SMR logoACI Quake Sub-woofer Review

Impressed with the ACI Titan sub-woofer, , moves down the ACI range to the new Quake, will this budget model live up to the reputation of its older and larger sibling?  One, two, three and we're away!

Many thanks go to Mr. Mike Dzurko for his help and for providing the review sample.

ACI Quake Specifications:

Dimensions: 20" tall, 14" wide and 14" deep
Linear Frequency Response: from 33-150Hz, +/-3db
Crossover Frequency: Adjustable Low Pass: 50-150Hz 12 db/octave, High Pass line level fixed at 80Hz 12/db/octave, High Pass speaker level at 100Hz
Bass Drivers: Proprietary Dual 8" long-throw woofers
RMS Power: Built in amplifier delivers 100 watts RMS at less than 0.5% distortion
Suggested Retail Price: $849
Factory Direct Sale Price: $449

(All specifications as per manufacturer)

General Description

After my successful experience with the ACI "Titan" sub-woofer (where I eventually bought it to replace my previous reference sub) I was particularly enthusiastic about getting my hands on ACIs new "Quake".  On paper, it sure looked like a great buy.  100 watts of power and two 8 inch polypropylene drivers for $449. Thats at least 50% more sub for the money than Ive ever seen.  At this price, you usually get a single 8 inch paper driver with about 60 watts of power in a box about 2/3 the size of the Quake.  At first glance the Quake is a lot of sub for the money, but turn it around and you see something that you wont see on too many budget subs out there.  You see a full compliment of controls.  Volume, low pass filter adjustment and phase adjustment, all continuously adjustable!  On the rear of the last $450 sub I had through here all you found was a volume control.

ACI Quake Sub-wooferFacilities for connecting the sub into your system are also generous.  You get the speaker level connections that allow you to hook the sub up to the speaker outputs from your receiver and then connect the speakers to the subs speaker outputs.  You also get preamp inputs and outputs.  The speaker level outputs place a 100Hz first order high pass filter in line with your speakers, the preamp outputs place a second order low pass filter.  The Titan doesnt even do that!!

At this price, you cant expect much in the way of finish.  Forget hardwood veneers and such, but on the other hand, the Quake is actually a pretty good looking sub.  It has good proportions, a fairly durable looking black textured finish and a "concave" shaped front facia into which the grill cover fits.  Its kind of hard to describe, but take my word for it, its a nice touch.  The grill is removable, but it takes some work and as its a subwoofer, its better to just leave it in place.

As I said before, on paper, the Quake looks like a lot of sub for the money.  But the real test would be in the listening room!


System One!

The first thing I did was put the Quake in my downstairs system where I was using a pair of NHT 2.9s. Now, the 2.9s dont have any need for a subwoofer, but they were bi-wired and it was just a matter of disconnecting the woofers and I was left with a pair of very fine speakers that dropped off rather sharply at 100Hz!  The Quake actually picked up the slack admirably.  Uh, too admirably!  Out of the box, the Quake was QUITE boomy.   I think what I was hearing was the result of some peaks in the response due to the fact that the woofers were not yet broken in.  But to lower the volume enough to get rid of the boom, I had to turn it down so low, that another smidgen of a rotation of the volume control would turn it off completely.  Immediately, it was obvious that the amp was set with pretty high gain and I had concerns that it was set too high to be used with some of todays smaller, inefficient speakers.  In other words, I was afraid that the sub would over power some of the smaller speakers with which it was intended to be used.  Well, eventually, with some break in, the response evened out and I was able to turn the volume up a hair with the 2.9s.  While the Quake didnt quite plumb the depths as well as the two 10 inch drivers I had disconnected on the NHTs, I have to say that as far down as it went, it did a good job keeping pace with the 2.9s and provided a good foundation to the music.  I was hearing some good weight and a surprising about of slam!


System Two!

Next, the Quake went upstairs and was used in conjunction with ACIs own Sapphire III speaker which just happened to be here for review also.   After some initial experimentation with the sub, I found what I thought to be a pretty good place for it and fiddled with the adjustments just enough to get a pretty good integration with the Sapphires.  It sounded pretty good, particularly for a $449 subwoofer so I let it alone and continued on with the listening.  I ended the day fairly impressed.

But the next day I started wondering if I had gotten all I could out of this little sub.  Sure, it sounded pretty good for a $449 sub, but it wasnt the absolute steal that the $800 Titan was.  So, I decided to spend some more time playing with positioning and adjustments.  Then, all of the sudden, it all "clicked".  I got the integration I was looking for between the sub and speakers, I got the smooth extended response I was looking for and I got the slam and speed I was missing the day before.  I was Jammin man!

From then on, I was actually listening to the Quake within the context of the review of the Sapphires [see separate review] and was very happy with what I was hearing.  This is no small feat as the Sapphires are an excellent speaker, albeit without the last iota of weight and authority in the bass and should have easily outclassed any subwoofer in this price class.  The Quake filled in very well the foundation on everything I threw at it and was not about to be embarrassed by its older, more experienced brother.  In my room, I measured (with warble tones and a SPL meter) strong output to about 31.5Hz with usable output at 25Hz.  As the low pass filter on the Quake starts at 50Hz, and the Sapphires were still strong down to 45Hz, I measured a pretty strong peak in the area of 50Hz, which actually sounded pretty good in my room!  Your mileage may differ though, so you may want to consider using the high pass filters built into the subwoofer.

Toy Story's Buzz LightyearThese high pass filters can do more than just alleviate such peaks at the crossover region, they can actually help your speakers do their job better by alleviating them of the burden of reproducing the bass frequencies that your sub is now intended to handle.  By filtering the bass from your speakers, you limit the stress imposed on the woofers by the bass frequencies, usually allowing them to do a better job articulating the midrange and you potentially increase the dynamic range of your speakers as they can play louder now without the large woofer excursions that would have left them bottoming out against their stops before.  Serendipity baby!!

Uh, getting back to the Quake, while its an excellent little sub for the money, Im afraid that its not the last word in subs.  For one thing, on classical music, I was occasionally aware of a little overhang.  Bass transients are not as sharp as what I get from the Titan.  This problem was really just one I observed on classical music, by-the-way.  Pop and Rock sounded great!   I cant say for sure, but I think this was a problem with the rather shallow slope of the low pass filter.  With the main speakers off, I heard a lot more vocals coming from the sub-woofer than Im used to hearing. This actually makes a lot of sense to me though.  In this price range, I think the Quake will be used with a lot of smaller, uh..., cheaper speakers, ones that really will need some help where the Sapphires didnt.  The shallow slope will actually help integrate it better with these speakers.

Speaking of smaller speakers and ones of less efficiency, I wanted to test the gain on the sub to ensure that it really wasnt too high to use with some less efficient speakers, so I took out my pair of NHT SuperZeros.  The SuperZeros have nothing in the way of bass below about 85Hz or so and are rather inefficient. It was the perfect speaker with which to test the two caveats I had encountered with the Quake.

Well, I still dont know if my theory on the low pass filter holds any water, but I can tell you that the Quake worked superbly with the SuperZeros!!  It was as if they were made for each other!  The SuperZeros had slam, weight and articulation in the nether regions galore!  They make a great combo!

The SuperZeros are a great little speaker, but, alas, they are no Sapphire, so back into the system went the Sapphires.  I have to make very clear that the problem I heard with classical music through the unfiltered Sapphires was a fairly mild one and was ONLY heard on classical.  No other forms of music were affected and they all sounded great.

(Hours pass)

Ok, I did it.  I didnt want to do it (who wants to mess with near perfection?), but I placed a pair of ACIs 65Hz high pass filters in line with the Sapphires.  I was wondering if that overhang problem I was hearing could have been related to the "bump" around 50Hz I was hearing.  It was!!   So the moral is this, if you are going to augment a pair of speakers with pretty good extension, you may want to wire your system through the sub.  Thereby taking advantage of the built in high pass filters.  Give it a listen both ways and see which you like.


Independence DaySystem Three!

Next up was a trip downstairs to the video system!  I inserted the Quake into my system which means taking out my 15 inch, 400 watt servo controled, almost 4 times the price Velodyne.  Once again, I had that gain problem.   This time it just meant adjusting the levels of my speakers until they were at there maximum while still being balanced.  No big thing.  Then I dropped the level of the sub from within the processors bass management controls and I was off and running.  Its not a big deal, but I wanted to warn anybody considering the Quake.  Better to be forwarned about something like this than to get the sub home and wonder why its so loud!  Anywho, I watched "Space Jam" (what you laughing at! I have a 19 month old who insists on it or "Toy Story" almost every day!) and was more impressed with the sub on video than I had been on music!  Space Jam has lots of transient bass, what with basket ball bouncing and "Mon-star" stomping around (not to mention a lot of looney tunes getting smushed!).  The Quake handled it with great aplomb.  Its a quck little sub!  But next up was "Independence Day" with its different kind of bass requirements.  Lots of space ship rumbles and the dog fight where Will Smith brings down the alien is a favorite of mine.  Well, I have to admit that I was a little suprised, but the Quake did a excellent job on this movie too.  I really expected it too be too much for the budget minded sub, but I was wrong.  It sounded great!



While I write all this, I have to work to keep my own opinions in context.  Even mentioning that little problem with classical was a HUGE nit pick in light of the price of this sub.  For what in the high end world is really pocket change (you can spend many times the price of this sub on speaker wire!), I must be some kind of an idiot to even fault this sub at all.  But the fact of the matter is this.  If I dont, the question comes up, "Why spring for the extra bucks to buy the Titan?"  Well, the Quake does an admirable job, but its no Titan.  Aside from the obvious fact that the Titan is a beautiful fixture, it goes deeper (by about 10Hz) plays louder and is indeed, tighter and more articulate.  If you have the extra bucks, do go for the Titan, you wont regret it.

But if money is tight, or if you are in a particularly small room, or if you are just looking for a small inexpensive sub for a second system (what a second system it would be too!) you wont do better than the Quake.  Highly recommended!


Good luck and listening,



More information about ACI products can be found at the Official ACI Web Site.

Audio Concepts Incorporated
901 South 4th Street
P.O. Box 212
La Crosse, WI 54601
Voice : 608-784-4570
Fax : 609-784-6367

Text John R. Potis Jr.; HTML SMR Home Theatre and Images SMR Home Theatre & ACI cannot be reproduced without permission.

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Last updated 23 March, 1998

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