Goodmans Magnet: Feroba ll or Alnico?

[Rockaway]

Can anyone identify the magnet type of this unbadged Goodmans. It should be
Feroba ll however my understanding of those is that they would be in a ring structure and of a brownish composite material, not an alloy as this image suggests.

Thanks,

Jason

http://img401.imageshack.us/img401/6958/goodmansbells.jpg

An externally hosted image should be here but it was not working when we last tested it.

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[Rockaway]

Nearly one hundred people have viewed this and not a single guess? This must be one hell of a unique magnet!

 

[devilsindetails]

Are these co-ax, tri-ax or single cone FR? Are you sure they are Goodmans? If they are I think they may be of American origin badged Goodmans perhaps at some point? I believe Lafayette and a few other companies including Knight utilized Goodmans drivers and/or just the Goodmans nameplate on other drivers manufactured elsewhere but licensed by Goodmans.

The Magnet cover is almost a doppleganger for many EVs of the period so it would seem to be some iteration/hybrid of a ceramic motor. I'm making this guess because the basket frame construction indicates very late 60s production IMO.

I've had many Goodmans over the years, yours are stumpers I believe some Stephens Trusonics and Utahs used a similarly constructed motor...I'll have to takes the magnet covers off of mine at some point and refresh my memory.

Perhaps someone else will zero in...I'll have to go through some old Goodmans Literature I have on hand. Regards. Leon.

 

[Rockaway]

Leon,

Thanks for getting back to me. First off, they are Triaxioms. The Lafayette connection has come up before. The "Made In England" cast stamp is pure Goodmans and supports your suspicion that these were made by Goodmans for Lafayette or other US distributor. I am including a shot of the front to help ID them. They have the corrugated treated fabric surrounds and the cast aluminum tweeter horn. They weigh 22lbs per. That would put them on par with the 612c I believe. Thanks again for your input.

Regards,

Jason

An externally hosted image should be here but it was not working when we last tested it.

 

[Rockaway]

Additional pics:

[IMG][URL=http://imageshack.us/photo/my-images/204/5a883.jpg/][IMGDEAD]http://img204.imageshack.us/img204/3104/5a883.th.jpg[/IMGDEAD][/URL]
[URL=http://imageshack.us/photo/my-images/832/5fa43.jpg/][IMGDEAD]http://img832.imageshack.us/img832/8899/5fa43.th.jpg[/IMGDEAD][/URL][/IMG]

[img=http://img832.imageshack.us/img832/8899/5fa43.th.jpg]

 

[devilsindetails]

Hi Jason. Can't zoom in on your photos except at photobucket

I have some older Triaxoms (Alnico) see pics with Trebax HF drivers but the motors are about half of what you have there. (Got em cheap cause they were missing the decal/tags)

If my memory serves me, Goodmans, Tannoy, Vitavox, Wharfedale and others of the period were experimenting with some kind of new magnet (pre-ceramic period) and post Alnico. Something with aluminum, cobalt, selenium and ferrous iron or some other mysterious mix....might be what you have there.

Definitely serious heavyweights you have there....my Stephens Trusonics weigh in at 28lbs per...but I'm pretty sure they are Alnicos....what you have there is a lovely mystery...I'll keep digging through my old Goodmans/Lafayette/Knight literature...no other ideas out there?

 

[devilsindetails]

Hi Again.....Well delving a little deeper into your Photo Bucket trove...I see you are using these as part of an OB multi-way project with some older Wharfedale Reds....and is that a Wharfedale Super 3 hiding under that waveguide you've constructed? Is it implemented with your OB?

Interesting..very interesting fusion you have going there....

I recognize the Realistic Bullet Supertweet, but what's the other cone tweet on the face of the baffle?

Oh Yah..back to your magnets.sorry.... My best guess looking at your magnet again is it is more than likely just another version of the tried and true ALuminumNIckleCObalt...

 

[Rockaway]

Good detective work Leon. The compression driver is a Russian Kinap thogh. Super 3 is too pricey. Horn as you noted is DIY (ticket roll with shellac poor man's Le CLeac) THe clamped on Tweeter is Bozak.
I am working through HF drivers JBL le26 etc. Currently listening to the Coral holey basket. Hard to find something that blends with the goodmans and is not too harsh.
I use a sony active crossover to blend this mess.

Thanks for your thoughts and images.

- J

 

[devilsindetails]

Jason. I was looking at your set up hoping to find some other clues as to the identity of your Goodmans...interesting Tweeter rolling you have going on...let me know if you discover the identity of those magnet motors.

 

[Rockaway]

Will Do.

- J

 

[Rockaway]

Came across this ad for the Lafayette sk-216 12" Triaxial driver. Made by Goodmans for Lafayette. Clone of the 612c. The ad does not stipulate Magnet type while other ads from the same catalog or era identify other drivers as having ceramic motors. Can't figure this one out. incidentally my speaker has the treated cloth or paper surrounds whereas these have a type of plastic or rigid rubber.

http://img607.imageshack.us/img607/7467/lafayettesk216.jpg

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ImageShack.us[/IMG][/IMG]

 

[Rockaway]

This Just in from Early at Hifitown.com. He has great video comparisons of vintage drivers on youtube and seemed the most knowledgeable person on Goodmans. I agree (albeit, somewhat biased in my view) with his assessment of the magnets on my drivers. I have cast metal using sand as an investment material and that is what the donut shaped hunks of metal on the backs of these look like. Mystery Solved? See letter below:

Dear Jason, at first glance I think they are late version Alnico -- which is a sandcast solid piece.

Ferrite usually consists of layered ceramic with metal on top and bottom forming the pole piece. It appears yours is a "donut" of cast material.

Thanks for your interest and will be posting videos of Goodmans Deco Studio units soon!

Nice drivers-- enjoy!

Best Regards,
Early

 

[devilsindetails]

Yes...likely..and yet, some doubt remains. My Goodmans friends in Britain have not seen this kind of magnet/motor on their side of the pond...

 

[sreten]

Hi,

Generally for drivers with that sort of bolt in the middle its holding a central
Alnico slug. Usually the outside pole piece is stamped steel but here it seems
its some form of cast piece. Its possible the cast piece is some form of
magnet and the bolts holding a plain pole piece. If so the magnet is not
feroba, its still Alnico (or very similar). It could be expensively all Alnico.

rgds, sreten.

 

[Rockaway]

What do you make of the vague wording in the description of the Lafayette SK 216:
"Massive 9lb magnet structure" with no further indication of the type as is nearly always the case with ads of this period?

 

[Rockaway]

Doubt anyone but me cares about the mystery has ended. The model for this driver is: Knight KN850. It was made in England for knight and listed in an Allied Electronics catalogue from 1960. Magloy is the magnet type and this driver uses 5lbs of the stuff. Sold for $79 USD In 1960. Upper frequency range claimed was 20cps. That is higher than many drivers I've seen from that era. I never cared for the built in tweeter so have spent large sums of money and time trying to better it. Weighs 22lbs. Hope to get specs on this some day. There are a few singles on eBay and pairs pop up but rarely.

 

[Rockaway]

I give up, image shack is the worst. Will try with another image host. Info can be found here: http://www.vintageradio.com/history/Allied1960.pdf

 

[kevinkr]

If you see the option "go advanced" click on it, otherwise scroll down, click "manage attachments" then click on "browse" and navigate to where your photos are stored, click browse and upload for each file in turn. It's easy and keeps your thread relevant over time. (Also works with other types of files as long as they are not too big.)

 

[Rockaway]

Ok figured it out......I think

 

[kevinkr]

It's working..