My Quad 15" ACI sub build Saga.

Well, I'm a bit disappointed with something and figured someone here may be able to give me some advice on how to use these matching 15" sub drivers I have. Long story, but I need advice.


ACI was having a clearance sale a few weeks ago for quite a bit of stuff. One thing was the SV-15" driver that they used in their Maestro. These drivers look great and have good specs and were used in a very nice subwoofer. Brand new!

Not only were they on sale, but one weekend they offered another 20% off. It didn't take me long to decide I wanted 4 of these new beasts. The price ended up being about $111 each! Sweet. I wanted to build 2 enclosures with 2 drivers in each, sort of like the JL Fathom.....forward facing.

So they were delivered in separate boxes. Guess what? 3 of them were identical and looked like the small photo on their Maestro page. The 4th? Well, it has an inverted dust cap and the surround is totally different. Bummer.


Here's what the first 3 look like: They are nice.






But, here's what the 4th one looks like next to it.




So my hopes for the dual "fathom" look started looking bad.

Photo comparing the surrounds:




I e-mailed ACI and they said the supplier changed the design a couple times, but the performance is the same. They had NO MORE SV15's to exchange for me to get a pair of exact subs. Bummer again.

So I thought maybe I could just do 2 down firing subs on each side so you couldn't see the driver's front difference. Then make 2 more single enclosures facing forward that match perfectly. Okay, things were looking up.

However, the surround is made of different material and the one on the right is much "softer" and it's much easier to push down on the cone. I tried this very lightly just to see. Night and day difference.


I began to worry about things being too different and whether the specs I had matched that 4th different driver. Different specs would not be good in 4 identical boxes.



But then by pure luck on their clearance-sale page they listed one final SV15. Man was I happy. The listing said it had a different looking dustcap but performance was the same, so I figured it was like my 4th odd ball driver's dust cap. Awesome. I'll buy it because shipping all of these back and forth made no sense. But it was $139. He lowered it to $125 after some e-mails and my problems. Uhhhhh, that's still more than I spent originally ($111)? Whatever, I didn't want to bicker. I told them I needed the inverted dust cap driver to match mine.

One would think that if the supplier changed designs a couple times, and then this unit pops up on the site with a different dustcap, it would be like my odd ball. Hey, at least I could have 2 matching pairs right? 1 pair inverted caps, one pair regular.

So today I get the package. Oh yeh, it's finally go time with the build! I open the shipping box, the inner packaging is a little different, no big deal. I continue to open, and then get disappointed in more ways than one.

The dustcap IS different! But NOT like I was expecting. It's just much smaller than my 3 good units. Bummer yet again. I got worried because it looked like someone used a pencil to draw a circle where the dustcap was to be glued on. No big deal, I could see that happening possibly.

Here's the photo: It looks like the supplier tried a larger cap, but changed it to a slightly smaller one (little glue left over?). You can barely see the pencil line below the "glue?" line up towards the top of the dust cap. It's not inverted.




Then I take it all the way out of the shipping box. Oh no, guess what? It's a dual voice coil unit??????? Say what? All the others ones are single. Total bummer.

Further looking, this is on the side and it looks like the driver has been mounted and used:




If you go back to my first picture, you can see a type of mesh they used around the copper guts inside. This driver doesn't have that. Notice right next to the terminals, you can see the insides. Probably no big deal.

But I'm pretty disappointed.

So, I ask the guys here for advice

This is what I am looking at right now:





What can I do? What can I build? What should I build? My dual "fathom look" is totally gone.

Obviously the 3 at the top are perfect. You can see the one with the inverted dustcap and different surround.

And the one I got today is obvious. But that one really can't be used, especially with having dual voice coils, and unknown specs. I'm also uncomfortable seeing it was marked as a sample and used. I would think ACI would really try to max out their suppliers sample units.

They were suppose to be new, so I still have a very tiny bit of hope that there was a mistake at their warehouse. But I don't think so because the first 5 e-mails they said they were sold out. I was just hoping for two matching pairs.

Thanks for the ideas guys. The thing about the first different one is that I know I can change the dust cap. But the surround is very different and it seems to take a lot less force to move the cone. It's just not as stiff. It's also a totally different material/rubber. But maybe that doesn't matter too much.



Robert, I will check about the extra pair of terminals, but I doubt they'll have the specs. I think they had to do some digging to find the specs for the current ones.



Here's why I'm a bit disappointed (cue up the sad music!). I'm not a huge fan of the Behringer EP2500. I bought a NHT B-20 amp and loved it because it's silent and puts out the juice. I liked it enough that I have THREE of them now just for this final project I've been planning.

I wanted to run a pair of nice ported 15's on two of the amps at 400-500 max each channel. Then use the other B-20 for the bass bins I just built with dual 10" NHT drivers.

So I took all my stuff down and spent a lot of time getting everything ready and tested this time around. And now I may not be able to do this. I gotta be honest, my family and friends are beginning to look at me a little weird! Seriously, and I'm beginning to wonder myself! Picture a 12' x 24' room with 4 amps wired all over the floor for testing, two ED 12" drivers, two 15" drivers, twelve 10" NHT drivers, and now five 15" ACI drivers.........also laying everywhere being tested. La la land......

So this was my final plan. And it's not looking so good now. A small thought says to pay shipping and have all 5 returned. I can sell one of the NHT B-20 amps easily. Then back to square one.

I would experiment with that 8th order type enclosure, but using the 10" NHT drivers first.

CZ Eddie, I asked Kevin if they were Exodus drivers and he said no. He mentioned that a lot of companies use very similar parts. The more I searched, they look even more similar to the 15" Dayton Titanic driver.


Mayhem, one thing about my room that seems to be a must is that I need symmetry up front with the subs. Two up front and one in the back may work. But I was hoping to use the B-20's with the modified HP filter on these guys. So they won't be getting 800 watts.

As of right now, I can't complain at all about the first 3. I guess I just need to hope the inverted dust cap unit truly has the same specs and then send back the other one.

The dual opposed idea did cross my mind. But I was really hoping for ported on these. I have 12 sealed NHT subs and they sound really nice, especially for music. So I decided to use them for a couple musical systems throughout the house in smaller sealed enclosures. And they sound absolutely great, no complaints at all.

I considered using 6 of them ported, but they required 4 cu ft per driver to get there. So at that point I thought 'save the 10" drivers for music' and try something new in a ported design.' That's pretty much the only reason I bought new 15" drivers......just to try my hand at ported enclosures.


BigMouthDC, I certainly will consider that, and did follow your amazing build since joining this site. I'm just a big fan of seeing the speakers you build. But I can change that idea possibly.


I'm going to e-mail ACI today and see what they think. I'll keep you guys posted.

That 4th driver with the same surround seems to have 2 pairs of speaker terminals, the others have one pair. So I don't know if it's a single voice coil or what at this point. It was also marked as 'sample', so I would imagine that the specs eventually changed from the end product.

Whatever I end up doing, the left and right front of the room has to be symmetric. And sadly, I don't have enough height to put anything under the center channel.


Obviously, it's not the end of the world or anything......just a bit disappointed. Maybe I can find the original manufacturer and see if they can make another one?

Well, if no one thinks that 4th one with the different surround will cause problems, then I won't worry about it either. The cone is easier to move, but the surround looks bigger, so maybe it has more room to move, or gets stiffer once it starts moving, I don't know. ACI said they had the same specs.

As for the original wall of 10" drivers, I take no offense. It was my first build and certainly a lesson. I know now that had I hooked up my EQ, they would have been better down low. I EQ'ed 2 of the NHT enclosures just for experiments and they did good, all 4 would have been nice.

But I found that out too late, the other 2 enclosures had been taken down and some drivers used in bass bins. They're awesome for music in a sealed enclosure, and that's what I will use them for. I should have ported them a year ago, but I was just too worried because it was my first build and thought the boxes would be incredibly large. I can't complain about them at all. I was dumb and should have listened to the pros here that recommended porting from the get go.

I'm moving on and now have some really nice 10" drivers for future bass bins throughout the home.



P.S. - As for the OCD comment.........yeh, tell me about it, you're not the first to mention it.