Philips EL3575

The Philips EL3575 (including variants like EL3575A /00, /19, or rebranded as Maestro 44 in some markets, RK57S in others, or export names like Continental series) is a late 1960s consumer reel-to-reel tape recorder, produced approximately 1966/1967–1971. It belongs to Philips' EL35xx series and represents a mature hybrid electronics design (transistors in preamp stages for low noise + vacuum tubes in output/power amplification for characteristic warmth). This transitional approach was common in mid-to-late 1960s Philips consumer decks before full solid-state dominance in the N-series.

It was a four-track (quarter-track) stereo-capable machine: mono recording on selected tracks (forward/reverse) with stereo playback when connected to an external stereo amplifier (or via built-in stereo amplification and dual speakers for self-contained listening). It included three speeds, 7" reel support, built-in speakers (one in cabinet, one in lid), and features like duoplay/multiplay overdubbing (limited track bouncing), making it suitable for home hi-fi music recording, radio dubbing, and family use.

Key Technical Specifications

• Recording/Playback System — Four-track (quarter-track); mono recording (tracks 1 or 4 forward, 3 or 2 reverse via tape flip/switch); stereo playback (built-in or external amp); duoplay/multiplay overdub facilities (basic bounce with external preamp assistance in some setups).

• Tape Speeds — Three speeds:1⅞ ips (4.75 cm/s)
  3¾ ips (9.5 cm/s)
  7½ ips (19 cm/s) (No ultra-slow 15/16 ips like some four-speed siblings; balanced for music fidelity at 7½ ips and longer recordings at slower speeds.)
  

• Reel Size — Up to 7 inches (18 cm) maximum diameter (standard, LP, DP, TP tapes supported).

• Frequency Response (approximate, within ~±3 dB or typical tolerances; varies by tape/condition):At 7½ ips: 40 Hz – 18,000 Hz
  At 3¾ ips: ~50–15,000 Hz (realistic)
  At 1⅞ ips: ~60–10,000 Hz Good consumer-grade extension, especially at higher speeds for the hybrid design.
  

• Wow & Flutter — Around 0.2–0.3% at 7½ ips (smooth single-motor belt/idler system when belts are fresh).

• Signal-to-Noise Ratio — Approximately 45–50 dB (transistor pre-stages help reduce input noise/hum over pure-tube designs).

• Heads — 2 heads: combined record/playback (permalloy) + erase head; quarter-track stereo configuration.

• Drive System — Single asynchronous motor; belt drive to capstan/flywheel (main belt common failure—~34.2 cm circumference, 3 mm round section in related models); idler tires; mechanical brakes; fast wind/rewind (e.g., <180 seconds for 1800 ft).

• Electronics — Hybrid: Germanium transistors in preamp/input stages + vacuum tubes in output (typically 3 tubes, e.g., ECL82 series for power) + EM87 (or similar) magic eye recording level indicator; printed circuit boards.

• Amplification & Speakers — Built-in stereo-capable amplifiers; dual internal loudspeakers (e.g., 7" × 5" elliptical in case + 4" round in lid); output power ~2.5 watts per channel (across 3–7 ohms); tone controls.

• Inputs —Microphone: ~0.25 mV / 2 kΩ
  Radio/diode/line: ~2 mV / 20 kΩ
  Phono: ~200 mV / 500 kΩ
  DIN-style connectors typical.
  

• Outputs —Radio/diode/line: ~1 V / 50 kΩ
  External speaker: 2.5 W / 3–7 ohms
  Headphones: 0–1.5 V / 1.5 kΩ
  DIN-style.
  

• Features —Track/direction selector.
  Recording level/mixing controls.
  Magic eye indicator.
  Pause, fast wind/rewind, auto-stop at tape end (some modes).
  Monitoring while recording.
  Portable/tabletop with lid and carry handle.
  

• Power — AC mains (110/127/220/245 V switchable, multi-voltage); consumption ~60–80 W.

• Build & Dimensions — Tabletop case (often wood/teak finish in export); approx. 444.5 × 336.5 × 216 mm (17.5 × 13.25 × 8.5 inches) or close (some list 440 × 215 × 340 mm); weight ~28 lb (12.7 kg).

• Manufacturing — Primarily Netherlands (Eindhoven) or Austria (Philips Österreich facilities).

Performance & Legacy Context

The EL3575 was marketed as one of Philips' more advanced consumer models in the late 1960s, with attractive styling, built-in stereo speakers, and solid performance at 7½ ips for home music/radio use. It offered better fidelity and features than earlier two-speed mono-focused decks (e.g., EL3553) while being less complex than four-speed variants (e.g., EL3556/EL3576). The hybrid electronics provided a pleasing tube-like warmth with transistor reliability advantages.

Compared to close siblings:

• EL3555 (mid-1960s): Similar hybrid, three speeds, stereo playback emphasis.

• EL3556 (1965–68): Four speeds (added 15/16 ips), hybrid, similar build but more versatile for dictation.

• EL3575 refined the three-speed stereo-capable layout with updated cosmetics and refinements (often called a "facelift" in some descriptions).

Common issues today: Belt hardening/slipping (main drive belt critical—kits for EL3575A often compatible), dried electrolytic capacitors, tube aging (output stages/magic eye), germanium transistor leakage, dirty heads, and mechanical wear. Restorations (belts, recap, alignment) are common and effective. Service manuals/schematics available (HiFi Engine, Elektrotanya, Radiomuseum.org—multiple versions including Maestro 44).