Why should i care about inductance in an SQ speaker????

Ooooh, did I get you thinking Zion? Do some specs actually matter?


Inductance is basically a measure of the flow of electricity through the speakers voicecoil (measured in millihenries mH). The lower, the better (or quicker) the signal can travel through the voicecoil, impacting on transient response of a driver.

Hence, a driver with a high inductance, can sound slow and sloppy, as it cannot respond as quickly to a music signal.

Note that the Le figure quoted in the T/S parameters is generally taken at 1khz.
Inductance obviously changes depending on the positioning of the voicecoil.
This is where Klippel measurements come into play

^^^ what he said......kinda

Inductance is the measure by which a coil can change direction within a magnetic field. The lower the inductance, the less resistance to the coil trying to change direction.

Inductance also allows the coil to act like a low pass filter. You might think that this is okay, but trust me, its not. A sub with a higher inductance has influences on its phase and output, and a unit with an inductance a lot higher then the integrating midbass, will be difficult to blend without audible evidence.

Your enclosure design will also have an impact on the inductance, which is why a well designed enclosure is so important.

EDIT: This is wrong

??? Ummm, that one I've never heard before......

Impedance is affected by enclosure, not inductance. Both Inductance and Enclosure affect transient decay (and therefore, damping), but they are mutually exclusive (could be wrong, would love to hear how they interact).

Inductance is a response (almost always measured) based on the voice coil, current flow and the magnetic field. Can be calculated by simply dividing the Flux through the voil by the current flow, with respect to time.

As there are no variables outside of these, and enclosure does not affect these, I cant see how it has an effect? My inductance will be the same, in a box, free-air or Infinite Baffle....??

I stand corrected.

Typed that on the fly, was meaning impedance which we aren't talking about.

Carry on

the inductance of a speaker coil acts as a 6db/oct low pass filter. The higher the inductance value the earlier the speaker will roll off or attenuate at high frequencies (moving mass also attenuates the driver in high frequencies too). Ive also read that a low inductance midrange driver sounds better...but have yet to read about inductance ranges or values to back up this claim.

ill look at a few midrange units i love then shall we

i will look at just a two specs in reality moving mass Mms and inductance Le.

audax areogel 5 1/4inch midrange driver

Le = 0.22mH
Re = 6.4ohms
Imp = 8ohms
Mms = 5.9grams

scanspeak 4inch midrange 12M/4831G00

Le = 0.22mH
Re = 3.2ohms
Imp = 4ohms
Mms = 6.5grams

seas excell 5 1/4inch midrange W15CY001

Le = 0.49mH
Re = 5.5ohms
Imp = 8ohms
Mms = 9.5grams

dynaudio MW150 5 1/4inch (the least liked in the upper midrange area compared to the other drivers)

Le = 0.16mH
Re = 3.0ohms
Imp = 4ohms
Mms = 12.3grams


so what can be gained out of this

well the midrange unit with the the lowest inductance in the group is my least favorite in the upper midrange region. The dyn has the largest voice coil so i think this would be the biggest reason for its low inductance measurements. The actual mass of the dyn is by far the highest and might be the biggest reason why the midrange isnt as extended compared to the other drivers listed.

I'm pretty sure the Dyn has Faraday shorting coils, which give it such a low inductance.

All the other drivers dont, AFAIK.

I'd also say the main reason behind the frequency response is due to the breakup nodes, and distortion levels, of the other drivers. Both the SEAS and the Scan have very good motors, compared to the Dyn, and higher breakup nodes with lower distortion levels.

my supremo 9 has VC inductance@1khz 0.22mh, i spose ill think of something else to waste my time on then.

how so? mass may slightly reduce some transient peaks while increase others (think inertia) but it won't resist the current changing in the VC (with a lagging effect), its this laggin effect which limits the drivers HF response.

i just think that one spec or even two can NOT tell the whole story. I think distortion graphs, frequency response graphs and impulse response graphs give you more of an idea of how a midrange will work and its limits. The seas while being the best midrange unit i have ever heard it has to be taimed. Without eliminating the onaxis upper resonant peak this mid can sound edgy and very harsh. A simple notch filter can help the situation.

the dyn has the lowest Le and has quickest roll-off in the top end response.

Mms, Cms, BL and Le should combine to effect rolloff in the top end. NOT just Le on its own, yes Le creates a 6db/oct low pass filter but as you have seen with the 4 examples of some of the better midrange units available the worst driver in the bunch (to my ears anyway) and had the lowest Le!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! NOTE it seems Cms which is compliance seems to be a spec thats only interested in low frequency response even though i believe the spider and surround must have influence on the high frequency response.

so what makes a good midrange unit its not just frequency response but also IMD, THD. Some guy on diy car audio has measured some of the midranges available and has found that the seas seem to be very good interms of not just frequency response but distortion as well.

from my experiences i do prefer a midrange size of between 4 to 5 1/4inches cone midrange design. Anything smaller than 4inch struggle below 400hz and anything bigger 5 1/4 inch seem to struggle above 2khz.

In terms of overall damping of a driver (Qts), it is influenced by both the mechanical (Qms) and the electrical (Qes).

If you look closely at the values though, you'll notice that Qes follows Qts quite closely, and that Qms has less of an influence (due to the calculations for Qms and Qes through to Qts).

Induction of a VC forms one of a few parameters which produces Qes. In real terms, Induction of the VC affects a drivers resistance to respond (overdamping), as does a few other parameters.

Qms is the purely mechanical factor. Both compliance, Cms, and effective Mass of system, Mms, contribute to this quite greatly. The stiffer the compliance, the greater the resistance to change. The greater the mass, the higher the momentum, the greater the resistance to change.

So overall, Mass has a large impact on resistance to change (of the overall system) but not on the electrical parameters. It is the overall resistance to change which affects HF performance, not just the electrical.

FR, IR, distortion plots etc. display how a system as a whole is performing, and all are effected by these parameters. When it comes to comparing Inductance across units too, you need to do it on a level playing field. Compare Inductance relative to impedance (or Le/R). That way, the information is not diluted by resistance. Having low Inductance levels (like 0.05-0.06mH per ohm) gives way to incredibly good drivers.

Comparing the SEAS to the Dyn, based purely on Inductance, isnt really fair either. The SEAS motor eats the Dyn for lunch. The Dyn has a softer breakup node, higher energy storage in its suspension and heavier moving mass with a weaker motor strength (AFAIK).

You dont, after all, compare cars based purely on the size of their wheels.

We are talking here about drivers in general, so lets not forget Pro Audio, where all the technology and smarts are. 12" drivers pushing midrange. Dont base opinion purely on size.

listen to your ears

they dont say much?

Its been said before. Anything that can be heard, can be measured. Any relationship that is enjoyable, can be displayed using measurements and data.

Anything that needs improvement, can realistically only be achieved through data. Manufacturers dont build wave after wave after wave of slightly different units, and then just select the one that 'sounds good'.

Wisdom is not the product of schooling, but the lifelong attempt to aquire it

its also been said, sounds good, measure's bad, then your measuring the wrong thing. Blanky nailed it, just listen...if you like, then do it, if you don't, then try again.




yeah right I built my car on *data*...unless you mean the *data* I got thru years of just listening *shrugs*




hmmm or is wisdom in the measuring ??? lmao @ spec heads

me thinks the wise know watt to measure, watt to listen to, and what(or whom) to ignore...<<<again *shrugs*
classic
Cyberpunky

also remember:

the inductance changes as the coil (and cone) move further from the centre-point of the field.

so the inductance at a certain power level will change with frequency X)

hahah

I have a strong feeling even you Cyberpunky, use measurement data to build your car. Otherwise, how else besides listening to your subs/midbasses freeair, and spending loads and loads of dollars and time, did you build your enclosures hmm?

T/S specs are measurements too.

And hence the incredibly useful data provided by Klippel testing!!!

If you had a driver with poorly behaved breakup modes, a higher Le would probably make it sound smoother.

I agree that for a well engineered driver, Le should be an afterthought. All that matters is that the Le (relative to the Re) is sufficiently low so that the driver has the required bandwidth.

The motor is the easy bit to get right, the perfect midrange cone assembly is more difficult.