Several weeks ago, I picked up a couple 9kv.2 D2 subs from Elemental Designs. I was hoping to find an 8" driver that would work well in the limited confines of a truck. The specifications on the ED site indicate the driver should work well (Qcb=0.707) in approximately 0.35 ft^3 resulting in an F3 of 54 Hz, and a stated sensitivity of 86 dB. I didn't have the time to verify any of these numbers prior to installation, but after a few weeks living with them, I was concerned that they didn't sound the way I expected, and their output was also less-than-expected given their stated sensitivity. To make sure I wasn't imagining things, I swapped in a single Vifa M22WR-09-06. The system played immediately lower, even though these predicted responses of these drivers appeared similar.

Detailed impedance measurements followed. I tested them in every possible configuration, but as with most DVC drivers, the typical setup would be with the coils wired in parallel. The measured and calculated specifications on both drivers were substantially different from those published. Instead of the ideal (Qcb=0.707) sealed box being 0.35, it turned out to be 0.60 and 0.5 respectively. When you're trying to get a sub into a small space, doubling the required box is a serious problem, regardless how small it is. The Qts for each driver was 0.52. The Vas and Fs were a moderate problems. My tests showed 14.4 and 13.1 liters respectively and 31 Hz / 34 Hz. The published specs are 45 liters and 23 Hz. The real issue is the stated sensitivity. I should have expected as much from a high-xmax driver, but the claimed number of 86 looked attainable. Well, it wasn't even close. Under controlled conditions, the value was 81. When you do the minor math involved to compare to the Vifa, the 9kv needs nearly four times the power to play at the same volume, and that's under ideal conditions.

Granted, this was only one pair of drivers, and some limited production variance is tolerable, but in my opinion and experience, these drivers were well-outside a reasonable variance from published specs. Combine this with some other questions that have come up regarding their products, I'm now somewhat leery of them.

 

I was curious about those speakers. Not anymore. I'm really not surprised, and I think I'm going to write Edesign off completely. Old deadener failed. New deadener failed, no response from Ben on it. I'm just going to throw away the remaining unused edead, I'm just glad I only wasted $50 on it. Shame on me, Elemental Designs fooled me twice.

If you go to pretty much any car audio board, aside from icix, and mention Edesign, you'll be greated by writhing festering hatred. There must be something to it.


Have you looked at the ARC 8s?
http://www.arcaudio.com/arc-05/pdf/arc_series_04.pdf

 

Man thats not what I wanted to hear. I have a pair of these waiting to go in my Z. I wander if all the bad remarks you mentioned are because of their seemingly horrible customer service. I ordered my sub boxes a month ago and still dont have them, all of my attempts to contact them have gotten now response either.

 

Since a buddy of mine thought the original post might be too technical for some readers, I decided to give you guys a simplified summary of what this all means.

The box means nearly everything when it comes to adding a subwoofer to a system. The box is designed by using certain published measurements of the subwoofer itself outside any box. These measurements determine how the subwoofer will sound, how loud it will get and how low it will play in different boxes. In many instances, the box is actually more important than the driver itself. Contrary to what some people say and do, you can't just build any old box and stick a subwoofer in it. It doesn't work that way.
These measurements (Vas, Qts, Fs, sensitivity, etc.) are typically published by the manufacturer of the subwoofer. They provide these numbers so you can determine beforehand which subwoofers will work to your liking in different situations and which wont. Since most people don't have access to the testing equipment necessary to measure these things, the manufacturer's measurements have to be accurate and repeatable, or they're really meaningless. In this particular case, these numbers are substantially different from what the company tells you they are on their website. What that means is when you go looking for a subwoofer to fit a certain application, you might rely on the company's inaccurate specifications to decide if these subwoofers will work for you. Then, once they're installed, their performance is disappointing.

Think of it this way... You want a new set of wheels for your car, and the manufacturer of the wheels you like claims a certain bolt-hole spacing. After getting the wheels delivered and unboxed, you find that the bolt-hole spacing is slightly different from the company's claim, and they don't fit your car properly. Now you're pi***d. Make sense?

These measurements, referred to as Thiele-Small parameters, are vital to building a box for a subwoofer. If they're wrong, you have no idea whatsoever how to build a box to suit them. When a company is this far off in listing the specs, it's hard to trust them in any other area.

 

Not until now, but I can tell you that most of the reason I use OEM drivers from places like Madisound is because the problem I found with the ED drivers is common throughout car audio. There are just too many little companies out there who simply order tweaked designs from Taiwanese companies that have lousy quality control, then slap their company logo on the product.

The problem with the ARC drivers as I see things before testing is that we have yet another set of high-Xmax drivers (absurdly high, actually) that also have a relatively high stated sensitivity. High Xmax usually means low efficiency and higher distortion, so beyond your recommendation, Kale, I wouldn't consider them.

The two things aren't directly related since this company doesn't actually appear to build anything themselves, but it is a symptom of a company that might not be long for this world.

 

I believe ARC is sourced through Image Dynamics and built on their assembly lines, and ID in my experience has a very respectable track record with the performance and measurements of their drivers.

ED has always been a question mark to me, and having my 7" Focal mid slap the 7" ED subs around from a midbass standpoint just reinforced my now validated hesitance regarding their products. I am not surprised in the least with your testing results.

I only vaguely mention their component sets based on Penta's support of them and numerous happy posts, but Penta now works for them, and bias is bias. (No offense bro)

Do your research, or form your own opinions and risk your hard earned $$, but they will not be getting any more of my cash, even though the edead v3 worked as promised and I am happy with it's results. There are many similar products with as good or better performance for the dollar, especially when talking about their deadening, which Raamaudio's product line far surpasses (and I have used both)

Fej

 

No offense taking, I am an authorized dealer of there product and do use it in a number or the install that I do, but I do use other stuff as well. I have been an elemental designs customer for over 5 years now and have always been well treated there even before I was a dealer. I know they have had problems and I dont expect everyone to like them. I have been happy with there product and as well have a ton of customers that are as well. I wont lie I do bias towards them just because I have had tons of good experience with them, but they arent the only brand I use. Hell I have polk speakers in my DD

 

I would like them, if Ben would at least respond to the issue I'm having. Like them more if they refunded at least part of my deadener purchase. And like them _even_ more if they stopped selling crap deadening and just went with something that sticks.


Spkrboy:

ARC 8s are built on ID subs. If you could help me with measuring them, I'd be happy to. I can say that on 70x2 they were pretty impressive in my WRX. In fact, if I go back to having subs, they will be it.

 

I'd be happy to test anything anyone wants to send me. If you want to do it yourself, it's about a $500 investment and a steep (at first) learning curve.

I've tested a number of ID subs over the years, but nothing very recent. The results have been mixed. It seems their low-dollar stuff has done very well, but their high-dollar stuff leaves me scratching my head. Same xmax problems I've mentioned. They had a cheap 10 a few years back that was just a killer for classic rock in about a half-foot. If you saw it, you'd laugh, but damn, did it sound good.

Just so we're all on the same page here, and I'm fair to ED...

Nowhere in my posts did you see me say these were bad drivers. On the contrary, the way they tested, they have some promise. The problem is driver consistency and an utter lack of SPL. There's no guarantee that the next pair someone buys will be similar to these. That's the problem. You don't know what you're buying. That's all. Well, that and the freaking dust-cap labels are crooked compared to the bolt-hole arrangement (AAARRGGHHHH!!!!), but you get the idea.

 

Have you ever tested the stock 8" c5 speakerS? I wonder if they have some potential, without all the mangling done by the factory amp's eq.

 

I have virtually no C5 experience. I know the C4 very well and the C6 well enough to feel comfortable taking it apart.

I'll say this much: Factory speakers are invariably bad compared to what's available. They're a tremendous engineering achievement considering how they're able to sound on a budget that approaches zero, but that's the extent of it.

 

I hate stumbling upon this thread after I just ordered a pair of the 9Kv.3 subs.

I'll see how they work...I can't imagine they'd be any less sensitive than the horribly inefficient Tang Band W8-740Cs that I have now.

I'm glad my circa 2004 13Kv.2 haven't had any problems, they are extremely efficient in my setup.

 

I haven't had any problems with my 9kv2s. I know that your test showed that the numbers given aren't true, but in the box they are in, the cubby hole boxes, they are performing better than my dual idq10s.

 

I joined this forum to do some research on a C2, I may be working on, but figure I might as well contribute a little bit

I'm going to join in with the group that has been satisfied with their 9kv.2's.

As you stated there is going to be a variance in production, but in addition to that third party test results are almost always going to vary from the published numbers.

I'm interested to know what procedure you use for testing drivers?

I see the same 'red lights' in your numbers as I would in pasmags, higher fs, tighter suspension, lower vas... The problem with small test systems is that they usually don't have enough ***** to push a subwoofer. The reason you are probably having so many issues with high excursion drivers is that you need quite a bit of power for accurate measurements

If you really want to be accurate you need to use LMS with a nice mic and a proper baffle. You also shouldn't use delta mass but rather an enclosure of known volume. When you're telling people specs are off using a different test method, it doesn't really mean much. Take for example horsepower/torque ratings. Different dynamometers, different days, or any other variable will cause changes in numbers. A mustang will read different than a dynojet, different test equipment/procedures = different results.

What needs to be understood is that there's no way to repeat the same exact parameter list twice with ANY speaker measurement system. Let alone across measurement systems. Thiele small parameters (that all change once the speaker sees ANY power) are not concrete values to how a speaker will perform.

Basically, if you're using delta mass, the numbers will be high just like if you tests any speaker with similar excursion. Just sitting on a table is going to raise things like fs, qts, qms, vas specifically resulting in a variation in bl as well which will effect spl since it's not measured but rather calculated by fs / qes / vas. So when you shift one by say 5%, it throws everything else off by a lot. If you retest, I'm positive your numbers won't be the same, whether you admit it or not.

If you're using LMS any variation in mass/box size or mic position your results will also be skewed.

Even if your numbers are 100% accurate I don't think that's too bad of a variation from different test systems.

 

I'm happy to see another forum member with this level of knowledge. Thanks for contributing, and I certainly appreciate my work being scrutinized. I'm certainly not a professional, and I don't claim to know everything there is to know about this stuff (The more I learn, the larger that gap appears to me), but I do know quite a bit. At the risk of causing everyone else to fall asleep...

Yes, they will, but these varied much more than I'm accustomed to.

Small and large signal impedance testing, via Liberty Praxis and Soundeasy.

An Adcom GFA-555 at 200-800 watts (stereo) is realistically more powerful than most car amps, and is more than capable of pushing any subwoofer. These 9kv subs had significant break-in time before testing and still had a high Fs.

I use Delta-V, and for subs, I generally use more than one enclosure for verification. There's no need to have a mic costing more than $50-100 as long as it's calibrated and used within its appropriate SPL range. I don't subscribe to the "golden sledgehammer" mentality. LMS is overkill unless you're a professional speaker-building company. There's also little need for a mic when testing a subwoofer since 95% of the driver's performance can be obtained through impedance analysis. Distortion is not usually a concern, so they get the benefit of the doubt there.

Yes, they will change with different levels of input power because the position of the coil in the gap changes constantly. A well-designed driver addresses this rather effectively. I've been doing this so long now that my routine is highly repeatable. Plus, the program itself allows averaging routines to remove most of the variance in test-to-test comparisons. Even then, most tests deviate less than 3-4% and that's at most in my experience. I've had little difference in results across four platforms in 12 years. I also calculate many parameters by hand instead of relying only on the curve-fitting algorithms in these programs (which are getting better and better).

I don't use Delta-mass as I think it questionable to be sticking stuff to a cone. Yes, numbers do change from test to test, but not a lot. I average results, do it over several days and have a well-practiced routine the results of which have been in line with published specs from reputable manufacturers.

I don't think it's very good. Of the hundreds upon hundreds of drivers I've tested, this variation ranks among the highest. Even notoriously varied manufacturers like Vifa have performed better. I've tested plenty of high-xmax drivers. Although most have a relatively low sensitivity, they generally meet or come close to the manufacturer's claims. Included are JBL, Audio Concepts, Adire, JL, RF, ID, Vifa, Peerless...

The nail in the coffin was the installed sound. They were soundly bettered by a single 6-ohm Vifa 8-inch driver. I'm not saying by any means that these drivers couldn't have a place in a system. My issue with them is the specifications imply a certain configuration that will be incorrect in the real world. The deviation was enough for me to want to get my hands on other drivers to see the pattern one way or the other. I've noticed this variance is more common among companies that farm out their production. When a driver is relatively cheap, the first thing to suffer is quality control, which logically causes the variance in specifications.

There may be a bit of opinion melded in with the next statement, but I prefer the sound of more conventional drivers over high-excursion models. There are exceptions, but they are few. This isn't one of them.

BTW, since you've joined the forum right about the time this thread was floated, and you have an abnormally high knowledge of this stuff... you wouldn't be from ED and defending these drivers, would you? If you are, that would be great, and I'd hope you'd be confident enough to admit it. I wouldn't ever rip someone for defending their product as long as it's done on the level, and the group as a whole could learn quite a bit from your experience. If not, sorry I pointed out the coincidence.

 

Hehe, I was worried I might come off as an actual employee, but I am merely a dealer like Pentavolvo. I really did sign up to do some research on a C2 that I might have the privelage of working on. When I saw a thread that I figured I could add something to, I decided to chime in.

edit: And my name is mr x on everyforum I'm on, not just this one