Thanks to everyone's help, prior posts or referrals, I have the chassis just about finished with this rebuild...a beautiful double door Philco Model 71 code 221 with dual speakers.

One of the speakers tests OK (K10), but due to age, I am leaning towards a PM repalcacement for both. I doubt that I will play this very much.
K9 is missing the cone and surrounding ring to the bucking coil.

K9 is a 3275 ohm field coil and K10 is a 1125 ohm field coil. It doesn't show this information on the schematic, but I got this data from a Philco speaker chart.

Is there anything like this on a schematic or other model/unit that I can use as a wiring guide?

As always, any help is greatly appreciated.

Terry F

:Thanks to everyone's help, prior posts or referrals, I have the chassis just about finished with this rebuild...a beautiful double door Philco Model 71 code 221 with dual speakers.
:
:One of the speakers tests OK (K10), but due to age, I am leaning towards a PM repalcacement for both. I doubt that I will play this very much.
:K9 is missing the cone and surrounding ring to the bucking coil.
:
:K9 is a 3275 ohm field coil and K10 is a 1125 ohm field coil. It doesn't show this information on the schematic, but I got this data from a Philco speaker chart.
:
:Is there anything like this on a schematic or other model/unit that I can use as a wiring guide?
:
:As always, any help is greatly appreciated.
:
:Terry F

Y9ou can replace the field coils with resistors, or for more hum reduction, chokes. However, it is my feeling that the field coils are part of the original design, and maybe you should check on reconing those speakers to keep the original radio.....well, original.
There is a complete schematic on this site, just click on resourses and the schematic and wiring drawings will be right on your screen.

Lewis

I also strongly recommend a re-cone. You can buy cones affordably at www.electronix.com in the speaker accessories section. For $10, you can purchase a nice variety of all of the cones you could ever desire. The process of re-coning is often very easy, if the original spider and voice coil is salvaged. You can send me pictures, and I will guide you through it all. You will save the original matched speaker, as well as the field coil, which filters so much better than a resistor. The hum bucking coil often found in speakers also makes for extremely good filtering. Field coils rarely fail, and usually do so because of a fault somewhere else in the radio, which shouldn't happen if you re-cap it all. Field coils never lose their magnetism, so your speaker will always perform like it did when new. You will be amazed at the sound quality of your new cones. Go for it! You have nothing to lose.

T.

If the field coil fails, you will have NO magnet. After all it is an electromagnet........

Resistors offer NO filtering at all. All the resistor does is replace the resistance of the field coil.

:I also strongly recommend a re-cone. You can buy cones affordably at www.electronix.com in the speaker accessories section. For $10, you can purchase a nice variety of all of the cones you could ever desire. The process of re-coning is often very easy, if the original spider and voice coil is salvaged. You can send me pictures, and I will guide you through it all. You will save the original matched speaker, as well as the field coil, which filters so much better than a resistor. The hum bucking coil often found in speakers also makes for extremely good filtering. Field coils rarely fail, and usually do so because of a fault somewhere else in the radio, which shouldn't happen if you re-cap it all. Field coils never lose their magnetism, so your speaker will always perform like it did when new. You will be amazed at the sound quality of your new cones. Go for it! You have nothing to lose.
:
:T.

I don't know who this smart guy is (Little Boss), but he obviously is a moron. Resistors do offer filtering. They dampen the current draw from the primary electrolytic, allowing it to maintain a more even charge. They don't have the flywheel effect of a choke, but they do improve filtering. Anyone with brains knows that if you take juice directly off of the first electrolytic, you'll get a lot of hum. Add a resistor and a second electrolytic, and you'll enjoy sweet music.

T.

Thomas: Let's watch the use of words like moron. Haven't you learned anything from your recent eBay fiasco? I think that we can all learn from this forum and you have often supplied very useful information. I appreciate your knowledge. However, it makes things feel a little less safe on this site if we aren't allowed to make a mistake. Mark from Kalamazoo

:If the field coil fails, you will have NO magnet. After all it is an electromagnet........

If the field coil fails, it doesn't matter if you have a magnet or not, the radio will not work. (Except for a few that connect the field coil to ground.)

Thomas,
Thanks for the speaker cone website. I'd be interested in your methodology for replacing speaker cones.

The web site was originally introduced to us by Peter. Re-coning many speakers is fairly easy. If the voice coil has an external spider, cut the cone all the way down to the voice coil, and remove as much from the voice coil as possible without damaging it. Use a sharp razor. The glue is usually brittle, so it will flake off. You might consider moistening it, and then gently coaxing it off, though you do not want to distort the voice coil or tear it. The water would have to be applied in a very delicate manner. The object is, though, to be able to seat the new cone as low as necessary.

If you need to remove the voice coil for any reason, and an external permanently glued spider is used, you may loosen the spider by carefully applying small amounts of water or acetone to the outer edge of the spider (where it attaches to the frame), depending on the glue that is used. Carefully coax the joint loose with a thin, sharp razor. Re-glue with Elmer's, once finished. Be sure to shim the coil when you re-glue it. If the spider is lazy, and won't hold the coil centered in the magnet poles (centered in the direction of its normal movement, not side-to-side centering), you may apply a coat or two of lacquer or varnish (varnish takes a long time to dry, but is more flexible). Shim the coil so that it is held in the center of its travel. Remove shims once the spider is dry.

If the new cone's inner diameter is larger than the original voice coil, then do not remove all of the old cone. Instead leave enough to overlap onto the new cone. If the voice coil wires go through the original cone, then you must leave that part of the cone in tact. If the speaker uses an internal spider, in that case you must also leave the portion of cone that goes from the coil to the spider in tact.

Gently remove the outer cushion from the edge of the frame with a sharp razor. You can also try soaking the glue with water or acetone, though in many cases you might wind up with a mess, since the cushion is cardboard. If you use a very sharp razor, though, you may be lucky. Do what works for you. Most modern speakers use glue that softens with acetone. Old speakers use organic glue that is softened with water (or possibly acetone).

With the voice coil in place and free to move, position the new cone. You will want the new cone to sit in a position on the voice coil that keeps the voice coil centered in its up and down travel when everything is at rest. If you are placing the cone on top of a section of old cone, you may want to consider carefully coaxing the section of old cone up through the hole in the new cone, so that the new cone lies below the old cone. That will correct the problem of the new cone pushing down on the voice coil. If the voice coil wires went through the old cone, slip the remaining part of the cone through the hole in the new cone very carefully. Poke holes in the new cone to accept the flex wires. Carefully pull them through. When all is completed, you will be gluing the remaining section of the old cone to the new cone to prevent rattling. If you can place the cone on top of the voice coil wires and remaining cone without pushing down too much on the voice coil, then you will be gluing the section of old cone with voice coil wires to the bottom side of the cone. It is more ideal to have the new cone sit low on the voice coil, which requires coaxing the small remaining portion of old cone, along with the voice coil wires, up through the underside of the new cone. Gently rotate the new cone until it seats properly on the voice coil. If it is difficult to get it to seat properly, you may consider gently enlarging the inside diameter of the new cone with the edge of a razor. You can either cut off a tiny amount, or simply roughen the edge so that it becomes fuzzy. The fuzzy part will slip over the voice coil easily, and, when covered with glue, will provide a nice strong joint.

If the speaker uses an internal spider, there will usually be no external items on the voice coil that would prevent it from dropping through the top of the new cone. That said, drop the voice coil assembly down through the new cone, and, of course, carefully pull the flex wires through as well (example: Philco 60 speaker).

Glue the coil assembly to the cone wherever you had to join it. If you are gluing right at the voice coil, be very careful with the glue. Use a toothpick to work the glue into the joint. I recommend Elmer's white glue because it is slow setting, and though it is rigid, it is also strong. There are some other glues that may work well, too. Hide glue is brittle, and should be avoided. Put a bead of glue around the part of the frame where the outer edge seats, too. Shim the voice coil with 3 or 4 strips of film negative (Peter's idea...works very well). They should be long enough for easy retrieval. Strips from 1/4 to 1/2 inch in width are ideal. Position the voice coil so that it is centered in the magnet field. If you are attaching the new cone to the underside of a remaining section of old cone, you may need to gently prop it against the gluing surface with some wads of soft tissue. Do nothing that will severely distort the cone. If you are gluing directly to the voice coil, usually the cone will stay put on its own. Place another bead of glue on top of the outer edge of the cone, and also on the speaker frame out to its lip (glue adheres to the metal better than to the foam, so it is a good idea to get a good grip on everything). Re-install the cushion. If you can without upsetting the cone, turn the speaker upside down and place on the floor. Place one leg of a heavy table upon the magnet assembly. The weight should not be so heavy as to distort the frame. Also be careful that the table does not fall and damage the new cone. If the rubber edge of the new cone strikes the floor and causes distortion, you may need to build a thick 'baffle,' with a hole in the middle wide enough to not touch the rubber edge. The baffle can be made out of cardboard. Thick corrugated would be ideal.

You can glue the voice coil joint before you glue the outer edge, but I feel that it is better to glue everything at once. When the outer edge of the cone is held in place by the weight of the table, the inner part will adjust so that the cone is facing in the right direction. If you make the voice coil joint first, and then glue the outer edge after the coil joint is dry, the cone might be tilted at an angle. Once the outer edge has been glued, the tension of the crooked cone might cause a mis-alignmente of the voice coil (rubbing).

Once everything is dry (after a couple of hours...perhaps longer), tighten the spider screw(s) if any are present. Remove the shims. Test movement with your fingers at 3 and 9 o'clock. Re-connect the leads and test your speaker.

There are some odd size speakers where improvizing is necessary. Also, not all speakers have the same depth cone. There was one speaker for the Crosley 148 that was a bit of a trick for me. A 6 inch cone wouldn't fit properly (the speaker uses a 5.5 inch cone or something like that), so I wound off taking about 1/4 of an inch from its edge. To do so I simply cut the rubber edge off neatly at a point that would make the cone appropriately smaller (cutting right at the edge of the rubber-paper overlap (inner edge of rubber on underside of cone) worked perfectly). Then I put a cut in the rubber edge radially so that I could decrease its diameter by overlapping. I overlapped and applied some glue, and then glued the cone to it, as well as it to the frame, and so-on. Since the cone was no longer attached to something that would properly level it to the frame, it was a bit of a trick getting it leveled. All worked out well, though. In that case it might have been easier to use something with a quick grab, such as rubber cement or contact cement. However, you still need to be able to re-position the cone until it is just right, and furthermore, rubber cement isn't long lasting. Elmer's was still ideal, though keeping all joints attached was a trick. I had to work somewhat in steps, though I didn't really want one part to be dry before the other, since perfect alignment relied on re-positioning at all pionts. It was a challenge. It looks great now, though, and works very well, too. One big help was that the phenolic spider is rather stiff, and so if I glued the cone at a slight angle (not perfectly parallel), the spider would be strong enough to correct for the problem without voice coil issues. If at all possible, though, you don't want to put extra strain on the spider (especially if it is phenolic), and a stiff spider isn't the best for bass reproduction, either. The speaker does sound quite nice, though. I have no real complaints....so it all worked out well.

T.

Thanks for all the great info Thomas!