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Philco 20, 70, & 90 spkrs
#1

I wouldn't under sell the cardboard spider. I've serviced a few of the "pie pan speakers". What I've found is that  the paper cone is pretty stiff and failing in the folds near the basket. If you are pinching pennies you maybe able to use some diluted fabric glue to keep it together.

The spider is fine if not broken or worn out the issue is the gap between the pole and frame is full of dust and dirt limiting the travel of the vc/cone. This makes the speaker sound like a bullhorn. A way to test it is to take two fingers and press gently on the edge of the vc. It should move down about 1/4" of so. If it moves 1/8" it's a whole lot dirty.

I've read a few different ways to remove the dirt w/o removing the vc. Facing the speaker front down and whacking the back of the frame (field coil) a bunch of times. Seems a bit brutal to me. The ultrasonic method which involves hooking an audio generator set for a low frequency tone to the audio amp in the set. Sort of trying vibrate it out. The problem is that the dirt gets impacted in by the constant hammering of the vc when the set is playing.

What I did was remove the cone. It's simple unsolder the wires for the vc and note their orientation. Remove the screws around the edge of the basket. Slip a sharp thin knife between the cone and basket to separate them. Once the separation is complete remove the screw in the center and the remove the cone straight up.  

Dusty in there ain't it! Next order of business brush out the dust and clean the gap. Paint brush and vacuum work fine to clean up the dust. The gap (the little circle where the vc fits into the frame) I used a scrap of thin plastic (blister pak) cut a small strip and went around and around the gap. If you are part of the civilized world you'll use a vacuum to vacuum the dirt out of the gap. Me I blew into it it's not a good idea. Got dirt in my eyes and face. Was a rather unpleasant experience. Once it's all cleaned up reverse the order and reassemble. Do note that the vc wires need to exit near the terminal strip and not 180 deg away. Before tightening check the the vc for rubbing reposition the cone slightly to fix. More than likely with the original cone it's a drop in and won't require any adjustment. When it's back together you'll notice an improvement in movement.

I had some replacement cones that were purchased for use on the later K style speakers but the angle was too great over all they were too tall. They were inexpensive about 79c ea. 5 or 6yrs later I found that they are just about a perfect match (in a modern type) cone for the 8" pie pan's. Had to trim a little off the foam outside edge and enlarge the vc hole. The depth was on the mark, on the newer K speakers from the mid '30s these cones are about 1/2" too tall.

Cut the foam edge to fit the basket and the vc hole to fit the vc but it must be on center. And have little snugness. With the vc inserted in the cone reassemble in cone into the basket. Check the wires that they are facing the terminal strip. Look it over to see if it seems to be in alignment. If not move the cone till it is or if it is tighten the screws and gently push on the edges of the vc. If you hear of feel any rubbing it's not centered. Rejust the position of the cone till the rubbing is gone.

Once it's centered gently press the edge of the vc down till it bottom out and tack the top of the spider in place of a few dots of hot glue. Hold it till the glue cools and push down a few times and check for rubbing. The nice thing about the hot glue is that you can pop it off with a knife so it's some what removable liquid glues could be a mess in this application. If all is ok w/o rubbing when run a small bead of h glue around the vc/cone junction.

The reconing is done solder up your wires and your good to go. The latest one I did is in my 370 (chairside model 70) and it sound great! Yes it does have low frequency response and it's nice and smooth. 1000X better that it did before. https://philcoradio.com/phorum/showthrea...hlight=370

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#2

Terry;
  That sounds like a logical course of action, especially with a dirty set, I will have to do something similar with a 10'' Magnavox speaker, in a Deforest Crosley, at some point, judging by the thick dust that was all over the chassis. I've often wondered how they centered the cone in a speaker with a solid spider, considering that you can use shims, it must have been by ear.
 I don't have a Philco with a pie pan, but I had to repair the speaker in a 620B, an 8'' one, where someone had reconed it with a more modern foam rimmed cone, and not very well. The spider was a 45 rpm adapter style, and was trashed, so I made a new one out of stiff card stock, and a razor knife, I used old film negative for shims, cut into strips, though the plastic from blister packs would also work. I also used contact cement to glue the spider in place, and painted the foam with it as well, just to preserve it, seems to have held up though I haven't inspected it lately. So if anyone wants to replace the solid spider in a pie pan speaker a stiff cardboard, or plastic, of the right thickness can be used to make a replacement.
Regards
Arran




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