KT77 EL34 JJ Electronics Matched Quad – AMPLITREX Tested – New Production – Original Box
MADE IN SLOVAKIA
General Description
The KT77 is an octal beam power pentode, usable in the vast majority of amplifiers designed for EL34. Compared to EL34 and E34L, it offers greater available power, more authoritative bass, and superior headroom, while maintaining a high level of detail and balanced tonal rendition.
The KT77 JJ represents one of the most successful modern interpretations of this historic tube: a production designed to ensure reliability, electrical consistency, and high-level sonic performance.
The tubes are NEW, supplied in their original JJ box, and carefully selected and matched in our laboratory using AMPLITREX, to ensure stable, uniform, and repeatable operation within the amplifier.
An extremely popular choice as an advanced alternative to the EL34, the KT77 JJ retains its underlying musicality while adding control, extension, and authority.
Sonic Characteristics
The tonal character of the KT77 JJ is modern, balanced, and solid, with a consistent response across the entire audio spectrum.
Bass: Deep, controlled, and well-articulated. The low end is compact and fast, with a feeling of greater substance compared to a traditional EL34, also ideal for amplifiers with generous transformers.
Mids: Rich, present, and well-structured. Vocals sound natural and well-sculpted, with excellent intelligibility and without excessive coloration.
Highs: Open, orderly, and well-extended. The extreme high end is clean and detailed, never aggressive, suitable even for high-resolution systems.
Dynamics: Reactive and controlled. The KT77 JJ responds promptly to transients and conveys a sense of constantly managed power, proving versatile and musical across a wide variety of genres.
Soundstage: Wide and stable soundstage, with good depth and proper instrument separation. The image is focused and credible.
🎧 Use in Hi-Fi Amplifiers
Ideal for EL34 / KT77 compatible amplifiers, both in push-pull and single-ended configurations where provided. An excellent choice for those seeking greater control and definition, without sacrificing musicality.
🎸 Use in Musical Applications
Also highly appreciated in guitar amps, where they offer a firmer and more defined sound compared to the EL34, with superior headroom and a more compact and controlled low-frequency response.
🎯 Note for audiophiles and technicians
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factory new,
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tested and matched on AMPLITREX,
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supplied in original packaging,
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designed for those who desire modern reliability and a solid, balanced, and authoritative sonic performance.
An ideal quartet for upgrading or maintaining EL34-compatible amplifiers at the highest level, with the assurance of a professional Vacuum Tubes Treasures selection.
Test Specifications
Tubes tested on Amplitrex AT-1000 Tube Tester
Measurements taken after 10 minutes of warm-up
Additional tests performed:
• Microphonics: standard – compliant for use in hi-fi and musical instruments
• Emission: excellent – strong and stable emission
• Short circuits and GAS: absent
The quartet is matched exclusively on real static parameters, to ensure consistency, reliability, and symmetry between the two channels.
Conditions
• Supplied in original box
• Functionality: impeccable
• Factory new, tested, and perfectly working tubes
Warranty:
• Consumers: 24 months (Legislative Decree 206/2005)
• B2B: articles 1490 et seq. of the Civil Code apply
Additional information
JJ tubes may have slight differences in glass envelope height, with no impact on technical or sonic performance.
🔍 Find out what we really think: read our complete guide to the 6550 JJ.
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