Sony TC-666D (1969)
A four-head, three-motor autoreverse reel deck that Sony priced at "less than $575" — and that a reviewer called well worth it.
Overview
Forty-eight and a half pounds of satin-finished anodized aluminum sitting on a black lower deck, with a sliding plate that hides the microphone jacks and record buttons until you need them — the TC-666D is a machine that wants to look as composed as it sounds. It is a four-track stereo/mono reel-to-reel deck built around three motors and four tape heads, and it was the subject of an Audio equipment profile in February 1969 (p.40), where the magazine's test bench put real numbers to Sony's claims.
The headline convenience is autoreverse without foil. Owners did not have to apply metallic sensing tape at the end of a side; the deck's sensor circuitry watches for roughly ten seconds of silence, then trips the direction selector and sends the tape the other way. Audio (February 1969, p.42) walked through the sequence plainly: drop the reels on, thread the tape around both tension arms, set the direction selector forward, press play — and when the music finished and the tape ran silent, the machine reversed itself. Both record and playback work in either direction, in stereo or mono.
That reversal scheme depends on the four-head layout: forward erase, forward record/play, the capstan between them, then reverse record/play and reverse erase. Spooling is handled by torque motors while a reversible hysteresis-synchronous capstan motor sets tape speed, and the transport's pushbuttons throw microswitches that key relay circuits — which is why the controls have the solid, solenoid-actuated feel that Audio (February 1969, p.44) singled out for praise. The deck also carries a scrape flutter filter, a four-digit counter centered up top, and a dual VU meter that stays visible whether the sliding cover is open or shut.
The noise-reduction story is Sony's own "Sony-Matic Noise Reduction System," which the company said shaves 6 dB of tape noise on playback with a single switch. The usual objection to such systems — that they color the frequency response — did not show up on the bench. Audio (February 1969, p.44) reported identical response at 0, −10, −20, and −30 dB, and measured the deck's own numbers comfortably inside Sony's published limits: wow and flutter at 0.075% at 7½ ips and 0.14% at 3¾ ips, signal-to-noise of 54 dB without the SNR circuit and 59 dB with it engaged, channel separation better than 45 dB, and inter-channel crosstalk of 44 dB — the last a real concern on any four-track machine that gets recorded in both directions, as this one normally would be.
Sony rated frequency response at 20–22,000 Hz at 7½ ips and 20–15,000 Hz at 3¾ ips, with wow and flutter under 0.09% and 0.15% respectively, and total harmonic distortion under 1.5% at 0 dB line output. The input flexibility is genuinely broad: the AUX inputs accepted levels above 61 mV (typically around 250 mV in practice), while the microphone jacks took a minimum of just under 0.2 mV — enough to accommodate practically any microphone, high or low impedance. Audio (February 1969, p.44) confirmed that less than 0.1 mV into the mic jacks produced a 0-VU recording level, and that a 29 mV signal did the same at the AUX inputs, with 0.8 V appearing at the output jacks for a 0-level signal. Spooling a 1200-ft reel took 54 seconds in either direction.
One design decision worth flagging for anyone who has fought a VU meter that reads pre-emphasis rather than program level: the TC-666D drives its meter from a separate monitor transistor through a transformer, avoiding the recording equalization. Audio (February 1969, p.44) called that a definite advantage, and it is the kind of detail that separates a deck built for careful recordists from one built to a price. There is no playback volume control — the deck expects to feed a stereo system's amplifier, or a pair of low-impedance headphones through its dual-level headphone output. It can sit horizontally or stand vertically on the supplied reel caps.
The chassis carries 32 silicon transistors and 19 diodes, two fuse holders protecting the main supply and the transport separately, a switched AC receptacle, and a recessed rear panel with phono receptacles for AUX in and line out. Sony shipped it with a plastic dust shield, patch cords, an elaborate instruction book, and — to the reviewer's complete satisfaction — a schematic listing parts values and transistor types. Physically it measures 17¾6" wide by 8¾6" high by 16¾" deep and weighs 48½ lbs.
At under $575 in 1969, the TC-666D was not cheap, and Audio (February 1969, p.44) said so directly — then concluded it was well worth the price for the "fusspot" recordist who wants both high quality and automatic conveniences. That is about as clean a period verdict as this deck is likely to get. Collectors chasing one today should expect the usual reel-deck service items — belts, idlers, and a careful look at the relay logic that makes the autoreverse work — though the deck's build quality and the availability of its full service schematic work in its favor. It is a machine from the moment when Sony was building serious tape hardware and pricing it accordingly, and the measurements back up the ambition.
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