On some songs with a lot of base my speaker rattles quite badly. Is there an easy cure? There are no holes or tears in the speaker and it is from a 1937 Philco.

Inspect the spider. If it is the corrugated fabric type (outside of voice coil), make sure that it is cemented properly both on the inside and outside of the piece (it is cemented to the voice coil on the inner diameter, and to the speaker frame on the outer diameter. If your speaker uses a perforated spider (paper or phenolic material) that is mounted in the center of the cone, make sure that it is not broken. If it uses a perforated or strap type spider on the outside of the cone, which may be made of paper or phenolic material, be sure it is not broken. Check to see that the voice coil is securely mounted to the cone (cement if necessary....use a toothpick to apply glue...or syrringe).

Other things to check for: see that the lead in wires to not strike the cone or any other objects. If they are near something, pull on them gently with a hooked wire or some other tool so that they curve neatly from the speaker cone to the terminals at somewhat of a right angle perpendicular to the cone. See to it that the wires are connected properly, as if there is a loose connection, vibration of the cone will cause crackling that sounds like a broken cone. Severe cases of this will cause intermittent sound. Since these wires are usually of the tinsel wire over fibre type, on occasion the tinsel wires can break and the fibre can still be attached to the terminal, making it appear as though the wire is still connected properly. Be maticulous with inspection. See to it that there are no beads of solder or bug shells or dust blobs floating around behind the cone. Bug shells do cause weird noises that sound somewhat like a broken cone. Sometimes solder blobs will stick to the cone or will lie at the outer edge between the cone and frame, if work was done to the speaker.

Gently push the cone in and out with your thumbs at 3 and 9 o'clock. Place an even pressure on both sides so that the cone moves naturally and is not forced at an angle. Is there any rubbing? If there is rubbing and the spider is adjustable (held down by screw(s)), obtain some index card material or some thin plastic that is as thin or slightly thinner than an index card (plastic works better as it does not wrinkle). If there is a felt dust cap on the speaker, gently remove the cap. Loosen the spider screw(s). Cut three 1&1/2 inch long strips that are 3/16 to a quarter inch wide, from the card or plastic. Insert these strips on the inside of the voice coil, between the voice coil and the metal pole piece. Space them evenly. Tighten the spider screws. Remove the strips and test speaker operation.

If the speaker does not have an adjustable spider, sometimes you can insert the strips and moisten the cone with a misting spray bottle or a wet rag. Wet the cone thoroughly, but do not soak everything. Try not to get the outer corrugation wet too much. It may be damp. After the cone is damp, do not touch it. Do not adjust the strips or anything. Allow it to dry. Most likely the paper will have adjusted and the cone will be centered again.

Thomas

What do you mean by the spider? At the center of this speaker is a screw head that fits a 1/4" nut driver. Is the spider part around that?

:Inspect the spider. If it is the corrugated fabric type (outside of voice coil), make sure that it is cemented properly both on the inside and outside of the piece (it is cemented to the voice coil on the inner diameter, and to the speaker frame on the outer diameter. If your speaker uses a perforated spider (paper or phenolic material) that is mounted in the center of the cone, make sure that it is not broken. If it uses a perforated or strap type spider on the outside of the cone, which may be made of paper or phenolic material, be sure it is not broken. Check to see that the voice coil is securely mounted to the cone (cement if necessary....use a toothpick to apply glue...or syrringe).
:
:Other things to check for: see that the lead in wires to not strike the cone or any other objects. If they are near something, pull on them gently with a hooked wire or some other tool so that they curve neatly from the speaker cone to the terminals at somewhat of a right angle perpendicular to the cone. See to it that the wires are connected properly, as if there is a loose connection, vibration of the cone will cause crackling that sounds like a broken cone. Severe cases of this will cause intermittent sound. Since these wires are usually of the tinsel wire over fibre type, on occasion the tinsel wires can break and the fibre can still be attached to the terminal, making it appear as though the wire is still connected properly. Be maticulous with inspection. See to it that there are no beads of solder or bug shells or dust blobs floating around behind the cone. Bug shells do cause weird noises that sound somewhat like a broken cone. Sometimes solder blobs will stick to the cone or will lie at the outer edge between the cone and frame, if work was done to the speaker.
:
:Gently push the cone in and out with your thumbs at 3 and 9 o'clock. Place an even pressure on both sides so that the cone moves naturally and is not forced at an angle. Is there any rubbing? If there is rubbing and the spider is adjustable (held down by screw(s)), obtain some index card material or some thin plastic that is as thin or slightly thinner than an index card (plastic works better as it does not wrinkle). If there is a felt dust cap on the speaker, gently remove the cap. Loosen the spider screw(s). Cut three 1&1/2 inch long strips that are 3/16 to a quarter inch wide, from the card or plastic. Insert these strips on the inside of the voice coil, between the voice coil and the metal pole piece. Space them evenly. Tighten the spider screws. Remove the strips and test speaker operation.
:
:If the speaker does not have an adjustable spider, sometimes you can insert the strips and moisten the cone with a misting spray bottle or a wet rag. Wet the cone thoroughly, but do not soak everything. Try not to get the outer corrugation wet too much. It may be damp. After the cone is damp, do not touch it. Do not adjust the strips or anything. Allow it to dry. Most likely the paper will have adjusted and the cone will be centered again.
:
:Thomas

Yep, that's the spider. It is perforated to make a sort of spring. They were perforated in different ways. Philco often perforated the piece into three curving arms, which sort of look like a spider. The device is cemented to the cone around its edge, and has a hold-down screw at its center.

Thomas

John/Thomas,
I have a close up .jpg of the 3 legged spider you described from an Edison 8P speaker/pwr supply chassis
if it would be helpful.
marv

:Yep, that's the spider. It is perforated to make a sort of spring. They were perforated in different ways. Philco often perforated the piece into three curving arms, which sort of look like a spider. The device is cemented to the cone around its edge, and has a hold-down screw at its center.
:
:Thomas

John,
Over many years these old paper speaker cones will absorb moisture, then dry, absorb moisture, then dry etc. Paper cones are sometimes unforgiving, and will warp, possibly overpowering the natural spring effects of the spider, which mis-aligns the spider/voice coil assembly into its gap. The spider itself, although less susceptable, can take on its own mis-aligned position. My 3 legged spider had a slight bend in one of the legs, and caused a mis-alignment. Having just completed a similar rebuild, I can provide a complete discussion, .jpg's, fixes etc by email at mavlusone@yahoo.com
marv

:On some songs with a lot of base my speaker rattles quite badly. Is there an easy cure? There are no holes or tears in the speaker and it is from a 1937 Philco.

Sometimes you can cure this warpage, too, by simply shimming the voice coil and wetting the cone (before shimming, loosen the spider if possible and then tighten after shimming). Allow it to dry (perhaps in an oven set at 170 F). This has always worked for me, but it may not work all the time. Of course, before you wet the cone, you should first try aligning the cone by simply using shims and loosening the spider. If it is necessary to wet the cone, wet it all they way down to the voice coil, but do not get the voice coil wet, and do not get the glue joint between the coil and the cone wet. Leave about an eighth to a quarter inch dry (water spreads due to capilary action...keep this in mind).

Thomas

Thomas,
The process of selecting appropriate shims and using them to re-position the voice coil is somewhat tedious, and should be addressed. Paper and poster board of varying thickness can be found at most craft stores. At least 4 shims should be spaced equally around the perimeter of the gap during the drying process. All 4 of equal thickness should offer only slight resistance at being inserted into the gap. Several thickness of shims should be created by cutting the paper/poster board into 1/8" x 1 1/2" strips. Larger diameter voice coils will accept wider shims without compromise. I would start with shims approximating 0.080" thick, unless pertinent technical data indicates otherwise. If the first three shims offer excess resistance being inserted, select a thinner set and conversely, if they fall into the gap, select a thicker group, until all 4 can be inserted with equal resistance. Make sure the shims don't get wet during any part of this procedure.
marv

:Sometimes you can cure this warpage, too, by simply shimming the voice coil and wetting the cone (before shimming, loosen the spider if possible and then tighten after shimming). Allow it to dry (perhaps in an oven set at 170 F). This has always worked for me, but it may not work all the time. Of course, before you wet the cone, you should first try aligning the cone by simply using shims and loosening the spider. If it is necessary to wet the cone, wet it all they way down to the voice coil, but do not get the voice coil wet, and do not get the glue joint between the coil and the cone wet. Leave about an eighth to a quarter inch dry (water spreads due to capilary action...keep this in mind).
:
:Thomas

You know...my dad has all sorts of thin plastic that he uses for model train work. I find that this works well, and it doesn't crumple or get wet. Some of it is from the hobby shop and some is scrap from such places as appliance shops. Some of the pieces of plastic are escutcheon scraps from washing machines and auto radios. I am sure, though, that you can find many thicknesses of plastic at a hobby shop.

Thomas

Thomas/John,
The plastic shims would work well, however a note of caution should be added. When cutting plastic or metal sheet stock with scissors or a knife, an uncontrollable raised edge/burr is created, adding noticably to its thickness. Paper stock doesn't have this drawback, is cheaper, readily available and easily cut. The primary goal is to align the voice coil with equal spacing around its inner perimeter and ON AXIS with the center pole piece of the magnetic structure. Hopefully the inner pole piece has been aligned with its counterpart as well, and this may be of interest to John. In one of my rebuilds, I found that although the center pole piece appeared to be rigidly bolted in place, the gap was off-center, but by making slight adjustments to the attachment structure, was able to re-align it. If I had not taken preliminary measurements, I'd still be fighting voice coil drag. Maybe antique radio parts still has a supply of speaker shims that were popular many years ago, before we became a "Throw Away Society" They were available in many thickness and also as an assortment in small plastic containers. Most were plastic, but some were non-magnetic shim stock, sheared into narrow strips without burrs or rough edges.
marv

:You know...my dad has all sorts of thin plastic that he uses for model train work. I find that this works well, and it doesn't crumple or get wet. Some of it is from the hobby shop and some is scrap from such places as appliance shops. Some of the pieces of plastic are escutcheon scraps from washing machines and auto radios. I am sure, though, that you can find many thicknesses of plastic at a hobby shop.
:
:Thomas

Cutting the plastic with a scissors works well, but of course if ridges do develop, they will hinder alignment, and may puncture the voice coil form. I have never had ridges develop with a scissors, but I guess they could.

T.D.

John/Thomas,
How'd you guys do that? Magic? Witchcraft? The internet? Jinx my old Edison 7R speaker. After my long desertation 'bout speakers an voice coils, I was chasin' a 120 Hz hum problem today, and then SILENCE. Scoped it out and found audio everywhere, except the speaker. Now this is interesting. The spider (voice coil) having flexible wires to the output xformer secondary measured 250K ohms. Open voice coil!! A Rewind with #32AWG is in order. Disassembled the entire speaker. This 3 legged spider is made of thin flexible phenolic, brass rivets, 1920's printed circuit board, more brass rivets and then #32 enameled wire on a 1.5 inch voice coil form. Got access to the actual winding, sans solder, brass rivets etc and measured 50 ohms DC. This is somewhat unique, 50 ohms DC voice coil. Your comments about this strange measurement would be appreciated. I seem to recall an earlier measurement of 12 ohms DC, prior to this failure. A magnafied visual inspection revealed nothing abnormal on the winding.
marv

:Cutting the plastic with a scissors works well, but of course if ridges do develop, they will hinder alignment, and may puncture the voice coil form. I have never had ridges develop with a scissors, but I guess they could.
:
:T.D.

The winding is copper and not aluminum, right? I don't think they started using aluminum until the late 1930s-early 1940s (for high frequency response purposes--FM). Aluminum is not solderable, and so the connections must be crimped. Corrosion develops. If your winding is copper, though, and is soldered, then it is not likely corroded at the solder connections. Has the tinsel wire perhaps broken (if tinsel wire is used)? Sometimes the tinsel will break or corrode and yet the fibres will make the wire appear to be complete.

I am by no means an expert on speakers, so this is about as much as I can guess. Some superb books for any radio hobbyist to read are those written by G.A. Briggs. I have his "Sound Reproduction." There is another that strictly deals with loudspeakers, but I do not know if it deals with their construction or with practical and scientiffically correct application. Read them anyway. They are a feast for the brain. Incidently, I saw my book sell recently for over $95.00 on the internet. It may be hard to obtain.

Thomas

Thomas,
Its interesting that you mentioned aluminum. Investigation of several abraded spots on the winding has the silver appearance of aluminum, but attributed that to another "senior moment" of eye failure. Like you, I didn't think they were using aluminum voice coils 'til much later. No evidence of crimping the actual wire has been located, (only hollow brass rivets and solder) but the odd 50 ohm voice coil measurement leads me to believe further investigation is in order. In addition, a replacement output xformer with 8 ohm secondary, was installed for first rebuild. The wire leads from the spider to frame feedthru was #22/24 solid, which I found troubling, but left as is on original rebuild to maintain authenticity. This time around though, I've found some tiny coax in my junk box with silver plated shield, and when stripped of its center conductor, makes a nice flexible wire for the spider connection. I would caution other users of this method to be careful in soldering it though. Use a minimum heat, assure that the added length of shield is aimed upward to avoid wicking of the solder into its entire length, and rendering it solid/inflexible. Even after pulling it taut (its like a Chinese Finger), it still has a hollow core, and will suck up solder better than most commercially available solderwik.
marv

:The winding is copper and not aluminum, right? I don't think they started using aluminum until the late 1930s-early 1940s (for high frequency response purposes--FM). Aluminum is not solderable, and so the connections must be crimped. Corrosion develops. If your winding is copper, though, and is soldered, then it is not likely corroded at the solder connections. Has the tinsel wire perhaps broken (if tinsel wire is used)? Sometimes the tinsel will break or corrode and yet the fibres will make the wire appear to be complete.
:
:I am by no means an expert on speakers, so this is about as much as I can guess. Some superb books for any radio hobbyist to read are those written by G.A. Briggs. I have his "Sound Reproduction." There is another that strictly deals with loudspeakers, but I do not know if it deals with their construction or with practical and scientiffically correct application. Read them anyway. They are a feast for the brain. Incidently, I saw my book sell recently for over $95.00 on the internet. It may be hard to obtain.
:
:Thomas

Forgot to mention that the VC is solonoid wound, with what appears to be 2 layers. Using #32AWG aluminum DC resistance figures and VC dims, would require 38 turns, for 50 ohms, although it appears that there are 62 turns on the core.
marv

:Thomas,
:Its interesting that you mentioned aluminum. Investigation of several abraded spots on the winding has the silver appearance of aluminum, but attributed that to another "senior moment" of eye failure. Like you, I didn't think they were using aluminum voice coils 'til much later. No evidence of crimping the actual wire has been located, (only hollow brass rivets and solder) but the odd 50 ohm voice coil measurement leads me to believe further investigation is in order. In addition, a replacement output xformer with 8 ohm secondary, was installed for first rebuild. The wire leads from the spider to frame feedthru was #22/24 solid, which I found troubling, but left as is on original rebuild to maintain authenticity. This time around though, I've found some tiny coax in my junk box with silver plated shield, and when stripped of its center conductor, makes a nice flexible wire for the spider connection. I would caution other users of this method to be careful in soldering it though. Use a minimum heat, assure that the added length of shield is aimed upward to avoid wicking of the solder into its entire length, and rendering it solid/inflexible. Even after pulling it taut (its like a Chinese Finger), it still has a hollow core, and will suck up solder better than most commercially available solderwik.
:marv
:
::The winding is copper and not aluminum, right? I don't think they started using aluminum until the late 1930s-early 1940s (for high frequency response purposes--FM). Aluminum is not solderable, and so the connections must be crimped. Corrosion develops. If your winding is copper, though, and is soldered, then it is not likely corroded at the solder connections. Has the tinsel wire perhaps broken (if tinsel wire is used)? Sometimes the tinsel will break or corrode and yet the fibres will make the wire appear to be complete.
::
::I am by no means an expert on speakers, so this is about as much as I can guess. Some superb books for any radio hobbyist to read are those written by G.A. Briggs. I have his "Sound Reproduction." There is another that strictly deals with loudspeakers, but I do not know if it deals with their construction or with practical and scientiffically correct application. Read them anyway. They are a feast for the brain. Incidently, I saw my book sell recently for over $95.00 on the internet. It may be hard to obtain.
::
::Thomas

Thomas,
It is indeed aluminum, and presumably oxidation and use
managed to degrade the crimp. I found it under some sort of black sealant, which I managed to scrape away and uncrimp. Gently scraped the wire and the crimp of any oxide. Re-clamped the crimp with sutchures and applied a small bit of super glue to hold the crimp. Applied a small drop of liquid contact cement as a sealant. I'm back to 10 ohms DC resistance at the VC terminals, so my old Edison 7R should be back in operation soon. The DC resistance of #32AWG aluminum is nearly equivalent to #34AWG copper, but still can't get the 10 ohm DC to agree with any of my calculations related to core size and wire length. Core is 1.61" O.D with 21 turns per layer x 2 layers. John, hope you're still out there. Didn't mean to ignore your rattle, which started this whole string.
marv

:The winding is copper and not aluminum, right? I don't think they started using aluminum until the late 1930s-early 1940s (for high frequency response purposes--FM). Aluminum is not solderable, and so the connections must be crimped. Corrosion develops. If your winding is copper, though, and is soldered, then it is not likely corroded at the solder connections. Has the tinsel wire perhaps broken (if tinsel wire is used)? Sometimes the tinsel will break or corrode and yet the fibres will make the wire appear to be complete.
:
:I am by no means an expert on speakers, so this is about as much as I can guess. Some superb books for any radio hobbyist to read are those written by G.A. Briggs. I have his "Sound Reproduction." There is another that strictly deals with loudspeakers, but I do not know if it deals with their construction or with practical and scientiffically correct application. Read them anyway. They are a feast for the brain. Incidently, I saw my book sell recently for over $95.00 on the internet. It may be hard to obtain.
:
:Thomas

Strange that it used aluminum! Neat, though. Aluminum was used in more recent speakers because it is lighter, and will cause a higher frequency resonance. With heavier copper wire, the voice coil cannot vibrate at super high frequencies. This sounds strange when one considers the weight of an entire speaker cone, but one must remember that the treble notes come from the center of the speaker, not the entire cone, and the cone actually does not vibrate as one, but instead different portions move differently to different frequencies. Sometimes waves are set up along the cone surface. This is also the reason why bands are sometimes stamped into the paper. Some speakers have this done in a scientiffic way and others just have a whole bunch of bands. The bands cut out certain peaks, though, and allow different parts of the cone to vibrate separately.

Well, hopefully the speaker works well now. One thing to keep in mind about the resistance: aluminum has a higher DC resistance than copper. I have run across several speakers with aluminum coils that have a resistance around 10 ohms DC.

Good luck!

Thomas

Well after a radio failure and computer failure, I'm back again to frustrate all willing to read. After speaker repair, got back to my original task of chasin' that nasty hum (120Hz) problem in my old Edison 7R. Showed up on the plate (27) of the first RF amp, at 5 discrete locations on the AM dial and even with the antenna terminal grounded. An RF signal actually showed up being modulated with 120 Hz. AH HA, must be coming in thru the power. Carried a little AC powered table top throughout the house, and sure enough it was everywhere. But wait, I can further verify this with a battery operated set. Using a small battery operated AM set as a RF sniffer, I was able to pinpoint the source. A cheap (probably video only) coax cable carrying internet and TV into one bedroom and another routed to an adjacent bedroom. High speed INET and CATV are great, but cheap, leaky coax cables can destroy AM radio reception. The computer had dirty contacts on the battery/holder for the BIOS data retention, and once cleaned, booted up and runs fine now. Next task, replace the coax cables and try my old Edison 7R again. Maybe I'll be able to hunt for Chocolate Bunnies tomorrow.
marv

:Strange that it used aluminum! Neat, though. Aluminum was used in more recent speakers because it is lighter, and will cause a higher frequency resonance. With heavier copper wire, the voice coil cannot vibrate at super high frequencies. This sounds strange when one considers the weight of an entire speaker cone, but one must remember that the treble notes come from the center of the speaker, not the entire cone, and the cone actually does not vibrate as one, but instead different portions move differently to different frequencies. Sometimes waves are set up along the cone surface. This is also the reason why bands are sometimes stamped into the paper. Some speakers have this done in a scientiffic way and others just have a whole bunch of bands. The bands cut out certain peaks, though, and allow different parts of the cone to vibrate separately.
:
:Well, hopefully the speaker works well now. One thing to keep in mind about the resistance: aluminum has a higher DC resistance than copper. I have run across several speakers with aluminum coils that have a resistance around 10 ohms DC.
:
:Good luck!
:
:Thomas
:
:

Computers themselves can cause a lot of noise, as well as the supposed interference supressors that they are sometimes plugged into. Unplug your computer and all of its associated conglomeration. Try operating the computer connected directly to the wall. We threw out our noise supressor gizmo. There wasn't much in it to protect the computer anyway--certainly nothing to correct voltage spikes. There's no way it would have supressed a lightning strike. Without the horrible beast, I am now able to operate all of my radios virtually static free. A friend of mine who I have lent my M-W 62-306 is not so lucky. His roommates have wireless internet. I put some extra electrolytics in the power supply at places where they were not before (by experimentation), put a choke on one side of the line cord (both sides would not allow use of the cord as an RF ground), and put a .001 MFD condenser from each side of the line to the chassis. This helped a bit. The plug must be inserted so that the choke is on the hot side.

Unless your power company is shady, you can likely get by with your computer plugged directly into the wall.

Thomas

Thomas,
Interesting , very interesting. It seems that my conclusion, (radiating coax cable solely) although very probable, was a bit hasty. All computers were off during a lot of my testing, so I can disregard them
as a source. The AC line protectors, of which there are several, were however, still active at somewhat lower levels. I do have wireless installed, but its contribution appears to be minimal. In my latest test, the CATV was disconnected at the house interface, modem and wireless router were unpowered, but the noise persisted. No Chocolate Bunnies today. Further tests required. Film at 11.
marv

:Computers themselves can cause a lot of noise, as well as the supposed interference supressors that they are sometimes plugged into. Unplug your computer and all of its associated conglomeration. Try operating the computer connected directly to the wall. We threw out our noise supressor gizmo. There wasn't much in it to protect the computer anyway--certainly nothing to correct voltage spikes. There's no way it would have supressed a lightning strike. Without the horrible beast, I am now able to operate all of my radios virtually static free. A friend of mine who I have lent my M-W 62-306 is not so lucky. His roommates have wireless internet. I put some extra electrolytics in the power supply at places where they were not before (by experimentation), put a choke on one side of the line cord (both sides would not allow use of the cord as an RF ground), and put a .001 MFD condenser from each side of the line to the chassis. This helped a bit. The plug must be inserted so that the choke is on the hot side.
:
:Unless your power company is shady, you can likely get by with your computer plugged directly into the wall.
:
:Thomas