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Field Coil 18inch woofer

F

FC Frank

New Member
Hi all,
Im new to Audiokarma and would live to let you know what is new. Have been working on a field coil 18 inch woofer system for a few months.
It giving me the tightest fastest bass I have ever experienced. Running at 12 to 22 VDC drawing 1 to 1.4 amps. I find the sweet spot at 18 VDC / 1.1 A.
Crossover at 400 Hz to JBL 2365 horn / JBL 2440 AlnicoV driver.
97 db so using 300B to drive the system. Yes Go Big or Go Home is my motto, Theses really show what lack of compression in
audio can do.
Cheers
Frank
 

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FC Frank said:
Hi all,
Im new to Audiokarma and would live to let you know what is new. Have been working on a field coil 18 inch woofer system for a few months.
It giving me the tightest fastest bass I have ever experienced. Running at 12 to 22 VDC drawing 1 to 1.4 amps. I find the sweet spot at 18 VDC / 1.1 A.
Crossover at 400 Hz to JBL 2365 horn / JBL 2440 AlnicoV driver.
97 db so using 300B to drive the system. Yes Go Big or Go Home is my motto, Theses really show what lack of compression in
audio can do.
Cheers
Frank
Click to expand...
Now that's a horn. I've wondered why a speaker manufacturer hasn't produced a field coil woofer, modern. Seems like the best way to go, controlled field that does not change with age and is adjustable.
 
spicer said:
Now that's a horn. I've wondered why a speaker manufacturer hasn't produced a field coil woofer, modern. Seems like the best way to go, controlled field that does not change with age and is adjustable.
Click to expand...
Well there are some field coil speakers out there but they are very expensive. Even mine is expensive due to cost of making the one off parts.
The driver starts life as a TAD 1801 woofer cone/basket assembly and custom field coil added.
Frank
 
Sorry for some reason I didn't take a photo of the back. Next time I lift the 55 pound woofer out I will take photos and post and post them.
Frank.
 
I would have to ask the gentleman who made it for me. As far as I know it took a few days to complete.
I had the choice between a JBL 18 or the TAD. Chose the TAD because it had a 18 Hz low end.
Frank
 
I find it rather amusing to look at your picture and then think of an Altec 604 with the tiny horn,
just the contrast. I'm sure that they both sound quite excellent!
 
FC Frank said:
Well there are some field coil speakers out there but they are very expensive. Even mine is expensive due to cost of making the one off parts.
The driver starts life as a TAD 1801 woofer cone/basket assembly and custom field coil added.
Frank
Click to expand...
As I posted was thinking there probably are some new ones and they would be quite expensive. Except for needing a power supply, plugging in the speakers, it doesn't seem that much more expensive to make an electromagnet versus a permanent magnet for the speaker, maybe less expensive, it's just a coil and a simple power supply. Kind of wonder why upper middle of the road offerings don't make use of it, would be great to control flux density on demand, tune things a bit to one's desire. I'm sure there's a reason.
 
Well have run 15 and 18 inch Neo coaxials with 3 inch compression drivers on them. Now I realize that the larger the driver is the more relaxed.
This is a byproduct of less audio compression. Everyone that header the big horn says that they are so smooth without loosing detail.

Unfortunately it is expensive to make field coil drivers in small numbers. The power supply has to be clean with no ripple and stiff so the voltage stays constant.
All this costs big bucks. So far field coil based speakers are $15K and up. Good power supplies are $ 3K plus. The manufacture of my 18 charges $8K for his.
 
A few year ago I built a pair with Walnut Yuichi horns for an other project. Used 18" Radian sub woofer with customer supplied JBL 375 com driver.
Now the 375 was unopened, still having the red wax in the screws. I could not get the 375 to sound good and my friend did not want to change
the diaphragm. He thought that would devalue the 375. Well I finally convinced him to go for the Radian Berilyum 4 inch diaphragm. Last week I got
an email from him raving on how great the Be was. He couldn't believe how huge the difference is.

The problem is some guys will live with old diaphragms which have metal fatigue and go off spec due to usage and age. Radian replacements
for JBL and Altec drivers are better than originals. If you look closely you will see tha Radian uses a Mylar surround. This give a much smoother
delivery than solid alum or titanium foil. Right alum left Beryllium

I have to say nice as the Yuichi horns(below) were they couldn't compare to the big JBL 2365 horn with the same driver.
Frank
IMG_2357.jpgDSCF0893 2.jpeg
 
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