Focusrite ISA One Single Channel Microphone Preamp
Back in the mid-1980s, the Focusrite Forte Recording Console was acclaimed as being among the finest designs of studio hardware to come along up until that time. Its legendary ISA110 mic pre and EQ was among the most revered and trusted amongst high-end studio professionals who demanded a clean, pristine, transparent sound but still yielding a bit of warmth to the signal. Over the course of many years, the same design was implemented in a slew of Focusrite products within their ISA and RED range of preamplifiers, favorites of discerning engineers the world over. The Focusrite ISA One Single-Channel Mic preamp makes it possible to own one of these fantastic preamps in the form of a portable, rugged chassis with a host of useful features, at a price that makes it accessible to engineers of all ilks. Let’s begin with the ISA110 module. The very same topology used on the original design is faithfully implemented here. A flexible, independent D.I. channel, complete with dedicated gain control, allows you to blend the direct guitar or mono instrument signal with the mic’d signal, making for some very interesting creative options. The variable impedance control lets you properly match up your microphone to get the best possible signal into the ISA One. You can hook up a compressor or EQ at the unit’s insert point, a handy feature enabling you to further enhance your signal on the way to your recording medium of choice. The line in jack allows for your active signal to pass through and a headphone jack with a dedicated volume control ups the ante, as you can monitor whatever signal (the whole stereo mix, for example) you route through it. Monitor your signal via the moving-coil VU meter together with two 6-LED meters. Inputs can be metered either pre or post input. The Focusrite ISA One’s rear panel analog outputs include 2 balanced XLR outputs (mic pre and D.I. output), as well as a TRS ¼” send. To further enhance the connectivity, Focusrite offers a digital output option with the ISA ADC providing 2 channels of the highest quality 24-bit conversion at all sample rates up to 192kHz. Digital output formats include 2 channel single/dual wire AES/EBU or 2 channel S/PDIF, all via a 9-pin D-type connector, as well as optical S/PDIF and ADAT. The ADAT (TOSlink) port is stereo and operates at 24-bit, up to 96kHz. Also available is the ISA One Digital, offering the ADC as a standard built-in feature, so remember to ask us about it. The same card can be used in Focusrite’s ISA 430 MKll channel strip. With all these useful features, together with pro sound quality packed into a single sturdy, portable box, you’d be hard-pressed to find a better professional solution at a better value than the Focusrite ISA One.
Specifications 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 OhmsISA110 = 1400 OhmsMed = 2400 OhmsHigh = 6800 OhmsEIN (equivalent input noise) = -126dB measured at 60dB of gain with 150 Ohm terminating impedance and 22Hz/22kHz band-pass filterNoise at main output with gain at unity (0dB) = -97dBu measured with a 22Hz/22kHz band-pass filterSignal to noise ratio relative to max headroom (9dBu) = 106dBTHD at medium gain (30dB) = 0.0009% measured with a 1kHz -20dBu input signal and with a 22Hz/22kHz band-pass filterFrequency response at minimum gain (0dB) = -0.5dB down at 10Hz and -3dB down at 125kHzFrequency response at maximum gain (60dB) = -3dB down at 16Hz and -3dB down 118kHzCMRR=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 = 84dBrALine Input Response Gain range = -20dB to +10dB in 10dB steps + 20 dB of variable gainInput Impedance = 10kO from 10Hz to 200kHzNoise at main output with gain at unity (0dB) = -96dBu measured with a 22Hz/22kHz band-pass filterSignal to noise ratio relative to max headroom (24dBu)=120dBSignal 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 filterFrequency Response at unity gain (0dB) = -0.3dB down at 10Hz and -3dB down at 200kHzInstrument Input Response Gain range = 10dB to 40dB continuously variableInput Impedance:High = greater than1MOLow =greater than 300kONoise at minimum gain (+10dB) = -92dBu measured with a 22Hz/22kHz band-pass filterNoise at maximum gain (+40dB) = -62dBu measured with a 22Hz/22kHz band-pass filterTHD at minimum gain (+10dB) = 0.001% measured with a 10dBu input signal and with a 22Hz/22kHz band-pass filterFrequency Response at 10dB gain with -10dB input = 10Hz-100kHz +/- 0.6dBFrequency Response at 40dB gain with -40dB input = -2.5dB down at 10Hz and 0dB at 100kHzHigh Pass Filter Roll off = 18dB per octave 3 pole filterFixed Frequency 75Hz measured at the 3dB down pointMeters 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 +26dBuRouting 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 = -20dBuFRONT AND REAR CONNECTIVITY Analogue Channel Inputs:Mic input: XLR x 1Line input: XLR x 1 and TRS x1Instrument input TRS Jack: XLR x 1External ADC input: TRS Jack x 1Return: TRS Jack x 1Analogue Channel Outputs: Send: TRS Jack x 1Balanced line output: XLR x 1DI output: XLR x 1DI through: TS Jack x 1Analogue Channel Additional I/O: Cue mix left input: TRS Jack x 1Cue mix right input: TRS Jack x 1Headphones output: ¼” TRS Jack x 1
| Audio Connections |
XLR Mic Input, XLR and 1/4 Inch Line Input, Insert Send/Return, External Input, Cue Mix Inputs, Main Out, DI Out, ADAT Out, SPDIF Out, Instrument In, DI In, Headphone Out |
| Sync/Timecode |
Yes |
| Presets |
None |
| Sampling Rate |
N/A |
| Compression |
No |
| MIDI Connections |
No |
| Model |
ISA One |
| Series |
ISA |
| Signal to Noise Ratio |
106dB |
| Memory |
None |
| Power Supply |
Internal |
| Frequency Response |
-0.5dB down at 10Hz and -3dB down at 125kHz |
| Number of Channels |
1 |
| Effects |
No |
| Crosstalk |
N/A |
| Display Type |
Backlit VU Meter |
| Phantom Power |
Yes |
| Other Features |
Optional Digital Converter with Cue Mix |
| Dimensions |
8.66"W x 11.4"H x 4.1"D |
| Product Weight |
8.6 lbs |
| EQ |
No |
Focusrite ISA One Single Channel Microphone Preamp
The manufacturer's warranty covers parts for one year and labor for one year from date of purchase. The warranty excludes damage from misuse, abuse, and contains other exclusions.
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