Repair of Valve
Amplifiers
Marshall JCM · Fender Twin/Bassman · Vox AC30/AC15 · Mesa Boogie · Orange · Laney
Valve amplifiers are complex high-voltage electronics requiring knowledge of audio circuits and safe working at voltages up to 500V AC. We repair all key faults — from valve replacement to transformer repair. Quote 24h.
Diagnostics included in repair
No-obligation quote
12-month warranty
Courier pickup from all of Europe
Bias set after valve replacement
Valve amplifier service — repair scope
Valve selection and replacement
Replacement of power valves (EL34, 6L6, KT88, EL84, 6V6) and pre-amp valves (12AX7, 12AU7, ECC83). Bias measurement and adjustment after replacement. Valves matched in pairs or quads to amplifier requirements.
High-voltage power supplies
Repair of HV power supplies in valve amplifiers: replacement of electrolytic capacitors (100–500µF/450–500V), selenium/silicon rectifiers, bleeder resistors and filter chokes.
PCB printed circuit boards
Repair of amplifier PCBs — replacement of burnt resistors, aged capacitors, broken PCB traces. Diagnostics and repair of reverb circuits, tremolo effects and FX loops.
Power and output transformers
Assessment and repair of power transformers (winding shorts) and output transformers. Replacement with Heyboer, Mercury/ClassicTone/TT-Electronics equivalents for classic models.
Fuses and protection
Diagnostics of fuse blowing — finding the root cause (shorted valve, capacitor, transformer). Upgrading protection circuits (plate current protection).
Switches and potentiometers
Service of mechanical amplifier components — cleaning and replacement of potentiometers, channel switches, STANDBY switches, speaker terminal sockets and instrument inputs.
Report fault of valve amplifier — no-obligation quote
Provide the amplifier model and fault description. An EFIXLAB specialist will contact you with a diagnosis and quote.
Dziękujemy! Our specialist will contact you shortly.Frequently asked questions — Valve amplifiers
Most commonly yes — a blown power valve (particularly EL34/6L6) or an inter-segment short in the filter capacitor. Send the amplifier (without speaker) for diagnostics — we will find the cause and quote the repair.
Yes — valve circuits from the 1950s–70s are well documented. We repair while preserving original circuitry. We use capacitors and resistors in period-correct styles (for “vintage restore” commissions).
Yes — after replacing power valves the bias must be set. Each valve is different and the bias from the previous valves is not correct for new ones. Bias adjustment is included in the cost of valve replacement with us.
Tube Amplifier Repair — Vintage and Modern Valve Audio Electronics
Tube (valve) amplifiers — from vintage guitar amps (Fender, Marshall, Vox, Mesa Boogie) to high-end hi-fi amplifiers (McIntosh, Audio Research, Cary Audio) and studio equipment (Neve, Universal Audio) — use vacuum tube technology that produces distinctive harmonic characteristics prized by musicians, audiophiles, and recording engineers. These amplifiers combine high-voltage analog circuitry with precision output transformers and carefully designed signal paths. Professional repair requires understanding of both vintage electronic techniques and modern diagnostic capabilities.
Common tube amplifier failures include output tube degradation (the most common issue — tubes are wear items), output transformer failures (shorted windings, broken leads), power supply electrolytic capacitor aging, coupling capacitor leakage affecting bias and signal quality, resistor drift changing operating points, potentiometer and switch contact degradation, and tube socket pin corrosion. Vintage amplifiers often need comprehensive capacitor replacement due to age, while modern production amplifiers may develop PCB-related issues such as cold solder joints or trace failures.
EFIXLAB provides tube amplifier electronic repair with appropriate respect for vintage circuit design. Our service covers high-voltage power supply rebuild, output tube matching and bias adjustment, coupling and filter capacitor replacement with appropriate-specification components, output transformer testing and repair, signal path component restoration, and comprehensive audio testing. We use calibrated audio analyzers to verify distortion, frequency response, and noise performance after repair.
Tube amplifier repair preserves instruments with established musical character and often irreplaceable vintage components. Repair costs vary with amplifier complexity but are typically 15–40% of instrument value. For vintage amplifiers with collector value, professional repair preserves both musical performance and investment value. All amplifier repairs include audio performance verification and our 12-month warranty on electronic workmanship.