Focusrite ISA Two Dual-Channel Microphone Preamplifier

Record two channels with a stunning 80 dB of clean Focusrite gain with the ISA Two microphone preamp, featuring high-end Lundahl LL1538 transformers.

Focusrite's ISA Two offers a totally independent pair of legendary ISA microphone preamps inspired by Rupert Neve's original ISA 110 module design, combining the best of traditional solid-state electronics with the original input transformer -- the Lundahl LL1538. Two is a nice round number -- ideal for recording, say, a vocal and an instrument, or a stereo piano. But though you may only need two mic pres, you owe it to your craft to choose the best.

See and hear the ISA Two on vocals and acoustic guitar in this video from Focusrite:

The ISA Story goes back to 1985, when Sir George Martin commissioned legendary designer Rupert Neve to design new modules for the console at AIR Montserrat. They were so successful that more were commissioned for AIR London. These original modules form the basis of today's Focusrite ISA range -- delivering the legendary Focusrite sound to leading studios, artists, producers and engineers around the world. Literally hundreds of hits have been made with the Focusrite ISA Range -- and continue to be made today.

Focusrite's ISA Two brings together a totally independent pair of legendary ISA microphone preamps inspired by the original ISA 110 module, combining the best of traditional solid-state electronics with the original input transformer specified by Rupert Neve -- the Lundahl LL1538. Two is a nice round number -- ideal for recording, say, a vocal and an instrument, or a stereo piano. But though you may only need two mic pres, you owe it to your read more craft to choose the best. (And if you need more, we offer ISA 428 Mk II 4-channel and ISA 828 8-channel units too.)

Focusrite has made one little adjustment to the mic pre. The original ISA 110 had a single input impedance that was ideal for the mics of the time. In the ISA Two there are three more, allowing you to get the very best out of any microphone, vintage or modern. Give a vintage mic the input it expects to get a traditional, warm sound. Pair the ISA Two with modern microphones and get the most transparent sound imaginable. Or experiment and pull out the inner character of any microphone you care to try. Couple that with up to 80dB of gain and you can be ready for anything.

In addition to the mic pres, there are front panel instrument inputs for instant access, along with rear-panel line ins. There's also a balanced insert point on the rear panel, actuated with a front-panel button so you can insert the EQ, dynamics or other processors you need. Add to that the user-calibrated 8-LED metering and variable cutoff high-pass filter and you know that with the ISA Two you'll have everything you need to get the highest quality sound into your recordings.


- Lundahl LL1538 mic input transformer: Rupert Neve originally chose the Lundahl LL1538 to be the input transformer on the ISA 110. It remains the best microphone input transformer available, and is used in every ISA Series mic pre.
- Up to 80 dB of gain: ISA Two offers up to 80 dB of clean, distortion-free gain. The much-heralded ISA topology also ensures low noise, even at the highest gain levels. The transformer supplies 20 dB of gain, while ISA's input stage offers up to 60 dB in addition, giving a total of up to 80 dB of maximum gain on the microphone input.
- Variable input impedance: Four choices of input impedance, including the original ISA 100 value, allow you to match the preamp to your microphone, even if it's a vintage type, giving you the best possible sound. The impedance is selected using a switch on the front panel, and the impedance choice is remembered even once the unit is switched off and back on.
- User-calibrated metering: Each channel has an eight-LED array to clearly display the level of your two signals. Line up your ISA Two levels to match your DAW converters with the calibration knob on the rear panel.
- Front panel instrument and rear panel line inputs: Two 1/4" jack sockets on the front panel of ISA Two give you instant access to a transparent DI input. TRS line inputs are available on the rear panel too, and you can step through them instantly to select the one you want.
- Variable cut-off high-pass filter: Built in, and easily accessed with its own large knob and illuminated button, is an extremely smooth sounding 18dB/octave high-pass filter of the same design as the original ISA 110 module. This is ideal for cutting out rumble, thumps and other unwanted low-frequency sounds and with a range of 16 to 420 Hz, it's easy to lose what you don't want, and keep what you do.
- Rear panel balanced inserts: Each channel of ISA Two has its own balanced insert point. With 1/4in. TRS send and receive connections, your choice of signal processor can be connected and switched in and out using the illuminated switch on the front panel.
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- Front panel, per channel:
- 1/4 inch instrument input
- Variable input impedance - Low, ISA 110, Medium, High
- Input selection - Mic, Line, Instrument
- 0 - 30 dB/30 - 60 dB gain switch
- Phantom power switch
- Phase invert switch
- 0 - 60 dB gain in 10 dB steps
- 0 - +20 dB continuously variable trim
- Variable high-pass filter with on/off switch
- Insert point on/off switch
- Eight-LED user-calibrated level meters
- Single power switch
- Rear panel, per channel:
- XLR-F mic inputs
- 1/4 inch TRS line inputs
- 1/4 inch TRS Sends
- 1/4 inch TRS Returns
- XLR-M line output
- Single peak meter calibration dial
- Single IEC power socket
- Dimensions (WxDxH): 480 x 280 x 44 mm
- Weight: 3.7 kg
Dimensions and Weight in Packaging
Base Item
Shipping Weight: 12.25 lbs
Shipping Dimensions: 26 x 15 x 6 in
Manufacturer Part Number (MPN): AMS-ISA-2

For support or warranty questions, please contact the manufacturer:
Phone: 310-322-5500

Reviewers gave this product an overall rating of 5 out of 5 stars. (1 ratings)
Submitted January 5, 2013 by Bruce B in Fort Collins, CO
"Steller Mic Pre!"
Overall: 5 out of 5 stars
(see rating details)
Verified Customer zZounds has verified that this reviewer made a purchase from us.
I needed a pair of "steller" Mic. preamps that were "matched" for stereo miking in the studio. I bought a Focusrite Liquid Channel preamp a few years back and have never been happier with the quality of sound. I had the choice of spending >2k for another Liquid Channel or try the new ISA 2 for less than 1/2 the price: I'm SO glad that I made the choice that I did! The ISA 2 has a huge ammount of gain (80dB) with basically no noise. I have used the ISA 2 mainly with a matched set of Neumann KM184s and as a keyboard and Bass guitar directbox / preamp in the studio to date. The detail in the sound and lack of any audible noise on the recorded tracks sold me! In the past I had issues with getting enough gain on soft instruments(finger picked acoustic guitars indian flutes ect..) without raising the noise more!! Now if I can figure out how to get folks not to breathe while recording ;-) You can hear EVERYTHING! The only thing that would have made the ISA 2 better is an A\D converter option. Most of us live in the age of DAWs. If that is you, rememeber that you need a great A\D converter paired up with this preamp to truly be blown away. P.S. I have never had any trouble with any of my Focusrite gear to date, so I can't really comment on the Mfg. Support question.
Musical Background:
Audio Pro. Avid musicain > 40 years
Musical Style:
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