Restoring the Orthophonic Sound Box

For the novice as well as the experienced collector of Orthophonic Victrolas, nothing is more frustrating than finding an otherwise pristine machine equipped with a rattling, buzzing or blasting sound box. Unlike pre-1925 talking machines, Orthophonic Victrolas (made from 1925 to 1930) are normally fitted with pot metal reproducers, and few repair shops today are willing to restore them. The work can be expensive, with no guarantees. An Orthophonic pot metal sound box is very fragile and can literally crack apart while it is being dismantled.


Above is Victor's portable known as the "2-55," with
automatic brake. It features the No. 5 Sound-Box, better known as
the Orthophonic Sound-Box. From the April 1928 issue of The Voice
of the Victor.

To put an Orthophonic sound box back into factory-new condition, one has to completely disassembl and rebuild it. This includes the removal of the back plate, the solder holding the needle bar to the diaphragm, the gaskets, the needle bar ball bearings, the needle bar, itself, and the ball bearing racers. All seals must be removed including those holding the spider's feet to the diaphragm.

After it is dismantled, all parts should be cleaned, including the fragile diaphragm. The sound box's casing must be inspected.

If it is warped, the sound box must be ground true before it is reassembled. All small cracks should be repaired. The gaskets as well as the ball bearings should be replaced, the ball bearing racers and pivot areas of the needle bar carefully polished.

Finally, all components must be reinstalled, soldered and sealed. Is it any wonder few are willing to tackle this arduous task?

While a non-professional should not even think of dismantling a pot metal Orthophonic sound box, there are a few things that the average person with little or no experience can do to bring back some of the sound quality, providing the following conditions are met:

1. The sound box should be intact, with no serious cracks running through the casing; nor should the casing be seriously warped.

2 The diaphragm should have no punctures or tears. A few dents are acceptable, providing they do not extend to the perforated region of the diaphragm. (This prevents the diaphragm from plunging evenly.)

3. The solder connecting the needle-bar to the spider should be solid. If it is loose, I recommend taking the sound box to someone who knows how to solder small electric components or to a jeweler.

If the sound box seems in overall good condition, the first thing to do is order some replacement ball bearings and bearing gaskets. These can be obtained from the Antique Phonograph Supply Company for a nominal fee. Once in hand, grab the sound box along with:

- a small screwdriver
- Denatured alcohol
- A few Q-tips
- Eye-dropper
- Tweezers
- Five or six pointed toothpicks
- Strong stick pin
- Orange Shellac
- WD-40
- Razor blade
- Large mixing bowl (that's right, a mixing bowl!)

You will also need to work in a well-lighted area on a large flat surface. If close-up vision is a problem, a good pair of reading glasses or a magnifying glass is needed.

The first step is to clean the surface of the diaphragm. Use the eyedropper to gently squirt some alcohol onto the front surface of the diaphragm and swish it around. This will loosen any chunks of grit or shellac flakes clinging the to the surface. (Shellac was originally used to seal the spider's feet to the diaphragm.) Any pieces of grit that float to the surface should be carefully swabbed away with a Q-tip. After this, tip the sound box over a sink to allow the excess alcohol to drain then set the sound box aside for about 30 minutes or until all of the alcohol evaporates.

The next step is to replace the ball bearings. In the Orthophonic sound box, the needle arm is held in place by a ring of ball bearings. Six to eight are installed on either side of the magnetized T-shaped joint, and are accessible by opening the bearing caps. I recommend working on one side at a time so that the needle bar is not moved to any great extent, out of alignment.

Hold the sound box over a large mixing bowl, and carefully loosen the bearing cap screw enough to swing the bearing cap to the right so it clears the hole. Then tighten the screw so the cap is held firm to prevent its swinging back into place.

Magnetic pull was supposed to hold the ball bearings in place--side by side--to form a ring around the needle bar's pivot joint or "post." However, Victor seated rubber gaskets over the ball bearings on later Orthophonic sound boxes to prevent them from repositioning themselves out of alignment. If the washer is in place, chances are it has petrified and may be stuck. Gently prod it with a stickpin. If it won't budge, gently spritz some WD-40 onto a Q-tip and swab the area. Wait a few seconds and pick at the gasket again. After a few tries, it should loosen and come out, along with one or two ball bearings that have fastened themselves to it.

Use the stickpin to gently nudge the remaining ball bearings up and out of the joint. If you tip the sound box slightly while doing this, they all should plunk into the mixing bowl. Normally, the ball bearings are coated with rust and are deformed which is why I recommend replacing them as soon as possible. After all have been removed from the joint, gather up the old ball bearings and throw them away!

Spray a fresh Q-tip with WD-40 and gently wipe the joint to clean off any surface rust. Once this is done, you are ready to install the new ball bearings. However, I strongly recommend that you look carefully to make sure that the needle bar's post is seated in the center of the hole. If it is slightly to one side of the hole--and it normally is!--take a toothpick and gently jam its point between the post and side wall (bearing racer) to align the post as closely to the center of the hole as possible. This done, leave the toothpick in place while you carefully grab the ball bearings with the tweezers, one by one, and drop them around the post. Gather any that have missed their mark from the bottom of the mixing bowl and try again!

When most of the balls have been installed, slowly pull out the toothpick and position the remaining ones. Normally, eight ball bearings are required to snugly hold the pivot post in place, but fewer may be needed depending on the size of the balls. The important thing is that the ball bearings form a neat ring around the post.

With the ball bearings in place, grab the gasket (normally supplied in the form of a rubber hose) and gently position it over the post and press down. This will push the ball bearings onto their seat evenly around the post. Then, using a razor blade, cut the hose to form a ring-type gasket that is flush with the top surface of the hole. It may protrude slightly, but no more than 1/16 of an inch. Loosen the bearing cap screw, position the bearing cap over the washer, and tighten the screw.

Flip the sound box around and repeat the above process to replace the ball bearings on the other side.

After all of the ball bearings and the gaskets have been replaced, I strongly recommend that you, once again, loosen the bearing cap screws and swing aside the bearing caps on both sides. Then, with your thumb and index finger, apply equal pressure on both gaskets, pushing toward the center of the needle bar. This will align the needle bar to its correct center position, and tighten the fit of the ball bearings. To test the fit, try gently moving the needle bar sideways--opposite to the direction required for tracking a record. If there is any sideways movement--or side play--apply more pressure, equally, to both bearing gaskets. After you are sure that the joint is tight, reposition the bearing caps and fasten them securely.

The next step--and you're almost done--is to make sure that the tiny stop screw--located just above the needle bar's thumb screw on the front plate--is not touching the needle bar. I recommend giving the screw a few counter-clockwise turns to back it slightly away from the needle bar. You may also want to inspect this area using a small flashlight and magnifying glass to make sure there is no contact between the stop screw and needle bar.

After this, look carefully to make sure that the spider's feet are sealed to the diaphragm. If you wish, you can put a tiny drop of orange shellac on each of the feet at the juncture where they mate with the diaphragm. Then allow at least 20 minutes for the shellac to cure.

One last point. Often, the rubber gasket holding the brass O-ring in the throat portion of the sound box has come loose due to shrinkage. This causes the sound box to rattle back and forth when a record is being played, and also makes for serious air leaks. If you can get the two screws holding the O-ring/gasket assembly out, remove the gasket and replace it. If the screws are frozen, DON’T TRY TO FORCE THEM!. You may still be able to stabilize the O-ring by wedging a few thin strips of paper soaked in Elmer’s Glue between the hardened gasket and the throat. Then, lightly coat the top surface of the rubber gasket with a thin layer of clear silicone caulk and allow it to dry for at least three hours. This will stabilize the gasket and fill in any gaps between the gasket and the throat casing, and can easily be removed in the event that the sound box is ever professionally overhauled.

You are now ready to test your work! Insert the sound box onto the tone arm and install a fresh loud-tone needle. Allow the needle bar to plunge gently back and forth while tightening the needle. Then, play an Orthophonic record that is in good condition and listen carefully! If any rattling is detected, repeat the above check for side play. If you followed all of the steps outlined above, however, you should be impressed with what you hear.

Othrophonic Credenza

Drawing of the inner workings of an Orthophonic Credenza