Elekit TU-8888 Monoblock PP Power Amp Kit

Description

The TU-8888 Monoblock PP Power Amp Kit is a high-fidelity DIY tube amplifier kit designed for audiophiles who appreciate both DIY assembly and high-performance sound. It’s built around a push-pull ultra-linear topology, which enhances power efficiency and reduces distortion while maintaining the rich, warm tonal characteristics of vacuum tubes. This kit combines versatility, high-end components, and meticulous engineering to deliver exceptional audio performance. One set of this kit contains TWO monoblocks and for proper work it is required to use the preamplifier, ie.: Elekit TU-8550.

• Versatile Tube Compatibility: Supports a wide range of octal-base (US 8-pin) beam output tubes, from KT88 to KT170.
• Premium Output Transformer: Equipped with the LL3733 transformer, custom-designed and manufactured by the renowned Swedish company Lundahl Transformers.
• Isolated Speaker Output: Ensures complete isolation from both the amplifier circuit and chassis ground for optimal performance.
• Adjustable Input Level: Conveniently located at the rear of the chassis for fine-tuned control.
• Superior Noise Reduction: Features a MOSFET ripple filter and DC-powered voltage amplifier tube heater circuit to effectively eliminate hum.
• Comprehensive Protection: Built-in safety measures include fuses and PTCs.
• Manual Bias Adjustment: Easy to set using the built-in meter for precise tuning.

Key Features & Highlights

Tube Flexibility & Compatibility
One of the standout features of the TU-8888 is its ability to accommodate a variety of beam power tubes with an octal (US 8-pin) base, including KT88, KT120, KT150, and KT170, offering different power levels and tonal characteristics. The ability to swap tubes allows users to experiment with different sonic profiles and tailor the amplifier’s sound to their preference.

Premium Lundahl Output Transformer
The LL3733 output transformer, custom-designed by Lundahl Transformers (Sweden), plays a crucial role in delivering high-quality sound. Lundahl is well-known for producing some of the best transformers in the audio industry, ensuring exceptional clarity and detail in sound reproduction, low distortion and high efficiency, thanks to precision winding and high-grade materials and reliable performance and durability, making it a long-term investment for serious audiophiles.

Optimized Speaker Connection & Isolation
Unlike many amplifiers, the TU-8888 ensures that the speaker output is fully isolated from both the amplifier circuit and chassis ground. This design helps minimize potential ground loops and unwanted noise and improve overall signal integrity, resulting in cleaner, more natural sound reproduction.

Adjustable Input Level for Greater Control
A rear-panel input level control allows fine-tuning of the amplifier’s gain, making it compatible with a variety of preamps and sources without requiring additional attenuation or signal adjustments.

Advanced Hum Reduction & Power Filtering
To keep noise levels as low as possible, the TU-8888 employs a proven MOSFET ripple filter, ensuring clean DC power to the amplifier circuit and DC-powered heater circuits for the voltage amplification stage, reducing hum that can be introduced by AC-powered heaters. These measures contribute to a low-noise floor, excellent dynamics, and a highly immersive listening experience.

Multiple Protective Measures for Longevity
The amplifier is built with safety and durability in mind, featuring fuses and PTC (Positive Temperature Coefficient) components to protect against overcurrent and excessive heat and carefully designed circuit protection to prevent damage to components and prolong the lifespan of the amplifier.

Manual Bias Adjustment for Precision Tuning
Unlike some amplifiers with automatic biasing, the TU-8888 allows for manual bias adjustment via a built-in bias meter. This feature lets users optimize the amplifier’s performance based on the selected output tubes and ensures balanced operation and longer tube life by setting the correct bias current. It allow also for experimenting with different tube brands and models for subtle tonal differences.

Why Choose the TU-8888?

The TU-8888 is ideal for audiophiles looking for:

• A high-performance monoblock amplifier with a classic vacuum tube sound.
• Customizable sound signature, thanks to tube-rolling capabilities.
• Top-tier components, including Lundahl transformers, for superior audio fidelity.
• Low-noise, high-durability design with multiple protective features.
• A rewarding DIY experience, allowing audiophiles to build and fine-tune their own amplifier.

If you enjoy the warm, dynamic, and detailed sound of tube amplifiers, the TU-8888 Monoblock PP Power Amp Kit is an excellent choice for a powerful, customizable, and reliable audio system upgrade.

Tube Selection & Customization

One of the most exciting aspects of the TU-8888 is its tube-rolling capability. The ability to swap out different output tubes allows users to fine-tune the sound to their preferences.

Compatible Output Tubes & Their Sound Signatures

Since the amp supports KT88 to KT170 tubes, here’s what you can expect from each:

• KT88 – A balanced, full-bodied sound with tight bass, smooth mids, and airy highs.
• KT120 – More power and dynamic headroom, with slightly deeper bass and punchier transients.
• KT150 – A warmer, richer tonal balance with excellent midrange clarity and a stronger low-end.
• KT170 – The most powerful of the group, delivering exceptional bass impact, wide soundstage, and high detail resolution.

Driver & Preamp Tubes

The amplifier also includes a voltage amplification stage, based on 12AU7 (ECC82) and 6267 (EF86) tubes. Changing these tubes can subtly alter the tone, adding more warmth or detail depending on the brand and model:

• Mullard (reissue or NOS) – Warm, rich, and smooth.
• JJ Electronics – Balanced, dynamic, and slightly modern-sounding.
• Tung-Sol (reissue) – Clear highs and well-defined bass.
• Electro-Harmonix – Crisp and detailed.

Sound Characteristics & Performance

The TU-8888 is designed for audiophile-grade performance, combining:

• High power output – Enough to drive even low-efficiency speakers.
• Low distortion – Thanks to its ultra-linear push-pull design.
• Excellent detail retrieval – Captures subtle nuances in music.
• Wide soundstage – Great instrument separation and depth.
• Natural tonal balance – Retains the warmth and musicality of vacuum tubes.

Whether used with high-efficiency speakers or low-impedance speakers that demand more power, the TU-8888 delivers deep, controlled bass, rich mids, and extended highs with a dynamic and engaging presentation.

Doubling the output power with two TU-8888s

The output transformer of the TU-8888 has a dedicated NFB winding, which makes it possible to isolate the speaker output from the amplifier circuitry and chassis ground (GND). This enables TU-8888 to connect the outputs in series, which is not possible with ordinary amplifiers. By connecting the outputs in series, the maximum output power can be twice that of a single amplifier. To make series connections, there are several important considerations:

• The exact same signal (same phase, same level) should be input to both amplifiers.
• Use an output terminal with an impedance of 1/2 the impedance of the speaker you wish to use. For example, for 8Ω speaker, the 4Ω outputs of the amplifiers must be used. Also, the 8Ω outputs can be used for 16Ω speaker. An example connection for an 8Ω speaker is shown below.

  
  Is This Kit for You?

  If you love DIY projects and high-end audio, the TU-8888 offers an exceptional tube amplifier experience. It’s a versatile, powerful, and customizable amp that can bring out the best in your speakers and music collection.

  About EK Japan

  EK Japan, the manufacturer of the TU-8888 Monoblock PP Power Amp Kit, is a well-regarded Japanese company specializing in DIY electronics. Founded in 1973, EK Japan has built a strong reputation in the world of educational electronic kits, robotics, and, most notably, high-quality DIY audio amplifier kits under its Elekit brand.

  Elekit is particularly known among audiophiles and DIY enthusiasts for producing well-engineered tube amplifier kits that combine excellent sound quality with ease of assembly. Their designs are crafted to be both accessible to beginners and rewarding for experienced builders, often incorporating premium components like Lundahl transformers and allowing for tube rolling to customize the sound signature.

  Among Elekit’s most acclaimed amplifiers are the TU-8200, TU-8900 (a high-end 300B amplifier), and the TU-8550 preamp, all of which have received widespread praise in the audiophile community. These kits are designed with precision engineering to ensure low distortion, high performance, and a rich, dynamic sound.

  Elekit’s reputation extends beyond Japan, with a strong following in the U.S. and Europe. Many audio enthusiasts appreciate their products for offering performance that rivals far more expensive commercial tube amplifiers while maintaining the satisfaction of a DIY build. Their amplifier kits strike a balance between affordability and high-end sound, making them a favorite choice for those looking to experience the warmth and detail of tube amplification without breaking the bank.