Grundig TK 247

The Grundig TK 247 (also known as TK247 de Luxe or TK 247 Deluxe Stereo) is a high-end solid-state open-reel (reel-to-reel) tape recorder produced by Grundig Radio-Vertrieb in Fürth, Germany. Manufactured primarily from 1967 to 1969 (with production peaking around 1968), it was a premium consumer stereo machine aimed at audiophiles and serious home users. It featured quarter-track stereo, two tape speeds, input mixing, sound-on-sound overdubbing, tone controls, and independent record/playback channels, making it one of Grundig's most advanced solid-state stereo recorders of the late 1960s.

The TK 247 was priced originally around 800–900 DM (a high-end consumer figure, equivalent to roughly £80–100 in export markets), positioning it as a flagship in Grundig's TK series. It gained strong collector interest for its clean, dynamic stereo sound, low noise, and versatile features, often praised as a "Hi-Fi" benchmark in Grundig's transistorized era.

Key Technical Specifications

Track System: 4-track (quarter-track), 2-channel stereo / monaural (stereo record/playback; monaural operation also supported; records on one quarter-track per pass, allowing four tracks total on standard tape by flipping reels twice)

• Tape Speeds: Two speeds — 9.5 cm/s (3¾ ips) and 19 cm/s (7½ ips); switch-selectable (higher speed for high-fidelity music, lower for extended runtime)

• Reel Size: Maximum 7 inches / 18 cm (standard for high-end domestic recorders of the era; supports NAB/international hubs)

• Heads: 2 heads — combined record/playback head + erase head (permalloy construction; no separate playback head or off-tape monitoring; quarter-track stereo design requires careful alignment for track compatibility)

• Motors: 1 motor (capstan drive; single-motor design with mechanical reel assistance; high-quality induction motor typical of late-1960s premium consumer machines)

• Drive System: Mechanical transport with push-button controls; constant tape speed; foil-sensing automatic stop at tape end; advanced tension regulation suitable for standard and thinner tapes; additional features include input mixing, sound-on-sound overdubbing (fade/mix), independent record/playback controls, tone control, and built-in twin amplifiers

• Frequency Response (all ±3 dB):40 Hz – 16,000 Hz at 7½ ips
  40 Hz – 12,000–13,000 Hz at 3¾ ips (very good for the era, especially at 7½ ips; meets high-fidelity standards with wide bandwidth and good extension)
  

• Signal-to-Noise Ratio: Better than 50–55 dB (weighted; excellent for mid-1960s/early-1970s consumer stereo, aided by low-noise solid-state circuitry)

• Wow & Flutter: Less than 0.1–0.15% at 7½ ips; less than 0.2% at 3¾ ips (outstanding for domestic use; among the lowest figures in Grundig's lineup)

• Equalization: IEC/CCIR/European standard for the period (some export versions note NARTB compatibility)

• Inputs:Microphone: Low-level (two inputs; dynamic mic via DIN or proprietary socket; often supplied external mics)
  Line/Radio: High-level via DIN connector (Grundig 5-pin standard)
  Phono/Grammophon: Additional high-level input for record players
  

• Outputs: Built-in loudspeakers (4 loudspeakers fed from twin 4-watt amplifiers for stereo dispersion); low-impedance ext. speaker; high-impedance line out (stereo preamp output for external amplifiers) via DIN socket; output power 2 × 4 watts (internal stereo amp)

• Power Supply: Alternating Current (AC) mains — 110; 130; 220; 240 V (multi-voltage taps for export); power consumption around 60–90 W; no battery option (mains-only domestic/portable hybrid)

• Dimensions: Approximately 430 × 190 × 340 mm / 16.9 × 7.5 × 13.4 inches (W × H × D) — compact suitcase/portable form factor with handle

• Weight: Approximately 12–14 kg / 26–31 lbs — substantial due to metal chassis, stereo components, and amplifiers

• Electronics: Fully solid-state (transistor-based; 21 transistors reported in some sources, including types like AD161/AD162 output pairs; no tubes, marking Grundig's shift to transistorization in hi-fi models; includes automatic/manual recording modes)

• Other Features: Recording level indicator (VU meter or glow type); mechanical tape counter; automatic tape-end stop; pause function; input mixing; sound-on-sound overdubbing; tone control; recording time up to 8 hours total (depending on speed, tape thickness, and track usage) on 7-inch reels with long-play tape

Design and Performance Notes

The TK 247 was a high-performance stereo recorder with a focus on versatility and hi-fi fidelity: quarter-track stereo allowed two stereo tracks (or four mono tracks by flipping), doubling capacity compared to half-track designs. Dual speeds provided flexibility—7½ ips for near-professional music fidelity (wide bandwidth, excellent transients), 3¾ ips for balanced domestic use. The solid-state electronics delivered clean, dynamic stereo sound with superior clarity and imaging—modern vintage ratings place it around 7–8/10 for sound (one of the finest stereo Grundig recorders of the late 1960s) and 7–8/10 for build reliability/durability.

The drive mechanism was robust and precise (1 motor, friction wheel/belt drive), with additional features like input mixing, sound-on-sound, and tone control enhancing creative use. Common long-term service needs include:

• Cleaning heads, capstan, pinch roller, and tape path

• Replacing rubber drive belts/idlers (common failure point in 1960s/1970s solid-state models)

• Replacing electrolytic capacitors (leakage common after 50+ years)

• Lubricating mechanisms

• Checking transistor stages and power supply

Historical Context

The TK 247 was part of Grundig's extended 1960s TK series that transitioned toward solid-state hi-fi models with stereo capability. It followed earlier mono machines like the TK 40–47 and preceded later multi-speed/stereo machines (TK 14x, TK 24x, etc.). Surviving examples are highly sought-after by collectors today, often prized for their outstanding audio performance and condition due to robust construction, but most require basic restoration (especially rubber drive components and capacitors) for reliable operation. They represent a high point in vintage solid-state open-reel collecting, especially for those interested in late-1960s German audio engineering and DIN-compliant quarter-track stereo designs with advanced features.