coils
 

whats the difference in coils for SPL SQ or daily SQL

1. kapton, aluminum, copper coil
2. flat wind or regular
3. layers of the coil ex. 4layer 8layer



want to learn and want to see what ppl know about this topic.

1. Aluminum coil = cheaper(better for your wallet),lighter(better for SQ but..), less conductive(not so good for SQ)

1a.copper coil = heavier(better for SPL cause...)generally speaking will take more power and dissaptes heat better. However it's more expensive(bad for your wallet)more conductive-Better for SQ but it's heavier than aluminum.

1c. Kapton- supposted to be the best of both worlds but I've never seen it nor know much about it

2. Flat wind vs. regular: with a flat wound coil you can fit more voice coil in the same amount of space which means a stronger magnetic field which means more cone movement. However more voice coil means more weight so it may even out, although my sub in perticular the flat wound coil will handle more power to is better suited for a SPL or SQL configuration. I use mine as a daily driver and the SQ is very good as well(I have the copper flat wound configuration)

3.4 layer vs 8 layer- same deal as flat vs. regualer more coil=more movement which should mean more volume but it does make the moving assembly heavier so you need a better amp with a better damping factor to retain any SQ qualities.

I have little to say on this as none of these are the criteria that need to be written in stone to differentiate a good vs great loudspeaker. The criteria for a great driver is systematic going from copper to aluminum can be great IF the system design changes as well. Copper and aluminum have different behavior patterns the engineer needs to design to the material properties (as the one who makes Tokyo shutter mentioned).

I would add to the list that copper deforms less under a thermal load (high current load) but if aluminum is wound correctly its deformation is predictable (both can be properly engineered but a straight swap would not work as well).
Also the flat windings tend to produce a more even magnetic flux and would require less compensation winding so it should be a denser flux and easier to control.

Speakers are way too complicated to just look at any individual part to determine performance. It's really all about the total package and the engineering.

It really has nothing to do with SPL vs SQ per say, as John and alpha suggest... Each aspect of a coil has a trade off.. (And you could add nomex fomers and aluminum wire to your list which are both quite common too)


On the otherhand if I'm choosing what I want in a coil, I'll pick flatwound copper on an aluminum former.. every time.. but that is just my preference..

interesting lol. well this is the thing. i can choose either alu. or copper. flatwind or normal. sooo lets say your looking at just 1 sub. and you had to choose these options. what would ppl pick .

haunz says copper flatwind. curious to see what other ppl would pick

I totally agree.

Also I'll add that Kapton is a coil former material not a coil winding material. It was initially developed by Dupont as a high temperature plastic for the aerospace industry. It's lighter than aluminum and is non-conductive, both of which contribute to a higher efficiency rating for an otherwise identical speaker with a metal former. The non-conductive former eliminates eddy currents which waste energy (even a split Al former has eddy currents).

No matter the type of speaker, material selection must suit the end goal. In my opinion no material is the single best. Even tweeters with diamond diaphragms have drawbacks.

i had a pair of fully loaded Fi SSD's flatwound copper coils.
other than the fact that these woofers smell... power handling was increased and the woofers took a beating.

although, i am curious as to how aluminum coils would handle ample amounts of power. i've been thing i'm reconing my AQ into a 15" with aluminum coils...

mine is also fully loaded and the copper flatwound(which i have) significantly increases the power handling. If I had the choice I'd pick the flatwound copper everytime IF cost wasn't a factor. Although I took those options even with the extra cost!

i wonder if someone tryed silver coil :p

no doubt someone has but it's probably too heavy and way to expensive. Can you amagine the price of a silver sub(well the voice coil at least!) would be!

how much power are you guys talking about?

did you think that the power handling doesnt actually increase? different type of coil, alum vs copper, might produce different imp rise. higher imp rise = you are able to feed more power, but might not actually mean the sub's power handling has increased any.

i have been wrong before tho.

in your particular case with the 1750.1 RD amp it wont make any diff if you go with a copper or alum coil. especially if the amp will be ran at 1 ohm. wont be enough power to make a difference.

copper has lower electrical resistance than aluminum therefor the impedance rise should also be less. Isn't impedance rise because of heat in the coil? Less heat in the coil(because less resistance to the flow of electrons)should mean more power handling. What your saying is they would cancel each other out if you added more power(more heat in the coil). I think the qestion was if all things were equal which was better. The answer should still be a copper coil(I know I'm splitting hairs here!)

This is getting into power compression. A bit of heat build up leads to increased resistance which leads to more heat build up which leads to... There is a term called "the 1dB point" which simply means that when you double the power you only get a 1 decibel increase in acoustic output. Normally of course you would see ~3dB but due to diminishing returns much of the power is wasted (think about that when you decide to sell your 500W amp and buy a new 3kW amp). SPL competitors take note, allow your coils to cool before you burp.:)

I don't mean to knock anyone on this forum, but I always wondered why the industry was going in the direction of multi-kilowatt systems instead of efficiency. A speaker designed for efficiency would not only require a smaller (cheaper) amp but the reduced moving mass would reduce rattles. A big problem in cars. We could do away with our distortion prone class D amps, at least until better ones are available and end this nonsense about how many batteries and caps we should be running. SPL contests aside, low efficiency-high power systems are a back wards approach.

edit: What do you guys think?

your right kev. back in the days was all about low power and high efficiency. but im pretty sure that the boxes were huge compared to today lol