Philips Pro 12

The Philips Pro 12 (also known as Pro' 12, LDB0001 /01, or marketed as a semi-professional model) is a late 1960s semi-professional stereo reel-to-reel tape recorder, produced approximately 1968–1972 (primarily manufactured in Austria by Philips Österreich). It was the entry-level or "smallest/cheapest" model in Philips' professional tape recorder range at the time, designed for broadcast, studio, or serious amateur use rather than pure domestic consumer applications. It offered professional features like separate record and playback heads/amplifiers (for after-record monitoring, echo effects, and sound-on-sound), while remaining more affordable than higher-end Philips pro models (costing roughly 1/3 of the next model up).

This was a 2-track (half-track) stereo recorder (some sources confirm 2-track stereo configuration), with three heads and three motors for reliable, stable operation. It lacked features like auto-reverse or 15 ips speed but provided good value for semi-pro applications (e.g., small studios, education, or home mastering).

Key Technical Specifications

• Recording/Playback System — 2-track (half-track) stereo/mono compatible; records and plays stereo on tracks 1-2 forward (no reverse pair without manual flip); mono compatible; sound-on-sound/multiplay overdub facilities via separate heads/amplifiers; echo recording possible; no auto-reverse.

• Tape Speeds — Two speeds:3¾ ips (9.5 cm/s)
  7½ ips (19 cm/s)
  

• Reel Size — Up to 7 inches (18 cm) maximum diameter (cine-type reels; tape lengths up to 540 m or 720 m depending on thickness).

• Frequency Response (approximate, typical tolerances; varies by tape/condition):At 7½ ips: 40 Hz – 18,000 Hz (or similar hi-fi range)
  At 3¾ ips: 40 Hz – 15,000 Hz Respectable semi-pro performance at higher speeds.
  

• Wow & Flutter —At 7½ ips: <0.1%
  At 3¾ ips: <0.13% Good stability from three-motor drive.
  

• Signal-to-Noise Ratio — Approximately 50–55 dB (typical for semi-pro transistor era).

• Heads — 3 heads: separate record, playback, and erase (permalloy; enables before/after monitoring, echo, and multiplay).

• Drive System — Three motors (capstan + two reel motors); belt drive to capstan/flywheel; idler tires/clutches; mechanical brakes; fast wind/rewind.

• Electronics — Fully transistorized; printed circuit board amplifier; built-in control amplifier.

• Amplification & Speakers — Built-in stereo amplifiers; internal loudspeaker(s) (control amp with speaker: 500 mW); output power modest for monitoring.

• Inputs —2 × microphone: 1 mV, 50–200 Ω
  Phono 1/2: 150 mV, 1.5 MΩ
  Tuner: 2–40 mV, 20 kΩ
  DIN-style connectors.
  

• Outputs —Line-out: 0.775 V, 10 kΩ
  Headphones: max. 1 V, 400 Ω
  DIN-style.
  

• Features —Twin separate level meters (one per channel; active for record/playback).
  Before/after tape monitoring.
  Echo/multiplay effects.
  Pilot tone head (in some configs for synchronization).
  Pause function.
  Portable/semi-portable design with handle/metal case.
  

• Power — AC mains (110–120 V / 220–240 V switchable); consumption 80 W.

• Build & Dimensions — Metal case with handle (silver/metal finish); approx. 520 × 250 × 350 mm (20.5 × 9.8 × 13.8 inches); weight 23 kg (heavy and robust for semi-pro use).

• Manufacturing — Primarily Austria (Philips Österreich).

Performance & Legacy Context

The Pro 12 was well-engineered for its price—better than many equivalent British models (e.g., Brenell, Ferrograph)—with strong points like separate heads/amplifiers for monitoring/echo, dual meters, and three-motor stability. It excelled for semi-professional tasks (small studios, education, or advanced home use) at 7½ ips, delivering clear, balanced sound with good dynamics. It was not a full studio beast (no 15 ips or 10.5" NAB standard) but offered pro-like features at a fraction of the cost of Philips' higher pro line.

Common issues today: Belt/idler degradation (goo/melting—kits needed), dried electrolytic capacitors, transistor aging, dirty heads (3-head alignment critical), worn idler tires/clutches, and mechanical wear. Restorations are common—many units revive well for vintage semi-pro sound. Service/user manuals available (HiFi Engine, Elektrotanya—schematics and alignment; English versions exist but some are German).

Compared to siblings:

• Pro 36 — Similar semi-pro vertical model.

• N44xx/N45xx series — Later consumer hi-fi line (e.g., N4408/N4520) with more domestic features.

• Pro 12 — Entry semi-pro with 2-track, three heads/motors, and value focus.