This article contains complete instructions for Volt 4 hardware controls and connections.
Note: To learn how to set up Volt with audio software and how to redeem your bundled software, please see How to set up your Volt Interface.
Article Contents
Getting Started
To begin setup, follow the steps below. The UA Connect software guides you through the process step-by-step.
- Download and install UA Connect from www.uaudio.com/volt/start
- Launch the UA Connect application
- Follow the instructions within the app
Introduction & Overview
Welcome to the Volt family. Whether you are a seasoned engineer or just starting your recording journey, this guide is designed to help you get the most out of your interface.
A Letter from Bill Putnam, Jr.
Thank you for choosing Volt as part of your music-making experience. We know that any new piece of gear requires an investment of time and money — and our goal is to make your investment pay off.
Universal Audio’s family of audio interfaces represents the best examples of what UA has stood for over its long history; from its original founding in the 1950s by my father, to our current vision of delivering the best of both analog and digital audio technologies.
Volt’s best-in-class audio quality serves as its foundation, but this is just the beginning. Volt is also the perfect "on-the-go" audio interface and features an exclusive analog Vintage Mic Preamp circuit, inspired by our legendary UA 610 mic preamp. Plus, some Volt models feature the analog 76 Compressor, inspired by our iconic 1176 limiter, heard on thousands of classic records. Volt also includes MIDI for connection to a wide range of devices and direct monitoring capability for latency-free recording.
At UA, we're dedicated to the idea that technology should serve the creative process — not be a barrier. These are the very ideals my father embodied as he invented audio equipment. We believe Volt will earn its way into your creative workflow by providing stunning fidelity and rock-solid reliability for years to come.
Please feel free to reach out to us via our website www.uaudio.com and our social media channels. We look forward to hearing from you, and thank you once again for choosing Universal Audio.
Bill Putnam, Jr.
Everything you need to record and mix music with legendary sound.
- Get the rich, full album-ready sound of UA’s classic 610 preamps with Vintage mode
- Capture every detail and nuance of your performance with up to 24-bit / 192 kHz quality and crystal clear converters
- Record and mix with the award-winning LUNA Digital Audio Workstation, giving you the sound and workflow of a real analog studio
- Create using the same UAD plug-ins trusted by top industry pros for the sound of your favorite records
- Level up your recording and mixing skills with tips and tutorials for beginners to advanced users
- Take Volt anywhere with support for MacOS, Windows, iPad, iPhone (iOS 14+) for laptops, desktops, and mobile devices
Record with Studio-Quality Sound at Home
Powered by Universal Audio’s award-winning preamp and converter technology, Volt elevates any recording with pro studio sound, even for those just starting.
Get Analog Warmth with Vintage Mic Preamp Mode
Plug in your mic or instrument, press the Vintage button, and experience the rich, full sound of the renowned UA 610 tube preamp — one of the most recorded mic preamps of all time.
Sound Like Your Favorite Records
We designed LUNA to bring the sound of classic tape machines and analog mixing consoles into a modern DAW, with intuitive workflows and unlimited track counts to capture your wildest ideas.
Level up Your Production Skills
From beginner tutorials to advanced techniques, Volt 4 USB Recording Studio includes tons of helpful content to get you up and running fast, plus a 3-month trial of PureMix Pro.
Features
- Desktop 4-in / 4-out USB audio interface with 2 preamps and class-leading 24-bit / 192 kHz audio conversion
- Vintage Mic Preamp mode for recording your voice, guitar, or any instrument with the rich, full sound of an iconic UA tube preamp
- Listen in real-time as you record with Direct Monitoring for latency-free recording
- Bus-powered and class-compliant for hassle-free setup with Mac, PC, iPad, and iPhone using the included USB-C to USB-A cable
- Studio-quality headphone amplifier for loud, clear monitoring
- 48V phantom power for condenser microphones
- Stylish, rugged construction built to withstand years of use
- Connect MIDI controllers, synths, and drum machines through the onboard 1-in / 1-out MIDI connection
System Requirements
Please visit this article for Volt system requirements.
Volt 4 Hardware Descriptions
All hardware controls, connections, and indicators are explained in this section.
Front Panel
(1) XLR/TRS Combo Inputs
Connect your microphones, instruments, or line-level sources here. The combo input connectors accept XLR and ¼” (6.35 mm) plugs.
A microphone is typically connected with an XLR connector, and an instrument or line-level signal is connected with a ¼” (6.35 mm) TS or TRS plug.
Preamp gain and impedance automatically adjusts for line or mic signals, based on whether the plug is XLR or ¼”, along with the state of the INST button.
Press the INST button to toggle the impedance and gain of the line input to accommodate a Hi-Z instrument, such as an electric guitar or bass.
Tip: The Vintage Preamp can be used on mic, line, and instrument inputs.
Balanced and unbalanced connections
- The line inputs on Volt are balanced when connected with TRS connectors to balanced equipment.
- Use TRS (balanced) audio cables for the best results with balanced audio sources. Balanced equipment uses three-conductor wiring (via TRS or XLR connectors) to reduce interference and electrical noise, and to provide better audio quality over longer cable runs.
- Use TS (unbalanced) cables for instruments that are not balanced, such as an electric guitar or bass, or an unbalanced synth or sound module. TS connections may also be suitable for shorter input cables, where electrical interference noise may not be an issue.
(2) Gain Knobs
These knobs adjust the preamp gain for the microphones, instruments, or line-level devices attached to the associated inputs. For optimum gain, rotate the gain knob to adjust the input signal level while monitoring the source that is connected, so the input meters (3) show signal but do not light red.
(3) Input Meters
The Input Meters show the signal level of the input, which is controlled by the Gain knob. The red input LED lights when the input signal is near 0 dB (clipping).
Tip: Clipping occurs when the signal is overloaded. When clipping occurs, the top of the waveform is squared off, creating distortion that may be unpleasant. Clipping has creative uses, but is usually avoided. To prevent clipping, adjust the gain so only green and yellow meters light, and the red LED does not light.
(4) Vintage Buttons
Press these buttons to toggle the Vintage Preamps. The Vintage Preamps can be used on mic, line, and instrument inputs.
The Vintage Preamp adds a carefully crafted analog tube preamp emulation, inspired by Universal Audio’s all-tube 610 console preamplifier, to the sound. When the button is lit orange, the circuit is active.
(5) Instrument Buttons (INST)
Press these buttons to toggle the impedance and gain of the line inputs to accommodate Hi-Z instruments, such as electric guitar or bass. These buttons are lit green when the Hi-Z inputs are enabled.
Tip: Generally speaking, the INST button should be off when connecting a line-level source such as a keyboard or sound module, unless you need more gain.
(6) 48V Phantom Power Button
Press this button to toggle 48V phantom power at the XLR microphone inputs. The LED blinks red while phantom power is activating or powering off. The LED is lit solid red when phantom power is active. Both XLR inputs receive phantom power when enabled.
Phantom power is required by most condenser microphones, but is usually not required with dynamic microphones or ribbon microphones (phantom power can damage some ribbon microphones).
Note: Disable phantom power before you connect or disconnect the microphone.
(7) Monitor Source Buttons
Important: One or both output pairs (OUT 1-2 or OUT 3-4) must be selected to hear audio from your computer.
The Monitor Source buttons select the audio that you will hear in the monitor and headphone outputs. When a monitor source button is lit, that source is routed to the speakers and headphones.
You can choose to monitor either the mic/line/instrument inputs (direct monitoring), outputs from the computer, or both.
IN (Direct) – The IN 1-2 and IN 3-4 buttons route Volt’s hardware inputs directly to the monitor outputs. Direct monitoring allows you to listen to your inputs through the device, without any software latency.
OUT – The OUT 1-2 and OUT 3-4 buttons route audio from the computer to the monitor outputs. Enable these buttons to hear sound from the audio software.
Monitor source notes
- You can monitor multiple sources at the same time. Enable all sources that you want to route to monitor outputs and headphones.
- Press the MONO button so it is lit blue to listen to the inputs panned to the center. By default, inputs are routed in stereo, so input 1 and 3 are routed to the left output, and input 2 and 4 are routed to the right output.
- You can still hear direct audio from the inputs if IN sources are enabled, even if no OUT sources are enabled for monitoring. In this scenario, you can monitor your input sources, even if you are not monitoring any output from the audio software, or when Volt is not connected to a computer.
- When any combination of both IN and OUT sources are enabled, the volume from your audio software is slightly reduced so you can clearly hear your input signals.
The monitor source buttons work as described below.
Monitor Source Button Settings
The Monitor Source buttons control how hardware inputs and software outputs are routed to the monitor and headphone outputs.
- Hardware Input Routing (IN 1-2, IN 3-4)
- Enabled: Routes hardware inputs directly to the monitor and headphone outputs, and also to the audio software.
- Disabled: Routes hardware inputs to the audio software only, not to the monitor and headphone outputs.
- Software Output Routing (OUT 1-2, OUT 3-4)
- Enabled: Routes audio software outputs to the monitor and headphone outputs.
- Disabled: Audio software outputs are not routed to the monitor and headphone outputs.
Default setting
From the factory, OUT 1-2 is selected. With this setting, you hear audio from your computer (most audio software will automatically route audio to outputs 1-2), but your inputs are not directly monitored.
Monitor Source Example
- Listen to preamp inputs and audio software: Select IN 1-2 to hear hardware inputs 1 and 2, and select OUT 1-2 to hear audio from your computer.
(8) Mono Button
Press the mono button to route the monitor source direct inputs in mono instead of stereo. The button lights blue when enabled.
Important: The mono button applies to Volt’s hardware inputs only.
(9) Host Indicator
The host indicator is lit blue when Volt is recognized by the computer or device.
(10) Monitor Knob
Rotate this knob to adjust the volume of speakers connected to the monitor outputs. The output signal level meters indicate the output levels.
(11) Headphone Output
Connect stereo headphones to this output. Headphones are connected with a ¼” (6.35 mm) TRS plug. If your headphones have a ⅛” (3.5 mm) plug, use a TRS ⅛” to ¼” adapter.
(12) Headphone Volume Knob
Adjust the headphone volume with this knob. The headphone volume control is independent from the monitor volume control.
Note: The monitor output and headphone signals are the same.
Rear Panel
(13) Monitor Outputs
Connect your stereo speaker system to the monitor outputs. Connect the left speaker to Monitor 1/L and the right speaker to Monitor 2/R. You can use TS (tip-sleeve) or TRS (tip-ring-sleeve) ¼” (6.35 mm) cables.
Monitor notes
- The sources that you hear in the monitor and headphone outputs are assigned using the Monitor Source buttons (7). To hear your computer or software in the monitor speakers and headphones, Monitor Source OUT 1-2 must be enabled. These outputs are enabled by default.
- When you enable direct inputs with the Monitor Source IN buttons, you will hear those inputs on the monitor outputs and the headphone outputs, even if no outputs are selected with the Monitor Source buttons.
Balanced and unbalanced connections
- The outputs on Volt are balanced when connected with TRS connectors to balanced equipment.
- Use TRS (balanced) audio cables for the best results with a balanced stereo speaker system. Balanced equipment uses three-conductor wiring to reduce interference and electrical noise, and to provide better audio quality over longer cable runs. TS connections may be suitable for shorter output cables, where electrical interference noise may not be an issue.
Note: The monitor outputs are not powered. You will need to connect the cables to either powered speakers or an amp with speakers.
(14) Line Outputs
Use the line outputs for monitoring unattenuated audio directly from the software. Audio can be assigned to these outputs in your software. These are ¼” balanced outputs. See (7) Monitor Source Buttons for related information.
- Line outputs 1-2 typically carry the main outputs from your software.
- Line outputs 3-4 must be specifically assigned as outputs from your software. These can be used for various monitoring purposes.
(15) Line 3-4 Inputs
Connect input sources for line inputs 3-4 here. These are ¼” balanced inputs designed for line-level sources, such as synths, external sound modules, or other line-level sources.
Note: There are no gain controls on the line 3-4 inputs. Any level controls must be configured in your software.
(16) MIDI I/O
You can connect a MIDI device to Volt with standard 5-pin MIDI DIN cables. To send MIDI from your device to Volt, connect the MIDI OUT of your device to the MIDI IN on Volt. To send MIDI from Volt to your device, connect the MIDI IN of your device to the MIDI OUT on Volt.
You may not need to make both connections. For example, a MIDI controller might only be connected to the MIDI IN on Volt, and a MIDI sound module might only be connected to the MIDI OUT from Volt.
(17) USB-C
Connect Volt to a USB 2.0 (or higher) port on your computer with a USB-C to USB-A cable (included), or with another cable.
For example, you can connect with a USB-C to USB-C cable if your computer has a USB-C port. For iOS or iPad devices, connect the interface with a USB-C cable (iPads with USB-C) or with the Apple Lightning to USB Camera Adapter (other iPadOS and iOS devices).
For more information, see the related video.
Note: Volt is bus powered when connected to ports that meet USB 2.0 specifications. However, some USB ports, such as those on low-quality hubs, do not meet USB specs and cannot supply adequate bus power. If Volt does not power on, connect Volt to external 5VDC power to compensate for the underpowered USB port.
(18) 5VDC Power
Volt is bus powered when connected to a USB port that supplies adequate power. You can use the 5VDC connector to connect to power when required (for example, if you want to reduce power drain on an iPad or laptop, or if the USB port or hub is not able to provide enough power).
Tip: You can power Volt by connecting the included USB-A to barrel-connector power cable to a USB power adapter, then connecting the barrel plug to this power inlet on Volt.
(19) Power Switch
Apply power to Volt with this switch.
(20) Kensington Security Slot
Use with Kensington-compatible security devices to secure Volt hardware.
Troubleshooting
Try these solutions if you encounter any of these issues.
- No Power
- Verify that the Volt is connected to a port that meets USB 2.0 specifications.
- If bus power is insufficient, connect the Volt to an external 5VDC power source to compensate for the underpowered USB port.
- Ensure the physical power switch is set to the ON position.
- Host Indicator Does Not Light
- Perform a power cycle by turning the unit off and back on.
- Test the connection using a different USB port or a different USB hub.
- Swap out the current cable for a different USB cable to rule out a faulty lead.
- Crackling Audio, Dropouts, or Glitches
- Increase the buffer size settings within your DAW or computer software. When recording at higher buffer sizes, use Direct Monitoring to eliminate latency issues.
- (PC Only) ASIO Driver Not Available in DAW
- Download and install the official hardware driver using the UA Connect app.
Volt 4 Specifications
For Volt specifications, please visit this article.
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