12" feild coil speaker "WOW" - diyAudio
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Old 28th December 2011, 01:33 AM   #1
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Default 12" feild coil speaker "WOW"

I inherited a Wards Airline radio from my uncle. This thing is from the 40s. Its open back cabinet measures 42" tall X 27" wide and 14" deep.

I've read a littel about these feild coil speakers being used in the 40s guitar amps. I thought this 12" speaker mounted in a 20" metal bell might sound good?

We it sounds awsome. I disconected the speaker voice coil from the radio OPT. Added leads with a 1/4" plug, turn the radio on to power the magnet. Then connected it to a 50s DB10A Bogen amp I've rebuilt.

The bass is astounding. Plenty of bite and for harp its amazing how loud and close you can place the microphone.

This thing sounds way bigger the 10 watts. I think the radio power was around 20 watts. It uses 4 6F6s in a ppp configuration. I figured I'd be safe at 10 watts. I didn't want to hurt this vintage speaker. It sounds so good at 10 watts, so I'm very happy.

Now to build a guitar amp type cabinet and a proper power supply for the magnet.

I realize a smaller cabinet will reduce bass.

Jerry
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Old 28th December 2011, 02:11 AM   #2
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I have a Wards Airline receiver as well mine is a 1939 model.
It used to work but it is in very sad shape right now.
I got it in 1977 or 78.

It had a very warm sound to it and I loved to listen to it.
It was a great tube receiver as it had a tuned RF amplifier stage and two I.F. stages.

I had a copy of the Sams Photofact print to it, but it got lost through the years.
The field coil was part of the power supply filter system that powered the High voltage for the whole radio.

With the 4 X 6F6's I am sure it is closer to 30 or 40 watts output max as they were rated a bit less than the 6L6 but more than the 6V6.

Someday I will do a complete restoration on it as I have had since I was 14.

I do need a new power transformer for it.
Because I thought I was going to be smart and solder in some diodes in place of the 5U4 rectifier tube because I needed the tube for my guitar amp and I didn't have a spare.

Well, I botched up the soldering job and shorted out the transformer and smoked it.
So it has sat lifeless as I dragged it with me through my travels.

The film drum has also deteriorated beyond repair and it will be quite a chore to make a new one,However it can be done if I get to it soon and scan in the peices I do have.
Otherwise I will have do some major art work and try to find out all of the radio call signs from that era that were on the film drum.

I am sure that you will get a nice creamy sound from that old speaker.
The little phenolic S shaped spider is what fascinated me the most about that speaker.

What Are you planning to do with the rest of it?


jer

P.S.Mine might be even earlier like 1934 or 35 model it has been a while since a I have even looked it over.

Last edited by geraldfryjr; 28th December 2011 at 02:17 AM.
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Old 28th December 2011, 02:39 AM   #3
jmsent is offline jmsent  United States
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Be very careful. Those speakers are not very robust, with a small voice coil using a paper former. The field coils are generally wired between 2 sections of the radio power supply and act as a filter choke. Additionally, there's a hum bucking coil that's usually in series with the field coil to cancel the hum added by the field coil. You should measure the voltage across the coil to determine the voltage. But be careful as there will be over 300 volts between the coil connections and chassis ground.
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Old 28th December 2011, 04:23 AM   #4
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I believe the voltage on that Chassis was in the order of about 420V to 480v.
On my model there was not a bucking coil.
I still can remember the schematic very well as I studied it for many many years and was it was only in the last five years that it had gotten lost.

If the chassis still works,you may be better off taping in after the 6H6 dual Diode detector.
This way you will still be able to use the speaker without risk of frying it with the original amplifier, as well maintaining the proper power source for the field coil.

If I remember correctly it also has a bass and treble control circuit as well,I would have to go out to the garage and look to confirm this.

That amp had I very nice High Fidelity sound when I got a decent station on it, and, Back then the best ones around here was CKLW,WJR and WWJ just to name a few.

I liked the sound so much that I was going to use a modern Hi-Fi speaker in place the the original because it had some very clean and crisp highs to it.

I did alot of SWL Dxing back then and that radio was a charm and quite sensitive for an old tube job.

But my little mistake kinda put a halt on that for a while.

Tomorrow I will charge the batteries for my camera and get some Pics for you and see if it is the same chassis or similar.



jer
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Old 28th December 2011, 10:35 AM   #5
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Join Date: Jul 2005
Location: North Derbyshire
Back in the 70's I was given the 'PA' from a very old cinema, it consisted of two field coil 18" bass units (BTH if I remember correctly?), a single treble unit with a wooden lattice horn, and a 19" rack amplifier 6 feet tall (which had just one single knob 4" for volume, and only outputed about 10W I think?).

Anyway, we built the bass units in two nice big cabinets (as we were starting a rock club at a fixed venue), along with a home made PSU for their field coils - we just guessed the voltage). We hung the treble unit from the ceiling on chains, and powered the whole lot from a 125W amplifier module - only mono in those days.

They sounded great, and withstood the power quite happily - considering we didn't have a clue as to their ratings.

They were still there when the club closed, I presume they probably got thrown away?.
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Old 28th December 2011, 02:51 PM   #6
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Quote:
Originally Posted by geraldfryjr View Post
I have a Wards Airline receiver as well mine is a 1939 model.
It used to work but it is in very sad shape right now.
I got it in 1977 or 78.

It had a very warm sound to it and I loved to listen to it.
It was a great tube receiver as it had a tuned RF amplifier stage and two I.F. stages.

I had a copy of the Sams Photofact print to it, but it got lost through the years.
The field coil was part of the power supply filter system that powered the High voltage for the whole radio.

With the 4 X 6F6's I am sure it is closer to 30 or 40 watts output max as they were rated a bit less than the 6L6 but more than the 6V6.

Someday I will do a complete restoration on it as I have had since I was 14.

I do need a new power transformer for it.
Because I thought I was going to be smart and solder in some diodes in place of the 5U4 rectifier tube because I needed the tube for my guitar amp and I didn't have a spare.

Well, I botched up the soldering job and shorted out the transformer and smoked it.
So it has sat lifeless as I dragged it with me through my travels.

The film drum has also deteriorated beyond repair and it will be quite a chore to make a new one,However it can be done if I get to it soon and scan in the peices I do have.
Otherwise I will have do some major art work and try to find out all of the radio call signs from that era that were on the film drum.

I am sure that you will get a nice creamy sound from that old speaker.
The little phenolic S shaped spider is what fascinated me the most about that speaker.

What Are you planning to do with the rest of it?


jer

P.S.Mine might be even earlier like 1934 or 35 model it has been a while since a I have even looked it over.
Its model # 62-403. A google search says 1939. There is an anteque radio site that has a down load for the schimatic.

I do plan on a complete restore of this old radio. I'm an old radio and crystal set hobbiest. I did a DIY build on a TRF radio a year ago. I listen to that daily.

I'll do a picture of the Wards and my TRF in a day or 2. I also have a 1920 Wards TRF as a daily listener in another part of my shop.

Intresting responces here. I glad someone else also has this radio.

Jerry
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Old 29th December 2011, 01:34 AM   #7
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Location: Jackson,michigan
I too am into such things !
I am happy to find some one whom might have the very same radio and that you plan on restoring it.

I didn't get a chance to get those pictures today as well but I will sometime very soon.

I once found a book an antique radios and it was listed in it,its worth back then (probably 25 years ago) was about $250 to $400 and mine was almost mint condition back then except for the burn't transformer.

Sadly there weren't any pictures of my model in the book but the models that they did show were very similar in the styling.

But now it has been badly damaged but it is very repair able and I will have to replace or repair a spot in the veneer when I do it.
And I had lost the wooden knobs with the brass inlays so I will have make those as well.

It may be worth a whole lot more once it is restored, But to me the thing is just priceless even in its broken state so I will probably never get rid of it as I would like very much to see it running again before there are no more AM radio stations for it to pickup and play again.

I also have an old all tube dual tuner AM/FM Stereo Fisher reciever with amps (500 series I believe) in my collection as well and it runs, also a tubed tuner / solid state Scott receiver, But I always want to have an Atwater Kent radio in my collection,Hmmmm...........Maybe one day !! he,he

jer

Last edited by geraldfryjr; 29th December 2011 at 01:38 AM.
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Old 30th December 2011, 01:56 AM   #8
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Join Date: Dec 2011
Default field coil speakers

I never heard of a field coil speaker. I bought a theater organ from a church last week and the speaker box has 2x15 and 2x12. The 12s are mounted on a gyro for a leslie tremelo effect. They have square magnets. But the 15's didn't have magnets and have their own output transformer. Then I was watching a Gerald Weber DVD on Tube Guitar Amplifier Servicing and Overhaul when he pulls out these 3 old Valco amps. He said the small one was the oldest because it has a field coil speaker in it. So a lightbulb went off in my head and I realized why my speakers looked odd.
Anyway, I am not sure how to use them as extra speakers for my combo amps, but I'm trying to study and learn about such things. I am glad to know that you were impressed with the sound.
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Old 22nd June 2012, 11:57 AM   #9
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Here is a link for a print to your radio,

Nostalgia Air: Montgomery Ward & Co. - 62-403



jer
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Old 22nd June 2012, 01:02 PM   #10
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I started out in this hobby making guitar amps out of old radios and TV sets in the 1960's. I did build some guitar amps using field coil speakers. A field coil speaker works very well on a tube guitar amp when used well within its power ratings (which were pretty low) and as some have found sound pretty good. I even used some 15 inchers from old organs for bass guitar.

I found out that a field coil speaker and a solid state amp doesn't work too well if the amp has good low frequency response. These old speakers with phenolic spiders are very easy to bottom out. I made a SS amp in high school using the Li'L Tiger (SWPTC) power amp design. The preamp was copied from a popular SS guitar amp of the day (Kustom or Acoustic probably) the amp destroyed two 15 inch field coil speakers due to bottoming. I finally spent the money on a real Utah guitar speaker. The amp sounded slightly less "alive" but lived on for several years without incident.

Back then I used SS rectified and filtered wall outlet to power the coil with a big green power resistor in series. That was over 40 years ago so I can't remember the value. Today we know that an isolation transformer would be needed to avoid frying guitar players.
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