KT88 Genalex Quad Gold Lion Röhren BTB matched Quartett

Genalex Gold Lion KT88 – BTB-matched quad for stereo and parallel push-pull amplifiers

This set contains four current-production Genalex Gold Lion KT88 beam power tetrodes. Each valve uses an eight-pin octal base, a nominal 6.3 V heater and carries a maximum plate-dissipation rating of 42 W.

BTB matches all four valves as one quad at a practical plate voltage of 500 V. The set is suitable for compatible stereo push-pull amplifiers using one pair per channel or correctly designed parallel push-pull stages.

Suitable applications

• Stereo push-pull output stages using two KT88 valves per channel
• Mono parallel push-pull stages using two KT88 valves per push-pull half
• Complete replacement of an existing four-valve KT88 set
• Hi-fi power amplifiers whose manufacturer explicitly specifies four KT88 valves
• New builds with adequately rated heater, high-voltage and bias supplies
• Professionally verified conversion of compatible four-valve 6550 stages

BTB matching and package contents

Package contents

Four Genalex Gold Lion KT88 valves

Selection type

BTB-matched quad

Matching plate voltage

A practical 500 V unless the particular product states otherwise

Test system

Roetest V11, current as of 2026

Parameters considered

Plate current, transconductance, grid currents, plate resistance and acoustic checks

Advantage over two individual pairs

All four valves are selected as one coordinated set

Technical data per valve

Valve type

Beam power tetrode

Base

Eight-pin octal K8A

Heater voltage

6.3 V nominal

Heater current

1.5 to 1.7 A

Total heater current for the quad

6.0 to 6.8 A

Plate current at the data-sheet test point

75 to 125 mA

Screen-grid current at the data-sheet test point

2 to 9.5 mA

Transconductance at the data-sheet test point

8.2 mA/V minimum

Maximum plate dissipation

42 W

Maximum screen-grid dissipation

6.6 W

Maximum cathode current

230 mA

Dimensions

Approximately 117 mm overall height and about 52 mm envelope diameter

Country of origin

Russia according to current BTB and manufacturer information

Four valves in stereo or parallel push-pull circuits

Stereo push-pull

One matched KT88 pair operates in each channel; channel bias and symmetry must still be checked

Parallel push-pull

Two valves operate in parallel in each push-pull half; the output transformer, control-grid stoppers, screen-grid stoppers and current sharing must be designed accordingly

Two independently matched pairs

These can operate correctly but do not automatically form one selected four-valve group

BTB-matched quad

All four valves are assembled together using the same selection procedure

Selection and application notes

The quad can require up to 6.8 A of heater current. The power transformer, fuses, wiring, connectors and sockets must provide this current in addition to all preamplifier and driver heater loads.

Matching does not replace channel-by-channel or valve-by-valve bias adjustment. Where multiple measurement or adjustment points are provided, check every valve or pair separately.

Parallel-operated valves require symmetrical wiring and individual control-grid and normally individual screen-grid stopper resistors. The output transformer must suit the valve count and intended plate-to-plate load.

The substantial plate and heater dissipation requires adequate valve spacing, airflow and heat-resistant sockets. High-voltage servicing requires suitable expertise.

Questions about selection and use

Is the Genalex Gold Lion KT88 BTB-matched quad suitable for a stereo push-pull amplifier?

Yes, the Genalex Gold Lion KT88 BTB-matched quad is suitable for compatible stereo push-pull amplifiers using one KT88 pair per channel. The heater supply, channel bias, output transformers, screen-grid circuits and cooling must suit the amplifier.

Can the KT88 quad be used instead of two independently matched pairs?

Yes, the KT88 quad can replace two individual pairs and is normally the more appropriate choice for a four-valve stage because all four valves are selected together. Channel-by-channel or valve-by-valve bias verification remains necessary.

Is the KT88 quad suitable for a correctly designed parallel push-pull stage?

Yes, the KT88 quad is suitable for a correctly designed parallel push-pull stage when two valves are used in each push-pull half and the output transformer, heater supply, grid circuits and current sharing are designed accordingly.