Tannoy Stirlings on the way!

Ceramic magnets are often used as a synonym for the kind of ferrite magnets ubiquitous to speakers. From online:

Ceramic (ferrite) magnets are composed of strontium carbonate and iron oxide. ... After the molding process, the magnetic material is then sintered at about 2,000°F. The sintering process is similar to that of kilning ceramic pottery, thus the popular name “ceramic” magnet.

I don’t know whether Tannoy’s barium ferrite magnets qualify as typical of "ceramic" magnets, but it looks like the nomenclature is based on a loose association (by processing) anyways! I assume the sintering process is extremely efficient at fashioning the kind of magnetic ring useful for speakers.

Interesting. Sintering came up in a different context, recently.  I'm thinking about getting a new cartridge.  One of the ones I'm looking at is the E.A.T. Jo No. 5.  The body of that cart is made by laser sintering some kind of powdered organic compound.

@mulveling thank you for the detailed information. I learned more about these speakers in your few concise paragraphs than all the videos and articles I’ve read.  Appreciate you taking the time. 

@mulveling Totally fascinating writeup thanks but I have a question, why couldn't they pair an Alnico magnet with the tulip waveguide? Or is it just tradition or users prefer the pepper pot sound?

@mulveling Totally fascinating writeup thanks but I have a question, why couldn’t they pair an Alnico magnet with the tulip waveguide? Or is it just tradition or users prefer the pepper pot sound?

I’m not entirely sure of that answer (I’m not an expert just a hobbyist trying to learn about the speakers I love), but my guess is that with ferrite magnets being stronger per mass / volume than alnico, the use of alnico necessitates a much larger & longer magnet to reach the desired flux density in the (very small) voice coil gaps. The pole pieces focus the entire magnet’s strength into the voice coil gaps. Each waveguide has been optimized to work with the lengths of magnet dictated by either type, so mixing them up would NOT produce good results.

Tulip / ferrite driver cross section - note the use of dual magnets (the medium gray rectangles) and the fact that each magnet is very short!

Pepperpot / alnico - one LONG magnet’s entire strength is focused onto both voice coils by the pole piece arrangements:

One more note on replacement driver costs - when I said the alnico drivers cost a LOT more, that is true - but only for the WHOLE driver. The replacement tweeters contain only the diaphragm and voice coil, and are quite affordable to replace (at most a couple hundred bucks each). I've had this done on my prior Kenstingtons. Since this is the most likely part to fail or degrade in a Tannoy driver (and indeed, it's happened to me), this is a good arrangement. The tulip tweeters include the waveguide and the tweeter magnet, and I think they actually cost a little more than the pepperpot tweeters.