Focusrite ISA One
The Focusrite ISA One is an excellent way to tap into the legacy of the Forte console in an ultra-portable format.
Featuring a rugged, portable all-metal enclosure, ISA One combines the classic Focusrite microphone preamp with a flexible, independent DI channel and optional 192kHz precision A-D conversion. At the heart of the ISA range is the microphone preamplifier with its Lundahl input transformer – essentially the same circuit, based on the original ISA 110, that has been used for 30 years in successive Focusrite designs. The input transformer imparts a special character to the sound that can't be truly emulated in any other way, while the modern twist of variable input impedance allows for a new degree of flexibility.
Whether you're an artist, engineer or producer, you'll appreciate the versatility of the ISA One, with its front-panel DI input. The DI includes low/high impedance switching and an amplifier output, and its own feed to the optional A-D converter and separate rear-panel XLR output.
- Mic and instrument preamplifier based on the Forte console
- Portable design for getting great sounds wherever you are
- Mix and match your mics with the impedance selector
- Mic, line, and instrument inputs
- Classic VU meter and ladder LEDs
- Cue mix stereo inputs
- Certificate of origin signed by Phil Dudderidge
- An optional 24-bit/192kHz A-to-D converter is available
Analogue Channel Inputs
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Analogue Channel Outputs
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Analogue Channel Additional I/O
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Mic Input Response
| Gain range | 0dB to 60dB in 10dB steps + 20 dB of variable gain | |
| Input Impedance | 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 | Noise at output with unity gain (0 dB) and 22 Hz-22 kHz band pass filter | -97 dBu |
| Signal-to-Noise Ratio | 106 dB relative to max headroom (9dBu) | |
| Total Harmonic Distortion + Noise | Measured at medium gain (30dB) with a 1kHz -20dBu input signal and with a 22Hz/22kHz band-pass filter | < 0.0009% |
| Frequency Response | At minimum gain (0 dB) | -0.5dB down at 10Hz and -3dB down at 125kHz |
| At maximum gain (60dB) | -3dB down at 16Hz and -3dB down 118kHz | |
| CMRR (Common Mode Rejection Ratio) | 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 | 10 kΩ from 10 Hz to 200 kHz | |
| Noise | Noise at main output with gain at unity (0 dB) measured with 50 Ω source impedance and a 22Hz - 22 kHz band pass filter | -96 dBu |
| Signal-to-Noise Ratio | Measured with a 22 Hz-22 kHz band pass filter | 120 dB relative to max headroom (24 dBu) 118dB relative to 0dBFS (+22dBu) |
| Total Harmonic Distortion + Noise | Measured with a 0 dBu input signal, and a 22 Hz-22 kHz band pass filter | 0.0001% |
| Frequency Response | At unity gain (0 dB) | -0.3dB down at 10Hz and -3dB down at 200kHz |
Instrument Input Response
| Gain range | 10dB to 40dB continuously variable | |
| Input Impedance | High = greater than 1M Low =greater than 300k |
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| Noise | Measured with 22 Hz-22 kHz band pass filter | Minimum gain (+10 dB): -92 dBu Maximum gain (+40dB): -62dBu |
| THD | At minimum gain (+10) | |
| Frequency Response | At minimum gain (+10 dB) | -10dB input: 10Hz-100kHz +/- 0.6dB |
| At maximum gain (+40 dB) | -40dB input: -2.5dB down at 10Hz and 0dB at 100kHz | |
Meters
| Moving Coil (MC) Meter | 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 | 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 |
| Frequency Response | At minimum gain (+10 dB) | -10dB input: 10Hz-100kHz +/- 0.6dB |
| At maximum gain (+40 dB) | -40dB input: -2.5dB down at 10Hz and 0dB at 100kHz | |
High-Pass Filter
| Roll-Off | 18 dB per octave (3 pole filter) |
| Frequency | Fixed 75Hz measured at the 3dB down point |
Weight and Dimensions
| W x D x H | 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) |
| Weight | 3.9 kg | 8.6 lbs |