Magnavox is weird. I have a model 3B phonograph made by Magnavox. It is actually gutted, sadly. All that is left is a very interesting circut diagram that uses 57, 2A3, and 80 tubes. With the grids drawn in zig-zag form, and the plates drawn as actual plates, and furthermore using 2.5 volt tubes with the very old 4 and 6 pin bases, one would think that this amplifier is from the early 1930s. Strangely enough, the volume control is also two units linked together. The first section is merely variable resistance in series with the pick-up. After some filter condensor and resistor networks--for tone purposes, it goes to the second section, which is wired in the traditional potentiometer way (all three legs are used). One would think that with audio taper controls available, Magnavox would simply use one of these, but Magnavox decided to do something more elaborate and quite interesting. The diagram is microscopic, though, and hard to read. Well, I decided to build this slightly odd amp., and so with a magnifying lense, I drew up a larger diagram. I might add that it is a fine sounding amp., with sound of unbelievably smooth quality. Later, after building the amp., I wanted to be sure of the components, so I called Antique Electronic Supply for a model 3B diagram, but they could not find a diagram for this model. It did not exist in their system. They kind of sounded like I was asking a stupid question. Several years later (now), I checked Nostalgia Air for the diagram (I built the amp. back when I was 15, but didn't discover Nostalgia air until a couple of years ago when I was 23). The model number does not exist in Nostalgia Air, either! I searched all the Magnavox amplifier diagrams listed, anyway, because the symbols used in other diagrams listed looked familiar--the early 1930s symbols. Other strange things I found like the use of #25Z5 and #42 tubes in amps. supposedly built in the late 1940s. Line cord resistors post war? How strange! Suddenly I found my diagram!!!!!!!! It is listed as a #A501B. Furthermore it lists as pre 1948! Actually there is a #A501, but it is drawn slightly differently. It is the same amplifier, though. I am not sure if this
is a chassis number or something, but obviously they did not list their diagrams under cabinet model number. This said (in much length), search the diagrams, and perhaps you may come up with something. Also, until the late 1940s, about 98% of home phonographs did not have any other speed than 78 rpm. On rare occasion you will find a 33 rpm or combination 78/33 rpm phonograph. This gets less rare by the post war period. The Webster Chicago example of this is post war. The long playing (LP) record of to-day did not really take off until the late 1940s. Prior to that, it used the standard 3 mil needle size, and only had about 15 or less minutes on it. Audio quality with this needle size was poor. Modern 33 rpm records use a 1 mil needle. The much older ones from the late 1940s and early 1950s use a 2 mil needle, but this will ruin modern 33s, and the 1 mil needle will work just fine on all 33s. The 45 rpm record was invented by RCA Victor in about 1947 (or was it 1949???...not sure). It wasn't until about 1950 that other companies put the 45 rpm speed on their phonographs. It wasn't until much after that when you could get a phonograph with the familiar 45 rpm adapter cylinder. Prior to that, most companies put the regular spindle on their phonographs, and you had to equip your records with little adapter discs (look like tokens) made by such companies as Webster Chicago. At any rate, it is not unusual to have a phonograph of your vintage with only 78 rpm. For 78 rpm records, you must use a 3 mil needle for enjoyable sound. This needle will not fit in the grooves of LP records, and the tone arm will skate to the center of the record. For high quality sound from a 78 rpm record, needle size and quality is very important. Many companies will sell you 3 mil needles that are actually undersize 2.5 mil or "all speed" needles. These sound poor, and ruine the records. Think in terms of surface tension, and exerting the same force over a smaller area. The larger needle size fits the groove properly, and sounds wonderful. Also a common find of the period is the blunderbus set-screw cartridge that takes steel needles. These needles last only one play. They must be changed after each play. You can get chromium needles that last up to 50 plays. These are actually designed for the automatic type phonographs like the one you own (that is, if your phonograph has a cartridge that takes steel needles). I would avoid the whole issue and find a diamond or saphire needle with shank designed to fit in this style of cartridge. Steel needles ruine records. They are too stiff, and leave steel crud in the grooves. I could go on and on in great detail, but I will leave the subject here. I own over 900 78 rpm records, most of which sound superb, and I play them quite regularily without wearing them out. I have many tricks that allow me to do this, though, and much knowledge that is too much for anyone to read about without falling asleep.
Thomas
:I own a georgian magnivox record player(electric)that I'm trying to get information on its year made. When I bought it the owner/dealer didn't have any idea as to the year from which it came from. It has a turntable that is not like others I've seen. The player itself is situated on the left and the radio(whithin an open door)is on the right side. That is where the speaker for the system is as well. It's electric, but seems to play only 78's(i've tried Lp's, 45's but they seem not to play as well-possible because of the needle or the way the tone arm is situated. Instead of facing forward as most turntables do it sets with the tone arm nearest the front of the cabinet. And 78's sit on the spindle but not straight across but tilted and held in place by a clamp that holds them in place until they fall on the wheel. Also the clam can be rotated to accommodate "10" or "12" inch records. Just wondering if anyone might know how I can find out more about the year in which it was manufactured.