Return to Part 1 of RECORD CHANGERS.
Advance to Part 3 of RECORD CHANGERS.
The advent of World War II in 1939 changed much of the record changer industry. Because of Roosevelt's embargo on trade to Japanese possessions, the record industry had to change the way they were making records. Shellac (used in 78-RPM records) was in short supply, so cheap binders were added to the material, and cardboard was sometimes embedded into the record. Also, the rims of the records, which had been rounded before, were now squared off. Most of the record changers produced before the war started breaking these records. The knives used to separate the records no longer fit between the (no longer rounded) rims, and instead chipped the edges of the records or broke them in half. The assembly line and Capehart changers also tended to break these records, and the RCA throwoff changers were the worst offenders, breaking most of the records they ejected. The changer manufacturers had a sudden panic, and searched for more gentle ways of handling records. At first, they tried removing one knife shelf and substituting a plain shelf in slicer changers. This helped only slightly. But the overall result was the general development of what was then called the "push-type" record changer. The first of these was the Garrard RC-6 on the previous page. In this kind of changer, the record stack is held up by a ledge on the spindle, and by one side platform. To drop a record, a lever or cam in either the side platform (Garrard - UK, and Utah-Detrola and Admiral - US) or in the spindle (General Instrument, Westinghouse, and Motorola - all US) pushes the bottom record to one side and off of the ledge and platform. An offset in the spindle or a latch holds the rest of the records back, so they don't drop. This device handled the records gentler than the knives used earlier did. Variations appeared where the entire side shelf (Webster - US, and the original Garrard RC-6), or the entire spindle (Philco - US) moved to drop the record. The Motorola, Silvertone, and later General Instruments (204 and 205) changers used a rotating cam in the spindle. The spindle cam changer is labeled "Spindle push and shelf" in the above diagram, except that the spindle had a rotating segment instead of a pusher blade (Diagram "Spindle B" shows a pusher blade). An example made by General Instruments appears below. But the earlier General Instruments 203 changer and the Galvin-Motorola B2RC had the first spindles with pusher blades. An interesting sidenote is that many users of the rotating spindle-cam-type changers damaged their records by not understanding that they had to turn the top of the spindle between the changing and the unloading positions. They put the records on in the unload position and they fell, breaking out the shellac around the center holes. The rotating cams also wore the edges of the center holes, beveling them. Since the pusher blades did not do this, most changer manufacturers eventually changed to pusher blades.
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Garrard RC-70 shelf-push changer Farnsworth-Panamuse P-2 double-push changer Farnsworth P-51 shelf-push changer Utah-Detrola shelf-push record changer |
General Instruments spindle cam 205 |
Webster-Chicago model 56 nodding-shelf changer |
Thorens CD-50 2-side changer |
RCA Magic Brain 2-side changer |
One disadvantage of the rim-push-type of changer was that record sizes could not be intermixed, because the shelf had to be adjusted for the size of the records. Webster (US), Garrard (UK), Thorens (Switzerland) and Zenith (US) made push-type mixer changers, but they were ungainly, and were easily damaged because the spindle had a very pronounced S-bend in it. Another more rugged mixer changer was made by Dual (Germany), which used a balancing disk (a forerunner of the overarm). All of these mixer changers except the Thorens use the shelf to push off the record to be dropped, and all shut themselves off after the last record. The Thorens had a pusher in the spindle that was actuated through the strange overarm that did not touch the stack, and its spindle was removed to remove the records, and for single play. V-M had a spindle cam changer with a shelf adjustable for 10" or 12", and a drop feeler. Sparton sold it under its own name. If the shelf was placed in the 12" position, and the first and last records were 12", it could intermix 10" and 12" records. But it then repeated that last 12" record as 10", spoiling an otherwise good design. The Lear PC 206A worked about the same way as the Sparton, but it shut off after the last record. The Collaro (UK) RC-1 push-type mixer changer also had a forerunner of the modern overarm. The entire crossarm hinges up to the rear for loading, taking with it the top half of the spindle. The records are loaded on the half of the spindle that goes up with the crossarm. This changer has the pusher in the spindle, actuated through the crossarm. It shut off after the last record. The spindles also underwent some changes during this time. The Garrard and Dual changers required that the spindle be removed before the record stack could be removed. Other manufacturers had fixed spindles, and used a sliding or revolving latch to hold the second record back (so it didn't drop too). Notice the hinged (instead of sliding) record latch (or guide) on the Zenith spindle. It swings one way to hold the stacked records in place, and the other way so they can be removed from the turntable easily. Another disadvantage of the drop-type changers (but not most mixer changers) that was not seen in earlier designs was that the last record repeated over and over, unless an extra mechanism was added to shut off the changer. So more research and development was needed. One item that was noticed early in development was that the shutoff had to be delayed from the time the spindle became empty, so that the last record would play. But all manufacture of this sort was commandeered by government for the war, so the designers went ahead and dreamed up new devices, and waited for the war to end so they could try them out on the public. After the war, the budget changers often repeated the last record, while the more expensive ones shut off after the last record. The early automatic shutoff methods were often different from the method used on all changers since the mid 1950s. The Zenith units turned off the power when the velocity trip actuated on the last record, instead of starting a change cycle. So the arm was left at the end of the last record. V-M changers with auto shutoff returned the arm to the beginning of the last record (mixer changers returned it to the 10" position no matter which size was last) and just turned off the motor. Garrard stopped the cam in the middle of the cycle for shutoff, and some of the Webster units returned the arm to its rest, but did not shut off the power. |
Zenith Cobra-Matic mixer changer had a unique
Dual 1000, from the 1940s |
Webster-Chicago model 70 mixer changer with velocity trip |
Collaro mixer changer RC-1 |
Garrard RC-60 mixer changer |
Thorens CD-40 mixer changer |
For two years after the war ended, the record changer industry got back on its feet. By now, the industry had discovered that a mixer changer generally has to feel each record while it is dropping from the stack. The sensor on the Zenith Cobra-Matic (above) is easy to find -- it's red. It moves toward the spindle at the beginning of the change cycle, and if a 12" record drops, it strikes the sensor and moves it away from the spindle. Near the end of the change cycle, the sensor moves away from the spindle, so the user can remove a 12" record from the turntable if needed. As record dropping methods improved, mixer changers became easier to make:
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VM 400C mixer changer with overarm 1949 Perpetuum-Ebner spiral changer Farnsworth-Capehart P72 Gravity Record Changer |
Markel Duo-Playmaster 70 playing bottom side of a record |
GE - Milwaukee-Erwood P6 |
Then a bomb dropped on the industry! In 1948, Columbia (US) introduced a new Long-Playing Record (LP) that rotated at 33 1/3 RPM, and had a new groove size about 1/4 the size of the 78 groove. The tracking force had to be much lower too, or the record would be ruined. Suddenly the changer manufacturers had to scramble again. They had to get something on the market to take the LP record too, or lose sales to their competition. The first results were turntables that rotated at either speed, with an automatic changer for 78s, and a separate manual arm for playing LP records.
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Milwaukee-Erwood 2-speed record changer Zenith Twin Cobra 2-speed changer |
V-M 800 D changed either 78- or 33-RPM records |
V-M 403 changed 78- or 33-RPM records,
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More fallout from the introduction of the LP came because the methods of tripping the record changer were found to be wanting at the lighter tracking forces needed for the smaller grooves. Here is some info on that:
By the end of 1948, most US changer manufacturers had models that could change either 33 or 78 records. But most European companies, including Garrard, hadn't even added 33 yet when the next innovation was announced. |
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Just when it seemed that nothing could make things worse, RCA dropped another bomb (a big one) on the industry with the 45. This record had a new speed (45 RPM), a new size (7" or 17 cm), no eccentric groove at the end, and a different center-hole size (1.5" or 3.8 cm). (Well, at least the groove size was the same as the LP.) PANIC!
With this new record came a new changer with a fat center spindle and a spindle-slicer dropping mechanism (RCA just would not drop the knife-type changer - but did design the record so the knives wouldn't damage it). This changer is shown to the right. The changer repeated the last record until it was stopped manually. All of the little 45-RPM changers used position trip, except the Webster one with velocity trip. And all repeated the last record, except the Webster models and the V-M 1500.
RCA actually developed the "45" system in 1939, but had shelved it because of the war. RCA had used "Vitrolac" (vinyl) recordings before as radio transcriptions (1932 on), but they rarely lasted longer than 7 plays, because nobody had developed a pickup that could track the records without destroying them. But it seems likely that when Columbia solved the problem of the lighter tracking pickup, it opened the door for RCA to make the 45. The 45 was designed to be thicker in the label area than it is in either the recorded area or the ring around the edge of the center hole. This kept the grooves of the records from touching each other, and provided a space for the record changing knives in the spindle to fit between the records without damaging them. Not to be outdone, Columbia introduced the 7" 33 for singles. V-M made them a changer that took all 3 sizes, but ran at only 33 RPM (see below). Webster-Chicago sold little coil springs that could be placed on the 33-RPM motor steps of their 2-speed changers so the platter could be made to rotate at 45 RPM. The user had to take the turntable off to add the spring for 45, or to take it off for 33. Manual play was needed for the 45s here, because the changer didn't have any automatic index for 7" records. Now the industry had to completely redesign for these new records. Some of the wackiest record changers I ever saw came out of this period, most of them being sold in only the years 1949 and 1950. (Not to mention some of the wackiest albums too, with RCA releasing classical albums on 45 - irking when you consider that all early 45 changers repeated the last record again and again.) |
A 45-RPM changer - RCA RP-168 WHY 45? Les Paul actually gave us the 45 rpm speed by accident. He ordered a record cutting lathe from a machinist. The specifications included 78 rpm, the 33 transcription record speed, and "another speed somewhere in the middle" The resulting design made it 45 rpm. Les Paul used it to record his sped-up guitar effects. A record lathe company bought the rights to his lathe and manufactured it for studios - 45 speed and all. RCA bought some. |
The first 3-speed changerWebster had the first changer that could change records at all 3 speeds and for all 3 sizes - but using only one kind of record at a time. It looked very much like the 2-speed model they came out with the previous year, with a small box of toys included. But you had to be an expert at mechanical devices to use it. You had to take the turntable off to change the "slow" position on the speed knob to be either 33 or 45 by putting the little spring on the motor shaft or taking it off (at least they provided a little stud to store it on). Then you turned the rest post to set the record size, either for 7", or for 10" and 12" records. In the 7" position, the pickup arm's rest position was closer to the spindle, so the auto shutoff didn't work and the changer repeated the last record (7" records were not heavy enough to work the spindle-weight auto shutoff anyway). If you were playing a 7" record, you had to clip an extension onto the nodding shelf (in the 10" position) so it could reach a 7" record. Otherwise, you rotated the shelf for 10" or 12" records. If a large-hole 45 was used, an adaptor ring (called a "spider") had to be snapped into the hole so the regular spindle could drop it. And the 7" shelf extension had to be adjusted for the different thicknesses of 7" 33 and 7" 45 records. The second production run of 356 had a 3-speed drive for the turntable, so it was no longer necessary to take off the turntable to change speed. A second-run Webster 356 is shown to the right, set up for 7" 45. Webster also made a conversion kit to make a 256 into a first-run 356. It included the motor shaft spring, a replacement rest post, the shelf extension, and a replacement arm raising disk. |
First 3-speed changer |
More early 3-speed changers
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RC 500 - Admiral's first 3-speed, set to 12" RC 550 - Admiral's second 3-speed, set to 7" |
Zenith's Twin-7 |
RCA console with two changers |
WHAT A MESS!This chaotic state of affairs caused one hi-fi equipment reviewer to speculate that nobody would ever produce a satisfactory record changer that could handle all speeds and sizes. But little did he know how soon he would be proven wrong. |
V-M 406 Tri-O-Speed Admiral version of |
Advance to Part 3 of RECORD CHANGERS.
Return to Part 1 of RECORD CHANGERS.
Special Record Changer Lists and Links
LINKS
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