ART Tube Mix: Five Channel Mixer with USB and Assignable 12AX7 Tube

Important Safety Instructions – Read First

⚠️ This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure. Voltage that may be sufficient to constitute a risk of shock.

❗ This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Please read manual.

• Read instructions: Retain these safety and operating instructions for future reference. Heed all warnings printed here and on the equipment. Follow the operating instructions printed in this user guide.
• Do not open: There are no user serviceable parts inside. Refer any service work to qualified technical personnel only.
• Power sources: Only connect the unit to power of the type marked on the rear panel.
• Power cord: Use the power cord with the mains plug appropriate for your local mains supply. Route the power cord so that it is not likely to be walked on, stretched or pinched.
• Ventilation: Do not position the unit where air required for ventilation is impeded. Ensure adequate ventilation in racks or furniture.
• Moisture: To reduce the risk of fire or electrical shock, do not expose the unit to rain, moisture, or damp conditions. Do not place liquid containers on it.
• Heat: Do not locate the unit near excessive heat or direct sunlight. Keep away from heat-producing equipment.
• Environment: Protect from excessive dirt, dust, heat, and vibration. Avoid tobacco ash, drink spillage, and smoke.
• Handling: Avoid rough handling and excessive vibration. Protect controls during transit. Use adequate padding. Take care when lifting or moving the unit.
• Servicing: Switch off and unplug the unit if exposed to moisture, spilled liquid, or if the power cord/plug is damaged. Refer servicing to qualified personnel.
• Installation: Install the unit according to the user manual instructions.

Introduction

The ART Tube Mix is a compact, versatile audio interface for your computer, converting analog signals from various audio sources into a digital signal. It can also function as a standalone mixer. It's ideal for personal home studio recording or mobile location recording, suitable for podcasts, song ideas, voiceovers, or jamming.

Key Features Include:

• CH1 and CH2 microphone (balanced XLR) inputs with trim control.
• CH5 instrument/Line (unbalanced 1/4-inch TS) input with trim control.
• CH3/4 Stereo line inputs.
• CH5 High impedance Instrument input with switchable amp simulator.
• Assignable 12AX7 tube for CH1 & CH2 or CH5 (Inst. input).
• Switchable low noise +48V phantom power for microphones.
• Balanced 1/4-inch TRS inputs for stereo or mono line-level sources on CH3-4.
• 1/4-inch TRS output jacks (balanced or unbalanced).
• Adjustable three-band EQ on each channel.
• Two pre-fader Aux sends per input channel for monitor mixes, effects, or recording.
• Control Room section for independent monitoring.
• Stereo 1/4-inch TRS headphone jack.
• Red LED signal/clip indicator for CH1, CH2, and CH5.
• Main output level shown on LED meter display.
• Switchable assignment of USB playback to Main or Control Room output.
• Analog VU meters for monitoring USB record level.
• USB 2.0 compliant.
• No special drivers needed for most modern Windows, Mac OS, and Linux versions.

Operation

Inputs and Outputs

Input Jacks

CH1 and CH2 XLR inputs accept microphone level signals with phantom power available via the +48V switch. The 1/4-inch jacks on CH1 and CH2 are for line level signals and accept both balanced and unbalanced signals. The Trim control affects both sets of input jacks.

Caution: Do not connect a microphone with an unbalanced output via an XLR plug, as it may be damaged by phantom power. Activate or deactivate phantom power only when the mixer is switched off or output controls are set to "0" to prevent switching noise.

Inputs 3/4 are for balanced or unbalanced line level signals. Using only the Left input jack processes a mono signal. Using both jacks for a stereo signal routes the Left channel to Aux 1 send and the Right channel to Aux 2 send. Panning to the extreme fades off the opposite channel on the Main Mix buss. CH5 accepts a mono instrument signal with high impedance, preventing loading or dulling of the instrument's output. The AUX return jack is stereo; a mono plug applies signal only to the left return channel.

Output Jacks

The MAIN and CONTROL ROOM 1/4-inch jacks provide balanced, low impedance outputs. The AUX SEND and HEADPHONES outputs are stereo. The HEADPHONES output level is controlled by the CONTROL ROOM-HEADPHONES LEVEL control. The AUX SEND level is the sum of individual AUX send controls, monitored via LED meters.

USB Jack

The USB jack provides a full-speed interface for two channels of audio. Standard Windows and OSX drivers recognize the interface automatically upon connection.

Controls

TRIM Controls

Trim controls adjust input levels for XLR or 1/4-inch jacks on CH1, CH2, and CH5. Start with the control fully counterclockwise (CCW) and rotate clockwise (CW) until the Clip LED lights on peaks, then back off slightly to maintain headroom.

EQ Controls

The three-band EQ processes audio before the AUX sends. Excessive boost may trigger the CLIP LED; if this occurs, reduce the TRIM control.

AUX Send Controls

The AUX send buss is used for effects or monitor mixes for live use or USB recording. It offers better left/right channel isolation than the MAIN MIX buss. Each AUX send sums a pre-fader signal. AUX1 is on the tip of the output jack, AUX2 on the ring. When assigned to VU meters/USB out, AUX1 is the left channel and AUX 2 is the right.

LEVEL and PAN Controls

These controls adjust the signal level and stereo panning for each channel's output to the Main Mix buss. The Pan control subtly adjusts gain for stereo panning enhancement.

Note: The LEVEL control can add significant gain; the CLIP LED does not monitor this.

CH 5 AMP SIMULATED Switch

When depressed, this switch applies a simulated guitar amp cabinet to CH 5, processed after the Tube function if the tube is assigned to CH 5.

TUBE ASSIGN Switch

The 12AX7 tube adds warmth to CH1/CH2 or CH5. The tube is placed between Trim and EQ for character tweaking. When the switch is out, the tube affects CH1 and CH2 after the TRIM controls. When depressed, both tube stages are in series on CH 5.

PEAK LEDs

Peak LEDs on CH1, CH2, and CH5 monitor signal level after the EQ section, aiding Trim adjustment. When lit, the signal is within 3dB of clipping.

Note: CH 3/4 lacks a PEAK LED. High-level signals (> +12 dBu) can clip on CH 3/4 if EQ is boosted excessively; use EQ to cut in such cases.

+48V Switch

Applies phantom power to XLR inputs when depressed. An LED indicates active phantom power.

METER LEDs and METER SELECT Switch

METER LEDs indicate the level at the MAIN output or AUX send output. "0" indicates 0dBu (0.775 V rms). The meters' fast response is useful for monitoring USB output levels to prevent clipping.

USB RECORD LEVEL VU Meters and USB SOURCE Switch

VU meters monitor the signal level at the USB ADC. When the switch is out, the Main mix output is the source for USB recording. When depressed, the AUX buss is the source, allowing recording of inputs independent of the Main output.

MAIN MIX Level

The MAIN MIX buss sums all inputs plus the AUX return signal. This signal is available at the MAIN OUTPUT jacks and can be routed to meters and the control room section.

AUX Return

Controls the signal level summed into the main mix buss. Useful for adding effects like reverb or as an additional input pair.

USB Return

Adjusts the level of audio returning from the computer before it's summed into the MAIN or CONTROL ROOM buss. The USB Return ASSIGN switch routes this signal to the MAIN buss (out) or CONTROL ROOM (depressed).

NOTE: Routing USB return to USB output while monitoring the same USB input can create a feedback loop. Select AUX SEND as the USB output source to avoid this.

CONTROL ROOM Section

Switches above the CONTROL ROOM-HEADPHONES LEVEL control select signals for these outputs. The LEVEL control governs both outputs. When all switches are out, the CONTROL ROOM output is silent. Depress switches to select desired signals.

NOTE: In this mode, the MAIN MIX signal is "pre-fader" and unaffected by the MAIN MIX LEVEL control.

Diagram Descriptions

Front Panel Layout

The front panel features two microphone/line XLR inputs (MIC 1, MIC 2) and two line inputs (LINE IN 1, LINE IN 2). It includes outputs for MAIN OUTPUT (Left/Right), AUX SEND, and CONTROL ROOM. Channel strips for CH1 through CH5 each have TRIM, EQ (Low, Mid, High), AUX 1 (left), AUX 2 (right), PAN, and LEVEL controls. CH5 also has an ACTIVE/BYPASS switch for AMP SIMULATOR and a TUBE ASSIGN switch. Other controls include +48V phantom power, METER SELECT, USB RECORD LEVEL VU meters, USB SOURCE switch, MAIN MIX LEVEL, and CONTROL ROOM-HEADPHONES LEVEL. PEAK LEDs are present for CH1, CH2, and CH5.

Block Diagram

The block diagram illustrates the signal flow. Inputs (CH1-5, AUX Return, USB Audio from computer) feed into channel processing stages including TRIM, EQ, and the assignable 12AX7 tube. CH5 also has an AMP SIMULATOR. Signals are routed to the MAIN MIX buss (stereo) and CONTROL ROOM buss (stereo). AUX SENDs are available per channel. The MAIN MIX buss feeds MAIN OUTPUTS. The CONTROL ROOM buss feeds CONTROL ROOM OUTPUTS and HEADPHONES JACK. USB AUDIO (to computer) receives its source from the METER-USB SOURCE switch, which can select between MAIN MIX or AUX SEND. USB Return from the computer can be assigned to the MAIN MIX or CONTROL ROOM buss via the USB Return ASSIGN switch. The diagram shows various signal routing options and level controls.

USB Computer Settings

Upon USB connection, the computer powers the interface and typically sets "USB Audio CODEC" as the default audio device. Manual selection may be necessary in the computer's audio settings or specific applications. Ensure the USB Mix and computer are connected and powered on during setup. The computer's audio output can be routed to speakers or the USB Mix monitor output. These settings are usually retained upon reconnection. The Tube Mix uses the standard "USB Audio CODEC," compatible with most modern operating systems, including Linux. For Linux, identifying "USB Audio CODEC" as the recording source or playback monitor output is key.

Applications

Recording a Track

Set the METER-USB SOURCE switch to "out" to send the MAIN MIX buss to the USB output. This method is less ideal for isolating tracks compared to using AUX sends, but allows effects before recording. Use the control room output for monitoring and the USB return if needed.

Track Bouncing

Set Meter/USB source to "IN" and USB return to "MAIN MIX." Monitor through the Control room (headphones). Use meters and Aux Send knobs to adjust recording levels. Isolate tracks by setting AUX SEND to Control Room "IN," Main to Control Room "OUT," and USB Return Assign to Main Mix ("OUT").

Live Use

With control room switches in the OUT position, the Tube Mix is configured for live use. Aux buss can provide monitor mixes, and the main output carries all input channels plus USB and AUX returns. Depressing the AUX SEND to CONTROL ROOM switch enables CONTROL ROOM outputs as monitor outputs with a master level control.

Warranty Information

Limited Warranty

Applied Research and Technology (ART) warrants the product and its components against defects in workmanship and materials for three years from the date of purchase. ART will repair or replace defective parts free of charge upon prepaid delivery to an authorized service center with proof of purchase.

Online Registration

Register your product online at www.artproaudio.com under "Support" > "Product Registration" for prompt warranty service.

Exclusions

The warranty does not cover misuse, abuse, unauthorized alterations, or repairs. It is void if the serial number is altered or removed. ART reserves the right to make design changes without obligation to apply them to previously manufactured products. ART is not liable for consequential damages; some states may not allow these limitations.

For units purchased outside the United States, an authorized distributor of Applied Research and Technology will provide service.

Service

In the event of service needs:

1. Verify the unit is the cause of the problem. Check power, cable connections, and cable condition. Consult your dealer for assistance.
2. If the ART unit is at fault, visit www.artproaudio.com.
3. Select "Support," then "Return Authorization Request" to obtain an RA number.
4. When returning the unit, pack it in its original carton or a suitable substitute. Consider an outer shipping box. Print the RA number and return shipping address clearly on the box.
5. Include a note with the RA number, contact information (including return shipping address, no P.O. boxes), a description of the problem, and a copy of your purchase receipt.

For your reference:

Date of purchase: ___________________

Purchased from: ___________________

Serial number: ___________________

Specifications

Note: 0 dBu = 0.775Vrms

ART maintains a policy of constant product improvement. Specifications are subject to change without notice. For the latest information and support, visit www.artproaudio.com.