Power · Beam power tetrode
KT66
British beam tetrode used in classic guitar and hi-fi amplifiers.
Base: Octal
- Specs not yet verified against a datasheet
- No replacement verified yet
Where to buy KT66
- ReverbNo affiliate relationshipSearch KT66 on ReverbOpens reverb.com search results
Online marketplace for new and used music gear, including vacuum tubes.
- Apos Audio isn't listed: its site search didn't return a KT66 when we checked on Nov 4, 2026.
Each button opens that retailer's own search for KT66. We don't see their prices or stock.
Before you buy, check that the listing names KT66. A listing that mentions another tube name isn't necessarily the same type. Affiliate disclosure
Specifications
Not yet verified
Electrical specifications are pending verification against a manufacturer datasheet. We don't publish numbers until they have a cited source.
Common uses
- guitar power amp
- hi-fi power amp
Replacing a KT66
A tube that fits the same socket is not automatically a safe replacement. Heater voltage, pin connections and electrical ratings must match what your amplifier is designed for. Check your amp's manual or a qualified technician.