Understanding field coil speaker

[loudthud]

There is a company that produced such a product but I don't think it caught on significantly. Probably because a single 12" speaker sold in the $800 range.

That company is called FluxTone. A year ago they had a booth at the Dallas Guitar Show, but not this year. They had an amp with the variable power supply built in and a knob on the front to control speaker sensitivity.

[Tom Phillips]

That company is called FluxTone...

Thanks. I found their web site at https://fluxtonespeakers.com/ and I see that my $800 cost estimate was low. Their 12' speakers list for $1,300 to $1,700 each. There is some interesting sound level info on their web site.

[J M Fahey]

I make speakers and going the field coil way easily costs 10-20 times as much as using a Ferrite ring.
It's a no brainer.
Not even Alnico is justified unless customer *insists* and then he has to pay 4-5 X extra.

[trem]

I make speakers and going the field coil way easily costs 10-20 times as much as using a Ferrite ring.
It's a no brainer.
Not even Alnico is justified unless customer *insists* and then he has to pay 4-5 X extra.

What is the big deal with AlNiCo.?
I am not a guitar player so i have no idea.
All else equal, and with a Ceramic Magnet and AlNiCo of equal strength, what difference do people hear between the two materials.?
Thank You

[The Dude]

There are others, but probably the biggest draw to alnico is weight. It is much lighter for the same amount of magnetism.

[Justin Thomas]

Go figure. I just picked up a projector with a field coil speaker today. Now's my chance to learn a bit, I guess. Once I figure out what to do with them 2A3s...

Jusrin

[pdf64]

I've got a FluxTone speaker, it's really good!
I bought it before they went very expensive, I think it was about £600 in total.
I find it enlightening to be able to have an amp cranked, with nothing interfering with the amp - speaker interaction, at a domestic friendly SPL. It allows artifacts to be heard that would normally get lost in the blast.
The FluxTone founder Steve Carey is a member here, Mr.coil
The field coil is energised by a variable 12V DC 1A supply box.

[Helmholtz]

There are others, but probably the biggest draw to alnico is weight. It is much lighter for the same amount of magnetism.

I don't think there's much difference in speaker weight, but I'm sure J M Fahey would know best.

A Celestion G12 Alnico Blue weighs 4.2kg, a ceramic Greenback is between 3.6kg and 4.7kg depending on type.
A Jensen P10R weighs 1.4kg, a C10R is only 1.2kg.
Alnico has higher magnetic energy density (requiring less magnet volume) but has a higher specific weight.
There are other differences like magnet shape, optimum aspect ratio and the different parts of the magnet circuit.
(Maybe JMF wants to talk about voice coil cooling by the magnet?)

A Neo magnet would be much lighter

[nosaj]

I've got a FluxTone speaker, it's really good!
I bought it before they went very expensive, I think it was about £600 in total.
I find it enlightening to be able to have an amp cranked, with nothing interfering with the amp - speaker interaction, at a domestic friendly SPL. It allows artifacts to be heard that would normally get lost in the blast.
The FluxTone founder Steve Carey is a member here, Mr.coil
The field coil is energised by a variable 12V DC 1A supply box.

I made one which i think I documented on this site from an old baldwin field coild speaker. I think G1 and The Dude helped me get it squared away. Id made it as a separate speaker enclosure so I could hook it up to any amp that used an 8 ohm output.
nosaj

[Helmholtz]

I think the hype for Alnico speakers comes from the fact that some early types really sounded very good giving many coveted vintage amps their voice.
As these early speakers used a low weight paper coil former, they couldn't handle more than 10...15W.
When Alnico was eventually replaced by ferrite (mainly due to increased Alnico cost), the early ceramic speakers had noticeably lower efficiency.
To compensate, power handling was increased using a different coil former (Nomex or Kapton) which could take more heat.
But this changed the tone of the speakers.
Meanwhile larger and stronger ceramic magnets are available, so with everything else being the same ceramic speakers can sound the same as Alnico types.
Still the low power paper voice coil types are a niche market.

The Celestion Vintage 30 was an attempt to duplicate the sound of an original Celestion G 12 Alnico as used in early Marshall cabinets (which was the 16 Ohm version of a Vox Blue) but with increased power handling and using a ceramic magnet, as I was told by a Celestion engineer on a trade fair in the 80s.
In fact the on-axis frequency response of the Vox Blue and the Vintage 30 is almost the same as measured by Prof. Zollner.

[Helmholtz]

Not even Alnico is justified unless customer *insists* and then he has to pay 4-5 X extra.

What justifies this huge difference?
Can't be only the higher cost of Alnico, can it?

[Justin Thomas]

What justifies this huge difference?
Can't be only the higher cost of Alnico, can it?

Being based in Argentina might have something to do with it. I'd imagine some things are just dang near impossible to get a hold of at times, aside from raw cost.
Having read some of Juan's stories here about having to reinvent the proverbial wheel at times, I've got a lot of respect for him.

Jusrin