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Discussion Starter · #1 ·
Does anybody know the advantages and disadvantages of aluminum coils? i am looking at getting a DD 9510 to run off my M3, and i was wondering if i would benefit from aluminum coils
 

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The main benefit to an aluminum coil is it is much lighter, and therefore lowers the cone's moving mass (which in theory, is like adding motor force, although obviously different with regard to other extranous effects). This changes the T/S Parameters of the driver. It increases efficency, allowing it play louder on less power (and generally louder overall). It's something that you normally use only for SPL applications, because if the driver was originally designed around a copper coil, its FS is usually raised to the point where its no longer very musical.

In short, unless it's an SPL driver, I would stick with copper. For daily use, its the way to go. Copper conducts better than aluminum, and all factors being equal (diameter, height, layers, flat vs. round wound etc....) will allow for increased power handling for extended use. (Generally, due to the physical and conductive properties of the material, this doesn't wind up being the case, but regardless...) if its going to play music, I'd go copper.

Hans
 

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Discussion Starter · #3 · (Edited)
Hmmm, well the DD9510 Fs is 35 hz(copper), while the AQ HDC3(aluminum) is 41, however audioque stats that the specs are from a woofer that isnt broken in. i know DD and AQ have very stiff suspensions that dont play low until broken in, so could the FS drop as the breakin occurs? i know that on aluminum coils, DD does 8 winds instead of 4, therefore increasing the electromagnetic force exerted by the coil.

you do know of the similarities of AQ and DD right? i wouldnt have used different woofers if they werent actually the same...

now for something completely different. i know people say(whether they can or not may be a different story) they can tell a solobaric by the sound the plastic cone makes. i was thinking about getting the kevlar composite cone to reduce moving mass, but im wooried the cone will sound different. im hoping that since the composite cone on a DD costs more than the entire solobaric woofer, that either this problem wll be mitigated or nonexistant. also, i plan on getting the carbon fiber "bubble" dustcap that nearly covers the entire cone, so if the kevlar cone dore sound "off", would the dustcap reduce this effect? are any of my "fears" warranted? ive never heard a DD woofer with the composite cone so i dont know.
 

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The main reason the square woofers sound funny isn't from the plasic cone, per se - its from the fact that by nature, the sqaure shape causes increased tension in the corners of the cone. At high excursion & power levels, this causes the cone's shape to distort, causing audible distortion. Thats why you see on the solo barics, they keep adding more and more gusseting to the cones... its to try to keep them from flexing.

That said, Yes, a stiffer cone will sound better. Any distortion or flex of the cone will color the sonic quality of the note being played. But the main reason people use those carbon cones & dustcaps isn't for SQ, its for SPL. As you stated, they are lighter... but also, they flex less and are more rigid. Since less energy is wasted on cone flex, the result is increased output. Thats the main benefit if you ask me.

And yes, the parameters will change somewhat as the woofer is broken in. But if the coil height and diameter is the same (and they are using the same type of former), a 4 layer copper isn't that far off, weight wise, from an 8 layer aluminum (aluminum is close to half the weight of copper). I'm not sure what the gap is on those motors - but that also will have an effect on things.

But the woofers you are comparing (the 9910 and the HDC3), even with their similarities (and the fact they come out of the same build house), are still quite different. The 9910 is a beast in comparison. The HDC3 is much closer to a 3500 than a 95/9900. Not that its a bad woofer by any means... (hell, for $220, its an absolute steal!), its just not a 95/99 series DD (Which costs over 5 times as much... go figure, lol.). Price aside, It really comes down to how much power you have to throw at it. The DD will really start to wake up if you are feeding it 2000+ watts RMS, where the AQ will start falling off and showing its limitations with that much power. Then again, if you only have say, 1200 RMS to feed it, the AQ would probably be just as loud, if not louder than the DD.

Both are GREAT drivers, without question. You can't really go wrong with either... but your M3 amp is a nice piece. Those things put out serious power, especially at 1/2 ohm. If you can afford the DD, it will without a doubt be capable of playing louder, and taking more abuse with the kinds of power that amp can provide.


Hans
 

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Discussion Starter · #5 ·
as far as the gap, ive seen a recone kit for the DD's. the things used to set the voicecoil are about the thickness of paper, maybe less. apparently you only need two...

maybe ill call DD tomorrow and ask what the difference in FS is. what would be an "acceptable" fs for musical applications? the only DD woofer with a higher fs is the 510, which i find odd... would the lighter cone raise or lower the resonant frequency? or would it affect it at all?

sorry, i know a good bit about the basics, but these t/s parameters throw me off. any sites u know of with a good explanation of what they are and what affects them?
 

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The lighter cone generally will raise the FS. In fact, in the old days, guys used to cheat more low end out of drivers by epoxying weights to the dustcap. They call this "Mass Loading" the cone. The same theory is used to tune a passive radiator. Obviously, cone mass isn't the only factor that effects the FS of the driver - it is a product of many things. You could certainly get a musical FS from a woofer with an aluminum coil, if you designed it around that coil when you were engineering it.

But thats not what most guys use aluminum coils for. Usually guys will take a driver that's designed for say, a 3" copper 8 layer flatwound coil, and replace it with an aluminum coil. This coil is much lighter, and therefore removes mass from the cone, making it more efficent, and allowing it to play louder.

The FS of the speaker refers to the frequency at which the entire assembly goes into resonace, when playing free-air. This is usually regarded as the lowest frequency the driver is capable of faithfully reproducing at high power levels. For a high power application, generally, you don't want to tune the port of the enclosure below the FS of the driver. Otherwise, you severely limit power handling, and increase cone excursion. Usually you want to port the enclosure a few Hz above the driver's FS. Meaning that if the FS is 35, you'd want to port it around 36-38 hz, at lowest. Now, if the driver's FS is 46 hz, that means that you are porting the enclouse at 48-50 Hz, and thats not very musical.

How high is too high depends on if its being used strictly for SPL or for music, and your personal taste. For playing low notes at high volumes (30 hz and below), I personally wouldn't want to port the enclosure much above 40 Hz, unless you have a certain specific set of conditions that would warrant doing otherwise. Then again, there are many bass guitar cabinets out there that utilize port tuning above 50hz, and sound decent doing so (But they generally aren't playing really low notes,, aren't using sub woofers, and aren't using much input power either). It depends on how low you want the speakers to play, the speakers themselves, input power, and the environment. The "DD box" that they recommend is based off of tuning around 40 hz.

Hans
 

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Discussion Starter · #8 ·
well, this will be a daily driver setup, so i guess i wont get either. aluminum coils are only availible at 1 and 1.5 ohm. athlough the .35 ohm coils i need are no longer available. damn. i guess 1 ohm it is.... i would like the composite cone, however i dont think its practical at this time...

thanks for the help!
 

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i have an hdc312 and i love it. im feeding it about 1800 rms and it could probably take up to 2500 under the right application. but as HS stated the AQ is a budget sub compared to the 9500 series. however is price is an issue then the AQ is an awesome sub for an awesome price.

and from what i have heard the aluminum coils can take more power but the copper can get louder with less power. also the copper coils tend to be more effecient with more motor strength and some say they sound better.
 

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Discussion Starter · #10 · (Edited)
price isnt an issue lol, the cost is merely a function of how long i have to wait to get it lol. my goal is to hurt as many peoples feelings as possible with a single 10" sub. aimin to street beat a 150

hmmm, are you sure? if im understanding that correctly, thats the opposite of what Hans is saying...
 

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it will be extremely difficult to pull of a 150 with a 10 inch sub off 2500 watts especially in a trunk car. can it be done? maybe but it will be very hard to pull off. my hdc3 does low 140s off 1800 rms. good scores are very hard to achieve in a trunk car unless you wall it.
 

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Discussion Starter · #12 ·
my dd1512s were doing a 143.8 outlaw on 1100w rms. i have enlisted many people, many opinions, and a LOT of research on every aspect of the build to ensure high numbers. will i get a 150? maybe, maybe not, lol its just a goal, only time will tell
 

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what type of enclosure are you planning? firing forward? sealed to the cabin? and your dds had about 2.5 times the cone area as well.
 

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Discussion Starter · #14 ·
lol fair enough

enclosure will be port and sub rear most likely. may end up being forard or upward firing if testing proves its louder. i have a few tricks up my sleeve tho. i havent decided if im gunna have an alternate box for comps yet. guess it depends on what i can do with my daily box.
 

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I've seen a pair of tens do 150s in a street car, but never a single ten, personally. If you're honestly shooting for that as your goal, your best bet will probably be a bandpass enclosure, and you will need a lot of structural work to the car. Reducing cabin airspace, and holding the pressure inside it with minimal flex are where you'll see the largest returns for your work. It certainly won't be easy without turning it into an extreme vehicle, with bulletproof glass & tons of concrete poured in the thing. You'll need to figure out the resonant frequency of the cabin space, and port accordingly, as well as run the proper reactive load for the amp, and a stout electrical system. The enclosure will have to be built like a tank, as well.

Like I said a while back (which I got jumped on about), I'm pretty darn confident my old pair of 12s broke into the 150's, outlaw. That was with about 4000W RMS and a 6th order bandpass enclosure, 45 Hz tuning, the rear seats folded down, the trunk stripped of all plastic & carpeting, and fully treated.

Regardless of score, I'm sure it will get plenty loud. Those 95/99 series woofers are nasty, and the M3 is a solid amp. I totally dig the "how much can I do with a single ten?" idea.

Go get em, Elliot :thumb:

Hans
 

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Discussion Starter · #16 ·
lol the enclosure will be double walled all around, and if that isnt enough, we'll triple wall the comp enclosure. my note is 54. and if im unsatisfied with 1 10, i can always get another one and drop the amp to half ohm. flex is a problem. the entire car is damplified, but my car still vibrates. ill be ordering a lot more once i get my system, but after that, i dont know what i can do to minimize flex and stay in stock 0-600 . as far as electrical, ill have a 34 under hood, 2 31s in the trunk, possibly a batcap, and a mechman alt, with 2pos 2 neg runs of 1/0. the amp power n ground will be no more than 6 inches from the batcap terminals.

and if, after all this, if i still cant get a 150, ill get 2 Z2-LV's and a 99z10. 16kw RMS should do it... :p
 

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Well if you ever decide to jump up outa your class maybe try a 12" (or 2) for your SPL needs!! It's just that I have 2x12" RD Elite Spl subs that are sitting in my closet....lol

They are rated for 2.5krm each and can take spl burts of over 6,000watts a piece. We may use one of the subs in my winter beater for SPL but it's a toss up right now.

Best I've done is a 147.4db (street B) in my 94 Saturn (trunk), hopefully if we try that single 12" out we go past that mark!

Post your TL scores and pics/progress :)
 

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Discussion Starter · #18 ·
nah, im stickin with DDs. the 9500s can take 4kw each daily with no problems, god knows what they can handle for just a burp. definately pics, but progress is slow, as i dont even have the sub ATM. nor the electrical to back it up...Approximately $2000 and ill be on my way lol
 

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DD all the way man, i use a 9500 in my house for a home theatre, a 9500 in a car that i used for SQ and comp's and an extra used one to plug in a wall socket now and then. Firofl. There are guys taht have hit 172+ with one dd 9510 and a directed 2500d (when it was good) in a rabbit. SHOW ME YER DOUBLE DEEZ!
 

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another thing to consider is the heat. aluminum typically takes more heat, so its harder to heat up, and will play a role in impedance rise.

as far as flexing. some people benefit from flexing, some dont. i dont know how our cars do with it. sometimes when people dynamat their cars, their scores go down. another thing to think about....


DD all the way man, i use a 9500 in my house for a home theatre, a 9500 in a car that i used for SQ and comp's and an extra used one to plug in a wall socket now and then. Firofl. There are guys taht have hit 172+ with one dd 9510 and a directed 2500d (when it was good) in a rabbit. SHOW ME YER DOUBLE DEEZ!
ummm proof?
 
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