Philips EL3566

Philips EL3566 Reel-to-Reel Tape Deck Technical Overview

The Philips EL3566 (including variants like EL3566/00, /20, or console-mounted versions) is a professional-grade reel-to-reel tape recorder introduced in 1963 and used through the late 1960s/early 1970s. Unlike the consumer-focused EL35xx series (e.g., EL355x models), the EL3566 was designed for broadcast, studio, and institutional use—famously employed by the BBC (often in console form for radio studios) and noted in historical contexts like Delia Derbyshire's work at the BBC Radiophonic Workshop, where customized versions were among the first high-quality machines for electronic music production.

This was a tube-based (valve) professional deck with high build quality, modular design (separate deck and preamp/amp units in some configs), and options for mono/stereo, half-track/full-track configurations.

Key Technical Specifications

• Recording/Playback System — Available in half-track (two-track) or full-track (monophonic); mono or stereo configurations (stereo often required separate preamps like EL3740); NAB or IEC equalization; remote control facilities (e.g., cueing, start/stop via BBC-style interfaces).

• Tape Speeds — Two professional speeds:7½ ips (19 cm/s)
  15 ips (38 cm/s) (No slower consumer speeds; optimized for broadcast fidelity and editing.)
  

• Reel Size — Up to 10.5 inches (26.5 cm) or 11 inches in some descriptions (NAB hubs standard; large capacity for long programs).

• Frequency Response (approximate, broadcast-grade claims; within tight tolerances):At 15 ips: 40 Hz – 15,000–18,000 Hz (or better; some sources note 40 Hz – 12 kHz at 7½ ips for related preamps).
  At 7½ ips: 40 Hz – 12,000–15,000 Hz. Excellent for the era—flat response suited to speech, music, and effects.
  

• Wow & Flutter — Very low: typically <0.1% or better at 15 ips (three-motor Papst drive ensured professional stability).

• Signal-to-Noise Ratio — Around 50–60 dB or higher (tube design but high-quality components; low hum in broadcast setups).

• Heads — 3-head configuration in many units (separate erase, record, playback heads for off-tape monitoring); permalloy or similar high-grade materials; configurable for half/full-track.

• Drive System — Three Papst hysteresis synchronous motors (capstan + separate supply/take-up); direct drive or high-precision belt/idler; solenoid brakes; fast wind/rewind at high speed; excellent tape handling and cueing.

• Electronics — Fully vacuum tube (11 tubes typical: EF86 ×4 for preamps, ECC82 ×3, EM84 magic eye level indicator, ECC83, ECC81, etc.); modular amplifier sections (often separate record/replay amps); high stability power supply.

• Amplification & Outputs — Professional line-level inputs/outputs (e.g., 600 Ω balanced or unbalanced); no built-in speakers (studio rack/console use); monitoring via external amp/headphones; magic eye (EM84) for levels.

• Inputs — Microphone/line (multiple, with mixing in some setups); DIN or XLR-style in broadcast configs; remote faders/cue facilities.

• Outputs — Line out (high level); cue/send; headphone monitoring.

• Features —Remote control (start, stop, cue, record safe).
  Tape monitoring (off-tape A/B comparison).
  Editing-friendly transport (precise braking, cue lever).
  Auto-stop or cue markers in broadcast versions.
  Rack-mountable or console-integrated (BBC used bench-mounted in studios like 3E).
  

• Power — AC mains (switchable voltages, e.g., 110–240 V); higher consumption due to tubes and motors.

• Build & Dimensions — Heavy professional chassis (often rack or console form); approx. large tabletop/rack size (deck + amp units); weight significant (20–30+ kg depending on config).

• Manufacturing — Eindhoven, Netherlands (Philips professional division); some customizations for broadcasters.

Performance & Legacy Context

The EL3566 was a true broadcast/studio workhorse—reliable, with excellent wow/flutter control, wide frequency response, and robust mechanics from the three Papst motors. It excelled in radio production, drama, music recording, and early electronic experimentation (e.g., Radiophonic Workshop). Unlike consumer EL35xx models (transistor/hybrid, slower speeds, smaller reels), this was Philips' pro-line equivalent to Studer, Telefunken, or EMI machines of the era.

Common issues today: Tube aging (EF86 preamps noisy if worn), capacitor drying, belt/motor lubrication needs, dirty heads, and mechanical wear on brakes/solenoïds. Restorations focus on recap, tube replacement, alignment, and cleaning. Service manuals/schematics exist (e.g., Radiomuseum.org has 17 schematics; BBC practical sheets detail operation; reel-reel.com lists specs).

Compared to consumer siblings:

• EL3556 (1965–68): Hybrid consumer, four speeds (up to 7½ ips), 7" reels, mono record/stereo play—home-oriented.

• EL3566 (1963+): Professional tube beast, 7½ & 15 ips, large reels, 3 motors—studio/broadcast quality.