If you are a connoisseur of analogue audio, it’s probable you may have a turntable as well as a stack of records at house somewhere. If you are of a specific age you may even have a cassette deck, though you’re a lot more likely to have abandoned that style a long time in the 1990s. If you are old sufficient to have been around in the 1960s or 1970s though, you may have had one more analogue audio format. one of a number of that you may have discovered in a well-equipped house of that period was the 8-track stereo cartridge, a self-contained tape cassette style that in shape four stereo tracks onto a single quarter-inch tape loop as eight parallel tracks, four each of left as well as right. A victory of marketing, really, it must a lot more accurately have been called 4-track stereo.
An 8-track stereo cartridge. government & Heritage Library, specify library of NC (CC BY 2.0).
8-track cartridges were established from earlier tape cartridge formats, mainly to satisfy the demands of the automotive market for interchangeable in-car entertainment. therefore if you had an 8-track player it was a lot of likely to have been discovered in your car, however it was not uncommon to discover them likewise incorporated into house hi-fi systems. Thus we come to our subject today. Our retrotechtacular series normally highlights a video showing a bygone technology, however today we’re going to get a bit a lot more hands-on.
Some time in the early 1990s, I obtained an 8-track player, a BSR McDonald system produced in the UK as well as dating from the early 1970s. BSR were much a lot more widely known for their turntables, so this is something of an oddity. Where I discovered it has disappeared into the mists of time, however it was most likely at a radio rally or junk sale. I definitely didn’t get it since I desired it to play 8-track tapes, instead I desired a speaking point for my hi-fi, something quirky to set it besides everybody else’s. So every incarnation of listening pleasure chez List for the last quarter century has had an 8-track player nestling within it, even if it has never played a tape while in my ownership. Thus we have a special chance for this retro teardown.
The player itself is about half the size of a typical hi-fi unit, instead of the typical approximately a 19 inch rack size it’s about 9 inches (23 cm) large as well as 4.5 inches (11.5 cm) high. The outer situation is made of fibreboard covered in stick-on wood-effect vinyl as was the fashion of the day, as well as the front panel has the cartridge slot as well as track selector button. On the rear panel is an audio level manage as well as the cables, the audio output is given a DIN plug instead of the phonos we’d a lot more frequently discover today. There was a period in the 1970s when DIN connectors were where it was at when it pertained to audio.
Sticky belt debris still connected to everything.
Turning the system over, unscrewing the feet enables the cover to be slid off to expose the mechanism. A extremely solid sheet steel chassis is revealed, with a mains-powered shaded pole motor as well as a belt drive to a considerable cast aluminium flywheel on the pinch roller shaft. The motor is likewise the mains transformer for the electronics, a characteristic BSR cost-saving technique that you would likewise have discovered in record players of the period.
Immediately, an regrettable side-effect of an ancient piece of devices ended up being apparent, in the decades considering that this player was last utilized the drive belt has softened as well as relied on a sticky black tar-like substance. This is extremely typical in belts from the 1970s, I’m told it has something to make with exactly how well the rubber was cured. An interlude of picking, rubbing, as well as scraping with tissue paper ensued, together with my hands getting covered in black gunk before a trip to the sink for a date with some industrial hand cleaner.
Upon inspection the chassis is exposed to be in two parts held together with self-tapping screws. The front half is the 8-track mechanism, while the rear holds the motor as well as the circuit board. It’s possible that this is since the exact same fundamental system was utilized in a variety of BSR products, though the 8-track style didn’t truly take off in the UK it’s likely BSR would have offered this system to other makers in the exact same method they did for their turntables.
Turning the chassis over, together with the electronics as well as the motor, we see the service end of an 8-track player, the solenoid as well as system that enables it to modification tracks. There is a cam that is turned incrementally with four positions by a solenoid, this cam moves the head up as well as down between the tracks. There are two methods the solenoid can be triggered, either with pressing the selector button on the front of the unit, or by a piece of conductive foil at the joinof the tape loop passing a pair of electrical contacts to immediately modification tracks. To show the operation of the cam I’ve recorded a video in which the solenoid is actuated with a pair of tweezers as well as the cam can be seen rotating.
You can just about see by the shadow, the tape head on the left is lower than that on the right.
Meanwhile on the other side of the chassis, the head moves up or down by a corresponding amount. considering that the width of the tape is only 1/4″ there isn’t much movement, however you can see from the family member positions of the shadows of the head in the two photos exactly how it moves up between the different tracks. The head itself integrates two private heads, one for every channel, as you can see these are spaced about a half-tape-width apart.
The channel selector light switch
On the bottom of the shaft for the cam is a PCB switch with a wiper that traverses four pads, one for every track. This routes power to one of a set of four sign lights on the front panel that show the currently chosen track. The sign lights are not the LEDs we’d expect today, however small incandescent bulbs. An LED was most likely a bit as well exotic for the early 1970s.
Finally, the preamplifier circuit is a collection of early-1970s discrete elements on a normal resin-bonded-paper board of the era. The artwork has undoubtedly been laid out the old-fashioned method utilizing crepe paper on acetate, providing it extremely much a feeling of its era. considering that the system hasn’t seen power in lots of decades, it’s rather likely that its electrolytic capacitors will have deteriorated somewhat.
Vintage elements on the pre-amp board.
The perception I came away from this maker with was of exactly how complex it was while concurrently doing so little. The sheer number of private assemblies contained within it need to have made it rather an costly gadget to manufacture, all of which might have contributed to it not being a industrial success here in the UK where it didn’t have the backing of carmakers to put it in new designs in the method it did in the USA. It’ll go back into my hi-fi rack, as well as ultimately there will come a point at which people ask “What’s that?” rather than exclaiming with glee since my hi-fi consists of an 8-track player.
Inside an 8-track cartridge. Isis (GFDL).
Before we leave this topic there is a final thing to examine, the 8-track cartridges themselves. They contained a constant loop of tape wound onto a single one-sided reel, as well as considering that the tape therefore had to pass over itself as it fed from the centre of the reel they utilized special lubricated tape with a graphite backing. They might as a result only go forwards, no rewinding was possible. The pinch roller was incorporated into the cartridge, from where it would mate with the capstan in the player. the central opening was where the head satisfied the tape, as well as that on the left was where the contacts for the tape end foil sensor satisfied the tape.
In a sense the 8-track stereo cartridge was doomed from the moment it was launched, for its nemesis, the compact cassette, had already reached the market. The cassette used a lot more capability as well as the capability to rewind in a smaller package, as well as did not experience the 8-track’s issues with head positioning because of the motion on track changes. Over the 1970s the cassette won the battle of the tape cartridge formats, aided by far smaller players incorporated into vehicle radios as well as ultimately into the wildly successful Sony Walkman as well as similar portable music players. By the 1980s there were still major releases in the format, however by the end of the decade it had faded into history, only being revived as an ocasional gag in movies.
We’ll leave you with one more video, this time around an advert from a time when an 8-track player was a awesome accessory for your car. It’s a bittersweet one, for of program not only has the style passed into history, now likewise has the store selling it.