Quick Pick: Focusrite ISA One

EM reviews the Focusrite ISA One, a single-channel mic preamp and DI
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The ISA One offers most advantages of Focusrite''s ISA 428 multichannel preamp and DI in a more portable, single-channel configuration.

The ISA series is based on the circuitry of Focusrite's legendary Forte consoles from the mid-'80s. The line's newest addition is the ISA One ($799), a portable single-channel mic preamp and DI that caters to smaller studios.


The ISA One's faceplate will be mighty familiar to users of the other ISA units; it has the same primary color scheme and large VU meter. The slanted front panel is jam-packed with controls, from the basic preamp features (Gain, +48V, 75 Hz HPF, and so forth) to the clock settings for the optional ISA Stereo ADC card ($399). The features that distinguish the ISA One from your average preamp are the four input impedance settings for the microphone preamplifier, two impedance settings for the DI, both a VU and an LED bar-graph meter, a parallel output to feed an amp from the DI input, and an integrated headphone amp.

On the back, you also get balanced Send and Return insert points, meter calibration pots, separate outputs for the DI and Main Input section, and two inputs (one stereo, one mono) for feeding the headphone amp prerecorded signals from a mixing console or DAW. This last feature will be extremely handy for a small studio in which most of the recording is done by a single musician doing overdubs, as it eliminates the need for an external headphone mixer.


Having been turned on enough by the ISA preamps to buy a couple of ISA 428 PrePacks about four years ago, I was interested to see how one of my most-used preamps survived the repackaging. I was immediately impressed by the box's solid feel and intrigued by the possibility of using it in my studio's live room as an oversize direct box. That was actually my first use of the ISA One, on Fender Rhodes as a DI. I'd recorded that particular instrument many times, and the ISA One quite ably captured the richness of the sound that I'm used to.

Over the course of the next couple of months, I used the ISA One anywhere I'd use the ISA 428, which is to say on just about anything. I especially love how it treats vocals, bass guitar, drum-room mics, horns, and strings; there's a huskiness to the sound that I attribute to the Lundahl transformer. Additionally, the four input impedance settings let you tune your microphone somewhat. Higher settings tend to bring out more detail and clarity, and lower settings generally soften the tone for a rounder sound. The only feature I miss from the ISA 428 is its awesome variable-frequency highpass filter, but the ISA One's 75 Hz filter is more than adequate for most applications.


In direct comparisons with the ISA 428 on both voice and bass through the DI, I could hear no discernible difference between the two cousins. In comparison with the Millennia Media TD-1 HV-3 preamp, I found the TD-1's DI (which has three different impedance settings) to exhibit a hair more detail, but keep in mind that unit is twice the price of the ISA One. The ISA One's DI input did have more clarity than that of the Vintech X73i, but the latter had a fatness and warmth that none of the other DI inputs really had. On male vocals through three different large-diaphragm condensers, the differences between the ISA One at high impedance and the reference preamps were very subtle (they were all highly usable). I heard way more difference when I used the ISA 110 impedance setting; at this setting the vocals had a more natural response, whereas in the higher settings the vocals came forward a bit, with more of a modern, present sound. In any case, the option of different sounds from a single mic is clearly quite useful.


I really have no choice but to give the ISA One the highest rating possible. It is functionally packed and sonically sublime. Even though our studio already possesses eight channels of ISA preamp, I'm pretty tempted to buy this box for the portability factor alone. Having an extra DI of this quality is in itself almost worth the price. Add to that the fact that you can run the mic pre and DI simultaneously on different sources, along with all the other features I've described, and you have quite a bit of bang for your buck.

Value (1 through 5): 5