HELP! I blew an old field coil speaker...

J D Sauser · Post by **J D Sauser** » 21 Jan 2005 10:30 am

I have an old little Rickenbacher amp, one of those that are the size of a briefcase and made of black wrinckle finish painted sheet metal.
Up to yesterday it was my best sounding amp for lap steel until I noticed a buzzing sound and after checking alomost everything else found that 3/4 of the cone's circumference was loose at the speaker's rim (the paper is torn).
Given that this is a field coil speaker (no magnet) and thus using a unique wirering I wonder if it can be replaced with a normal speaker. This is not what I really want to do. I would much rather have the original speaker repaired or find an acceptable replacement that works with this setup and fits the style of vintage of this amp.
Anyway... I need help with "do's and not do's", addresses and so forth.

Thank in advance... J-D.

Blake Hawkins · Post by **Blake Hawkins** » 21 Jan 2005 11:17 am

JD, There are people in the antique radio business who restore field coil speakers.
I'll have to dig a little to find an address.

The field coil speaker can be replaced with a regular dynamic speaker.
Since most amplifiers use the field coil as part of the filter choke, you could obtain a filter choke and wire that into the circuit in place of the field coil.
A source for chokes is "Antique Electronic Supply." Their web site is: www.tubesandmore.com

It is also possible to use a resistor in place of the choke. You might then have to increase the value of the filter caps a bit.

With a ripped cone, you can use another old technique to repair the tear: That is to take some cotton from a cotton ball, saturate it with glue and press it on the cone to bridge the gap. It may change the tone of the speaker, but will get you going
until a better way can be found.
Since your cone is torn around the rim, you can get a large piece of felt, cut it so that it fits around the rim and covers the tear, then cement it in place. Repair kits are sold for the '70's hi fi speakers that originally had a foam suspension. But you can make your own easily.

These speakers also have an extra "hum bucking" winding on the voice coil, so an ordinary reconing kit can't be used.

Do you have a schematic of the amp?

Blake
[This message was edited by Blake Hawkins on 21 January 2005 at 11:22 AM.]

J D Sauser · Post by **J D Sauser** » 21 Jan 2005 11:45 am

Thanks for your time and valuable input, Blake.
No, I don't have chematics of this amp. Keep in mind this is an map that was made before and during WWII.
I would really prefer to keep the circuitry as is, in other words to keep the field coil design because of the vintage and the value of an original piece of history.
So, repair, professional or DoItYourself would be my preferred way to go.

Thanks! ... J-D.

Jon Light (deceased) · Post by **Jon Light (deceased)** » 21 Jan 2005 2:13 pm

Stand by, J-D---I have an inquiry in to Ted Weber at Weber speakers. I can't recall but they may do field coil work. I'll get back to you here when I get an answer.

Jon Light (deceased) · Post by **Jon Light (deceased)** » 21 Jan 2005 4:15 pm

OK, J-D----here's the Q & A at the Weber board.
http://www.webervst.com/speakers/messages/1436.html

And here's the Weber website with contact info:
http://www.webervst.com/

Luck.

Andy Zynda · Post by **Andy Zynda** » 21 Jan 2005 5:15 pm

Ted Weber is the King of the cone. If he can't repair or recone it, I'm a bearded gnome.
-andy-

Sam Marshall · Post by **Sam Marshall** » 22 Jan 2005 6:39 am

Fender purchased jukebox speakers for this application about 12 years ago. There must be a vintage jukebox component supplier out there. I seem to remember that it was a standard replacement part available from whoever was left in the jukebox business back then.

Also try Antique Electronics in Tempe, AZ.

Ted Weber does great work as witnessed by the Weber/Eminence speaker in Fender's '57 Twin re-issue. Weber designed it; Eminence manufactures it with Weber tone approval.

Regards,
Sam[This message was edited by Sam Marshall on 22 January 2005 at 06:44 AM.][This message was edited by Sam Marshall on 22 January 2005 at 06:45 AM.]

Blake Hawkins · Post by **Blake Hawkins** » 22 Jan 2005 8:52 am

Jon has found the answer.

That's where I'd send it if it were mine.

Blake

J D Sauser · Post by **J D Sauser** » 24 Jan 2005 1:55 pm

Jon and all others, thank you very much...
<BLOCKQUOTE>quote:<HR>Yes, we recone between 20 to 30 field coil speakers a month. So far we haven't had any we couldn't do. We'd be happy to take a look at that one.

Thanks,

Ted<HR></BLOCKQUOTE>
Now THAT sounds good, doesn't it?
The day looks brighter again...

Thanks! ... J-D.

Jennings Ward · Post by **Jennings Ward** » 25 Jan 2005 8:42 pm

I HAVE SOME EXPERIENCE IN THIS FIELD, REALLY IN ITS SIMLEST FORM AND TERMS, A "FIELD" COIL IS ONLY A CHOKE THAT IS PART OF THE POWER SUPPLY CIRCUIT...THE REASON THAT IT WAS PUT ON VERY EARLY ELECTRONIC AMPS AND RADIOS IS OR WAS SIMPLY COST AND SPACE....THE MAGNET OF THE SPEAKER SERVED AS PART OF THE " FIELD " FOR THE POWERSUPPLY CHOKE. SIMPLY A L0T OF WIRE WRAPPED ARROUND A MAGNET.... THE CONE AND VOICE COIL ARE NOT CONNECTED IN ANY WAY, EXCEPT FOR MOUNTING, TO THE FIELD COIL "CHOKE" ANY REPUTABLE PLACE THAT RECONES SPEAKERS SHOULD BE ABLE TO RECONE THE SPEAKER...THER IS SUCH A PLACE IN FT. WAYNE , INDIANA THAT IS VERY GOOD AND REASONABLE, AND GUARENTEES THEIR WORK....GET INFO FROM INFORMATION......I SEND MINE TO A FRIEND.....IN FT. WAYNE.... I HOPE THIS HELPS IN SOME SMALL WAY,, IT IS NOT THE MONSTER THAT SOME WOULD HAVE YOU BELIEVE....P.S. YOU CAN USE A REGULAR SPEAKER OF THE CORRECT IMPEDANCE AND ADD A CHOKE { OUTBOARDED ] USE CORRECT MILI HENRIES.AND VOLTS AND AMPS. IT CAN BE DONE, I HAVE DONE IT IN A PINCH. WORKS GREAT....BUT YOU MUST MATCH REPLACEMENT PARTS... TAKES SOME DOING THE FIRST TOME ,,AGAIN I HOPE THIS HELPS............JENNINGS

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