01 · Source
15 documented inputs
XLR/TRS combo + IEC C14
- Arrives as
- 15 documented inputs
- Connector
- XLR/TRS combo + IEC C14
- Signal
- analog audio
Audio Interface
Focusrite Scarlett 18i20 4th Gen
Focusrite Scarlett 18i20 4th Gen USB Audio Interface. Plan its source-defined physical connections and placement in your rig.
Photos
Manufacturer product photography — the drawn faceplate stays true to panel layout; these show the hardware itself.
- Documented outputs
- 1717 destination connections
- Documented inputs
- 15Based on documented inputs
- Rack space
- 1UBuilder checks available rail space
- Power draw
- UnverifiedPower requirement is not verified in the catalog
- Catalog estimate
- ~$769.99Use retailer rows for current price and stock
01 · What it does—and what that changes in your rig.
Product overview
Start with the payoff, then work through how it functions, where it fits, and the details that change a real build.
The payoff
Audio Interface decisions, organized around the whole rig.
Focusrite Scarlett 18i20 4th Gen USB Audio Interface. Plan its source-defined physical connections and placement in your rig.
- Documented outputs
- 1717 destination connections
- Documented inputs
- 15Based on documented inputs
- Rack space
- 1UBuilder checks available rail space
02 · Know the whole path before you buy.
Signal path
Learn the route as a block diagram: source, product function, transport, and destination. Select any block to see what enters, what changes, and what leaves.
Interactive block diagramAuto-looping · hover, focus, or tap to hold a stage
Port-type signalProduct functionSystem boundary
Follow one signal from source to destination
01 · Source · selectedEach block answers the same three questions: what arrives, what changes here, and what leaves.
03 · What this product asks of the rest of the system.
Compatibility
Treat connector names as the start of the check—not the answer. These are the boundaries that determine a complete working path.
Best fit · Audio Interface
Use it when 1U and 260 mm of depth fit the case.
Plan the companion path
Complete the path with upstream and downstream gear that matches connector, direction, signal type, protocol, and wiring standard.
Connector boundary
Documented connectors: XLR/TRS combo, ¼-inch TRS, IEC C14, usb c. Match connector, direction, and signal type—not shape alone.
04 · Every connector, grouped by job.
I/O ports
Switch the product view and the documented port inventory updates with it—hardware and data stay side by side.
Every connector, grouped by job.
Switch panels to keep the hardware view and the documented port list in sync.
| Port | Panel | Connector | Direction | Signal | Channels |
|---|---|---|---|---|---|
| INPUT 1 · FRONT MIC / LINE / INST | front | XLR/TRS combo | input | analog audio | — |
| INPUT 2 · FRONT MIC / LINE / INST | front | XLR/TRS combo | input | analog audio | — |
| HEADPHONES 1 | front | ¼-inch TRS | output | analog audio | — |
| HEADPHONES 2 | front | ¼-inch TRS | output | analog audio | — |
| AC INPUT · IEC | rear | IEC C14 | input | power | — |
| USB · COMPUTER DATA | rear | usb c | bidirectional | data | — |
| S/PDIF OUT | rear | rca | output | digital audio | — |
| S/PDIF IN | rear | rca | input | digital audio | — |
| WORD CLOCK OUT | rear | bnc | output | data | — |
| OPTICAL OUT 1 | rear | toslink | output | digital audio | — |
| OPTICAL OUT 2 | rear | toslink | output | digital audio | — |
| OPTICAL IN 1 | rear | toslink | input | digital audio | — |
| OPTICAL IN 2 | rear | toslink | input | digital audio | — |
| MIDI OUT | rear | midi din5 | output | data | — |
| MIDI IN | rear | midi din5 | input | data | — |
| LINE OUTPUT 9 | rear | ¼-inch TRS | output | analog audio | — |
| LINE OUTPUT 10 | rear | ¼-inch TRS | output | analog audio | — |
| LINE OUTPUT 7 | rear | ¼-inch TRS | output | analog audio | — |
| LINE OUTPUT 8 | rear | ¼-inch TRS | output | analog audio | — |
| LINE OUTPUT 5 | rear | ¼-inch TRS | output | analog audio | — |
| LINE OUTPUT 6 | rear | ¼-inch TRS | output | analog audio | — |
| ALT OUTPUT 3 | rear | ¼-inch TRS | output | analog audio | — |
| ALT OUTPUT 4 | rear | ¼-inch TRS | output | analog audio | — |
| MAIN OUTPUT 1 | rear | ¼-inch TRS | output | analog audio | — |
| MAIN OUTPUT 2 | rear | ¼-inch TRS | output | analog audio | — |
| INPUT 8 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 7 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 6 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 5 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 4 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 3 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 2 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
| INPUT 1 · REAR MIC / LINE | rear | XLR/TRS combo | input | analog audio | — |
Showing 33 of 33 documented physical ports. Scroll to review the remaining rows.
05 · Compare the decision, not just the price.
Alternatives
The rows are organized around fit, power, I/O, and system role so a cheaper unit cannot hide a more expensive workflow.
| Compare |  | |||
|---|---|---|---|---|
| Fit | 📐 1U | 📐 1U | 📐 2U | 📐 1U |
| Power | ⚡ Unverified | ⚡ 30W | ⚡ Unverified | ⚡ Unverified |
| Weight | ⚖️ 7.3 lb | ⚖️ 9.1 lb | ⚖️ 12.3 lb | ⚖️ 6.3 lb |
| I/O | 🔌 33 | 🔌 24 | 🔌 50 | 🔌 33 |
| Estimate | 💵 ~$769.99 | 💵 ~$899.99 | 💵 ~$2,299.99 | 💵 ~$799.99 |
| Deep dive | Current selection | Full comparison → | Full comparison → | Full comparison → |
06 · Resolve the questions that can change the purchase or build plan.
Planning questions
Short, source-backed answers surface rack fit, power, cabling, and connection details before they become surprises.
How will the Focusrite Scarlett 18i20 4th Gen affect rack fit and case depth?
It occupies 1U. Its documented depth is 260 mm.
How much power does the Focusrite Scarlett 18i20 4th Gen draw?
Its power requirement is not yet verified in the catalog.
What connections does the Focusrite Scarlett 18i20 4th Gen have?
33 documented physical ports, including INPUT 1 · FRONT MIC / LINE / INST, INPUT 2 · FRONT MIC / LINE / INST, HEADPHONES 1, HEADPHONES 2, AC INPUT · IEC, USB · COMPUTER DATA.
07 · See this unit inside a real rack plan.
Builder preview
Placement is only the start. Builder checks space · depth · weight, power headroom, dependencies, and compatible signal paths around this exact catalog item.Open in Builder08 · Related gear, in the order you may need it.
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