Philips EL3520

The Philips EL3520 is a mid‑1950s, single‑speed, 2‑track mono reel‑to‑reel tape recorder designed as an improved, more compact successor to the EL3510, using the same basic transport concept but a revised electronics layout and drive system.

Era and General Design

• Introduced around 1957 and built by Philips Italy (Milano) for the European domestic market.​

• All‑valve (tube) recorder with four tubes, intended for home recording, speech, and casual music use rather than studio work.​

• Electronics are moved to the front chassis (unlike the EL3510’s “radio chassis” underneath), giving a flatter, more conventional appearance and easier servicing.​

Transport, Tape Format, and Performance

• Tape format: 2‑track mono on ¼‑inch tape (record/playback in one direction only).​

• Speed: single speed 9.5 cm/s (3¾ ips), chosen as a compromise between fidelity and tape economy.

• Maximum reel size: 5‑inch spools, consistent with Philips’ early domestic series.​

• Bias frequency: 45 kHz AC bias.​

• Mechanical refinement over EL3510: the original large figure‑8 spring belt is replaced by two smaller belts that can be changed without full strip‑down; a pulley under the left reel table now remains stationary in play/record, reducing flutter.​

Amplifier, I/O, and Loudspeaker

• Tubes: 4‑valve audio amplifier (exact complement varies by market, but Radiomuseum notes 4 tubes in total).​

• Output power: approximately 3 W to an internal elliptical permanent‑magnet loudspeaker.​

• Output load: 5 Ω rated speaker impedance.​

• Inputs and sensitivities (per front‑panel sockets): microphone 3 mV, radio 5 mV, pickup 200 mV; this reflects separate low‑level and line‑level paths.​

Power, Dimensions, and Weight

• Mains operation only, no battery option.

• AC supply selectable: 110 / 127 / 220 V, 50–60 Hz (multi‑voltage primary).​

• Power consumption: 45 W.

• Cabinet material: Bakelite or early plastic shell with metal chassis inside.​

• Dimensions (W×H×D): about 363 × 165 × 290 mm.

• Net weight: ~10 kg (about 22 lb).

Position in Philips Lineup

• The EL3520 continues the concept of the EL3510—simple one‑speed 2‑track mono—but with improved mechanics, more compact styling, and a more informative EM81 “magic‑eye” recording level indicator instead of the smaller DM70 used earlier.​

• It sits below later stereo, multi‑speed Philips decks of the early 1960s but is a representative example of Philips’ first affordable domestic tape recorders.