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Focusrite ISA One Classic Single Channel Mic Pre

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Back in the mid-1980s, Sir George Martin commissioned console design legend Rupert Neve to build a series of new, ˜no compromise™ console modules for AIR studios. They were an enormous hit and formed ... Click To Read More About This Product


Gear returned in mint condition. If you're looking for a virtually new instrument in possibly less-than-perfect packaging, this is a great value.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
Gear returned in great condition, with only minor signs of use, such as slight scuffs or pick marks. It looks and plays like new and may be considered an equivalent to display units found in retail stores.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
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Back in the mid-1980s, Sir George Martin commissioned console design legend Rupert Neve to build a series of new, ˜no compromise™ console modules for AIR studios. They were an enormous hit and formed the basis of the Focusrite Studio Console, widely regarded as the best-sounding analogue recording console of all time. Today, the descendants of those modules are used in leading studios around the world, and their sought-after Focusrite Heritage Sound lies behind hundreds of hit records. Today™s ISA Range from Focusrite puts the classic sound of Focusrite into your own studio or live performance.

Featuring a rugged, portable all-metal enclosure, the ISA One combines the classic Focusrite microphone preamp with a flexible, independent DI channel and optional 192kHz precision A/D conversion.

At the heart of the ISA range is the microphone preamplifier with its Lundahl input transformer “ essentially the same circuit, based on the original ISA110, that has been used for 30 years in successive Focusrite designs. The input transformer imparts a special character to the sound that can™t be truly emulated in any other way: inseparable from the microphone itself, the transformer input stage is ideal for use with classic microphones. But this mic pre has a twist the original didn™t have, which makes it far more versatile: four carefully-selected impedances allow you to match microphone to input in different ways. Bring out the character of a classic mic or emphasise a special feature, or go for a totally transparent, modern sound “ it™s up to you.

Whether you'e an artist, engineer or producer, you™ll appreciate the versatility of the ISA One, with its front-panel DI input. The DI includes low/high impedance switching and an amplifier output, and its own feed to the optional A/D converter and separate rear-panel XLR output.


  • ISA Series Transformer-based Preamplifier
  • Flexible Independent DI Channel
  • Switchable Impedance
  • Headphone Output with Volume Control
  • Dedicated Insert Point
  • Optional stereo 192kHz A-D converter
  • Lundahl LL1538 Input Transformer
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: 10kΩ 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 than1MΩ
  • Low:greater than 300kΩ
  • 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
  • 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
    Analog 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
    Analog Channel Outputs:
    • Send: TRS Jack x 1
    • Balanced line output: XLR x 1
    • DI output: XLR x 1
    • DI through: TS Jack x 1
    Analog Channel Additional I/O:
    • Cue mix left input: TRS Jack x 1
    • Cue mix right input: TRS Jack x 1
    • Headphones output: º" TRS Jack x 1
    • 8.6 Ib. (3.9 kg)
    Dimensions(H x W x D)
    • 8.66" x 4.1" x 10" - 11.4", (220mm x 104mm x 254 - 290mm)
    • Related Products
    • ISA Stereo ADC (compatible with ISA 430 MKII and ISA One)ISA Stereo ADC (compatible with ISA 430 MKII and ISA One)
    Pro Coverage
    All Focusrite products are built to the highest standards and should provide reliable performance for many years, subject to reasonable care, use, transportation and storage.

    In the event of a Manufacturing Defect becoming evident within 12 months from date of purchase Focusrite undertakes that the product will be repaired or replaced free of charge if the product is returned to the authorised dealer from whom it was purchased. In these circumstances, or if you need an out-of-warranty repair to your Focusrite product, please contact your local Focusrite distributor in your country of residence or business : Find your local distributor here and you will be advised of the correct return procedure.

    Alternatively contact the Focusrite Reseller from which you purchased the product. If you purchase a Focusrite product outside your country of residence or business you will not be entitled to ask your local Focusrite Distributor to honour this Limited Warranty, although you may request a chargeable repair.

    Alternatively, the unit may be returned at your cost to the dealer you purchased the unit from so that they can organise a Warranty repair with their Focusrite Distributor.

    This Warranty does not include cost of shipping to and from the authorised dealer from whom it was purchased. In every case it will be necessary to provide the original invoice or store receipt to accompany the defective product to the supplying dealer. This Limited Warranty is offered solely to the first purchaser of the product from an Authorised Focusrite Reseller (defined as a reseller which has purchased the Product directly from Focusrite Audio Engineering Ltd. in the UK or its Authorised Distributors outside the U.K,) and is not transferable.

    This Warranty is in addition to your Statutory Rights in the country of purchase.

    Please note: A Manufacturing Defect is defined as a defect in the performance of the product which may be expected from a reasonable interpretation of the published description and performance specifications as published by Focusrite Audio Engineering Ltd. This does not include damage caused by post-purchase transportation, storage or careless handling, nor damage caused by misuse.

    A significant proportion of products returned under Warranty (which are very few in number compared to numbers sold) are found not to exhibit any fault at all. Please check that the mains voltage is correctly set for your local supply and that your connecting cables are in good order and correctly connected.

    If in doubt about the product functions please read the user guide and if necessary contact your dealer for advice before returning the product to the supplying dealer. You can also contact the Focusrite Tech Support team at the Focusrite Answerbase for general advice.

    Pro Coverage gives you added warranty protection for your gear. Stepping in where the manufacturer's "normal wear and tear" coverage ends, our Pro Coverage program offers you upgraded coverage if your product ever fails Click To Read More About This Product.

    Pro Coverage includes
    • Accidental damage protection
    • Expedited repair or replacement
    • Free shipping (for returns or repairs)
    • 100% coverage for commercial use
    • Extended price protection
    • No lemon guarantee
    • Free transfer of coverage to a new owner
    • Repair costs covered for up to five years from date of purchase
    • Repair authorization-toll-free by phone or via the web
    • Customer Reviews

    Review Snapshot

    by PowerReviews

    (based on 9 reviews)

    Ratings Distribution

    • 5 Stars



    • 4 Stars



    • 3 Stars



    • 2 Stars



    • 1 Stars



    Reviewed by 9 customers

    Displaying reviews 1-9

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    (18 of 18 customers found this review helpful)


    Transparent with a hint of...

    By Vivid Studio

    from Springfield, MO

    This thing is great, just gotta throw that out. It has a character you can't mistake. Because of the lundhall transformers, you get this sort of sizzle that you have to hear to understand. When ABed with some less expensive preamps you will notice the effects immediately. I also enjoy the fact that you can use it as a latency free piece. During a session, the singer was having trouble singing through pro tools and my latency. I didn't want to sacrafice plug's to improve latency, so we ran it through the ISA. This really is the centerpiece of my pro tools rig. I find myself running everything through it. I would say it is a great value that can stand up to all the other big name pre's.

    (14 of 16 customers found this review helpful)



    By Big Tymer

    from Texas

    This pre is the TRUTH!. lol, I use the pre as my go to for vocals in conjuction wit a blue blueberry mic. I record hip hop, and rnb vocals on a day 2 day basis and my clients love the sound of this unit. Its hard to describe u just gotta hear it for yourself to understand. If you can imagine your vocals with this "glossy sheen" to them, thats what it sounds like. They come across very focused and and transparent. Please do yourself a favor and get this pre!

    (2 of 2 customers found this review helpful)


    A "No-Brainer"! A Great Preamp and A Great FIRST Preamp

    By Bob Gallagher

    from Bloomington, IL 61704

    I ordered the Focusrite ISA One and the Universal Audio Solo 610 so I would have one very nice Solid State transformer based Preamp and one very nice Tube Preamp in my home studio. In my opinion, this is "the preamp" everybody should save up for and buy as a first preamp as opposed to buying a couple of lower priced preamps before buying a "good" preamp. For less than the price of an ART MPA II and a Focusrite Trakmaster Pro, the ISA One gives you a multi-faceted, "multi-color" preamp that you'll most likely keep for a long time. I love how my Solid State and Tube Condensor microphones sound going through this thing, especially at the ISA 110 setting. That setting, its Swiss Army Knife capabilities and its incredible price make purchasing this unit a "No-Brainer". PS-I have owned the ISA One for 3 months. It is built like a tank. The look and feel is fantastic for what that might be worth. More importantly, though, I think it sounds great!

    (2 of 4 customers found this review helpful)


    Wow, what a smart buy.


    from Bakersfield, CA

    I use an AKG C414 XLS, and I wanted a good tube preamp to compliment the clarity of my AKG. I had done lots of comparisons of other preamps, but they were in the $1,000+ price range. I was reluctant to buy the ISA One because I thought it was ugly, but I decided that the price I bought it for was worth trying out. I was so surprised and pleased with how my mic sounded after using it. So much clarity and smoothness. It felt fuller and warm. I did some sound comparisons without it, just to see if it was my head playing tricks on me. Nope, the signal was fatter, the sound was full and smooth, and the artifact noises were diminished. I just wish it looked more modern.

    (1 of 1 customers found this review helpful)


    ISA One is excllent

    By CC51

    from newbie tx

    This unit was recommended often on the forums and articles by pro's for a someone wanting a pro pre amp. I took it home and tried this to see what a "pro" unit is. Out of the box it was built like a tank. Plugged in and turning the pots it was just impressive, the layout and feel of the pots and also the extreme tones one can get from the various settings. Its also a 2-channel unit which makes this unit over the top a great value. 2 professional channels. Plugging in a microphone the gain is there for any mic type you can toss at it. The sound can be super clean, or if ran with certain settings a pure compressor tone from the transformer is obtained for that familiar sound we hear on records or the radio. This unit is an extremely great value, because of the 2 channels with separate outputs. A DI and a Main Mic Channel would also work great for coffee house gigs for a beautiful sound. A company good enough for Sir George Martin, and this unit is of that design family tree with Lindy Transformers and color layout.

    (1 of 1 customers found this review helpful)


    ISA One ome Recording dual channel preamp

    By ronald riekena

    from Dallas Texas

    I dont do a lot of reviews but this unit is special. Its built well, it has TWO CHANNELS, which many miss that point. The most important fact is the great tone. I was ready to return it if it didnt improve my HR setup, but not only did it improve the sound, the ease of use and ability to plug in a Bass DI, or a SM7 (dynamic) mics into the main channel was why I give it a 5 star rating. I plug its outputs straight into my Recording Interface Line In and there is such a high quality sound without adding anything is amazing and makes it a solid piece to own and enjoy.

    (1 of 1 customers found this review helpful)



    By Mark Westphal

    from Centreville, Virginia

    What a great pre-amp! I've been dealing with a lot of cheap ones that sound ok, but when I connected this ISA ONE to my Shure SM7b, it was like the clouds rolled away, and all was great. Absolutely no noise, and this holds true for all of my mic locker...condensers, ribbons, etc. I can't recommend this enough, and talk with your Guitar Center pro audio guy, and he will probably give you a nice break on the price. got it right.


    Never use a Shure SM7B without this!!!!

    By Cas

    from West Palm Beach

    About Me Experienced


    • Clear Sound
    • Easy To Use
    • Powerful
    • Professional Functions
    • Versatile


      Best Uses

      • Home Studio
      • Professional Recording

      I bought a Shure SM7B about 3-4 years ago and was starting to get discouraged because my vocals never seemed to stand out or be CLEAN. But after me driving myself to the verge of insanity with trying to get good CLEAN vocals, I decided enough was enough time to buy a Mic Pre. I was told about a cloud lifter but i didn't want to hold back to have to buy something again later so i decided on the ISA One. Vocals instantly became better and CLEAN. I can't crank the mic pre too much as my room isn't fully treated so it will start too pick up noise in the environment. Also having the ability to choose between Line level or Mic level really helps. Great Mic Pre

      (0 of 1 customers found this review helpful)


      Great Pre

      By Austin

      from Salt Lake

      Site Member

      Awesome Preamp! I've had this for about 2 years now and I've never been disapointed. Also just added the a/d card to optimize performance. Sweet unit.

      Displaying reviews 1-9

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