Grundig TK 28

The Grundig TK 28 (also known as TK28 or TK 28 in various markets, sometimes labeled TK 28 R for export versions) is a mid-1960s open-reel (reel-to-reel) tape recorder produced by Grundig Radio-Vertrieb in Fürth, Germany. Manufactured primarily from 1960 to around 1962–1963, it was a mid-range mono domestic machine aimed at home users, radio enthusiasts, and hobbyists seeking improved performance over entry-level models like the TK 20–TK 25 series.

The TK 28 was priced originally around 500–600 DM (equivalent to roughly £50–70 in export markets), positioning it as a premium mid-tier option in Grundig's TK lineup. It was valued for its dual-speed capability, push-button controls, superimposition (sound-on-sound overdubbing), input mixing, resettable tape counter, and enhanced audio quality, making it suitable for creative recording, radio dubbing, or home entertainment.

Key Technical Specifications

Track System: 2-track (half-track / full-track mono configuration), single-channel monaural (monaural record/playback; records on upper half of tape in one direction, lower half in reverse; some sources confirm full-track mono capability)

• Tape Speeds: Two speeds — 9.5 cm/s (3¾ ips) and 4.75 cm/s (1⅞ ips); front-panel switchable (lower speed for longer runtime, higher for improved fidelity and detail)

• Reel Size: Maximum 18 cm (7 inches); commonly used with 13–18 cm reels; supports standard NAB/international hubs

• Heads: 2 heads — combined record/playback head + erase head (permalloy construction; no separate playback head or off-tape monitoring)

• Motors: 1 motor (capstan drive; single-motor design with mechanical reel assistance; reliable induction-type motor typical of early-1960s consumer machines)

• Drive System: Mechanical transport with push-button controls; constant tape speed; foil-sensing automatic stop at tape end; basic tension regulation suitable for standard and thinner tapes; superimpose button for sound-on-sound (fade/mix overdubbing); input mixing capability

• Frequency Response: 60 Hz – 15 kHz (±3, –5 dB at 3¾ ips); 60 Hz – 8 kHz at 1⅞ ips (respectable for a dual-speed mono recorder of the era, with good clarity and extension for voice and music)

• Signal-to-Noise Ratio: ≈45–55 dB (typical; good for mid-1960s consumer mono, aided by quality circuitry)

• Wow & Flutter: ≈0.2–0.3% (at 9.5 cm/s; low and acceptable for domestic use; single-motor designs had tolerable variations)

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

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

• Outputs: Built-in loudspeaker (high-flux elliptical permanent-magnet dynamic type); line out via DIN socket; output power ≈2.5–4 watts

• Power Supply: Alternating Current (AC) mains — 110–240 V (multi-voltage taps for export); power consumption around 55–80 W; no battery option (mains-only domestic/portable hybrid)

• Dimensions: Approximately 380 × 200 × 340–380 mm / 15 × 7.9 × 13.4–15 inches (W × H × D) — compact suitcase/portable form factor with handle

• Weight: Around 10–12 kg (22–26 lbs) — portable yet substantial due to metal chassis, transformers, and tubes

• Electronics: Valve/tube-based (typically 7 tubes): 2× EF86 preamp (dual for channels or stages), ECC81 phase splitter/driver, EL84 output (push-pull), EM84 magic eye level indicator; metal rectifier for power supply

• Other Features: Magic eye (EM84) recording level indicator (glow for level monitoring); 3-digit resettable tape position indicator; superimpose button for sound-on-sound overdubbing; input mixing capability; automatic tape-end stop; pause function; recording time up to 4 hours total (depending on speed, tape thickness, and track usage) on 7-inch reels with long-play tape

Design and Performance Notes

The TK 28 was a refined mid-range domestic recorder with a focus on versatility and creative features: dual speeds provided flexibility—1⅞ ips for economical extended recording (speech/dictation) and 3¾ ips for better music fidelity. Push-button controls, superimposition (fade/mix for overdubbing), and input mixing made it user-friendly for creative applications. The tube circuitry delivered a warm, musical tone suitable for radio dubbing or home entertainment, with improved frequency response over earlier models—modern vintage ratings place it around 6–8/10 for sound (solid mono performer with nice dynamics) and 7–8/10 for build reliability/durability.

The drive mechanism was durable and straightforward, with minimal electronics complexity. Common long-term service needs include:

• Tube replacement/check (EF86 microphonics; EL84 output wear)

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

• Replacing electrolytic capacitors (leakage common after 60+ years)

• Lubricating mechanisms and checking drive belts/pulleys

• Magic eye alignment and rectifier checks

Historical Context

The TK 28 was part of Grundig's foundational 1950s–1960s TK series that popularized open-reel recording in Europe and export markets. It followed models like the TK 20–TK 25 and preceded later multi-speed/stereo machines (TK 14x, TK 24x, etc.). Surviving examples are collectible today, often in good cosmetic condition due to robust construction, but most require tube and capacitor restoration for reliable operation. They represent an accessible entry into vintage tube-era open-reel collecting, especially for those interested in early-1960s German audio engineering and dual-speed mono designs with creative overdubbing features.