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Universal Audio Apollo x4 Desktop Thunderbolt Audio Interface | UAD Analog Classics Pro

Universal Audio Apollo x4 Desktop Thunderbolt Audio Interface | UAD Analog Classics Pro

SoundPro Item: 146473 | Part Number: APX4G2-STU

$2,299.00
$2,873.75 $2,299.00
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MSRP: $2,873.75 | MAP: $2,299.00

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  • Four Unison Preamps Enable Realtime Hardware-Accurate Emulation Of Iconic Analog Signal Chains
  • QUAD Core DSP Offloads Plug-In Processing From The Host CPU For Larger, More Complex Sessions
  • Gen 2 D/A Conversion Achieves 129 dB Dynamic Range On Monitor Outputs For Critical Playback
  • Apollo Monitor Correction Powered By Sonarworks Calibrates Monitors And Headphones For Accurate Mixes
  • Auto-Gain Automatically Sets Input Levels Across Multiple Channels So You Never Miss A Take
  • Bass Management Integrates A Subwoofer Into Your Monitor Chain For Full-Range Low-End Reference
  • Thunderbolt Expansion Links Up To Four Apollo Interfaces For Scalable Multi-Room I/O Growth
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The Apollo x4 Gen 2 is built for project studio engineers, producers, and serious collaborators who need professional-grade I/O, preamp emulation, and DSP power in a compact desktop form factor. With a 12 x 18 Thunderbolt channel count, four Unison mic preamps, dual front-panel Hi-Z inputs, and optical TOSLINK I/O supporting both ADAT and S/PDIF, it covers the connectivity demands of tracking sessions, overdub work, and mix-ready monitoring without requiring a rack unit.

What sets the Apollo x4 apart from competing Thunderbolt interfaces in its class is the combination of Gen 2 D/A conversion — delivering up to 129 dB dynamic range on monitor outputs — with onboard QUAD Core DSP that enables realtime tracking through UAD plug-ins at 1.1 ms round-trip latency at 96 kHz. Unlike native-only interfaces that offload all processing to the host CPU, Apollo x4 runs Unison preamp emulations from Neve, API, Avalon, and Manley directly on dedicated hardware, freeing the DAW for larger session counts and complex mix chains. Apollo Monitor Correction powered by Sonarworks adds calibrated playback correction for both monitors and headphones, a capability absent from most interfaces at this price point.

The UAD Console app serves as the central routing and monitoring hub, with Auto-Gain for fast level setting across all inputs, Bass Management for subwoofer integration, Plug-In Scenes for recall, and immersive audio monitoring support. The interface expands via Thunderbolt to link up to four Apollo units for up to 128 channels of I/O, making it a scalable foundation as studio demands grow. Compatible with LUNA, Pro Tools, Logic Pro, Cubase, Ableton Live, and all major DAWs via VST, AU, and AAX 64 formats.

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Specifications

I/O Complement
Simultaneous Channel I/O Count (analog + digital)
12 x 18 (ADAT mode)
Microphone Inputs
Four
High Impedance (Hi-Z) Instrument Inputs
Two
Analog Line Inputs
Four
Analog Line Outputs (DC coupled)
Four (six including Monitor outputs)
Analog Monitor Outputs (DC coupled)
Two (one stereo pair)
Headphone Outputs
Two stereo
Digital Audio Ports (ADAT or S/PDIF, selectable)
One input, one output
Thunderbolt 3 Port
One (Mac only: Thunderbolt 1 and 2 connections supported via Apple Thunderbolt 3 to Thunderbolt 2 adapter)
A/D - D/A Conversion
Simultaneous A/D conversion
Four channels
Simultaneous D/A conversion
10 channels
Supported Sample Rates (kHz)
44.1, 48, 88.2, 96, 176.4, 192
Bit Depth Per Sample
24
Analog Round-Trip Latency
1.1 milliseconds @ 96 kHz sample rate
Analog Round-Trip Latency through four UAD legacy plug-ins (included) via UAD Console software
1.1 milliseconds @ 96 kHz sample rate (no additional latency via Realtime UAD Processing)
Microphone Inputs 1-4
Frequency Response
20 Hz - 20 kHz, ±0.05 dB
Dynamic Range
123 dB (A-weighted)
THD + Noise (1 kHz @ 24 dBu, -1 dBFS)
-117 dB (0.00014%)
Maximum Input Level (PAD on)
25 dBu
Default Input Impedance (variable via Unison plug-ins)
5.4 K Ω
Gain Range
+10 dB to +65 dB
Pad Attenuation (switchable per mic input)
20 dB (variable via Unison plug-ins)
Phantom Power (switchable per mic input)
+48V
Connector Type
XLR female, pin 2 positive (combo XLR/TRS)
Hi-Z Inputs 1 & 2 (600 K Ω input termination)
Frequency Response
20 Hz - 20 kHz, ±0.05 dB
Dynamic Range
122 dB (A-weighted)
THD + Noise (1 kHz @ 11.4 dBu, -1 dBFS)
-111 dB (0.00028%)
Maximum Input Level (at minimum gain)
12.4 dBu
Default Input Impedance (variable via Unison plug-ins)
1 M Ω
Gain Range
+10 dB to +65 dB
Connector Type
1/4" female TS unbalanced
Line Inputs 1-4
Frequency Response
20 Hz - 20 kHz, ±0.05 dB
Dynamic Range
124 dB (A-weighted)
THD + Noise (1 kHz @ 19.2 dBu, -1 dBFS)
-115 dB (0.00018%)
Maximum Input Level
20.2 dBu
Input Impedance
10 K Ω
Gain Range
+10 dB to +65 dB
Connector Type
1/4" female TRS balanced
Line Outputs 1-4
Frequency Response
20 Hz - 20 kHz, ±0.05 dB
Dynamic Range
128 dB (A-weighted)
THD + Noise (1 kHz @ 19.2 dBu, -1 dBFS)
-117 dB (0.00014%)
Maximum Output Level (Reference level @ +4 dBu)
20.2 dBu
Maximum Output Level (Reference level @ -10 dBV)
14.5 dBu
Output Impedance
100 Ω
Connector Type
1/4" female TRS balanced
Monitor Outputs L & R
Frequency Response
20 Hz - 20 kHz, ±0.04 dB
Dynamic Range
129 dB (A-weighted)
THD + Noise (1 kHz @ 19.2 dBu, -1 dBFS)
-120 dB (0.0001%)
Maximum Output Level
20.2 dBu
Output Impedance
100 Ω
Connector Type
1/4" female TRS balanced
Stereo Headphone Outputs 1 & 2
Frequency Response
20 Hz - 20 kHz, ±0.01 dB
Dynamic Range
124 dB (A-weighted)
THD + Noise (300 Ω load, 1 kHz @ 14.4 dBu, -1 dBFS)
-108 dB (0.00040%)
THD + Noise (600 Ω load, 1 kHz @ 14.8 dBu, -1 dBFS)
-112 dB (0.00025%)
Maximum Output Level (300 Ω load, 1 kHz, 0 dBFS)
15.4 dBu
Maximum Output Level (600 Ω load, 1 kHz, 0 dBFS)
15.8 dBu
Maximum Output Power RMS (300 Ω load, 1 kHz @ 15.4 dBu, 0 dBFS)
69 mW
Maximum Output Power RMS (600 Ω load, 1 kHz @ 15.8 dBu, 0 dBFS)
38 mW
Connector Type
1/4" female TRS stereo
Digital I/O
Digital Audio Port (ADAT or S/PDIF, selectable)
One input, one output
Connector Type
Optical TOSLINK JIS F05
S/PDIF
S/PDIF Channels
One stereo input, one stereo output
Format
IEC 958
Supported Sample Rates (kHz)
44.1, 48, 88.2, 96
ADAT
ADAT Channels
Up to eight input & eight output channels
Format
ADAT Lightpipe with S/MUX
Supported Sample Rates (kHz)
44.1, 48, 88.2, 96, 176.4, 192
Channel Assignments @ 44.1 kHz, 48 kHz
Channels 1-8
Channel Assignments @ 88.2 kHz, 96 kHz
Channels 1-4
Channel Assignments @ 176.4 kHz, 192 kHz
Channels 1-2
Clock Synchronization Sources
Internal, ADAT, S/PDIF
Conditional per selected digital input type
Electrical
Power Supply
External AC-to-DC power supply, level VI compliant
AC Input Connector Type
IEC C8, non-polarized
AC Requirements
100V - 240V AC, ≈ 50 - 60 Hz, 1.2 A MAX
DC Connector Type
Male barrel plug, 2.1 mm x 5.5 mm, center positive
DC Requirements
12 VDC (±5%), 4.2 A
Maximum Power Consumption
19 Watts (when portable host computer not charging)
Environmental
Ambient Temperature Range
32º to 104º F (0º to 40º C)
Mechanical - Dimensions
Width
9.17" (232.98 mm)
Height
2.51" (65.81 mm)
Depth, Chassis Only
5.87" (149.13 mm)
Depth, Including Knob & Jack Protrusions
6.12" (155.60 mm)
Shipping Box (Length x Width x Height)
11" x 8" x 5" (279 mm x 203 mm x 127 mm)
Mechanical - Weight
Shipping Weight (with box & accessories)
5.86 lbs (2.66 kg)
Weight (bare unit)
3.2 lbs (1.47 kg)
Package Contents
Included
Apollo x4 Gen 2 Audio Interface, External Power Supply, AC Power Cable (IEC C7, non-polarized, region specific: USA, EU, UK, ANZ, or Japan), Getting Started URL Card
Whats included
Software Bundle
UAD Analog Classics Pro (80+ plug-ins)

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