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Conventional 6.3mm / ¼" TS unbalanced input for connecting a guitar.
Controls for Clean Gain, Bass, Middle, and Treble EQ settings.
Controls for Lead Gain, Presence, and Volume settings.
Master volume knob and Gain Boost push button for enhanced gain.
Switches for selecting Clean/Lead channel, Stand By, and mains Power.
Selects output power levels: 20W, 5W, 1W, or Speaker Off.
Mains power socket (IEC C14) and access to mains/spare fuses.
Connects to footswitches for channel switching and effect control.
Serial FX Loop (Send/Return) and Reverb Mix Level adjustment.
Headphone, Line Out (Cab Sim/Pure Signal), and Poweramp outputs.
Details output power, input sensitivity, output level, and power consumption.
Lists fuse types, tubes used, unit dimensions, and weight.
Guidance on gain settings, feedback prevention, and managing background noise.
Solutions for fluctuating volume, no sound, and humming noise problems.
Information on contacting service and proper packaging for transport.
Diagram illustrating TRS footswitch connections and pin assignments.
The ENGL E633 Fireball 25 is an all-tube guitar amplifier designed for both head (E606) and combo (E600) configurations, offering a range of features for guitarists seeking powerful and versatile tone.
The amplifier features two primary channels: Clean and Lead. The Clean Gain control adjusts the gain for the Clean channel, providing a range from pristine cleans to slightly overdriven tones. The Lead Gain control similarly manages the gain for the Lead channel, allowing for high-gain distortion suitable for heavier genres.
The tone shaping capabilities are extensive, with a passive EQ section comprising Bass, Middle, and Treble controls. These knobs allow for precise adjustments to the bottom end, mid-range, and upper range frequencies of the preamp, respectively. For the Lead channel, a dedicated Lead Presence control defines the treble response in the power amp stage, adding clarity and cut to the distorted tones.
The amplifier's output level is managed by two main controls: Lead Volume and Master. The Lead Volume control, located pre-FX Loop, influences the send level and is crucial for balancing the levels between the Lead and Clean channels. The Master volume knob, positioned post-FX Loop, controls the overall power amp output level.
A Gain Boost function can be activated or deactivated via a push button, indicated by a red LED. This feature can also be controlled externally using a dual footswitch (like the ENGL Z4) connected via a conventional 6.3mm / ¼" TRS jack. Similarly, toggling between the Clean and Lead channels is done via a push button, with a red LED indicating when the Lead channel is engaged. This channel switching can also be managed by an external dual footswitch.
A key feature for flexible playing environments is the Power Soak. This allows the user to select different power levels: Full Power (approx. 20 Watts), 5 Watts, 1 Watt, and Speaker Off (zero Watts). When activated, the Power Soak's resistors convert excess power amp output into heat, enabling lower volume playing without sacrificing tone. The "Speaker Off" position is particularly useful for silent practice with headphones or for direct recording.
The amplifier includes an FX Loop (serial) located post-preamp and before the Master controls. This allows for the integration of external effects processors or pedals. The FX Loop Send (output) connects to the input of an effect unit, while the FX Loop Return (input) receives the processed signal from the effect unit's output.
For monitoring and recording, the amplifier offers several output options. A Headphone Output (conventional 6.3mm / ¼" TRS) allows for private practice, especially when the Power Soak is set to "Speaker Off." The Line Output - Cab Sim port provides a line out signal at approximately 0 dB, filtered to simulate the sound of a speaker cabinet, ideal for direct recording or feeding into a PA system. The Line Output - Pure Signal port also provides a 0 dB line out, but with a frequency response identical to the power amp output signal, without any compensation or correction. This raw signal can be fed into another linear power amp, an outboard filter for speaker emulation, or an IR-loader like the ENGL CABLOADER for advanced signal processing before recording or PA system integration.
The Poweramp Output is where the speaker cabinet connects. For the E600 Ironball Combo, the internal 12" speaker is connected here. For the E606 Ironball Head, a single 8-16 ohm cabinet can be connected.
The amplifier is designed for ease of use with clearly labeled controls on both the front and back panels. The Input jack (conventional 6.3mm / ¼" TS) is for connecting your guitar using a shielded instrument cable.
The Stand By switch is an important operational feature. It allows the user to put the amp into a low-power mode during breaks, keeping the tubes warm and ready for immediate full power operation. When powering up the amp, it is crucial to first set the Stand By switch to Stand By, then switch on the Power (mains power). After about 30 seconds, allowing the tubes to heat up, the Stand By switch can be moved to the "on" position to activate the power amp. This procedure helps prolong the life of the tubes.
External control via footswitches enhances live performance. A dual footswitch (like the ENGL Z4) can control the Master Volume Boost and Reverb (Tip: M.V.B. on/off, Ring: Reverb on/off). Another dual footswitch can control channel switching (Clean/Lead) and Gain Boost (Tip: Clean/Lead, Ring: Gain Boost on/off).
When using the Power Soak, it's important to ensure adequate air circulation around the back of the amp, as the resistors convert power into heat.
For headphone use, it's critical to remove headphones before powering up the device to avoid potential hearing damage from sudden noise.
Proper impedance matching is paramount when connecting speaker cabinets. Always verify that the connected cabinet's impedance matches the amplifier's output impedance to prevent damage to the power amp.
The amplifier's design emphasizes durability and serviceability. The Mains Fuse Box on the rear panel contains both the mains fuse and a spare fuse. It is crucial to replace fuses only with those of the same type and rating, as specified in the technical data and on the type panel.
The amplifier uses specific tubes: ENGL ECC83 First Quality (FQ) for V1, ENGL ECC83 Selected (S) for V2/V3/V4, and ENGL EL84 Hand-matched Duet for V5/V6. If background noise (hissing, sizzling, crackling, popping) becomes a constant issue, replacing tubes might be considered, though intermittent noise is normal for tube amplifiers.
In case of troubleshooting, it is recommended to systematically check all cables, effect devices, and guitar connections. If issues persist, contacting ENGL customer service with a detailed description of the problem, including control settings and potentially a video, is advised.
For shipping, using the original packaging is strongly recommended to ensure the device's protection. The original packaging consists of thick cardboard and custom-made molded foam parts, designed for multiple uses. Damaged packaging should not be used, and flight cases are not considered suitable shipping packaging by ENGL. Devices should be packed separately, not together.
General| Power Output | 25 Watts |
|---|---|
| Tubes (Power Amp) | 2 x EL84 |
| Master Volume | Yes |
| Presence Control | Yes |
| Reverb | No |
| Effects Loop | Yes |
| Speaker Outputs | 1 x 8 Ohm, 1 x 16 Ohm |
| Channels | 2 |
| EQ Controls | Bass, Middle, Treble |
| Weight | 10 kg |
| Tubes (Preamp) | 4 x ECC83 |
| Footswitch | Z-4 (Channel switching, Master Volume Boost) |
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