Roll Not The Barrel (Jan, 1952)
Roll Not The Barrel
The recreation room in your home will be enhanced by this out of the ordinary, record changer cabinet.
By Loren Collins
THIS is an unusual project requiring a minimum of material and only the simplest hand tools. When completed it will not only be an attractive addition to your den or rumpus room but a serviceable record player, rivaling many large consoles in tonal quality. Using the unbreakable 45 rpm 7-in. disks that come in a wide choice of classical and popular selections, it will play ten selections, or from 30 to 50 minutes of music with one loading.
The keg used is a 2-1/2-gallon size, measuring 12-1/2 in. long by 9 in. across. Any cooperage should be able to supply you, or they can be obtained from ship supply concerns. The changer mechanism is handled by radio stores throughout the country and is available with cords, plugs and permanent needle, ready to be hooked up to any amplifier. The amplifier described in this article uses three miniature tubes and will yield excellent performance. A wooden spigot, some small pieces of 1/4-in. plywood and a few hardware items will complete your material list.
Before proceeding with the construction, the keg must be glued together. To do this, simply remove the hoops on one end and the staves will spread enough to permit glue to be applied to all joining edges and around the head. Replace the hoops, turn the keg over and repeat the operation. Be sure to align the heads so that their grain runs in the same direction. A small nail driven in the head will help to handle them during the gluing process. If the hoops are driven on tight with . a block and mallet, no other clamps will be needed. Allow ample time for the glue to set as there is considerable stress developed in the wood. Next remove the hoops and smooth up the uneven joints with a plane, then sand the whole keg smooth.
The cradles are cut from 3/4-in. stock and are fastened to the bottom section with screws driven from the inside. Use rubber-headed tacks on the bottom for table protection.
Now fasten cleats of 3/8 x 3/4-in. stock around the inside of each section to receive the panels. The lower panel should be recessed about 1-1/4 in. and the upper 3/4 in., or just enough to clear the pickup arm when the player is closed. The panels are cut from 1/4-in. plywood. Trim a piece of cardboard until it fits and use it for a pattern. The cutout for the changer is made in the lower panel with a jig or coping saw. Be sure to allow clearance for all moving parts during the changing cycle. Drill three 1-in. holes in the keg below the turntable motor to provide ventilation.
There will be some unused space at one end of the lower section and this should be partitioned off with plywood to form a storage compartment for the power cord. Drill a 1-in. hole through the head of the keg into this space to receive the spigot. A notch filed in the edge of this hole will allow the cord to be clamped in place at any desired length. For traveling, the whole cord may be pushed in and the spigot replaced. A couple of saw cuts in the end of the spigot to hold the plug will keep it from getting lost inside. The 110-volt wires and the phone lead, lead to chassis-mount type receptacles at the rear of the panel so that the two halves may be easily separated for service. Now hinge the sections together, using one sturdy ornamental hinge in the center. Attach two lengths of small brass chain to stop the upper section, a few degrees past vertical.
In laying out the upper panel, first determine the location of the hole which provides clearance for the record post, by shutting the lid against the post. A small kitchen strainer, less handle, is fastened over this opening to provide cooling air for the amplifier tubes.
This amplifier circuit is quite conventional and should present no problems even to an . inexperienced builder. However, the components must be placed in a rather unorthodox manner to make use of the space available.
The chassis is formed of a 4×5-in. piece of aluminum about 1/16-in. thick. Lay out the location of the holes directly on the metal. You must also provide holes for the socket mounting screws unless you are using the type secured by a snap-ring.
The 5/8-in. hole for the 150-ohm, 10 watt resistor (R-9) should be omitted if you are not using the through-chassis type pictured, but since this part will get quite warm, it should be mounted on the outside of the chassis.
Clamp the chassis between the blocks of wood and make the 90° bend as shown. Now mount the potentiometers and tube sockets. . If you are doubtful about following a schematic diagram, you can mark all parts with the code numbers shown on the parts list (C-l, R-9, etc.) before starting. It will also help to mark each connection off with colored pencil on your diagram as it is completed.
First wire the filaments, merely omitting the leads to the indicator light if you are not using one, and making no connection to terminal 6 of the 35W4. Next make the short connections between sockets and install resistors, leaving the larger components for last. Most of the connections are made directly but I used one small terminal strip located centrally to avoid crowding the wiring on the sockets.
You will note there is only one ground connected directly to the chassis, the others being run to a common ground. One terminal of the switch works out nicely for this purpose. The power cord and the shielded wire from the record changer are run through holes in the wooden panel before soldering them into the circuit.
The speaker wires are led through a small grommet and connected to the larger, or primary wires of the output transformer, which is mounted on the speaker itself. The secondary wires are soldered to the speaker voice coil terminals.
Before trying the amplifier, double-check your wiring, looking especially for shorts between the lugs on the tube sockets. If a hum is noticed, try reversing the power cord plug in its socket.
The amplifier and speaker can now be located on the panel and the holes drilled for the control shafts, speaker and indicator light. Place a suitable grill cloth under the speaker before fastening it in place. For best tone, be sure all parts are solidly mounted. Lining the inside of the upper section with Fibreglas or other sound absorbing material will also help to eliminate vibrations.
A small rubber pad glued to the upper panel above the pickup arm will hold it securely on its rest while the player is being carried. The correct length for this pad can be determined by placing a lump of modeling clay or putty on the arm and closing the lid on it.
Give the wood at least three coats of spar varnish, rubbing lightly with steel wool between coats. If any open grain woods such as mahogany are used, they should be given a coat of filler before varnishing. The keg may be stained before varnishing if you wish, however, the fir will be very attractive in its natural color.
The hoops are sawed in half and fastened in place with 1/4-in. No. 3 screws. A carrying handle and suitable hasp or snap will complete the job. A couple of final suggestions: don’t shut off the player during its changing cycle. Wait for the arm to return to the record, then turn off the switch and place it on the rest. Always keep a record on the turntable to protect the needle against breakage.