Philips N4520

The Philips N4520 (including variants like N4520/00, often paired with the N4522 as its 2-track counterpart) is a late 1970s flagship professional-grade consumer stereo reel-to-reel tape recorder, produced approximately 1978–1983 (manufactured primarily in Austria by Philips Österreich). It was the pinnacle of Philips' open-reel lineup in the final years of the format's consumer prominence, designed to challenge high-end competitors like the Revox A700 series. The N4520 was marketed as a "home studio" or semi-professional deck with exceptional fidelity, massive build, and advanced features like quartz PLL capstan control, three-motor direct drive, glass-ferrite heads, variable bias, NAB/IEC equalization, and support for 10.5-inch NAB reels.

The N4520 is the 4-track (quarter-track) version, while the N4522 is the 2-track (half-track) variant (both at 38 cm/s max speed). This model represented Philips' last major push in open-reel before cassettes and digital fully took over.

Key Technical Specifications

• Recording/Playback System — 4-track (quarter-track), 2-channel stereo/mono compatible (N4522: 2-track); records and plays stereo on tracks 1-4 forward and 3-2 reverse (manual flip for second pair); mono compatible; sound-on-sound/multiplay overdub facilities; no auto-reverse.

• Tape Speeds — Three speeds:3¾ ips (9.5 cm/s)
  7½ ips (19 cm/s)
  15 ips (38 cm/s) (Professional speeds; 15 ips for maximum fidelity.)
  

• Reel Size — Up to 10.5 inches (26.5 cm) NAB hubs (large professional reels for extended playtime).

• Frequency Response (approximate, within tight tolerances; varies by tape/condition):At 15 ips: 30 Hz – 26,000 Hz
  At 7½ ips: 30 Hz – 22,000 Hz
  At 3¾ ips: ~30 Hz – 15,000–18,000 Hz Exceptional extension—among the widest in consumer/professional decks of the era.
  

• Wow & Flutter — 0.035% at 15 ips and 7½ ips (outstanding from quartz PLL servo and three-motor direct drive).

• Signal-to-Noise Ratio — 64 dB (DIN; often >60 dB with low-noise tape; very high for the time).

• Total Harmonic Distortion — <1%.

• Heads — 3 heads: separate record, playback, and erase (glass-ferrite construction for longevity and high-frequency performance).

• Drive System — Three motors (1 × quartz PLL servo capstan motor + 2 × direct-drive reel motors); electronic logic transport; variable spooling speed; hydraulic or electronic tape tension stabilizers; fast wind/rewind; precise braking.

• Electronics — Fully transistorized; printed circuit board amplifier; variable/stepless bias adjustment; NAB/IEC equalization switchable at 38 cm/s; electronic counter in some configs.

• Amplification & Speakers — Deck-focused with line-level preamp outputs (no built-in power amp/speakers in pure deck form; some integrated versions allow external amp drive).

• Inputs —Microphone: low-level (~0.2 mV).
  Line/radio/tuner/phono/aux: standard line level (~100 mV).
  DIN-style connectors (often with RCA options in export).
  

• Outputs —Line out: ~1 V / 50 kΩ.
  Headphones (monitor, 6.3 mm jack, 8–2000 Ω, ~40 mW at 600 Ω).
  Monitor output: 0–1 V adjustable / 11 kΩ.
  DIN-style.
  

• Features —Twin illuminated VU meters (needle type; active for record/playback).
  Electronic logic transport (push-button with smooth response).
  Variable bias and equalization.
  Input mixing/attenuators.
  4-digit electronic tape counter (in some).
  Off-tape monitoring (source/tape switch).
  Pause function.
  Optional DIN 5-pin remote control.
  Vertical/horizontal operation; massive "beast" chassis.
  

• Power — AC mains (110–120 V / 220–240 V switchable, multi-voltage); consumption 75 W.

• Build & Dimensions — Massive tabletop case (often wood/teak or black/silver); approx. 530–557 × 527 × 230 mm (20.8 × 20.7 × 9 inches); weight 25 kg (very heavy due to motors, heads, and chassis).

• Manufacturing — Primarily Austria (Philips Österreich).

Performance & Legacy Context

The N4520 was Philips' ultimate consumer/professional open-reel machine—renowned for its massive scale (10.5" reels look small on it), quartz PLL capstan precision (ultra-low wow/flutter), glass-ferrite heads (long life and HF extension), and wide 30 Hz–26 kHz response at 15 ips. It delivered outstanding clarity, dynamics, stereo imaging, and low noise—often described as "wonderful" or "professional-grade" in collector circles. Serviced examples frequently exceed factory specs and rival high-end Swiss/Japanese decks of the late 1970s.

Common issues today: Belt/idler goo (multiple belts need full kits), dried electrolytic capacitors, transistor aging, dirty heads (3-head alignment critical), worn idler tires/clutches, capstan motor (quartz PLL) faults, and electronic counter/logic issues. Restorations are challenging due to size/complexity but yield exceptional results. Service/user manuals available (HiFi Engine, Elektrotanya—full schematics, alignment, bias procedures).

Compared to siblings:

• N4522 — 2-track (half-track) version (same chassis but for higher fidelity per track).

• N4450 — Auto-reverse flagship with 6 heads but slower max speed (no 15 ips).

• N4506/N4512 — Earlier/predecessor high-end models with similar three-motor/3-head setup but less advanced (e.g., no quartz PLL or glass heads).