Grundig TK 248

The Grundig TK 248 (also marketed as TK 248 Hi-Fi or TK 248 de Luxe Stereo in various markets) is a high-end solid-state open-reel (reel-to-reel) tape recorder produced by Grundig Radio-Vertrieb in Fürth, Germany. Manufactured primarily from 1968 to 1971 (peak production around 1969–1970), it was one of Grundig's flagship consumer stereo models of the late 1960s/early 1970s, aimed at audiophiles and serious home users. It featured quarter-track stereo, three heads, two tape speeds, input mixing, sound-on-sound overdubbing, tone controls, and independent record/playback channels, delivering true hi-fi performance meeting DIN 45500 standards.

The TK 248 was priced originally around 900–1,100 DM (a high-end consumer figure, equivalent to roughly £90–120 in export markets), positioning it as a top-tier model in Grundig's TK series. It earned legendary status among vintage collectors for its clean, dynamic stereo sound, low noise, low wow & flutter, and versatility, often considered one of the finest solid-state stereo Grundig recorders before the brand shifted to cassette dominance in the mid-1970s.

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: 3 heads — separate erase, record, and playback (permalloy construction; allows real-time off-tape monitoring during recording, a significant hi-fi advantage over 2-head designs)

• Motors: 1 motor (capstan drive; single-motor design with mechanical reel assistance; high-quality induction motor typical of late-1960s/early-1970s 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 controls, and built-in twin amplifiers

• Frequency Response (all ±3 dB):30 Hz – 18 kHz at 7½ ips
  30 Hz – 13 kHz at 3¾ ips (excellent for the era, especially at 7½ ips; meets DIN 45500 hi-fi standards with wide bandwidth and good extension)
  

• Signal-to-Noise Ratio: Better than 55–60 dB (weighted; excellent for late-1960s consumer stereo, aided by separate playback head and low-noise solid-state circuitry)

• Wow & Flutter: Less than 0.07–0.12% at 7½ ips; less than 0.15% at 3¾ ips (outstanding for domestic use; among the lowest figures in Grundig's lineup, thanks to precise drive)

• 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 4–5 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 × 4–5 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; typically 21–25 transistors, including output pairs like AD161/AD162; no tubes, marking Grundig's shift to transistorization in hi-fi models; includes automatic/manual recording modes)

• Other Features: Recording level indicator (VU meters 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 247/248 series represented Grundig's push toward solid-state hi-fi: 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 three-head design enabled real-time off-tape monitoring during recording, a significant upgrade over 2-head models. 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 247/248 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.