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UAFX MAX Preamp & Dual Compressor Manual

This article contains complete operating instructions for the UAFX Max Preamp & Dual Compressor effects pedal.



A Letter From Bill Putnam, Jr.

Congratulations on your new UAFX pedal. We know that buying any new piece of gear requires an investment of time and money, and we aim to make your investment pay off!

At UA, we are dedicated to the idea of building “instant classics” — the type of music and audio gear that delivers album-worthy sounds to inspire you for decades.

UAFX pedals represent more than 20 years of research into vintage analog effects, coupled with next-generation digital engineering and rock-solid reliability.

Please let us know how we’re doing. Feel free to reach out to us via our website, and via our social media channels.

Thank you for your support, and enjoy your sonic exploration!


Bill Putnam Jr.



Max Quick Start


Download Max Quick Start Sheet



Get the Latest Firmware

Be sure to update your pedal’s firmware with UA Connect to get the latest features and functionality. To learn how to use UA Connect with your UAFX pedals, go here.



Max Overview

Your sound, perfected.

Built upon award-winning UAFX dual-engine processing and a burning desire for the ultimate in sonic legitimacy, Max Preamp & Dual Compressor puts the colorful sound of three legendary limiters and an iconic tube preamp, right at your feet. 

  • Get the classic compression colors of a Teletronix LA-2A, UA 1176, and classic Dyna Comp,* all in one pedal
  • Explore the grit and character of UA's legendary 610 tube mic preamp 
  • Stack compressors in any combination for even more tones and textures
  • Tweak preamp EQ settings, serial/parallel operation, add a sidechain bass filter, and more with the UAFX Control app

Stack Compressors for Tones that Go Beyond the Norm

With Max, you can easily layer compressors in any combination for a dizzying array of sounds and textures, letting you push your tones to the front no matter how much limiting you apply.

Personalize your Pedal with a Mobile App

With the UAFX Control mobile app, you can tweak EQ settings, get serial/parallel operation, and add a sidechain bass filter for fully customized compression and preamp effects.

Get UAFX Control


  • The most authentic emulations of classic UA 1176, Teletronix LA-2A, and classic Dyna Comp compressors, in a single pedal
  • Full emulation of UA's legendary 610 tube preamp and EQ
  • Stack and layer any combination of compressors 
  • Tweak preamp EQ settings, configure footswitches, add a sidechain bass filter, and more with the UAFX Control mobile app
  • Silent switching, buffered bypass, stereo operation

*All trademarks are property of their respective owners and used only to represent the effects modeled as part of Max Preamp & Dual Compressor.



Max Power

Note: Power supply sold separately.

UAFX pedals require an isolated 9 volt DC, center negative, 2.1 x 5.5 mm barrel connector (same as standard Boss connectors) power supply, which can provide 400 mA (milliamps) of current. Each UAFX pedal must be connected to a separate power supply, or connected to an isolated power connection from a multi-output power supply. Connect the power supply to the 9VDC connector on the pedal’s rear panel. 

When you first connect your UAFX pedal to a power supply, the footswitch LEDs cycle, showing that the pedal is starting up. The startup sequence takes about 15 seconds. There is no signal through the pedal during startup.

If power to your UAFX pedal is interrupted during operation, audio stops. 

Important Power Notes 

  • Each UAFX pedal requires 400 mA of current. Make sure your power supply can deliver at least 400 mA to the pedal for proper operation and performance.
  • An isolated supply provides power and grounding that is electrically separated, usually by means of a transformer for each connector. Some low-cost power supplies might have separate connectors, but might not provide true ground and power isolation, causing noise and ground loop hum. 
  • If your power supply has multiple outputs, make sure that each output provides true isolation, or that you connect your pedal to its own power supply.
  • It’s OK to connect a power supply that can deliver more than 400 mA. The pedal only draws the current it needs and will not be damaged if the supply is 9VDC.
  • If your power supply is not isolated, you might hear additional hum in the pedal signals. If the supply cannot provide 400 mA of current, the pedal might not operate properly, even if the LEDs and switches seem to be working. 
  • Daisy-chaining (running multiple pedals from one output of a power supply) is not supported.



Max Connections

To learn how to wire your UAFX pedals, go here.



Max Operation

Max features two completely independent stereo compressor effects (Comp 1 and Comp 2), and each Comp has its own stereo UA 610 tube preamplifier and EQ. Each Comp can be independently switched to one of the three available compressor effects.

The left footswitch always toggles Comp 1 on/off, and the right footswitch always toggles Comp 2 on/off.

Knobs Control

Important: When Comp 1 OR Comp 2 is on, Max knobs control the sound you hear. When BOTH Comp 1 and Comp 2 are on, knobs control the compressor that is set on the Comp Select switch.

Default Settings

Max is set to Serial mode by default, where both Comps can be enabled at the same time, and the output of Comp 1 is routed into the input of Comp 2.

Optional Settings

Max can be set for other footswitch and routing modes, and EQ and sidechain settings for each preamp can be set, in the UAFX Control mobile app.

Get UAFX Control



Max Controls

Max’s knobs and switches control the preamp and compressor controls for one Comp at a time.

Important: When Comp 1 OR Comp 2 is on, Max knobs control the sound you hear. When BOTH Comp 1 and Comp 2 are on, knobs control the compressor that is set on the Comp Select switch. 


Controls the level of the UA 610 tube preamp for the selected Comp. Increase the Preamp level to add drive and harmonics. When set to off (fully counter-clockwise), the preamp and its EQ are disabled, and the Comp has clean unity gain. 

Preamp Tips

  • To keep the preamp EQ active without tube coloration, set the Preamp knob to slightly above its OFF position.
  • Adjust your preamp EQ and the sidechain bass filter settings in the UAFX Control app.


Adjusts the compression amount for the selected Comp. Rotate clockwise for more compression and sustain. Comp controls different settings for each compressor effect.

Note that unlike the original hardware, as Comp is increased, the compressor’s level is also automatically increased to compensate for the compression effect.

Important: With OPTO LA-2A and FET 1176 comp effects, when the Comp knob is at its minimum setting, you will not hear any signal. Rotate the knob clockwise to hear your signal.

  • DYNA – Controls the Sensitivity knob from the original hardware. Rotate clockwise for more compression, squish, and crunch.
  • OPTO LA-2A – Controls the level of input gain and compression. Rotate clockwise to increase the gain and the amount of compression and distortion.
  • FET 1176 – Controls the Input knob from the original hardware. Rotate clockwise to increase the gain and lower the threshold, for more compression, squish, and distortion.


Adjusts the pedal output level for each Comp.

Attack (FET 1176 only) 

Adjusts reaction time of the compressor once the signal passes the threshold. Unlike most compressors, you rotate this control clockwise for faster attack (as with the original hardware). 

Note: For DYNA and OPTA LA-2A compressor effects, the footswitch LED for the selected Comp blinks rapidly when Attack is rotated, indicating the knob has no effect.


Adjusts the amount of compression of the signal once it passes the threshold. This works differently for each compressor type, and is not used on the DYNA compressor effect.

  • DYNA – Unused. The footswitch LED for the Comp blinks rapidly when Ratio is rotated, indicating the knob has no effect.
  • OPTO LA-2A – Adjusts the compression ratio. The original hardware had only two ratios, controlled by the COMP/LIMIT switch. We’ve added more compression ratios for greater flexibility. Set this control to 4:1 to match the COMP setting on the original hardware. Set this control to 20:1 to match the LIMIT mode settings on the original hardware (the ALL setting is the same as the 20:1 setting). Set to OFF for circuit color without compression. 
  • FET 1176 – Adjusts the compression ratio from 4:1 to 20:1. Set to ALL for the unique “all buttons in” response. Set to OFF for circuit color without compression.


Adjusts how long it takes for the compressor to let a signal return to normal after compression. This works differently for each compressor effect, and is not used on the DYNA compressor effect.

  • DYNA – Unused.The footswitch LED for the Comp blinks rapidly when Release is rotated, indicating the knob has no effect.
  • OPTO LA-2A – The original hardware has no release time control. We’ve added release settings for greater flexibility. Set at noon to match original hardware. Rotate clockwise for faster release.
  • FET 1176 – Adjusts the release setting from the original hardware. Rotate clockwise for faster release.

Comp 1 & Comp 2 Effects

This switch selects the compressor effect for each Comp. There is a brief audible pause when you switch between compressor effects while the effect loads.

The following compressor effects are available on Max.

Effect Description
DYNA Add the grimy squeeze of this (in)famous red box to your sounds for lo-fi compression and funky overdrive — perfect for slide tones.
OPTO LA-2A This legendary optical tube limiter gives you softer, warmer dynamics control versus the 1176. Plus, you can fine tune your compression with a pedal-exclusive Ratio feature, for limiting beyond the vintage hardware and UAD plug-in versions.
FET 1176 From the mind of UA founder Bill Putnam to your pedalboard, Max gives you the same FET compressor used on decades of legendary studio guitar sounds, whether you're looking to make your funk a little funkier, add soulful sustain, or inject subtle infusions of tone.

Comp Select

Sets which Comp is controlled by the knobs only when both Comps are on. When only one Comp is on, the knobs on the pedal control that Comp.

Note that when you switch between Comps, the knob settings you see may not be the same as the knob settings stored in the current Comp. As you rotate a knob in this state, the Comp setting will “jump” to the new knob setting, sometimes audibly. 

Left and Right Footswitch LEDs

The left and right footswitch LEDs are lit when Comp 1 and/or Comp 2 is active. The LEDs change colors to indicate compressor activity.

  • Green – The compressor is not responding to the signal
  • Yellow – The compressor is moderately responding to the signal
  • Red – The compressor is heavily responding to the signal


  • The compressor LED colors do not always indicate the presence of a signal. For example, with a slow release time on the OPTO LA-2A, the indicator LED may illuminate red and yellow well after the signal ends, because the LED is indicating the compressor activity (the compressor release time) and not the current compression amount.
  • To see compressor activity on the footswitch LEDs, be sure to update to the latest firmware with UA Connect.

Left Footswitch

Press to toggle Comp 1 on/off.

Right Footswitch

Press to toggle Comp 2 on/off.



Max Footswitch Modes

With the UAFX Control mobile app, you can change how signals are routed within Max. Serial, Parallel, and Exclusive modes are available. The table below summarizes how signals are routed and controlled in each of the three available modes.

Note: To learn how to use UAFX Control, go here.

Get UAFX Control


Press the left or right footswitches to toggle Comp 1 and Comp 2 on/off. One or both can be on at the same time. The output of Comp1 feeds the input of Comp 2. 


Press the left or right footswitches to toggle Comp 1 and Comp 2 on/off. One or both compressors can be on at the same time. The input signal is split before feeding into each Comp separately, and the outputs of both Comps are mixed before the pedal output. 


Press the left or right footswitches to toggle Comp 1 or Comp 2 on/off. Only one Comp can be on at a time.

Footswitch Modes

Footswitch Mode
(UAFX Control)
Both Comps
Can Be On?
Signal Routing Knobs Control
(ONE Comp on)
Knobs Control
(BOTH Comps on)
Serial* Yes


In > Comp 1 > Comp 2 > Out

(Both inputs feed Comp 1)

Comp Select
switch setting
Parallel Yes


In > Comp 1 > Out

In > Comp 2 > Out

(Both inputs feed both Comps;
Comp outputs mixed)

Comp Select
switch setting
Exclusive No


In > Comp > Out

(Both inputs feed both Comps;
only one Comp active)

*Default setting from factory and after restoring defaults



Max EQ and Sidechain Settings 

With the UAFX Control mobile app, you can adjust low and high EQ settings for each of the two UA 610 tube preamps to further tweak your tones. The FET 1176 effect also has a configurable compressor sidechain bass filter control.

Get UAFX Control

Low EQ

The low shelf EQ adjusts frequencies below 100 Hz. You can cut or boost the lows by 6 dB. Set Low EQ to Off for flat bass response. 

High EQ

The high shelf EQ adjusts frequencies above 10 kHz. You can cut the highs by 6 dB or boost the highs by 3 dB or 6 dB. Set High EQ to Off for flat treble response. 

Sidechain Bass Filter (FET 1176 only)

The sidechain bass filter removes low-frequency content from the compressor’s control sidechain. This filter reduces FET 1176 compression and “pumping” on bass-heavy audio signals, without reducing the bass content of the audio signal itself.



Max Specifications

All specifications are subject to change without notice.

Power requirements

(power supply sold separately)

Isolated 9VDC, center-negative, 400mA minimum 

2 x ¼” unbalanced TS

(input 2 for stereo connections)


2 x ¼” unbalanced TS

(output 2 for stereo connections)

Bypass mode Buffered bypass
Input impedance

500 Kilohms (Mono In)

1 Megohms (Stereo In)

Output impedance 500 Ohms
Maximum input level 12.2 dBu
Maximum output level 12.1 dBu
Frequency response 20 Hz to 20 kHz, ±1 dB
USB Type-C For registration and firmware updates via computer

Wireless technology

Transmitted Frequency Range

Maximum Output Power

Bluetooth v5

2.400 GHz – 2.4835 GHz

+4.35 dBm


(with knobs and protrusions)

Height: 2.56 inches, 6.5 cm

Width: 3.62 inches, 9.2 cm

Depth: 5.55 inches, 14.1 cm

Weight (unboxed)

1.24 lbs

0.567 kg



Max Safety

safety-symbol-exclaim.png Caution: To help maintain the safety of your product, the chosen power supply must be a certified power supply complying with Limited Power Source (LPS) requirements with the following characteristics and electrical ratings: Isolated 9VDC, center-negative, 400 mA minimum, 2.1x5.5 mm barrel connector. Additional details at

safety-symbol-book-info.png Before using this unit, be sure to carefully read the applicable items of these operating instructions and the safety suggestions. Afterwards, keep them handy for future reference. Take special care to follow the warnings indicated on the unit, as well as in the operating instructions.

  • Read the instructions.
  • Keep these instructions.
  • Heed all warnings.
  • Follow all instructions.
  • Do not use this apparatus near water.
  • Clean only with dry cloth.
  • Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions.
  • Do not install near any heat source such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.
  • Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. • Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.
  • Only use with attachments/accessories specified by the manufacturer.
  • Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
  • This equipment does not contain a fuse or any other user-replaceable parts.
  • A compliance marking label is provided on bottom of the unit.

United States Class B Manual Statement

NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try and correct the interference by one or more of the following measures:

  • Reorient or relocate the receiving antenna.
  • Increase the separation between the equipment and the receiver.
  • Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
  • Consult the dealer or an experienced radio/TV technician for help.

Japanese Class B Manual Statement

この装置は、クラスB機器です。この装置は、住宅環境で使用することを目的としています が、この装置がラジオやテレビジョン受信機に近接して使用されると、受信障害を引き起こ すことがあります。取扱説明書に従って正しい取り扱いをして下さい。VCCI-B

(This is Class B equipment. Although this equipment is intended for use in residential environments, it could cause poor reception if used near a radio television receiver. Please follow all instructions in the instruction manual.)

License exempt. This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the following two conditions: (1) this device may not cause interference, and (2) this device must accept any interference, including interference that may cause undesired operation of the device.

Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de licence. L'exploitation est autorisée aux deux conditions suivantes : (1) l'appareil ne doit pas produire de brouillage, et (2) l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d'en compromettre le fonctionnement.

Taiwan NCC Warning Statement

本公司產品取得NCC 低功率射頻器材審驗證明依據「低功率射頻器材技術規範」之新警語如下:「取得審 明之低功率射頻器材,非經 核准,公司、商號或使用者均不得擅自變更頻率、加大功率或變更原設計之特 及功能。低功率射頻器材之使用不得影響飛航安全及干擾 合法通信;經發現有干擾現象時,應立即停用,並 善至無干擾時方得繼續使用。

The company's products have obtained the NCC low-power radio frequency equipment verification certificate according to the new warnings of "Low-power radio frequency equipment technical specifications" as follows: "The low-power radio frequency equipment that has obtained the verification certificate shall not be changed by the company, firm or user without approval. Frequency, increase power, or change the features and functions of the original design. The use of low-power radio frequency equipment shall not affect flight safety and interfere with legal communications; continue to use.


Used electrical and electronic equipment should not be mixed with general household waste. Please dispose in accordance with local regulations.

  • IEC 62368-1
  • FCC ID: 2AXKQ2029
  • IC ID: 26610-2029
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