Engl E633BO-KT77 Fireball 25 Blackout

The Fireball in Blackout version: a darker, more aggressive ENGL icon

The Fireball series holds an essential place in the ENGL universe: that of tube amps designed for guitarists seeking modern, precise saturation with no lack of punch. With the Fireball 25 Blackout KT77 E633BO-KT77, the German brand presents this identity in a compact head with an entirely black look, enhanced by its horizontal protective grille.

This version is more than just a new aesthetic. Its power amp, equipped with two KT77 tubes, delivers a more responsive feel and a sharper attack, making it ideal for low-tuned riffs, highly defined rhythm parts and high-gain tones that need to remain clear in a dense mix.

A compact high-gain head for the studio, rehearsals and the stage

The ENGL Fireball 25 Blackout is aimed at intermediate to advanced guitarists who want the feel of a genuine tube amp without necessarily having to transport a 100-watt head. Its 25 watts already provide substantial volume headroom for rehearsing with a drummer, playing on stage or recording with a real guitar cabinet.

It is particularly well suited to modern metal, heavy metal, hard rock, metalcore, thrash, death metal and hard-hitting rock. Thanks to its Clean channel and effective EQ, it can also be used in more versatile projects requiring an expressive clean tone, a powerful crunch and a very generous Lead channel gain.

The Power Soak makes the amp much easier to use at home or in the studio. By lowering the power to 5 W or 1 W, the guitarist retains the dynamic response of the tube power amp while reducing the volume level. The Speaker Off mode can be used to mute the loudspeaker, depending on the setup.

Two effective channels and controls designed to get straight to the point

The Fireball 25 Blackout KT77 prioritizes clear ergonomics. The Clean channel has its own Gain control, allowing you to go from a bright clean tone to a rougher character when pushing the preamp. The Lead channel also features an independent Gain control and delivers the powerful saturation that has made the Fireball range renowned.

The three-band Bass, Middle and Treble EQ makes it quick and easy to shape a tone suited to the guitar, cabinet and playing style. The Lead Volume control makes it easy to balance the level between the two channels, while the Master Volume controls the overall volume. The Presence control affects high-end definition and helps the guitar stand out in a band.

The Mid Boost switch enhances the midrange to give riffs greater presence and allow solos to cut through the mix. The adjustable Noise Gate on the rear panel is dedicated to the Lead channel: it reduces unwanted noise at high gain settings while preserving the impact of the attack. An effects loop makes it easy to integrate delay, reverb, chorus or an external processor after the preamp saturation.

KT77 bite for precise high gain

Built entirely around tubes, this ENGL head combines four ECC83 tubes in the preamp with two KT77 tubes in the power amp. This configuration is designed to provide a fast response, tight lows and pronounced mids—three essential qualities for maintaining clarity with power chords, fast palm-muted passages or low tunings.

The Clean channel retains brightness and dynamics under the pick. By increasing its gain, it can develop a clear, lively crunch. The Lead channel then takes over with thick, articulate saturation rich in harmonics, capable of remaining precise for technical rhythm parts as well as singing solo lines.

The Fireball 25 Blackout KT77 favors a modern, tight character over loose vintage-style saturation. Its headroom, natural compression and direct attack make it an excellent platform for boost pedals placed before the amp, particularly when you need to tighten the lows further or enhance the projection of the mids.

Technical specifications

Category	Guitar amp head	Number of channels	2
Technology	Tubes	EQ	3 channels
Effects loop	Yes	Color	Black
Pre-amp tubes	ECC83	Power output	25 W
Attenuator	Yes

Type	all-tube guitar amplifier head	Channels	Clean and Lead
Power	25 W	Loudspeaker outputs	8 and 16 ohms
Preamp tubes	4 x ECC83 / 12AX7	Finishing	Blackout
Power tubes	2 x KT77	Dimensions	420 x 200 x 230 mm
Power Soak	full power, 5 W, 1 W and Speaker Off	Weight	11 kg