The Focusrite ISA One is an analog microphone preamp that will amaze you in the recording studio with its many distinctive features, and allow you to craft a colorful and rich gain stage.
The Nicest D.I. Box In The Room
In live situations, the ISA One works as a fantastic direct input box when you want to run a high-impedance, line level, unbalanced output signal to a low-impedance microphone level balanced input, like a mixer or a powered speaker. As a D.I. it delivers a great, noise-free sound. The unit is also ruggedly built and is highly portable with a carrying handle right on top.
Versatile and Intuitive I/O
The Focusrite ISA One preamp has a single XLR and TRS line input. The D.I. channel is independent, and utilizes its own dedicated gain control. There is a switch for Active or Passive impedance to allow different signal sources to be routed quickly. A single TRS Jack output is provided for routing to other amps. There is also an independent XLR output on the rear. The headphone output has a dedicated volume control.
A Tribute to a Great Vintage Microphone Preamp
The Focusrite ISA One is based on the vintage ISA110 module microphone pre-amplifier. It features the same circuitry and componetry as that legendary and celebrated unit, including the Lundahl L1538 transformer and bespoke zobel network. These were the preamps that made Focusrite a household name, and they have been lovingly recreated for this excellent-sounding amp. It is unquestionably a product reflecting many years of continued innovation.
Extensive Features For Tonal Crafting
The circuity is a variable impedance design, allowing you to switch between four different input impedance settings. This allows you to fine tune the impedance with other preamps or microphones in your chain. There is even an additional Insert Point where extra processors or FX can be introduced in between the pre amp and the D.I.
Phase Reverse and a 75 Hz, 18dB/octave high-pass filter round out the tonal shaping capabilities. The ISA One preamp also delivers phantom power.
A moving coil VU meter with variable calibration gives you clear input metering for both channels. Helpfully, the meter calibrations utilize all the same reference points as Pro Tools, allowing your digital meters to sync perfectly to your analog meters.
Exceptional for Dual-Signal Application
Focusrite developed this innovative design to accommodate guitars running via a D.I. while mic'ing the guitar cabinet simultaneously. It serves well as a great single solution for musicians looking to run their guitars and vocals through the same pre-amplifier.
- Variable impedance design with four switchable input impedance settings
- 1 x XLR and 1 x TRS instrument input
- 1 x TRS External ADC input
- 1 x TRS Return
- 1 x TRS Jack Send
- 1 x Balanced XLR Line Output
- 1 x XLR DI output
- 1 x TS Jack DI through
- 1 x headphone jack with independent volume
- 75 Hz high-pass filter
- Moving coil VU meter can be calibrated
zZounds is an authorized dealer of
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 = 84dBrALine Input Response
- Gain range = -20dB to +10dB in 10dB steps + 20 dB of variable gain
- Input Impedance = 10kOhm 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 200kHzInstrument Input Response
- Gain range = 10dB to 40dB continuously variable
- Input Impedance:
- High = greater than1MOhm
- Low =greater than 300kOhm
- 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 100kHzHigh Pass Filter
- Roll off = 18dB per octave 3 pole filter
- Fixed 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 +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 = -20dBuFront 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: 1/4 in. TRS Jack x 1Case NOT Included.
Weight: 3.9kg, 8.6 lbs
- Dimensions and Weight in Packaging
- Base Item
- Shipping Weight: 13 lbs
The 'ISA One' microphone pre-amplifier delivers Focusrite's prestigious ISA transformer-based pre-amp in a rugged and portable chassis, at a groundbreaking price.
ISA One features the classic vintage microphone pre-amplifier topology from the original ISA110 module, including the Lundahl L1538 transformer and bespoke zobel network. (The original 110 pre amp formed the cornerstone of each channel of Focusrite's legendary Forte console.)
The pre-amp is complemented by a line input (XLR and TRS Jack) and an independent D.I. channel, complete with dedicated gain control, active or passive impedance switch, a TRS Jack output for routing to an amp and an independent XLR output on the rear. This flexible independent D.I. makes the ISA One ideal both for engineers wishing to blend a D.I.'d guitar signal with a mic'd guitar cabinet, and for demanding performers who require a single classic solution for both guitar and vocals. A variable impedance circuit has been added, allowing the user to switch between four carefully selected input impedance settings. In addition to the original ISA110 impedance, three further impedance settings allow perfect matching, or creative mismatching of the pre amp with any microphone. ISA One also features an insert point, should the need arise to place extra processing between the pre amp or D.I. and the optional converter. Phantom power, phase reverse and a 75Hz, 18dB/octave high-pass filter are also available from the angled front fascia.
Independent input metering for both channels is provided in the form of a moving coil VU meter with variable calibration to suit analogue and digital recording media, alongside two six-LED peak meters; inputs can be metered either pre- or post-insert. The meter calibrations utilise all the same reference points as Digidesign's Pro Tools HD system, allowing effortless line-up.
ISA One's headphone output features a dedicated volume control, which delivers an external stereo cue mix, (a simple click track, or a stereo mix feed from an interface or a live console,) fed to the headphones via two TRS jack inputs on the rear of the unit.
An optional state-of-the-art stereo A-D converter is also available (the same card as used with the ISA430 Mk II)
, embodying cutting-edge conversion technology seated within Focusrite's custom analogue circuitry. This optional card can be retrofitted at any time and provides two channels of 24 bit/192kHz A-D conversion with a dynamic range of 119dB.