GBG120 Tube Amp

This knob controls a noise gate function that affects the entire signal path.

A global noise gate helps eliminate unwanted noise, such as hum or buzz, from your instrument when you're not actively playing. Turning the knob clockwise increases the noise reduction threshold. When the signal level falls below this threshold, the gate cuts off the sound, resulting in a cleaner overall sound. Each channel on the amplifier has dedicated switch that activates the gate for that channel.

The most over-engineered input socket is designed for secure and reliable instrument connection.

It features a unique aluminium adapter that mechanically prevents the body from spinning even if the nut loosens slightly. If the nut is removed, the whole assembly will fall inside the amp which will require opening the front to mount it back. Just make sure that itʼs tight. Additionally, the jack is soldered to a PCB with convenient connectors, allowing for easier maintenance and servicing.

The GAIN knob is the control that unlocks a world of tonal possibilities, taking you from pristine cleans to extreme distortion. Here's a breakdown of how it works:

FUNCTION: The GAIN knob controls the amount of pre-amplification applied to your guitar signal before it reaches the power amp section. In simpler terms, it regulates how much "boost" the signal gets in the preamp stage.

IMPACT ON SOUND:

Low Gain: At low settings, the GAIN knob allows the clean character of your guitar and pickups to shine through. The sound remains relatively uncolored and undistorted.

Increasing Gain: As you turn the GAIN knob up, the pre-amp stage starts to push the signal harder. This creates a gradual increase in:

Overdrive: A warm, gritty distortion that adds richness and sustain to your notes. Think classic blues and rock tones.

Distortion: At higher gain settings, the signal becomes more clipped and distorted, leading to heavier rock and metal tones.

SWEET SPOT: The ideal GAIN setting depends on the desired sound and your playing style. Clean Tones: Keep the GAIN low for a pristine, uncolored sound. Experiment with the EQ to further refine the clean character.

Blues & Classic Rock: Explore the mid-range GAIN settings for a touch of overdrive that adds warmth and bite to your playing.

Heavy Rock & Metal: Crank the GAIN knob for high-gain distortion, perfect for aggressive rhythm and lead playing.

Remember:

The interaction between the GAIN knob and other controls like volume and EQ also shapes your tone. Experimenting with them in conjunction will help you dial in your desired sound. Different channels have their own independent GAIN controls, allowing for a wider range of tones on a single amp.

TUBES & TONE: The type of preamp tubes used in your amp also influences the character of the distortion produced by the GAIN knob. Different tubes have varying clipping charac- teristics, leading to subtle differences in the sound of the overdrive and distortion.

The CHANNEL VOLUME knob might seem straightforward, but it plays a crucial role in shaping your overall tone and sound pressure level. Here's a deeper dive into how it functions:

FUNCTION: The volume knob controls the level of the pre-amplified signal after it has been boosted by the GAIN stage. In simpler terms, it regulates how loud the signal gets before it reaches the power amp section.

IMPACT ON SOUND:

Low Volume: At lower settings, the volume knob allows you to play quietly without sacrificing the tonal character set by the GAIN and EQ controls. This is perfect for practicing at home or late-night sessions.

Increasing Volume: As you turn the volume knob up, the pre-amplified signal gets louder. This can lead to several sonic effects depending on your GAIN setting and the amp itself:

Clean Channel: With low GAIN settings, increasing volume simply makes the clean sound louder without introducing much distortion.

Overdrive & Distortion: With higher GAIN settings, pushing the volume knob can further enhance the overdrive or distortion character. You might experience:

Increased sustain: Notes ring out for longer with a more saturated sound.

More harmonic richness: The clipping process in the preamp stage introduces additional harmonics, adding complexity and fullness to the distorted sound.

Power Amp Breakup: In some tube amps, particularly those known for their overdrive, cranking the volume knob can push the power amp section into overdrive as well. This adds a unique character to the distortion, often described as spongy or compressed.

SWEET SPOT: The ideal volume setting depends on your playing situation and desired tone:

Bedroom Practice: Keep the volume low while experimenting with GAIN and EQ to dial in your desired clean or overdriven sound.

Band Practice/Gigs: Gradually increase the volume to balance with your bandmates. Remember, microphone placement can often compensate for lower amp volume.

Power Amp Breakup: If you seek the specific distortion characteristics of your amp's power amp section, experiment with pushing the volume knob in a controlled environment (avoid damaging your ears or speakers).

TIPS:

MASTER vs. CHANNEL volume: This amp features both a master volume and individual channel volume controls. Here's the difference:

Channel Volume: Controls the pre-amplified signal level for a specific channel before the master volume stage.

Master Volume: Acts as a final volume control after the preamp section, allowing you to achieve high-gain tones at lower overall volumes.

Remember:

The volume knob interacts with the GAIN and EQ to create your overall sound. Experimenting with them together helps you find the perfect balance between volume, distortion character, and tonal clarity.

FUNCTION: Controls the level of low frequencies. Think of the low rumble, body, and warmth associated with the bass guitar or the low-end thump of a kick drum.

IMPACT ON SOUND:

Boosting Bass: Turning the knob clockwise increases the low frequencies, making your sound fuller, thicker, and potentially boomy if overdone. This can be useful for heavy riffs, bassier tones, or compensating for a thin-sounding guitar.

Cutting Bass: Turning the knob counter-clockwise reduces the low frequencies, resulting in a thinner, brighter sound. This can be helpful for taming muddiness, cutting through a dense mix, or achieving a more scooped midrange sound for lead playing.

FUNCTION: Controls the mid frequencies, which are the heart of most instruments and vocals. They define the punch, growl, and body of your sound.

IMPACT ON SOUND:

Boosting Mids: Enhances the core body and character of your instrument. This can be useful for cutting through a mix, adding definition to chords, or achieving a more aggressive lead tone.

Cutting Mids: Scoops out the midrange, resulting in a scooped or scooped-in sound often used in metal and heavy rock. It can also help your guitar sit better in the mix alongside vocals or other instruments that occupy the midrange frequencies.

FUNCTION: Controls the high frequencies, which are responsible for the bite, brightness, and articulation of your sound.

IMPACT ON SOUND:

Boosting Treble: Increases the high frequencies, making your sound brighter, sharper, and potentially harsh if overdone. This can be useful for adding presence, accentuating pick attack, or achieving a more cutting lead tone.

Cutting Treble: Reduces the high frequencies, resulting in a warmer, mellower sound. This can be helpful for taming harshness, compensating for bright pickups, or achieving a smoother clean tone.

The SOLO function boosts your sound for leads and solos. The volume level of the boosted signal can be tweaked using the Volume knob right to the SOLO switch.

Depending on the SFX switch, the SOLO FX LOOP (SFX) will be activated automatically when SOLO is switched on.

MIDI Controllable Send Control Change #89 (CC #89).
Values: 0 = OFF, 127 = ON.

Connects the chanel to the gate system with global potentiometer control

Each channel on the amplifier has dedicated switch that activates the gate for that channel.

Cuts the lows below 200 Hz with a soft curve

This optional filter helps tame unwanted low-end rumble, particularly beneficial when using high-gain pedals or playing at high volumes.

Adds more aggressive gain

This switch provides a subtle increase in gain when engaged, adding a touch of warmth and edge to your clean tone, perfect for bluesy leads or pushing the clean channel into a breakup territory.

Warmer, old school sound

This switch selects between two variations of the crunch character. Experiment to find the perfect balance between a tighter, more focused crunch or a looser, more vintage-flavored breakup.

Adds more aggressive gain

Similar to the clean channel, this switch injects a touch more gain to the crunch character, pushing it towards a more saturated and aggressive territory, ideal for heavier rock and blues solos.

Warmer, old school sound

Just like in Channel 2, this switch offers two distinct distortion flavors. One might provide a tighter, more modern high-gain character, while the other delivers a more classic, scooped midrange distortion reminiscent of 70s and 80s rock.

Adds more aggressive gain

Crank it up! This switch injects a significant gain boost to the distortion channel, perfect for achieving those ultra-saturated, face-melting tones for the heaviest genres.

A tight boost for the lows below 200 Hz. Present on CH4 only

This optional switch adds a low-end boost to the extreme distortion, ideal for achieving a massive, earth-shaking bottom end for heavy riffs and djent styles.

Modifies the tube distortion to more modern style

This switch engages a modifier circuit that further sculpts the extreme distortion character. A scooped midrange for a scooped metal tone, a tighter focus for aggressive rhythm playing.

In OFF position the button is flush with its housing, in ON position it is recessed.

By pressing the button CH 1 / SOLO+FX OFF, a MIDI Program Change #4 (PC #4) is sent to the device. This switches to CH 1 and turns off SOLO and FX. This can be used to initialize GBG120 when remote controlling it via a MIDI controller.

ZUTA GBG120 Remote Control & Manual v1.0.0

Engage the primary FX loop

This switch activates the FX chain. When engaged (illuminated), the signal passes through the FX loop, allowing you to add effects like reverb, chorus, or delay. When disengaged, the signal bypasses the FX loop.

MIDI Controllable Send Control Change #90 (CC #90).
Values: 0 = OFF, 127 = ON.

Toggle between line and instrument level. Affects only the Line/Instrument and In/Out sockets

This toggle switch allows you to choose the input source for the jacks located on the rear panel of the amplifier.

LINE switch light off: This is the default setting. When selected, the rear panel INSTREUMENT IN jack is active, but the amplifier prioritizes the instrument connected to the main input jack on the front panel.

LINE switch light on: the rear panel LINE IN jack become active for connecting line-level audio sources. Line-level signals are typically stronger than instrument-level signals and may come from keyboards, external processors, or recording equipment.

Important Note: This switch only affects the functionality of the jacks on the rear panel. The main input jack on the front panel is always operational for instrument connection regardless of the LINE switch setting.

A tight boost for the highs above 2 kHz

A bell curve boost for the mids, peak at 1 kHz

A dedicated control that emphasizes the middle frequencies.

When this switch is turned on, the range of control through the Presence potentiometer changes, so instead of high, high mid tones are highlighted.

Toggle between serial and parallel connection for FX

This switch determines FX working mode, default serial mode, pushed in parallel mode.

Engage the secondary SOLO function dependent FX Loop

The SOLO FX LOOP switch enable the serial SFX loop to be activated or deactivated via the SOLO function. This chain might be dedicated to modulation effects like phaser, flanger, or tremolo.

A special distortion typical for the Gothenburg sound

GBG button activates DIODE bridging for the channels 2-3-4, adding more compression and clipping to the signal.

Two 4Ω Output Sockets that can be used to connect one 4Ω or two 8Ω speakers.

One 4Ω speaker: This presents the ideal impedance match for the amp, delivering full power and optimal tonal response.

Two 8Ω speakers: When connected in parallel, the total impedance becomes 4Ω, matching the amp's preferred load. However, this halves the amp's power delivered to each speaker.

Two 8Ω Output Sockets that can be used to connect one 8Ω or two 16Ω speakers.

One 8Ω speaker: Similar to the 4Ω setup, this provides the optimal impedance match for full power and tone.

Two 16Ω speakers: Connected in parallel, the total impedance becomes 8Ω, again matching the amp. However, power is halved per speaker.

Connection for a single 16Ω speaker.

Single 16Ω Connector: This is for connecting a single speaker with a 16Ω impedance. This provides a safe option if you only have one speaker, but it won't utilize the amp's full power output.

Connect the supplied FS-1 or FC6L to FOOT CTRL with a standard XLR cable.

The foot cotroller is being phantom powered via this connection.

This jack provides a buffered, unaltered, and equally-levelled signal from your instrument.

This can be used to:

1. Connect to a second identical GBG120 amplifier for a stereo rig setup.
2. Send your instrument signal to an external processor or recording equipment while also using the main amplifier output.

Rear instrument input for fixed rack-mount installations.

The INPUT on the front panel is “Master“ and overrides both the INST IN and the LINE IN on the rear panel, even if the LINE switch is engaged on the front panel.

Rear line output for use with Cabinet Simulators / Impulse Responses (IRs).

This TRS jack outputs a balanced line-level signal derived from the power amp section, after it has gone through the preamp and power amp but before reaching the speaker cabinet.

This TRS jack allows you to connect a balanced line-level signal to your amplifier.

This could be used for:

1. Re-amping:Send a previously recorded guitar track from your DAW (Digital Audio Workstation) back through the amplifier for further processing with its tone and effects.
2. External Hardware Plug-ins: Connect an external processor with your desired effects plugins via your DAW's AD/DA converter (analog-to-digital/digital-to-analog) for additional tonal shaping.
3. Line-Level Source: Connect a line-level signal from a device like a wireless system.

This jack sends the signal from the preamp section of your amplifier out to your external effects pedals in the FX chain.

This allows you to process your clean signal with effects before it reaches the power amp section.

Serial SOLO FX loop.

This jack functions similarly to the FX SEND, but for the SFX chain (controlled by the front panel Solo function).

This jack receives the processed signal from your FX device and feeds it back into the power amp section of your amplifier.

This jack functions similarly to the FX RETURN, but for the SFX chain SFX are only active when the SOLO button and the SFX button are both engaged.

The LINE/INST switch determines whether the SFX SEND and SFX RETURN jacks are used to deliver instrument-level or line-level signals. The SFX loop is serial only.

This control introduces a boost to the high frequencies. Imagine adding a touch of brightness and shimmer to your sound. It can help cut through the mix in a band setting or add a bit of sharpness to your clean tones. Presence usually interacts minimally with gain and volume. It refines the overall character without drastically changing the distortion.

This knob controls the volume level of the boosted signal for solos. Turning it clockwise increases the solo volume relative to the clean signal.

This control often targets the low frequencies. A bass boost can add fullness and body, especially at lower volumes. Conversely, cutting the bass can tighten up your sound and make it less boomy. Depth usually interacts moderately with gain and volume. At higher gain settings, the bass becomes naturally more prominent, so you might use the depth knob to tame it.

This knob operates as a “Send” in serial mode and “Mix” of dry vs wet signal when engage the parallel mode of FX function.

This knob controls the overall output volume of the amplifier.

The seemingly simple rotary switch on your tube amp unlocks a world of tonal possibilities, allowing you to tailor your playing experience to the situation. Here's a breakdown of its four positions and how they impact your sound:

STANDBY

This position essentially puts your amp on hold. While the preamp section is powered up, the high voltage isn't yet delivered to the power tubes. This is ideal for:

Starting the amplifier: Protects the tubes from damage caused by inrush current.

Extending tube life: Reducing thermal stress on the power tubes when you're not playing.

Short breaks: Taking a quick pause during practice or performance without having to. completely shut down the amp and wait for the tubes to warm up again.

AB, A, B power modes:

These positions determine how your power tubes are utilized, affecting both the volume and tonal character of your amp. Mixing 2 different types for tube pairs is possible but it must be done by authorized personel even if the waranty is void. The amplifier must be properly set up for tube change. Failing to set it up properly might cause serious damage to internal components.

AB (Full Power): This is the standard operating mode for most situations. All power tubes (both the inner - B, and outer - A pairs) function together, delivering the full power capability of your amp. This setting provides the most headroom (clean volume) and allows you to explore the full range of overdrive and distortion available in your amp's design.

A (Outer Half Power): This mode utilizes only the outer pair of power tubes. It also delivers approximately half the power of the full AB mode, depending on the tubes configuration.

B (Inner Half Power): This mode utilizes only the inner pair of power tubes. It also delivers approximately half the power of the full AB mode, depending on the tubes configuration.

Voltage Switch and Fuse: Make sure that the Voltage Switch and the Fuse are matching to the electrical grid.

Voltage Switch and Fuse: Make sure that the Voltage Switch and the Fuse are matching to the electrical grid.

The FUSE must be matched with the power grid. 2A slowblow for 230 VAC and 4A slowblow for 115 VAC grids. In case of a grid with different properties like in Japan, check for additional information on the back of the amp. The amplifiers factory setup is matched to delivery destination. There is small compartment with another fuse but that is not a spare fuse. If needed, use the secondary fuse only in with conjunction with the voltage selector.

Grounding: The GBG120 must be properly grounded to prevent electrical shock. Always use a grounded power cable and connect it to a grounded outlet.

Always use a 3 pin power cord to connect Mains AC power socket (28) to grounded power grid socket, no matter in what country, region or anywhere you are.

Ultra silent industry quality level built in fan, for cool operation under any circumstance.

Heat Dissipation: The GBG120 utilizes a silent Noctua fan for ventilation. However, it's crucial to ensure proper airflow around the rackmount unit. Avoid blocking ventilation slots or installing the amp in enclosed spaces with restricted airflow.