@curiousjim wrote:
Thank you for the link. I’ve probably watched a dozen videos so far and I understand how field coil works, but I still don’t understand the why. Before we were all born, a radio that produced 1/2 watt was amazing, but watts are not a problem anymore.
Back then few tube wattages were more efficiently turned into acoustic output with larger and typically horn-loaded, very efficient speakers. Watts in abundance is now easy to come by, yes, but more power is turned into more heat in the voice coils and passive crossovers of the smaller and much less efficient speakers of today, and thus heat dissipation becomes a challenge and the new problem; thermal compression is said to enter the picture already at 1/8 of a driver’s rated power handling, and as a dynamic phenomena thermal modulation is believed to have its effect in stunting the transients with very short heat built-ups and rise in resistance in the voice coils.
More efficient speakers have lesser issues here in needing less power for a given SPL, and active configuration is a way to aid an amp’s ability to control the cone of a driver more precisely - not wholly unlike the advantage of an electromagnet and its better control over the cone movement.
The why of electromagnets back then was necessity and doing what needed to be done; the why of and demand for them now is better sound.
Someone said that field coil speakers were better because the power could be adjusted. I didn’t find anything about that at all. I guess if you are looking for a Dipole full range driver maybe’s?
Electromagnets are inherently better due to their ability to control the moving mass much more precisely, which is the main takeaway, while adjusting the voltage of the DC power supply lends the opportunity to vary the magnet flux density and thereby tune the overall character/tonality of the sound.
I’m still having trouble with this strong magnet vs that strong magnet. Either way it seems to be a more expensive way to build a driver.
More expensive, heavier, larger, generating heat, the need for a (quality) DC power supply, yes, but really it’s about this weaker permanent magnet vs. that very powerful electromagnet and all that entails. They’re a tougher sell for sure, but if the benchmark is better sound followed by will to get there, they make sense.
