Grundig TK145
A four-track reel-to-reel built around a single rotary control and an automatic gain circuit Grundig called the "Magic Ear."
Overview
The TK145 shows how it thinks the moment your hand finds the main control. Instead of the usual piano-key cluster, Grundig fitted what it called the Easy G Control - a rotary knob that steps through the transport functions in sequence. From stop, one click anticlockwise gives fast rewind. One click clockwise gives pause, a further click starts normal 9.5 cm/s transport, and a final push through a momentary stop reaches fast forward. Studio Sound (August 1968, p.38) walked through the arrangement in its equipment review and found it simple enough once the sequence was understood. The logic is idiosyncratic, though, and new owners will want the manual nearby for the first week.
Recording level is handled automatically by the "Magic Ear" AGC circuit. Grundig's own advertising claimed it acts with split-second precision and preserves natural loudness variations without distortion. The record button is spring-loaded into the automatic-music position. Turn it against a weak spring and you get a speech setting with a shorter time constant, or turn it clockwise for full manual control. The music setting recovers slowly, the speech setting quickly, and manual mode hands everything to the operator.
The transport is a four-track, single-speed design running at 9.5 cm/s with a 14.5 cm spool capacity. Grundig's advertising quoted a frequency response up to 12,500 Hz, wow and flutter below ±0.2%, and a signal-to-noise ratio of 48 dB. The manufacturer's specification sheet in Studio Sound (August 1968, p.38) listed a 40 Hz-12 kHz range and a 50 dB S/N figure. The magazine's own bench work told a more nuanced story. Record/replay response to the line output stayed within ±2 dB from 45 Hz to 12 kHz. Unweighted signal-to-noise after erasing a peak-level 500 Hz signal came in at 45 dB, with erased tape hiss measuring 51 dB below peak recording level through a 250 Hz high-pass filter. Third-harmonic distortion on the manual setting at 500 Hz measured 3.5% at 12 dB above reference tape level. Readings of 3% and 3.2% at 1 kHz and 3 kHz were flagged by the reviewer as slightly suspect, because high-frequency flutter made accurate measurement difficult. The overall acoustic response, plotted from third-octave noise bands measured a foot off the speaker axis, held smoothly across 200 Hz-12 kHz, a respectable showing for a domestic four-track at this speed.
A four-digit tape position indicator is driven from the take-up spool carrier and clocks up seven digits for every ten turns of the reel, with a press-button reset on the de luxe version. The main panel carries a pair of edge-type volume and tone controls, and the track selector buttons live on the head cover. Connectivity covers recording/playback sockets, a monitor headphone jack, and a switchable extension loudspeaker output. Synchronised recordings are possible using the optional Monitoring Amplifier MA2 and Earphones type SE3, both sold as extras. Grundig also made much of the single-unit combination of motor and mains transformer, intended to keep the machine cool over long recording and playback sessions.
The machine measures 39 x 29 x 18 cm and weighs 19 lb. Grundig's advertising described an "uncrushable" steel chassis finished in teak with a Silver G-line grille, and the de luxe package shipped with 1,200 ft of tape and a dynamic microphone. Pricing moved around during the model's run. Studio Sound (March 1968, p.8) advertised the TK145 de luxe at 46 guineas, and the August 1968 specification sheet listed £53 11s including purchase tax. Street pricing and list pricing rarely agreed even then.
Studio Sound (October 1968, p.22) followed up its August review with a servicing look at the machine. It treated the TK145 as the most complicated of the family and used its circuit as the reference point for the auto/manual arrangement shared across the range. Collectors should expect the usual age-related work on a machine of this vintage - belts, idlers, and capacitor replacement. The AGC circuit's long music-setting recovery time means a unit with a tired capacitor network may behave noticeably differently from the published figures. The rotary transport control is a distinctive piece of Grundig design, but it is also a single point of failure. A stiff or worn mechanism turns a clever idea into a frustrating one.
Against the other four-track decks of the period, the TK145's appeal is the automatic recording system and the compact footprint rather than outright tape performance. At 9.5 cm/s with a 14.5 cm spool limit it is a domestic machine, not a studio one, and the wow-and-flutter figure of below ±0.2% per Grundig is honest about that. It offers a three-mode AGC and a solid steel chassis.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.