Discussion on the speaker driver unit

2022 05/06

Most of today's horn speakers use ferrite magnets, so there will be a fairly large cavity between the T core and the magnet, because each small space or cavity has its own resonant mode, The cavity behind the voice coil (in the magnetic circuit structure) produces distortion. The characteristic of this distortion is a worthless, shrill metallic sound. This distortion can be easily identified after passing through the voice coil out, and as a result, a spike in the frequency response curve.

Magnetic circuits using aluminum-nickel-cobalt (AlNiCo) and neodymium-iron-boron (NdFeB) generally have no or very small cavities - see the following example: what a good magnetic circuit should look like. In front of the voice coil, there is another cavity between the T core post and the dust cap. With this thing, the speaker horn will also produce a resonance peak in the frequency response curve. It can prevent the horn loudspeaker from accurately reproducing the music signal. The nature of this distortion depends largely on the size of the dust cap (smaller caps are better) and the material of the voice coil bobbin. Either way, the dust cap will smear the sound, it prevents the clarity of the panning Focusing. If the cavity is small enough that the resonant frequency is well above 20kHz, this problem is largely solved. A phase plug (material made of painted wood is the best!) is a simple There are effective measures to eliminate the front-end cavity effect. As shown in the figure below, the later Fostex FE164 horn has been modified. If dustproof is required, the cavity problem can also be solved by using only sound-transmitting materials - such as woven yarn for dustproofing caps instead. This design can also be found today-like Celestion's Vintage30 and Greenback guitar horns

So let's sum it up: any speaker that eliminates the cavities in front and back of the voice coil and uses a paper cone and paper tube voice coil will sound good! Any Loudspeaker horn! It's that simple. Is a nice speaker easy? Of course!!! A perfect speaker unit

A perfect speaker unit uses a non-plastic paper cone, a paper tube or a Nomex tube voice coil, it can use any kind of magnet, but avoids the appearance of cavities in the magnetic circuit structure. A perfect speaker also always Without dust cap, but with phase plug (wood) that just fills the cavity in front of the voice coil. If dust must be avoided, sound transmissive material is used in combination with a short phase plug. See picture below for correct speaker construction .It avoids the formation of cavities. The speakers discussed above are not expensive and do not require precise and complex crossovers, because the main distortion has been avoided.