This article contains complete operating instructions for the UAFX Knuckles '92 Rev F High Gain Amp effects pedal from Universal Audio.

In this article

• A Letter From Bill Putnam, Jr.
• Getting Started with Knuckles '92
• Knuckles '92 Overview
• Knuckles '92 Operation
• Knuckles '92 Controls
• Knuckles '92 Cabs
• Knuckles '92 Channels
• Knuckles '92 Overdrive
• UAFX Control with Knuckles '92
• Knuckles '92 Specifications
• Knuckles '92 Safety

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 www.uaudio.com, and via our social media channels.

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

Sincerely,

Bill Putnam Jr.

 

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Getting Started with Knuckles '92

Knuckles '92 Quick Start

UAFX pedals include a quick start sheet in the box. To download the sheet, go here. 

 

Knuckles '92 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.

Knuckles '92 Power

To learn how to power your UAFX pedal, go here.

Knuckles '92 Connections

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

 

 

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Knuckles '92 Overview

Get the raw sound of punk, alt rock, and metal under your boots. 

Knuckles '92 Dual Rec Amplifier delivers the searing high-gain tone that powered legendary punk, alt rock, and metal bands from Foo Fighters and Incubus to Metallica, Dream Theater, and more.*

Giving you six classic mic and speaker pairings, built in TS-style OD/boost, and noise gate, Knuckles puts the authentic genre-defining sound of one of the world's most ferocious high-gain amps under your boots.

Six Epic Mic & Speaker Pairings

Experiment with six mic and speaker pairings used on countless iconic records. From alt rock anthems to de-tuned nu-metal brutality, Knuckles '92 captures the full essence of playing through one of the greatest aggressive amps ever made. 

• UK V30: 4x12 Marshall cab with V30s
• CA V30: 4x12 Oversized cab with V30s
• White 75: 4x12 Marshall cab with Celestion 75s
• 3 bonus cabs: 1x12 EV12, 4x12 Celestion 80, 4x12 Brown JB**

*Use of artist names does not constitute official endorsement of UAFX Knuckles '92 Dual Rec Amplifier.

**Available upon registration.

UAFX Control and UA Connect software

UA Connect and UAFX Control are the companion apps for your UAFX pedal. 

UA Connect Computer App – UA Connect is for firmware updates and getting your free bonus speaker cabinets.

UAFX Control Mobile App – UAFX Control is for getting your free bonus speaker cabinets and factory/artist presets, and deeper editing.

UAFX Control also has preset management and deeper editing for global settings such as footswitch modes, and per-sound settings for overdrive pedal type, amp signal flow, channel styles, tubes, rectifiers, and power mode.

Free Bonus Speaker Cabinets and Presets

Register your pedal with UA Connect or UAFX Control to get three bonus speaker cabinets and factory/artist presets for more great tones. To get UA Connect and UAFX Control, visit: https://www.uaudio.com/downloads/ua-connect.

 

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Knuckles '92 Operation

Live Mode and Preset Mode

Note: Knuckles '92 is in Live | Preset mode by default. You can use UAFX Control to change footswitch assignments.

In Live mode, the sound reflects the current positions of the knobs, switches, and LEDs on the pedal, and the left footswitch toggles the Live mode effect on/off.

In Preset mode, you hear the settings that are stored as a preset, and the current positions of the knobs and switches do not reflect the sound. Instead, all knob and switch positions are internally set to their stored positions, and the right footswitch toggles the preset effect on/off.

You can store a preset you've made with your own settings by holding down the STORE switch until the green PRESET footswitch LED blinks rapidly (about 0.5 seconds)

Live Mode

To enter Live mode, press the left footswitch. Press the left footswitch again to toggle the live effect on/off. The left footswitch LED is lit red when the Live mode effect is on.

Preset Mode

To enter Preset mode, press the right footswitch. Press the right footswitch again to toggle the preset on/off. The right footswitch LED is lit green when the preset is on.

Note: The left and right footswitch functions can be changed in UAFX Control.

Stored Preset

You can store a preset on your UAFX pedal, and recall it using the right footswitch. All presets you store, and other artist and factory presets, are available in UAFX Control.

When you store a preset while in Live mode, the position of all knobs and switches on the pedal (including ALT values) are saved. When you make a great sound in Live mode, storing it is as easy as holding down the STORE switch until the green PRESET footswitch LED blinks rapidly (about 0.5 seconds).

When you store a preset while in Preset mode, only those knobs and switches that have changed since you loaded the preset are saved. So, when saving in Preset mode, what you hear is what is saved, and not the current positions of the knobs and switches.

To store your sound as a preset

1. Set your sound as you want it stored in the preset.
2. Press and hold the STORE switch in the down position until the green PRESET footswitch LED blinks rapidly (about 0.5 seconds).

Preset Notes

• The settings for Preset mode and Live mode are completely independent.
• When you move a knob or switch in Preset mode, the settings for the sound immediately jump to the new knob or switch position.
• You can view and audition all of your pedal's presets with UAFX Control.
• Presets can only be stored when the pedal is not bypassed.

 

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Knuckles '92 Controls

The following controls are available on the Knuckles '92 pedal. For additional settings, use UAFX Control.

Gain / Room

Adjusts two different settings, depending on the position of the Alt / Amp / Store switch. 

• AMP mode: Gain adjusts the level of preamp gain. As you turn this up, the sound gets increasingly distorted and saturated, especially on the ORG and RED channels.
• ALT mode: Adjusts the amount of room ambience mixed into the signal.

Presence / Gate

Adjusts two different settings, depending on the position of the Alt / Amp / Store switch. 

• AMP mode: Presence adds high end sparkle and grit to the sound. 
• ALT mode: Gate adjusts the noise gate threshold for the sound. See Knuckles '92 Noise Gate for more information.

Note: Adjusting the Gate control enables the noise gate if it is not enabled. 

Output

Adjusts the overall output level from the pedal. Output allows you to set the level for your setup. Output level is strictly the volume level from the pedal, and not the same as the Master control, which is more like a master volume. 

Output level from Knuckles varies depending on the channel and mode. 

Low / Overdrive

Adjusts two different settings, depending on the position of the Alt / Amp /Store switch. 

• AMP mode: Adjusts the low frequency response of the amp's tone stack.
• ALT mode: Adjusts the overdrive gain amount (TS overdrive) or the low EQ amount (TC preamp)

Mid / OD Tone

Adjusts two different settings, depending on the position of the Alt / Amp /Store switch. 

• AMP mode: Adjusts the mid frequency response of the amp's tone stack.
• ALT mode: Adjusts the overdrive tone control (TS overdrive) or the treble EQ amount (TC preamp).

High / OD Level

Adjusts two different settings, depending on the position of the Alt / Amp /Store switch. 

• AMP mode: Adjusts the high frequency response of the amp's tone stack.
• ALT mode: Adjusts the overdrive output volume (TS overdrive) or the output level (TC preamp). Set to minimum to disable the overdrive pedal. 

Tip: Overdrive is routed before the pedal input, so the overdrive output level does not increase the pedal's output level, but instead increases distortion by pushing the front end of the amp. 

TS Overdrive and TC Preamp settings

The TS overdrive or TC preamp are typically used to push the amp's input stage harder to increase gain. These pedals are renowned because they also provide a necessary cut in the low-end EQ, which can make the heavily distorted amp sound tighter for classic palm-muted riffing and chugging.

TS suggested settings

• Overdrive – Set low or completely off. Used with active or high output pickups, many players prefer to turn the gain all the way off. With lower output pickups some players will add a small amount of overdrive.
• OD Tone – Start at noon and adjust. Typically, this sounds best between noon and 2 o'clock.
• OD Level – Crank this up! This pushes the front end of the amp into thick distortion. Adjust to taste.

TC suggested settings

• Overdrive (Bass) – Set this completely off for ultra tight djent tones. Add some bass for looser or thicker metal sounds.
• OD Tone (Treble) – Start at noon and adjust. Typically sounds great between noon and 2 o'clock
• OD Level (Volume) – Crank this up! This pushes the front end of the amp into thick distortion. Adjust to taste.

Cab Switch

Push this switch up or down to change the speaker cabinet and microphone. When you push the switch repeatedly in the same direction, the pedal cycles through all available speaker cabinets. See Knuckles '92 Cabs for complete descriptions.

Tip: Register your pedal to get free bonus speaker cabinets.

Cab LED

The currently selected speaker cabinet is indicated by this LED. A red LED indicates that the speaker cabinet printed on the pedal is selected. A bonus speaker cabinet is selected when an LED is green (the bonus speaker cabinets don't have labels).

When the LED is off, the amp is active but no speaker cabinet simulation or room sound is applied.

Tip: When playing through a real guitar amplifier and speaker cabinet, you might want to bypass the speaker cabinet emulation by pressing the pedal's CAB switch until its LED is unlit.

Alt / Amp / Store

In AMP mode, the standard knob controls are available for the amp.

In ALT mode, the Room, Gate, Overdrive, OD Tone, and OD Level controls are available on the Gain, Presence, Low, Mid, and High knobs.

To store a preset, press and hold the ALT/AMP/STORE switch in the down position until the PRESET footswitch LED blinks rapidly (about 0.5 seconds).

Channel Switch

Knuckles includes three independent amplifier channels, each of which provides different amp character and features.

Use the channel switch to select the channel. See Knuckles '92 Channels for more details about the channels. Unlock alternative Channel Styles with the UAFX Control App. 

Left Switch LED

By default, the left footswitch LED is lit red when Live mode knob and switch settings are active. Other states for the left footswitch LED are detailed in the table below.

Left Footswitch

By default, press to toggle the Live mode sound on/off with the current knob and switch settings. This footswitch can also toggle other options, depending on the footswitch mode, as detailed in the table below.

Preset Footswitch LED

The preset footswitch LED is lit green when stored settings are active. There are other modes for the right footswitch LED, as detailed in the table below.

Right Footswitch

By default, press to toggle the Preset sound on/off. This footswitch can also toggle other options, depending on the pedal footswitch mode, as detailed in the table below.

Footswitch modes

With UAFX Control, you can change the operation of your pedal and your pedal's footswitches for your amplifier setup and performance preferences. 

For more information on footswitch modes and how to enable them, see UAFX Control with Knuckles '92.

 

 

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Knuckles '92 Cabs

Each speaker, cabinet, and mic setting has a unique sound. Toggle up or down to cycle through the list with the Cab switch. When you register your pedal with UAFX Control software, you get three free bonus cabs (indicated by green LEDs).

Knuckles '92 bonus speaker cabinets

When you register your pedal using the UA Connect or UAFX Control apps, your free bonus speaker cabinets are added to the pedal. To select these speaker cabinets, push the Cab switch until the top, middle, or bottom Cab LED is lit green.

Note: The speaker cabinet labels on the pedal apply only when that speaker switch's LED is red. The labels when the LED is green are only visible in UAFX Control.

 

Note: Product names used herein are trademarks of their respective owners, which are in no way affiliated with Universal Audio Inc. These name(s) are used solely to identify products studied in the creation of the sound models found in Knuckles '92.

 

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Knuckles '92 Channels

Each channel has a unique gain structure and sound. The Orange and Red channels include Channel Styles, which provide alternate gain and EQ structures for the channels. Channel Styles can be switched in the UAFX Control App. See Channel Style / Orange Presence for complete descriptions. 

• CLN – Cleanest channel on the amp. Ranges from clean to relatively thick and wooly distortion, very loose at high gain settings. 
• ORG – Good all-around distortion, with plenty of gain and midrange character. Excellent pushed cleans with the gain reduced. Alternate Modern Channel Style adds more gain and scooped EQ. 
• RED – Massively heavy, saturated rectifier sound with scooped mids and big lows and highs. Alternate Vintage Channel Style has lots of high end brightness, with dual presence controls, and reduced gain for a more sizzly rock tone.

 

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Knuckles '92 Overdrive

Knuckles' overdrive knobs add gain and EQ control by employing one of two classic pedals with multiple controls to "juice" the front end of the amp, adding tightness and boosting gain. Pedal controls are available in ALT mode on the Low/Mid/High knobs. To enable overdrive, turn the High/OD Level knob above minimum with the pedal in ALT mode, or toggle overdrive on/off in Overdrive | Live/Preset footswitch mode. You can choose the TS or TC overdrive in the UAFX Control app.

Note: The Overdrive controls are only active In ALT mode.

 

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UAFX Control with Knuckles '92

With UAFX Control, you can manage your presets, change the operation of Knuckles '92's footswitches, switch a number of amp characteristics including channel style, tubes, rectifier, and power, adjust the noise gate, adjust the master and toggle 4-cable mode for your amplifier setup and performance preferences.

In UAFX Control, tap the icons at the bottom of the screen to access the Presets, Edit, and Settings screens. You may need to scroll down on this screen to see all available settings.

Knuckles '92 footswitch modes

The footswitch functions can be changed to suit your preferences. You can configure Knuckles '92 to switch between Live and Preset modes, or have Boost on the left footswitch and toggle between Live/Preset modes on the right footswitch.

Choosing a footswitch mode

To select a footswitch mode, open the Settings screen. Then tap the current footswitch mode (colored bar) and choose a mode from the drop menu.

Note: See Assigning the preset or live sound for information about how to set the pedal sound when you use a footswitch mode that cannot be bypassed.

Live | Preset

In Live | Preset mode, you can access Live mode (knobs and switches) and the stored preset.

• Left Footswitch toggles the Live sound on/off
• Right Footswitch toggles the stored preset on/off
• Pedal can be bypassed
• 4-cable mode is available

Overdrive | Live/Preset

In Overdrive | Live/Preset mode, you can switch Overdrive on and off, and toggle between Live mode (knobs and switches) and the stored preset.

• Left Footswitch toggles Overdrive on/off
• Right Footswitch toggles between Live mode (red LED) and the stored preset (green LED)
• Pedal is always on and cannot be bypassed
• 4-cable mode is not available

Gate | Live/Preset

In Gate | Live/Preset mode, you can switch the Gate on and off, and toggle between Live mode (knobs and switches) and the stored preset.

• Left Footswitch toggles Gate on/off
• Right Footswitch toggles between Live mode (red LED) and the stored preset (green LED)
• Pedal is always on and cannot be bypassed
• 4-cable mode is not available

Knuckles 4-cable mode

4-cable mode lets you add another switchable channel to any real guitar amplifier that has an effects loop. This special mode lets you switch between your guitar amplifier's built-in preamp section and the sounds in your pedal.

Warning: Power off your amplifier before wiring the pedal and enabling 4-cable mode. If you enable 4-cable mode with incorrect wiring, you can cause extreme feedback.

To learn how to set up and operate 4-cable mode, .

Adjusting Knuckles Editor settings

Knuckles includes an editor that allows you to make further adjustments to the amp's settings.

To open the Editor, tap Edit at the bottom of the UAFX Control screen. 

In Live mode, editor settings apply either globally or per-channel. Preset sounds can have different global settings but Live mode global settings are restored when you switch back to Live mode. 

 

Overdrive

Selects the overdrive pedal type. The overdrive type is global in Live Mode. You can enable the overdrive pedal by turning the High/OD Level knob past minimum in ALT mode, or toggling overdrive on in Overdrive | Live/Preset mode. Adjust the overdrive settings with the Low, Mid, and High knobs in ALT mode.

TS

The default overdrive is the classic green pedal with gain, tone, and volume controls. The TS is the perfect front end for crushing metal tones with Knuckles. This pedal emphasizes high mids and cuts bass, providing for tighter sounds with tons of gain on tap. 

Tip: For classic 90s metal tones set the overdrive fully counter-clockwise, or just above if you use passive pickups, with treble at noon and volume fully clockwise. 

TC

Rare vintage black preamp pedal with volume, bass, and treble controls gives a massive amount of control when pushing the front end of Knuckles. Controls are available on Low/Mid/High knobs when the ALT switch is enabled. 

Tip: For huge metal tones, set bass fully counter-clockwise, treble at noon and volume fully clockwise.

Knuckles '92 Noise Gate

Toggle the Knuckles '92 Noise Gate by tapping the gray button next to Noise Gate. Adjust the Noise Gate settings for your current instrument and sound to eliminate any extraneous noise.

Knuckles' noise gate silences extraneous noise generated by these high gain tube amps by detecting your guitar signal at the input, but acting at the end of the signal chain. This clever design is extremely effective at both detecting and stopping extraneous noise.

Signal Flow

To set the signal flow for the pedal, tap the current signal flow (colored bar), then choose an item from the drop menu.

 

 

 

Channel Style / Orange Presence

To set the channel style for the pedal, tap the channel style. Channel style is available for the Orange and Red channels only. 

 

 

 

 

Power Tubes

To set the power tubes for the channel, tap the power tube type. 

• 6L6 – 6L6 tubes are the classic factory configuration. Brighter, deeper, with scooped midrange.
• EL34 – EL34s give a more British sound with warmer midrange and less bottom and top end.

Rectifier

To set the rectifier for the channel, tap the rectifier type.

• Solid State – The solid state rectifier responds faster to transients, and will result in a tighter, more articulate feel. Good for fast, articulate tones.
• Tube – The tube rectifier sounds looser and responds more slowly. Good for cleans, rock rhythm, and open lead tones.

Power Mode

To set the power mode for the channel, tap the power mode.

• Bold – Bold runs the power tubes at increased voltage, for a more aggressive, punchy sound. 
• Spongy – Spongy reduces the power tube voltage for a softer, more heavy rock sound.

 

Master

Master adds another level of output gain with some harmonic content, based on the Master Volume control from the original amp. Use this to add more output volume for your setup, or for creative effect. 

Revert to Default (Live sound only)

Tap to revert to the default Edit screen settings for the Live Sound (knob and switch settings are unchanged). Reverting to default also reverts all per-channel and global settings for all channels on the pedal to their default settings. 

Restore Preset (Preset sound only)

Tap to revert any changes you have made to the current preset. 

 

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Knuckles '92 Specifications

Note: All specifications are subject to change without notice.

 

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Knuckles '92 Safety

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 help.uaudio.com.

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 instructions in the instruction manual.)

ISED Canada Manual Statement

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.

This device is in compliance with the essential requirements and other relevant provisions of Directive 2014/53/EU. All essential radio test suites have been carried out.

Changes or modifications made to this equipment not expressly approved by Universal Audio and may void the FCC and IC authorization to operate this equipment.

• IEC: 62368-1

• FCC ID: 2AXKQ2077

• IC: 26610-2077