Product Information:
The ISA One microphone
preamplifier delivers Focusrite's
prestigious ISA transformer-based preamp in
a rugged and portable chassis, at a
groundbreaking price.
ISA One features the classic vintage
microphone preamplifier topology from the
original ISA110 module, which formed the
cornerstone of each channel of Focusrite's
legendary Forté console.
The preamp is complemented by a line input
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 preamp with any
microphone. ISA One also features an insert
point, should the need arise to place extra
processing between the preamp 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 Avid'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 MkII).
Specifications:
We always quote 'real
world' performance figures (measured to the
AES17 standard). Some companies choose to
quote chipset performance, which is
misleading, and here's why.
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)
