Very low speaker impedance

Engineering anything (whether a speaker or a car) is a series of complex compromises and choices and the answers chosen will vary with the intended use.

For example, which is faster for a 200 mile trip - a Greyhound bus or a Porsche? You can't really answer that question until you know more about the trip. If 40 people need to make it, the Greyhound bus is going to be a lot faster no matter how fast the top speed of the Porsche.

Take just a single factor in voice coil design. The impedance will vary with the length of the wire (among other factors.) A longer wire raises the impedance and gives a more concentrated magnetic field, but also increases the mass of the coil. So we have a balance that needs to be struck - you can't have both any more than you can put 40 seats into a Porsche.

For most consumers, it is best not to worry about the engineering issues the speaker designer faced. You're better off listening to lots of different speakers and you'll eventually find one where the design goals (with the inherent compromises) closely align with the strengths you find important in a speaker. Keep in mind the others will have those priorities in a different order. That helps explain why there are probably 1000 different makes and models of speakers on the market today.

Thank you for your explanation. Does this mean that in fact a low impedance design gives a more fast and dynamic response (with the restriction that one should use a kilowatt amplifier)?

Chris

Other than your needing an amplifier that will behave itself at very low impedance loads, it is not possible to give a simple answer.

The impedance versus wire mass (length) is just one of =many= factors that affects impedance. Crossover design affects impedance. Cabinet design affects it. The other parameters of driver design (magnet strength, gap distance, other voice coil materials, suspension, cone material/mass... etc., etc., etc. also affect it. It is a juggling act for a designer to gain the attributes they want without losing too much ground elsewhere.

And with that, we haven't even gotten to the more exotic driver designs such as planar, electrostatic and so on.

I think it is a mistake for an end user to get wrapped up with technical issues that can be difficult even for professionals. To declare a speaker will be "fast and dynamic" based on a single spec is a simplistic mistake.

I'll be up front and state that I have no idea why Kinoshita speakers exhibit a low impedance. As noted, the voice coil wire length was simply an example of one of many factors. Their impedance spec may well be due to something else. I've not heard them and would find it impossible categorize their sound based on the fact they are low impedance.

I'll restate it this way. Technical issues are very important considerations in helping the designer reach his goal. But without knowing the design goal, specs by themselves can be quite misleading.

I believe it's mainly because they want the box a certain shape (narrow). If the speaker box can be made whatever size the deisgner wants (wide but not aesthetically pleasing) then a lot of trade-offs can be eliminated.

My guess is that, in the case of the big Konishita speakers, the designers perceive a worthwhile advantage in wiring many voice coils in parallel instead of using some other configuration. For one thing, the amplifiers will deliver a lot of wattage into this configuration - or die trying!

When confronted with having to choose between wiring for a 4-ohm load vs a 16-ohm load, I chose the 16-ohm configuration. My priority was compatibility with specialty tube amps, and I think that even solid state amps sound better into a high impedance load as long as the result isn't premature clipping. Apparently I'm very much in the minority here.

Seldom is the impedance curve one of the primary driving factors in a loudspeaker design; usually other things are higher priority and the impedance falls where it falls. In unusual cases (Apogee, Konishita, InnerSound/Sanders Sound panels), the speaker's impedance curve falls outside the comfort zone of most amplifiers, but in that case there are usually still specialty amplifiers that will work well, though the number of choices will of course be more limited.

Rating amplifiers by their 2.83 volt sensitivity rather than their 1-watt efficiency gives an advantage to lower-impedance speakers, at least on paper. Wired for 16 ohms my speakers are 89 dB/2.83 volts, but wired for 4 ohms they'd be 95 dB/2.83 volts. In either case, they're 92 dB/1 watt.

Duke