How much gain does the Focusrite ISA Two provide?

The ISA Two provides up to 80dB of clean, low-noise gain. This high gain range makes it particularly suitable for microphones with low output levels, such as ribbon microphones.

What type of input transformer does it use?

The unit utilizes the Lundahl LL1538 input transformer. This component is central to the unit's signature sound, providing high-quality coupling and a specific musical character.

Does the ISA Two have an instrument input?

Yes, the unit features two high-impedance (DI) instrument inputs located on the front panel. These are designed for direct connection of guitars, basses, or keyboards.

What are the selectable impedance settings for?

The four selectable impedance settings allow users to match the preamp to the microphone. This can optimize the frequency response and transient handling of both vintage and modern microphones.

Can I use external hardware with the ISA Two?

Yes, each channel features a balanced insert point on the rear panel. This allows you to patch in external processors like compressors or EQs into the signal chain.

Does it include a high-pass filter?

The ISA Two includes a variable high-pass filter for each channel. The cutoff frequency can be adjusted between 16Hz and 420Hz to remove unwanted low-end rumble.

How many channels does the ISA Two have?

The ISA Two is a dual-channel preamplifier. It provides two independent channels of microphone, line, and instrument amplification in a single rack unit.

Is the gain control stepped or variable?

The gain is controlled via a combination of a stepped switch and a continuously variable trim pot. This allows for precise settings that are easy to recall across two channels.

Does it require phantom power?

The unit can provide 48V phantom power to condenser microphones. Each channel has its own dedicated phantom power switch on the front panel.

What is the typical price for the ISA Two?

The typical price range for a new Focusrite ISA Two is approximately £832 GBP. Prices may vary depending on the retailer and regional taxes.

Is the ISA Two suitable for ribbon microphones?

Yes, it is highly suitable for ribbon microphones due to its 80dB gain range. Additionally, the variable impedance settings allow you to find the ideal load for vintage ribbon designs.

Does the unit include digital outputs?

No, the ISA Two is a purely analogue device. It provides balanced XLR outputs for connection to an audio interface or external AD converter.

Gear article

Focusrite ISA Two 2-Channel Rack Preamp

The Focusrite ISA Two is a high-quality dual-channel microphone preamplifier based on the legendary ISA 110 module circuit. It features Lundahl LL1538 input transformers and provides up to 80dB of clean gain, making it a versatile tool for recording vocals, instruments, and stereo sources.

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Background and Heritage

The Focusrite ISA (Input Signal Amplifier) series traces its lineage back to the mid-1980s when Sir George Martin commissioned Rupert Neve to design a console for AIR Studios. The resulting ISA 110 module became a benchmark for clean, musical amplification. The ISA Two carries this legacy forward in a modern 1U rack format, utilizing the same Lundahl LL1538 transformer-coupled input design that defined the original sound.

Technical Features

The unit provides two identical channels of preamplification. Each channel offers up to 80dB of gain, divided between a stepped gain control and a continuously variable trim. A significant feature is the variable input impedance, allowing users to select between four settings (Low, ISA 110, Mid, and High). This allows for precise matching with various microphone types, including vintage ribbons and modern condensers. The unit also includes a variable high-pass filter with a cutoff range from 16Hz to 420Hz.

Connectivity and Routing

For versatility in the studio, the ISA Two includes multiple input and output options. The front panel features two high-impedance instrument inputs (DI), while the rear panel houses XLR microphone inputs and TRS line-level inputs. A dedicated balanced insert point for each channel allows for the integration of external hardware processors, such as compressors or equalisers, before the signal reaches the analogue-to-digital converter.

Sound Profile

Characterised by its 'clean but with character' signature, the ISA Two is known for its high headroom and low noise floor. The Lundahl LL1538 transformer adds a subtle warmth and smooth top-end air without the heavy saturation found in some vintage designs. The ability to switch impedance significantly affects the tonal response of the connected microphone, providing a range of textures from dark and rounded to bright and open.

Comparison to Alternatives

Compared to units like the Warm Audio WA273-EQ, the ISA Two focuses strictly on preamplification rather than a full channel strip with EQ, though it offers more gain (80dB vs 70-80dB) and specific impedance matching. While entry-level preamps like the Behringer PP400 or inline boosters like the sE Electronics DM2 TNT serve specific utility roles, the ISA Two is a professional-grade rack solution designed for high-fidelity studio capture.

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Frequently asked questions

How much gain does the Focusrite ISA Two provide?: The ISA Two provides up to 80dB of clean, low-noise gain. This high gain range makes it particularly suitable for microphones with low output levels, such as ribbon microphones.
What type of input transformer does it use?: The unit utilizes the Lundahl LL1538 input transformer. This component is central to the unit's signature sound, providing high-quality coupling and a specific musical character.
Does the ISA Two have an instrument input?: Yes, the unit features two high-impedance (DI) instrument inputs located on the front panel. These are designed for direct connection of guitars, basses, or keyboards.
What are the selectable impedance settings for?: The four selectable impedance settings allow users to match the preamp to the microphone. This can optimize the frequency response and transient handling of both vintage and modern microphones.
Can I use external hardware with the ISA Two?: Yes, each channel features a balanced insert point on the rear panel. This allows you to patch in external processors like compressors or EQs into the signal chain.
Does it include a high-pass filter?: The ISA Two includes a variable high-pass filter for each channel. The cutoff frequency can be adjusted between 16Hz and 420Hz to remove unwanted low-end rumble.
How many channels does the ISA Two have?: The ISA Two is a dual-channel preamplifier. It provides two independent channels of microphone, line, and instrument amplification in a single rack unit.
Is the gain control stepped or variable?: The gain is controlled via a combination of a stepped switch and a continuously variable trim pot. This allows for precise settings that are easy to recall across two channels.
Does it require phantom power?: The unit can provide 48V phantom power to condenser microphones. Each channel has its own dedicated phantom power switch on the front panel.
What is the typical price for the ISA Two?: The typical price range for a new Focusrite ISA Two is approximately £832 GBP. Prices may vary depending on the retailer and regional taxes.
Is the ISA Two suitable for ribbon microphones?: Yes, it is highly suitable for ribbon microphones due to its 80dB gain range. Additionally, the variable impedance settings allow you to find the ideal load for vintage ribbon designs.
Does the unit include digital outputs?: No, the ISA Two is a purely analogue device. It provides balanced XLR outputs for connection to an audio interface or external AD converter.