Ray Tubes SELECT KT88

New Old Stock KT88 has become scarce, and sets of it can be expensive to find and match. The SELECT KT88 is a new-production beam tetrode that Ray Tubes builds to its own audio specifications and keeps only when it ranks among the best of its batch.

The power tube you can buy new, matched, and warrantied.

The Design

SELECT takes the reliability and consistency of Ray Tubes' CORE line as its starting point and aims at one thing: more nuanced sound. Ray Tubes builds each tube with manufacturing partners to its own audio specifications, then sells only the best tubes from each batch; Ray Tubes says fewer than 5% of production meets its standard. Audio engineers with decades of experience take part in the selection from start to finish, including listening sessions in real-world conditions. The pins are gold-plated for corrosion resistance and improved conduction.

Every Ray Tubes tube passes a seven-step process in three phases. Phase one checks reliability: soldering inspection under a microscope and a 24-hour burn-in. Phase two measures critical parameters, matches tubes by current draw, and tests for microphonics. Phase three is an amplifier test with listening by Ray Tubes' sound engineers, plus targeted expert listening sessions on randomly chosen tubes. Measurements are recorded under each tube's serial number.

How It Sounds

Ray Tubes describes the SELECT KT88 as strong in the bass and high in resolution: solid, powerful, controlled low end; full, delicate mids with a warm, multilayered tone; clear, pure treble with rich detail; and a very wide dynamic range inside a wide, deep soundstage with accurate positioning. Tharbamar reviewed the SELECT KT88 together with the SELECT 12AX7 and 12AU7 and heard clear, precise sound with refinement across the range and a rich tube signature.

Where It Fits

The KT88 is a beam tetrode introduced in 1956 as a variant of the smaller KT66, named for the kinkless tetrode, and it has been popular in high-fidelity stereo systems ever since. Check your amplifier's manual for the tube type, then choose a single tube, a matched pair, or a matched quad for your output stage. Have your amplifier's bias checked whenever you change output tubes. Ray Tubes publishes a compatibility list, and we can check your amp with you. If you want to go further, the RESERVE KT88 is Ray Tubes' top version.

Warranty and Break-In

Ray Tubes' One Year Warranty covers manufacturing defects for twelve months, tied to the original invoice and the serial number on the box, so it transfers to a new owner. If one tube in a matched pair or quad fails, Ray Tubes replaces the whole set. Give new tubes 48 to 96 hours of use to break in; early quirks such as slight background noise or imbalance usually fade as hours accumulate. Each tube comes with a user handbook with burn-in guidelines and a certificate of authenticity and warranty.

Press Recognition

Ray Tubes' tubes have drawn reviews from Positive Feedback, Stereophile, and HiFi.nl, among them reviews of the RESERVE KT88 and of Select and Reserve tube sets. Reviews of the SELECT KT88 by itself are on the way. Read HiFi.nl's review of Ray Tubes

Wondering whether the SELECT KT88 suits your amplifier, or how many tubes you need? Give us a call. We'll check your amp's tube complement with you.

Specifications

• Tube type: KT88
• Socket: 8-pin
• Max anode dissipation: 42 W
• Max screen dissipation: 8 W
• Max anode plus screen dissipation: 46 W
• Max anode voltage: 800 V
• Max screen voltage: 600 V
• Max cathode current: 230 mA
• Heater: 6.3 V, 1.6 A
• Transconductance: 12 mA/V
• Amplification factor: 8
• Total height: 119 mm
• Pins: Gold-plated
• Availability: Single, matched pair, or matched quad
• Includes: User handbook with burn-in guidelines; certificate of authenticity and warranty
• Warranty: One year, transferable