quarter-inch line in and out, which is true of both channels, although most mono players would use Channel A only. That channel has both a Gain and Heat knob. Gain adjusts the level input, whereas Heat alters the level of valve gain in the upper frequencies (adding compression and harmonics), which helps keep the signal sparkly and punchy for finger-pickers, whereas flat-pickers will experience better results by keeping the Heat down (unless you want a sharp attack). The EQ is straight forward, in that you can mix as much bass, treble and midrange as desired, whereas the midrange also has a sweepable Frequency knob to select the center frequency from 180Hz – 1.8kHz, a feature that really adds to tonal shaping. Channel A is very warm and organic sounding, whereas Channel B has a flatter response not driven by the internal 12AX7/ECC83 tube (meant as a very clean channel for a mic or secondary guitar input, e.g., a guitar with two pickup outputs). Channel B has the same EQ controls with a Gain control. Both Channels are affected by a Line Volume control, but also a Main Volume (which affects the XLR outputs). There also is a 48V phantom power that you can switch on for Channel B’s XLR input (if you choose to use that input, although that channel also has a quarter-inch input). Both channels have a Phase Inversion switch, which reverses the audio waveform, ideal if a guitar with two pickup sources run out of phase. However, when flipping this switch with a regular guitar you do get a more ‘pinpoint’ or dynamically narrow tone (if that’s what you like). Both channel XLR outputs have a ground lift, to reduce any background noise/hum. A cool feature is that both channels has its own FX Loop, which means you can add a phaser or flange to one channel, whereas the other could have a delay or tremolo, making for a lot of different hookup possibilities and sounds. Finally, there is a built-in reverb, which is very natural and quite good in its own right, affecting both channels concurrently.
OTHER DETAILS: A beast of a pedal, the Orange Acoustic Pre measures 11.4 (l) x 5.9 (w) x 3.5 (h) inches (29 x 15 x 9 cm) and weighs 5.5 lbs (2.5 kg). Its solid-steel chassis with rack mount handles has a power-coated paintjob and was built for rigorous road use. Although it may seem large and heavy, it is meant for acoustic instruments, and so most acoustic-based musicians will not have large pedalboards that are common among electric players. Therefore, having the Orange Acoustic Pre on a pedalboard, along with a handful of modulation/delay pedals certainly would not be out of place or excessively heavy/large. There are no foot switches, and turning the unit on and off is controlled either by a toggle switch (Mute) or via a separate foot pedal (that connects to the back of the unit). There are fourteen control knobs, all of which are of good quality and the pots turn with a solid and smooth feel. There are six toggle switches that control mute, ground lift, phase inversion and +48V boost (XLR Channel 2) that all produce a solid click, located at the top of the unit. All cable (including power) inputs/outputs are located in the back for tidiness and to keep any cables out of the way. The LED is a large high-quality crystal-type light. The Orange Acoustic Pre also comes with a 12V 1.25A power supply with interchangeable plug ends (to accommodate various countries). Overall, this ‘tank’ will provide years of service, whether in studio or on the road.