Detail 01
Variable input impedance: 600, 1400, 2400, 6800 ohm
Changes how the preamp loads the mic. Lower settings thicken and tame a bright mic; higher opens up top end and detail.
Product detailSKU #1314230539162
FocusriteISA428 MKII 4-Channel Microphone Preamp
1/5
Independent shopping perspective
The Korena take
Four channels of Focusrite ISA transformer-coupled preamp in a 2U rack unit. For studios tracking drums, ensembles, or ribbon and dynamic mics.
Strong match
Who this is for
- Tracking a drum kit or small ensemble with matched, quiet channels
- Ribbon and low-output dynamic mics that need clean, high gain
- Rooms with long cable runs from live space to control room
Consider the trade-offs
When to look elsewhere
- Home setups that only ever record one source at a time
- Anyone needing built-in USB or Thunderbolt to a computer
- Buyers wanting compression, EQ, or effects in the same box
What matters in use
The specifications, translated
Catalog numbers tell only part of the story. These are the details most likely to change how this product feels, sounds, or fits into a setup.
Detail 02
EIN of –126dB
Self-noise sits far below anything you record. Quiet ribbons and SM7-class dynamics can be pushed hard without hiss rising with them.
Detail 03
THD+N 0.006%
Distortion is low enough to be inaudible on clean sources, so any color you hear comes from the input transformers, not from errors.
Detail 04
88dB CMRR
Strong rejection of noise picked up along the cable. Useful when mic lines run past lighting, power, or across a large tracking room.
Detail 05
Response reaching –3dB at 122kHz at unity gain
Bandwidth well past hearing keeps phase behavior clean in the audible band. At high gain the top rolls off earlier, near 103kHz.
Detail 06
19 x 3.5 x 11 inch, 12.2 lb
Two rack spaces and moderately deep. Leave room behind it for XLR and TRS cable bends in a shallow rack.
Final check
Know before you order
- 01A preamp, not an interface — you need line inputs or converters to record it
- 02Four channels of XLR and line cabling are on you to supply
- 03Two rack spaces plus depth; heavy enough to want rear support in a road case
Product questions
Before you decide
Straight answers to the questions shoppers most often ask about this product.
01Can I plug this straight into my computer?
No. The outputs are analog line level. You need an audio interface or converter with line inputs to get the signal into a DAW.
02What does the variable impedance actually do?
It changes the load the mic sees, which shifts frequency response and feel. Same mic, four usable voicings — most noticeable on ribbons and vintage dynamics.
03Is four channels enough for drums?
It covers kick, snare, and a stereo overhead pair, which is a complete kit sound. Add a second unit if you want toms mic'd individually.
04Does it work well with ribbon microphones?
Yes. The very low noise floor and high available gain mean you can drive a low-output ribbon without hiss, and impedance selection tailors the response.
Reference
Full specifications
The complete catalog record, organized around the decisions musicians make when comparing gear.
6 detailsSound
- Frequency Response At 10db Gain
- -0.2dB at 20Hz and 0dB at 200kHz
- Frequency Response At Maximum Gain 60db
- –2.5dB at 20Hz and –3dB 103kHz
- Frequency Response At Minimum Gain 0db
- –0.35dB at 20Hz and –3dB at 122kHz
- Frequency Response At 40db Gain
- -3dB at 20Hz and -3dB at 38.4kHz
- Frequency Range
- 16Hz to 420Hz (continuously variable, measured at the 3dB down point)
- Frequency Response At Unity Gain 0db
- –0.3dB at 20Hz and –3dB at 94kHz
3 detailsConnections & power
- Noise At Main Output with Minimum Gain 10db
- –95dBu (measured with a 20Hz/22kHz bandpass filter)
- Noise At Main Output with Unity Gain
- –91dBu (measured with a 20Hz/22kHz bandpass filter)
- Input Impedance Variable
- 600 ohm, 1,400 ohm, 2,400 ohm, 6,800 ohm
2 detailsSize & weight
- Dimensions Wxhxd
- 480 mm x 88 mm x 280 mm, 19 inch x 3-1/2 inch x 11 inch
- Weight
- 12.2
6 detailsOther
- Cmrr
- 88dB
- Maximum Headroom
- +11.5dBu
- Gain Range
- +10dB to +40dB continuously variable
- Thd N
- 0.006% (measured with -20dBu input signal, at minimum gain (+10dB), with a 20Hz/22kHz bandpass filter)
- Noise Ein
- –126dB (measured at 60dB of gain with 150 ohm termination and 20Hz/22kHz bandpass filter)
- Snr
- 113dB (relative to 0dBFS +22dBu). Input Impedance: 10 kohm
