Focusrite's most affordable ISA pre-amplifier now has a digital card as standard. The ISA One Digital is now perfect for getting the legendarily transparent Focusrite sound directly into your recording system.

In addition to the ISA mic-preamp, ISA One Digital also has a direct input. This means that you can record an instrument and microphone simultaneously. This makes it ideal for recording singer songwriters, allowing you to track vocals and guitar at the same time. Or, the tried and tested technique of mic-ing up an guitar/bass amp cabinet and taking a direct out at the same time.

ISA Series Transformer-based Pre-amplifier
Encased in a rugged and portable chassis, ISA One offers the classic Focusrite microphone pre-amplifier at its lowest cost to date.

Stereo 192kHz ADC
Cutting-edge conversion technology, incorporating Focusrite analogue circuitry to deliver the best A-D performance in its class (Dynamic range of 119dB).

Flexible Independent D.I. Channel
ISA One is ideal for both engineers and demanding performers alike, featuring independent gain control, an output for routing to an amp, an independent XLR output on the rear and routing to the optional ADC.

Switchable Impedance
Choose one of four carefully selected input impedances, including the original ISA 110 setting, to suit any microphone.

Headphone Output with Volume Control
ISA One can feed either a sum of the two inputs to the headphones output, or an external stereo cue mix (such as a stereo mix feed from an interface) via two TRS Jack inputs on the rear of the unit.

Dedicated Insert Point
Allows you to place extra processing between the pre-amplifi er or D.I. and the optional converter, such as an EQ or compressor.

The ISA microphone pre-amplifier was first introduced back in 1985. This transformer-based pre-amplifier formed the first half of the ISA110 mic-pre and EQ module on Focusrite's critically acclaimed Forte console. This console, and the later Studio console were hailed by many as the finest sounding consoles ever built.

The ISA microphone pre-amplifier went on to form the cornerstone of all ISA and RED Focusrite products. The topology has never changed, except for the addition of a variable impedance circuit, allowing ISA users to either perfectly match the pre-amp with any microphone, thus maximizing level, or to use different settings creatively to shape the sound of the microphone being used. The original ISA110 setting was supplemented by three further impedance settings.

The Focusrite pre amp is renowned for its transparency, but there's also that subtle warmth that transformer core saturation contributes. This seeming contradiction of warmth plus beautifully open, unrestricted high frequencies, is a classic hallmark of the mid 80's Focusrite designs.

With processors whose bandwidth is strictly limited to the audible (20Hz to 20kHz) bandwidth alone, significant roll-off can still occur, affecting the higher audible frequencies of the signal. Therefore, in order to capture every subtle nuance, exactly as it occurs whilst avoiding any roll-off, the pre-amp must operate over a far greater bandwidth. The extremely broad frequency response of Focusrite pre-amps - close to 200kHz at the top end - guarantees accurate phase response across the much narrower range of human hearing, the roll-off point being moved entirely outside of the audible hearing range.

Mic Input Response
• Gain range = 0dB to 60dB in 10dB steps + 20 dB of variable gain
• Input Impedance, variable as follows:-

(Switched Impedance setting Equivalent Input Impedance at 1kHz)
Low = 600 Ohms
ISA110 = 1400 Ohms
Med = 2400 Ohms
High = 6800 Ohms

• EIN (equivalent input noise) = -126dB measured at 60dB of gain with 150 Ohm terminating impedance and 22Hz/22kHz band-pass filter
• Noise at main output with gain at unity (0dB) = -97dBu measured with a 22Hz/22kHz band-pass filter
• Signal to noise ratio relative to max headroom (9dBu) = 106dB
• THD at medium gain (30dB) = 0.0009% measured with a 1kHz -20dBu input signal and with a 22Hz/22kHz band-pass filter
• Frequency response at minimum gain (0dB) = -0.5dB down at 10Hz and -3dB down at 125kHz
• Frequency response at maximum gain (60dB) = -3dB down at 16Hz and -3dB down 118kHz
• CMRR=98dB (Channel 1, 1kHz, maximum gain with +24 dBu input)
• Crosstalk Channel to Channel: with 10dB@1kHz input to chA, chB output =104dBrA. With 10dB@10kHz input to chA, chB output = 84dBrA

Line Input Response
• Gain range = -20dB to +10dB in 10dB steps + 20 dB of variable gain
• Input Impedance = 10k? from 10Hz to 200kHz
• Noise at main output with gain at unity (0dB) = -96dBu measured with a 22Hz/22kHz band-pass filter
• Signal to noise ratio relative to max headroom (24dBu)=120dB
• Signal to noise ratio relative to 0dBFS (+22dBu) = 118dB
• THD at unity gain (0dB) = 0.001% measured with a 0dBu input signal and with a 22Hz/22kHz band-pass filter
• Frequency Response at unity gain (0dB) = -0.3dB down at 10Hz and -3dB down at 200kHz

Instrument Input Response
• Gain range = 10dB to 40dB continuously variable
• Input Impedance:
High = greater than1M?
Low =greater than 300k?
• Noise at minimum gain (+10dB) = -92dBu measured with a 22Hz/22kHz band-pass filter
• Noise at maximum gain (+40dB) = -62dBu measured with a 22Hz/22kHz band-pass filter
• THD at minimum gain (+10dB) = 0.001% measured with a 10dBu input signal and with a 22Hz/22kHz band-pass filter
• Frequency Response at 10dB gain with -10dB input = 10Hz-100kHz +/- 0.6dB
• Frequency Response at 40dB gain with -40dB input = -2.5dB down at 10Hz and 0dB at 100kHz


High Pass Filter
• Roll off = 18dB per octave 3 pole filter
• Fixed Frequency 75Hz measured at the 3dB down point


Meters
• Moving coil (MC) meter is factory calibrated to 0VU = +4dBu with 1kHz sinewave. With the VU Cal button pressed the meter can be adjusted on the rear panel to allow 0VU to equal +10dBu to +26dBu with the centre detent being equal to +22dBu.
• Peak LED meters calibrated in the detent position for 0dBFS = +22dBu, calibration is adjustable on the rear panel to allow 0dBFS to equal +10dBu to +26dBu
• Routing for MC and Peak1 meter is after the HPF, pre insert send or switched post insert return. Peak2 is always pre ADC channel 2, which can be fed by external input or Instrument input.
• LED levels are as follows when peak calibration is set to center detent on the rear panel. (This is when using the internal ADC).

0 = +22dBu
-2 = +20dBu
-6 = +16dBu
-12 = +10dBu
-18 = +4dBu
-42 = -20dBu

FRONT AND REAR CONNECTIVITY

Analogue Channel Inputs:
• Mic input: XLR x 1
• Line input: XLR x 1 and TRS x1
• Instrument input TRS Jack: XLR x 1
• External ADC input: TRS Jack x 1
• Return: TRS Jack x 1

Analogue Channel Outputs:
• Send: TRS Jack x 1
• Balanced line output: XLR x 1
• DI output: XLR x 1
• DI through: TS Jack x 1

Analogue Channel Additional I/O:
• Cue mix left input: TRS Jack x 1
• Cue mix right input: TRS Jack x 1
• Headphones output: ¼” TRS Jack x 1

Weight
• 3.9kg
• 8.6Ibs

Dimensions
• 220mm (W) x 104mm (H) x 254 - 290mm (D - top to bottom)
• 8.66" (W) x 4.1" (H) x 10" - 11.4" (D - top to bottom)