FOCUSRITE ISA 428 FOUR CHANNELS MIC PREAMPLIFIER

Overview:

The ISA 428 Pre Pack is the perfect multi-channel front end for any professional DAW.
Four classic Focusrite transformer-based pre amps with switchable impedance and direct
instrument inputs. An optional eight channel 192kHz ADC, preceded by the all new proprietory
Soft Limiter circuit, provides the perfect path into your Pro Tools HD system.
The benefits of the pre amp's topology include superb common-mode rejection, an excellent
overload margin and, with its shared gain structure (20dB from the hand-wound transformer and
up to 40dB from the amplifier), an extremely low noise floor and super-wide bandwidth (10Hz to
200kHz). This pre amp design is the cornerstone of Focusrite's signature 'warm-yet-transparent'
sound and is a point of reference for any discerning audio professional.
In addition, the input stage provides enhanced control and creativity allowing you to switch between
four carefully selected input impedance settings. The original ISA 110 setting is supplemented by
three further impedance settings to either perfectly match the pre amp with any microphone and
maximise level, or use different settings creatively to shape the sound of the microphone being used.
Should the need arise to place extra processing in between pre amp and conversion, insert points are
also featured on every channel.
Protecting the ADC, the Soft Limiter opto circuit is a new design from Focusrite, entirely preventing any
'digital overs', whilst minimising the undesirable distortion that standard limiter circuits often generate.
Finally, the new ADC embodies cutting-edge conversion technology, encompassed within pristine Focusrite
circuitry, providing eight conversion channels of the highest quality, at frequency rates of up to 192kHz.
Running at 96kHz allows for up to 16 (2 x 8, parallel) simultaneous digital outputs in addition to the four
main analogue outputs. Digital output options include dual AES/EBU, SPDIF and dual ADAT lightpipe.
Full digital metering is provided for every channel, alongside new 'moving coil' peak meters, designed to
catch even the fastest of transients.
A second analogue unit can be connected utilising the four extra ADC input channels on the rear of the unit
containing the optional ADC. This makes full use of the eight channels provided on a single optional ADC and
expands your front-end capacity from four pre amps and eight digital outputs to eight Pre amps and eight digital
outputs.
Classic preamp technology, custom Focusrite input and limiting circuits and the very best in A/D conversion
technology, the ISA 428 Pre Pack raises the bar for multi-channel recording solutions into Pro Tools HD, or any
other professional DAW. Equally, it can be used as an additional set of high quality pre amps for any analogue
or digital console or hard disk recorder.
Four classic Focusrite transformer-based preamps.
8 channels of cutting-edge A/D conversion, running at up to 192kHz. Protected by proprietory optical Soft Limiter
circuit.
Switchable Impedance for unparalleled mic matching or extended mic creativity - includes the classic ISA 110
setting.
Multiple Front Panel Instrument DI. No separate DI box required.
Analogue insert points on every channel.
High Pass Filters on every channel.
New moving coil peak meters & full digital metering (dBfs).

ADAT is a trademark of Alesis Corp
Pro Tools HD is a trademark of Avid Technologies plc.
The 192kHz ADC is an extra cost option.

Specifications
Inputs
Transformer-based ISA design
Gain range: Line = +/- 18dB, Mic = 0 to 60dB (both in 6dB steps), Inst = +10 to +40 dB
variable
Input impedance: Line = 10k ohm, Mic = Variable - 600, 2k4 and 6k8 ohm + original ISA 110
settings, Inst = >1M ohm

Analogue Performance
Noise: Line = -96dB, Mic = -128dB (EIN with 150 ohm input resistance at 60dB of gain)
THD: Line = 0.003% with 0dBu, 1kHz input and 20Hz to 22kHz band-pass filter, Mic = 0.003%

Analogue Input and Output connectors (balanced)
D.I inputs: 1/4 inch Jack (unbalanced)
Mic inputs: XLR (balanced)
Line: TRS Jack (balanced)
Insert Sends and Returns: TRS Jack (balanced)
Additional ADC inputs: XLR (balanced) Line level
Analogue Outputs: XLR (balanced)

Digital Output Option
AES/EBU and S/PDIF dual 9-pin D-types
Optical - ADAT Lightpipe
Bit depths 16-, 20- or 24-bit
Frequency options 44.1, 48, 88.2, 96, 176.4 and 192kHz
Clock options Standard or ?256 x?
Meter - 0 dBFS = +22dBu
Digital Performance
SNR - 120dB A-weighted

At PreSonus, weʼve been designing preamps for a long time, and we always focus on audio quality first. So when we decided to upgrade our popular TubePre V2, we focused on improving an already high-quality sound—without jacking up the price. Like the originalTubePre, the new version is a fully professional tube preamp, with a dual-servo (no capacitors) gain stage that lets you boost the program signal to smoking hot levels without significantly increasing the background noise. Discrete components and high-voltage operation offer dynamic range and detail not found in other single-channel tube preamps in its class.

Housed in a rugged case, the TubePre V2 rear panel sports separate unbalanced, ¼” instrument and balanced, XLR mic inputs and unbalanced ¼” and balanced XLR line outputs. Weʼve included all of the extras you need for professional operation including a high-pass filter, phantom power for condenser mics, polarity reverse switch, and a backlit VU meter.

Features
Superlative sound
Studio quality mic preamp
Total control - Input Gain, EQ contour, Output Gain,
Overload indicator
Multiple output connectors
XLR/jack combo input 
Switchable 48 V DC Phantom Power for condenser Mics
Compact, computer friendly package
Needs no external power supply
 
ARX is proud to introduce the e-pre - the ultimate microphone pre-amp for
hard disk recording, designed by audio professionals, not computer engineers.
The all-new e-pre is so much a part of your system that it fits right into a spare
5?" slot in your computer case! It's the perfect tool for all your day-to-day
recording requirements. No equipment racks to plug in, no masses of cabling to
connect - the e-pre is ready and waiting when you need it.
The e-pre is a studio quality microphone pre-amp using the same internal components
as high end mixing consoles, built into a compact, computer friendly package.
It has controls for:
Input Gain - fully variable from 10dB through to 60dB to suit all types of microphones,
plus switchable 48 V Phantom Power to enable condenser microphones to deliver
their best.
A Contour control for EQ sweetening, providing fast, easy access to a whole range
of useful EQ curves
Output level control - fully variable to match the e-pre's output to the input of the sound
card. From -10dB consumer cards through to +4dB for professional sound cards, the
e-pre can handle it.
Multiple output connectors match up with any kind of sound card, including mini jacks,
standard jack, RCA (phono) plugs, and even a connector to link to the internal CD ROM
audio input of your sound card (if fitted).
We've even fitted a 12 VDC input connector on the rear to enable the e-pre to run from an
external power supply if required (eg for use with notebook computers or stand-alone use).

Any way you look at it, the e-pre by ARX is the total professional microphone pre-amp for
all your hard disk recording needs

e-pre Benefits
Professional Balanced XLR mic input
True 48v phantom power
Runs into the Line input of ANY sound card - uses the card you've already paid for
High headroom = clean recordings
Smart EQ
Compatible with non-computer audio equipment
Professional performance and specs in a user friendly package
 

T E C H N I C A L  S P E C I F I C A T I O N S
Input Impedance
Mic 2 K Ohms Balanced; XLR type Pin 1 Audio Ground, Pin 2 +, Pin 3-
Line 25 K Ohms Balanced, ?" TRS jack Tip +, Ring , Sleeve Audio Ground
Phantom Power Voltage Switchable +48 V DC on XLR Pins 2 and 3
Max Input Level Mic +15 dB, Line +20 dB
Input Gain 10 dB Minimum, variable to 60 dB Maximum
Output Level -10 dB variable through 0 dB to +4 dB
Overload Indicator Measured at all Gain points throughout the circuitry
Output Noise -90 dB Unweighted, -97 dB 'A' weighted
(Measured with Gain nominal 20 dB, Output level -10 dB)
Frequency Response 20 - 20 KHz ± 0.25 dB
Distortion
100 Hz 0.0085%
1 KHz 0.008%
10 KHz 0.0083%
(Measured with Mic Gain 20 dB, Output 0 dB)
Power Requirements 12 V DC from either computer supply or external supply
(external power supply not included in e-pre package)
Size 148mmW x 42mmH x 150mm D (5?“W x 1?H x 6“D)
Weight Under 1 Kilo (2.2 lbs)
 

The PRE-73 Mk2 is the first one-channel low-cost preamp on the market that is using a fully discrete signal path with three separate transformers for the balanced mic input, the line input and the output.

The circuit is very similar to the classical preamp section of the Neve 1073 pre/eq module with a corresponding sound character that is warm, punchy, sweet and musical.
This classical sound has been heard on countless recordings through the years and it is a versatile sound that works very well on most sound sources and in most genres.

The PRE-73 Mk2 has a maximum gain of 80 dB on the mic input and the gain range on the Line input is -20 to + 10 dB. There is also a high-impedance instrument input.

The PRE-73 Mk2 is perfect for almost any signal source, no matter if it's a microphone with a high or low sensitivity (like a passive ribbon mic), a syntheziser or sound module or an electric guitar or bass.

The input impedance of the microphone input can be switched between 300 and 1200 ohms, which makes it possible to affect the tone of most microphones. There is also phase switch and an simple 4-step LED signal level meter.

The output level control makes it possible to make fine gain adjustments and also to overload the main gain stage for more character and then lower the signal to a suitable level before the output stage.

The Mk2 update consists of:
- An unbalanced insert jack (nominal level about 18 dBu) added on the back panel for inserting units like the coming GAP EQ-73, a three band eq.
-  LED meter levels adjusted.
- 600 Ohm termination resistor and jumper added to power supply board (accessible from the inside of the unit).
- Revised Gain switch, turning the know clockwise now increase the gain.
- Reduced noise at high gains by a change to the power supply grounding scheme.

• Maximum of 66 dB of gain, in eleven discrete steps
• Dynamic range exceeding 120 dB
• 10 Hz to 50 kHz audio bandwidth
• High immunity to RF interference
• High current line output driver
• Transformer-balanced input and output
• Extended range peak limiter via dual opto-isolators makes preamplifier virtually "unclippable“
• Selectable 48-volt / 12-volt phantom power or 12-volt "T" power
• High-pass filter @ 80 or 160 Hz, 6 dB per octave
• Headphone monitoring of microphone audio, monitor audio, or a mix of both
• Monitor input accepts mono, balanced or unbalanced line-level inputs on 1/4-inch tip-ring-sleeve connector
• Separate level control of Monitor gain and overall headphone gain
• Split ear function via DIP switches
• Internal battery power (two-AA)
• Excellent battery life with alkaline and NiMH rechargeable batteries
• External 5-17 VDC powering (plug included)
• High-strength aluminum chassis with durable belt clip

Having had great success with the PRE-73 preamp, we have received many requests for a version for the 500 eries rack format. We are therefore happy to present the PRE-573, expected to start shipping in late September.
 
The PRE-573 is a one width module that has the sound and the features that made the PRE-73 so successful and a few additional ones.
The circuit still uses the preamp and output section from the classic 1073-module, adapted to work in the api rack format. It has a total  gain range from -15 to +80 dB. The 10 - 70 dB range is handled by a turn switch  and there is a separate toggle switch to select an additional 5 or 10 dB gain. The input can be configured to accept line level signals by another switch, the gain is then lowered by about 25 dB and the input impedance increased to about 15 kohm.
 
The input impedance of the mic input mode can be switched between 1200 and 300 ohm. Phantom power and phase reverse is also selectable by front panel switches.
 
An added feature, using the same circuit as in the PRE-73 DLX, is the active DI-input with a high input impedance of about 1,5 Mohm. The output signal from the active DI circuit passes through the input transformer for some extra character.
The DI-input is very flexible since it can be changed to a purely passive one by a front panel switch. The DI input is then exactly the same as in the PRE-73 Mk2 where the signal is feed directly into the second gain stage, bypassing the transformer and with an input impedance of about 100 kohm.

These two DI-options makes it possible to get different tones from electric instruments and the passive DI input mode is more suited for injecting active units like sound modules. 
 
A new feature is the switchable AIR mode that  adds a small boost above 10 kHz that peaks at 2 dB at about 35 kHz.

A simple but effective signal and overload indicator is offered by a single LED that starts glowing red at about +4 dBu and then increases its intensity up to the maximum output level.
 
The PRE-573 has a dedicated insert connector at the back allowing it to interface with other GAP 500 modules. The insert can be activated by removing a jumper connector at the back of the module.
The second Golden Age Project module for the api 500 rack will be the EQ-573, expected to ship in November 2012. The EQ-573 consists of the inductor based high pass filter section  and the 3-band eq section from the classic 1073 module with some added frequencies. These two modules together will offer a fully fledged 1073-module in a compact format at a very low cost.
 
There is a second jumper at the back of the module that selects 600 ohm termination on the output. The standard mode is termination on, since it gives the flattest response when the PRE-573 is used with modern line inputs that typically has an input impedance of 10 kohm or more. The user can chose to remove the jumper and deactivate the termination resistor, this will increase the level above 10 kHz and create a peak in the response for an even more pronounced  "Air" effect.
The output is transformer balanced and fully floating and can drive a 600 ohm load up to level of about 28 dBu.