ISA 428 MkII
intermediate
$2,299
Used market: $1,885*
Specifications
2 of 6 values have a recorded source- Type
- outboard_preamp·
- Added Gain dB
- 60✓
- Input Connector
- 4x 3-Pin XLR Mic + 4x 1/4" TRS Line + 4x 1/4" TS Instrument (front)·
- Output Connector
- 4x 3-Pin XLR Line + 4x 1/4" TRS Insert Send·
- Expert Description
- En: Four ISA channels in 1U: mic gain 0-60 dB in 10 dB steps plus 0-20 dB trim, instrument inputs 10-40 dB continuous, four selectable mic input impedances (600 Ω, 1400 Ω, 2400 Ω, 6800 Ω), a variable 16-420 Hz high-pass filter, and a slot for the optional ISA ADN8 A-D card. · Uk: Чотири канали ISA в одному юніті: мікрофонне підсилення 0–60 дБ кроками по 10 дБ плюс trim 0–20 дБ, інструментальні входи 10–40 дБ плавно, чотири варіанти вхідного опору (600 Ω, 1400 Ω, 2400 Ω, 6800 Ω), змінний фільтр низьких частот 16–420 Гц і слот для опційної плати АЦП ISA ADN8.·
- Requires Phantom Power
- no✓
Expert Audio Engineering Commentary
Gain Staging Advice
Maximum headroom at the mic input is 7.4 dBu — a loud source into a hot condenser can clip the input stage before any gain is applied, and no amount of turning the gain down will fix that. The pad lives on the microphone, not in this box.
Production Warning
Focusrite publish no phantom power statement for this unit anywhere on the product page, and unlike the ISA One and ISA Two there is no online user guide for it, so the catalogue leaves "passes phantom to the mic" unknown rather than assuming it. The +48V switches exist on the front panel; what is missing is a document to cite.
What the datasheet actually says
Quoted verbatim from the manufacturer’s own page, with the date we checked it. We state what is printed, not what anyone intended by it.
««Up to 60dB of gain is available on the four-position rotary and gain range switches, with a further +20dB of continuously variable trim, meaning a huge 80dB of gain is available should it be required» — при тому що в таблиці: «Gain Range (Mic): 0dB to 60dB in 10dB steps, plus 0dB to 20dB continuously variable trim»»
The same page gives two different headline gain figures: 80 dB in the description and 60 dB (plus a separate trim) in the specification table. Both describe the same circuit — the description adds the trim to the stepped range, the table does not — but a reader comparing preamps by their headline number will get 80 dB here and 60 dB from the ISA One and ISA Two pages, which are electrically the same front end. The catalogue records the stepped maximum, 60 dB.
checked 8/5/2026* Estimated with the depreciation fallback (~82% retained value). · checked on 8/5/2026