Magnet Manufacturers
Most loudspeaker companies bought their magnets from various suppliers. The five big names of magnet manufacturers are listed below.
You will find almost any speaker producer has used at least two or three of
these "outsourced" suppliers.
Siemens makes an exception: after around 1952/53 Siemens has ONLY used the magnets of VAC Vacuumschmelze Berlin,
being part of the Siemens empire. Before that Siemens has used Tigges and Magnetfabrik Bonn for example.
DEW Magnetfabrik Dortmund also makes an exception as they have build entire speaker systems (magnet, frame, cone)
on commission and to the specification of other radio/speaker companies. The role of DEW as a speaker producer must be
investigated further!
VAC Vacuumschmelze Berlin Tigges Magnetfabrik Bonn DEW Magnetfabrik Dortmund
[F's Comment: Short history of permanent magnets]
KS Steel: magnetic steel including ironl, Cobalt, Tungsten and chrome, developed by Dr. Mitsutaro Honda in 1917.World-wide invention.
MK Steel: epoch-making magnetic steel including iron, alminum and Nickel developped by Dr.Tokuhichi Mishima in 1931.
Cheaper than KS Steel, twice stronger than it. MK was named after Mishima and Kisumi which was his birthplace.
Basis of AlNiCo. Tokyokozai co. had its patent in Japan, GE in US, Bosch in Europa.
AlNiCo: MK improved in America in 1932. MK added Cobalt and Copper was called AlNiCo.
Its magnetic flux density is higher, Magnetostriction is lower, and Fluxgap is sharper than
that of Ferrite magnet having the same flux quantum.
1.Magnetfabrik Bonn
The Magnetfabrik Bonn was founded in 1932 by Gerhard Grönefeld. Being one of the leading manufacturers of permanent magnets
the companie's marketshare grew fast. But, like so many other companies, it suffered drastic setbacks during and after WWII.
Due to raw material shortage Grönefeld even had to change the production line to household appliances. As of 1947 the company
returned to the production of permanent magnets. At present the Magnetfabrik Bonn employs around 200 people. Production focuses
on the development, production and sale of magnets. Today it is the only company in Germany which can produce all common magnetic
materials in their own production plants.
2.VAC Vacuumschmelze Berlin
The company was founded in 1923 under the name of Heraeus-Vacuumschmelze AG.
In 1933 Siemens bought the stock majority. With the Vacuumschmelze Berlin Siemens had it's magnet manufacturer
under it's own roof. Only Siemens and Klangfilm loudspeakers were equipped with VAC magnets. Before around 1952/53
Siemens used various magnet suppliers for their drivers.
3.DEW / Magnetfabrik Dortmund
(Frank's comment:There seems to have been a relation between Magnetfabrik Dortmund and Thyssen Edelstahlwerke.
Maybe They were in the same place.The name DEW stands for "Deutsche Edelstahlwerke".
Edelstahlwerke seems to have belonged to Bosch. Bosch possessed the patent of AlNiCo on the name "Oersit" in the area of Europe
in those days.)
4.Tigges Magnet
5.CKS
6.OERSTIT
I know nothing about the origin of the company Oerstit. But it seems that they belonged to DEW at some point in their history.
Today they are part of the Tridelta group. The choice of the name "Oerstit" can't be a coincidence: Find above the portrait of
Hans Christian Ørsted (August 14, 1777 – March 9, 1851). For those of you who can't know this: some scandinavian alphabets include
the letter "Ø"; this letter is pronounced the same way as the German letter combination "Oe". He was a Danish physicist and chemist,
influenced by the thinking of Immanuel Kant. He is best known for discovering the relationship between electricity and magnetism known
as electromagnetism.The oersted is the CGS unit of magnetic field strength (or magnetic induction).
The magnetic field produced at the center of a plane circular coil of one turn and a radius of one centimetre,
which carries a current of 5 amperes.
H(oersteds)=0.4πN(turns)I(ampere)/l(centimeter)
In SI units, 1 oersted = 1000/(4π) A/m = about 79.577 A/m
In vacuum, magnetic field strength of 1 Oe is equvalent to magnetic flux density of 1 gauss.
F's comment:
I found the following engraved mark on an Oerstit magnet.
---------------------
OERSTIT
O.R.G.M 1275415
FR.PAT. 754819
D.E.W.(between OERSTIT logos)
---------------------
Apparently OERSTIT logo, E in the hexagon indicates Edelstahl and the original shape of OERSTIT magnet.
Concerning the relation between D.E.W. and Edelstahl, see the section D.E.W.
Most loudspeaker companies bought their magnets from various suppliers. The five big names of magnet manufacturers are listed below.
You will find almost any speaker producer has used at least two or three of
these "outsourced" suppliers.
Siemens makes an exception: after around 1952/53 Siemens has ONLY used the magnets of VAC Vacuumschmelze Berlin,
being part of the Siemens empire. Before that Siemens has used Tigges and Magnetfabrik Bonn for example.
DEW Magnetfabrik Dortmund also makes an exception as they have build entire speaker systems (magnet, frame, cone)
on commission and to the specification of other radio/speaker companies. The role of DEW as a speaker producer must be
investigated further!
VAC Vacuumschmelze Berlin Tigges Magnetfabrik Bonn DEW Magnetfabrik Dortmund
[F's Comment: Short history of permanent magnets]
KS Steel: magnetic steel including ironl, Cobalt, Tungsten and chrome, developed by Dr. Mitsutaro Honda in 1917.World-wide invention.
MK Steel: epoch-making magnetic steel including iron, alminum and Nickel developped by Dr.Tokuhichi Mishima in 1931.
Cheaper than KS Steel, twice stronger than it. MK was named after Mishima and Kisumi which was his birthplace.
Basis of AlNiCo. Tokyokozai co. had its patent in Japan, GE in US, Bosch in Europa.
AlNiCo: MK improved in America in 1932. MK added Cobalt and Copper was called AlNiCo.
Its magnetic flux density is higher, Magnetostriction is lower, and Fluxgap is sharper than
that of Ferrite magnet having the same flux quantum.
1.Magnetfabrik Bonn
The Magnetfabrik Bonn was founded in 1932 by Gerhard Grönefeld. Being one of the leading manufacturers of permanent magnets
the companie's marketshare grew fast. But, like so many other companies, it suffered drastic setbacks during and after WWII.
Due to raw material shortage Grönefeld even had to change the production line to household appliances. As of 1947 the company
returned to the production of permanent magnets. At present the Magnetfabrik Bonn employs around 200 people. Production focuses
on the development, production and sale of magnets. Today it is the only company in Germany which can produce all common magnetic
materials in their own production plants.
2.VAC Vacuumschmelze Berlin
The company was founded in 1923 under the name of Heraeus-Vacuumschmelze AG.
In 1933 Siemens bought the stock majority. With the Vacuumschmelze Berlin Siemens had it's magnet manufacturer
under it's own roof. Only Siemens and Klangfilm loudspeakers were equipped with VAC magnets. Before around 1952/53
Siemens used various magnet suppliers for their drivers.
3.DEW / Magnetfabrik Dortmund
(Frank's comment:There seems to have been a relation between Magnetfabrik Dortmund and Thyssen Edelstahlwerke.
Maybe They were in the same place.The name DEW stands for "Deutsche Edelstahlwerke".
Edelstahlwerke seems to have belonged to Bosch. Bosch possessed the patent of AlNiCo on the name "Oersit" in the area of Europe
in those days.)
4.Tigges Magnet
5.CKS
6.OERSTIT
I know nothing about the origin of the company Oerstit. But it seems that they belonged to DEW at some point in their history.
Today they are part of the Tridelta group. The choice of the name "Oerstit" can't be a coincidence: Find above the portrait of
Hans Christian Ørsted (August 14, 1777 – March 9, 1851). For those of you who can't know this: some scandinavian alphabets include
the letter "Ø"; this letter is pronounced the same way as the German letter combination "Oe". He was a Danish physicist and chemist,
influenced by the thinking of Immanuel Kant. He is best known for discovering the relationship between electricity and magnetism known
as electromagnetism.The oersted is the CGS unit of magnetic field strength (or magnetic induction).
The magnetic field produced at the center of a plane circular coil of one turn and a radius of one centimetre,
which carries a current of 5 amperes.
H(oersteds)=0.4πN(turns)I(ampere)/l(centimeter)
In SI units, 1 oersted = 1000/(4π) A/m = about 79.577 A/m
In vacuum, magnetic field strength of 1 Oe is equvalent to magnetic flux density of 1 gauss.
F's comment:
I found the following engraved mark on an Oerstit magnet.
---------------------
OERSTIT
O.R.G.M 1275415
FR.PAT. 754819
D.E.W.(between OERSTIT logos)
---------------------
Apparently OERSTIT logo, E in the hexagon indicates Edelstahl and the original shape of OERSTIT magnet.
Concerning the relation between D.E.W. and Edelstahl, see the section D.E.W.
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