Forced air cooling subwoofer driver?

Speakers should be liquid cooled
Zigzagging copper pipes attached to magnet structures carrying heat to a back panel mounted radiator, fins exposed to free air.
Run tubing into the cabinet and pump ice water through the darn thing. When the ice melts in the reservoir, add a couple more bags. The heat exchanger pipes ought to be machined into the backplate/pole piece.
 
  • Like
Reactions: 1 users
Plastic injection dies and paper cone pressing ones both have piping embedded/machined inside them, go figure.

Plastic injection ones to keep them cold and speed up production by making molten plastic harden quicker, paper cone pressing ones get 200C superheated steam to dry paper pulp quickly.
 
Troels examined in a project that same size bucking ferrite brought a healthy 1.5 decibels extra.

Neodym easily dominates a ferrite for more gain but I would always fear that the Neodym would harm the ferrite on the long run.

Anyone can tell from experience concerning that?

Subjectivity won't help here only measurements after longer use period.

Not so easy.
 
Interesting idea. However all cooling is only necessary for very rough use of speakers at their limits.

Heard from ATC that they color also the pole piece and all parts inside the magnet with special black color so that heat transfer from voice coil in direction to the outer parts works better.
 
Neodym easily dominates a ferrite for more gain but I would always fear that the Neodym would harm the ferrite on the long run.

Anyone can tell from experience concerning that?
No idea what you are actually asking about.
Neodymium has more magnetic strength than a ferrite slab magnet for a given mass.
More mass takes longer to heat up, and it's larger surface area can dissipate more heat.

In a good driver voice coil vent design, most of the heat is carried away from the magnet structure.

From experience, I can tell you that the LAB12 ferrite slab driver (the one the heat transfer plugs were designed for, which only reduced magnet temperature by 3 degrees) heats up far faster and suffers from more thermal compression at rated power compared to the ferrite slab B&C18TBW100 or the Neodymium BC18SW115.

LAB12- 400w
18TBW100-1500w
BC18SW115-1700w

Of interest, judging from current low frequency driver's power ratings, the use of ferrofluid to wick heat from the voice coil to the magnet structure does not seem to cool as well as proper air transfer.

Art
 
Yes, I remember heat pipe technology it works well in a passive way

Heat pipe on wikipedia

Due to the very high heat transfer coefficients for boiling and condensation, heat pipes are highly effective thermal conductors. The effective thermal conductivity varies with heat pipe length and can approach 100 kW/(m⋅K) for long heat pipes, in comparison with approximately 0.4 kW/(m⋅K) for copper.[2]
So glad you mentioned heat pipes. I’ve been thinking they would be attached with thermal epoxy to the inside of the pole ventilation and the other end to a heatsink on the cabinet wall could work for a closed box.
 
Of interest, judging from current low frequency driver's power ratings, the use of ferrofluid to wick heat from the voice coil to the magnet structure does not seem to cool as well as proper air transfer.
Fane measured turbulent air around voice coil transferring heat to magnet structure had heat transmission "comparable to solid silver"
You can't get better than that and it's definitely better than ferrofluid
Which is useful on "tweeters* for obvious reasons: no turbulence there.
 
Fane measured turbulent air around voice coil transferring heat to magnet structure had heat transmission "comparable to solid silver"
Silver transfers heat just a bit better than copper (what most voice coils are made of) but copper is about 13 times better transferring heat than steel (what the conductive part of magnet structures are made from).
Screen Shot 2024-06-07 at 5.34.58 PM.png


The trick to keeping a voice coil cool is transferring heat directly to the outside air, rather than heating the steel (and ferrite ceramic) magnet structure.