Rocket ULW-10 Subwoofer Review

Rocket is a brand of Onix Audio, a 20 year old British hi-fi manufacturer. Onix is currenty owned by a partnership between Mark Schifter and a Chinese entity. Onix owns a factory in China where Onix, Rocket and many other speakers are made under Mark's personal supervision. Reportedly, Mark spends about nine months a year in China and is very involved with all aspects of manufacturing. This is a considerably different setup from the current trend, of designing a product in North America or Europe and outsourcing production to a third-party in China. Mark actually goes to China to oversee manufacturing and design aspects of the product.

It seems Mark is bent on business models that break from tradition, both in manufacturing and retail. Established in Louisville, Colorado in 2000; AV123 was founded by Mark Schifter. They are an internet-direct retailer of consumer electronics. Though they carry a few conventional retail brands, most of the products they carry are made exclusively for them under the badges of Emotiva, Onix and Rocket.

The traditional retail model of a manufacturer to "brick and mortar" retailer to consumer, and sometimes even an importer/distributor layered in, has some inherent disadvantages. Each independent entity in the chain has a separate overhead structure and profit margin. From a cost-to-consumer perspective, this is not very efficient.

A somewhat common alternative is a factory-direct model. Here, of course, there is only one layer of overhead and profit margin. The big downside is the opportunity to audition before purchase, but the better outfits offer a reasonable return program. For example, AV123 provides a 30 day return policy and you only pay the two-way shipping expense. That is an extremely generous policy, many others also charge a re-stocking fee. Though AV123 is generous enough not to charge it, I feel the re-stocking fees are typically fair, since the seller then would have to markdown the product as "open box" to be able to sell it off.

Actually, while we are on the topic of personal auditions, it is time for another pontification by Arvind Kohli. Common conviction states that the biggest "benefits" of a traditional brick-and-mortar retail model are, that the consumer has a chance for personal audition and can benefit from the expertise of the retail staff. I do not think that there is any guarantee that a traditional retailer will deliver satisfactorily on either of those metrics. There, of course, abound horror stories of shopper snubbed by haughty staff at audio boutiques when seeking a personal audition, check out AudioAsylum for anecdotes. And even in the best cases, you may be permitted to take the product home for a couple of days. However, I do not think that is enough audition time, unless you did almost nothing but audition till you had to return the product. An extended in-house audition (30 days+), as provided by the better factory-direct outfits (and AV123), is more like what you will need to make a proper decision. And in the matter of expert opinion, I would say the consumer is better off gathering information independently from reviews, fellow-hobbyists and acquaintances. There is plenty of that resource freely available on the internet, though you have to keep your wits about you to filter out the pseudo-science and hack claims. So in the end, if you can get better pricing buying remotely, rely on an extended in-house audition and independently gathered information to cement your decision, you are probably better off than going to a "full-service" traditional retailer. Of course, there is a segment of the population (likely a sizeable segment) who could not be bothered with research. They want convenience, and that is where the "brick-and-mortar" folks fit in perfectly.

For folks who read reviews, participate in forums and constantly update their knowledge base; the AV123 business model is likely to deliver better value, since they are "informed consumers" and would not benefit much from knowledge and support given by traditional retailers. But that is just my guess, I will probably never have access to all the data I need to conclusively find that answer.

Sorry for the digression... now back to the review.

I have noticed a paradoxical trend in the marketplace for audio products, the past few years. There are some manufacturers, who mechanically repeat their churn of new products and occasionally slide up their prices for no significant improvement in product (not that their claims will ever admit that). On the other hand, I see products like this and when I look at the features, I am floored. I am honestly mystified as to how AV123.com can afford to offer these features at this price point. Let me furnish you the details, and you can judge for yourself.

The hottest feature of this beauty is the SOS or "Subwoofer Optimization System". What does that mean in non-hype? Well - it is a one-band parametric equalizer, with the settings automatically established by the subwoofer.

Huh - what does that mean? The subwoofer comes supplied with a microphone and 20' chord. You plug the mic into the back of the sub, place the mic in your normal sitting location, at your seated ear level. Turn on the "calibrate" mode, and abra-cadabra - you have the audio equivalent of a rabbit pulled out of a hat.

When you turn on the "calibrate" mode the sub generates a series of tones and measures the overall response at the listening position, including the impact of the room. The SOS module picks the single largest peak and flattens it, relative to the rest of the curve. Brilliant! Executed correctly, this should result in the elimination of a boomy or resonant artifact, as it did in my listening tests below.

The owner's manual is well written for this setup, but here are some points I feel need to be mentioned or reinforced;

I have to applaud the designers to not try and use "digital processing" as a gimmick to sell this unit, and in the process introduce a set of A/D and D/A conversions that can only pollute the source signal. While this sub does employ "digital processing" to perform the SOS calibration, the digital portion of the circuitry is turned off after calibration so as to not interfere with the analog signal. Brilliant!

Pink curve = Rocket ULW10 without SOS
Purple curve = Rocket ULW10 with SOS
Yellow curve = ACI Force

With each sub placed in the same spot, I individually measured their in-room response. Using my True Audio TrueRTA, I measured the in-room response of the Rocket ULW-10 (with and without SOS activated) and my reference ACI Force ($799).

Now consider, that this is an in-room response and not the innate response of the sub itself. Nonetheless, since they were all measured at the same spot and using the same process the results are useful to explain comparative differences. Also, I intentionally measured the Force at a slightly lower level so the curves would show better, it is the relative differences that matter here.

The Force has a much more extended response, as expected. Its response is within 7db from 20 to over 60hz, not bad at all. If it were mated with speakers of a -3db point of 65hz or lower (as most speakers are) the combined output would be fairly impressive, as far as in-room flatness goes. My room would be troublesome with either subwoofer, if I tried to used speakers that rolled off at a higher frequency.

The Rocket is fairly flat down to about 24hz and then drops sharply. This is outstanding performance at this price point. Many budget units presume to call themselves subwoofers if they have an audible response at 40hz 舰 making such claims should be illegal. The curve (pink) without the SOS activated has a tremendous hump between 32 and 49hz, which I would attribute to the 'resonant' and 'boomy' qualities I describe further on in my listening tests. This however, is not a design attribute but a room integration issue based on my room dimensions and the location of the subwoofer relative to my primary listening position.

Relatively speaking and considering an inherent room mode between 32 and 49hz, the Rocket (without SOS) had a larger hump than the ACI. After SOS, that hump almost completely disappears (purple curve), and the resulting response is within 7db from 24 to 65 hz, very close to the ACI.

This test measured the response curves at 200, 400, 800, and 1000 mV of output. The editor's analysis concludes that there isn't any compression to speak of, and thus the preamp overload issue identified in our review of the Rocket UFW-10 has been addressed since then.

With the SOS function turned off , the SPLs on the ULW-10 were plenty engaging but there was a bit of resonance and boom. With the SOS feature turned on it was like listening to a whole different subwoofer. The bass was much tighter and the boom and resonance was almost gone.

To be completely unfair, I also compared it to my other reference, the Velodyne F1500R ($1700). The fundamentals were much deeper, and the response was absolutely tight. But that is a whole lot more money for a small improvement on an absolute scale, and an even smaller improvement on a relative scale. The purpose of comparing to the F1500R is to illustrate that there is a bit "more" you can get in terms of performance if you were to spend a few multiples more, and that the ULW-10 does not deliver the ultimate in performance, but its pretty darn good. That should be no surprise; reference level performance for $500 is simply not a reality in subwoofers. But this test should give you an idea of how far away the Rocket is from reference level.

Finally, I compared the ULW-10 to the previously reviewed and similarly priced Velodyne DPS10 ($449). With the SOS feature turned off, I preferred the Rocket slightly to the Velodyne. With the SOS turned on, the Rocket was in a different league, much closer to the Velodyne F1500R than the DPS-10 in terms of extension and tightness.

For the audio-only listening tests, I compared the ULW-10 (with and without SOS activated) to my reference ACI Force and the previously reviewed Velodyne DPS10 . I played the following tracks straight thru each sub and without the accompaniment of satellite speakers, so I could better evaluate the performance of each subwoofer. Keep in mind, this test is designed to pick apart and compare the smallest nuances of the audio performance of a subwoofer, and is suitable for units that cost beau coup . Subjecting an entry-level priced unit to such scrutiny may not be deemed fair by some manufacturers, and has not won me friends in the past. But I do not write reviews to make friends, and will not shy away from critical tests because of the price point of a unit. Here is what I heard;

'Rimshot' (Eryka Badu; Baduism; Universal; UD53027)

'All or nothing at all' (Diana Krall; Love Scenes; Impulse; IMPD233 )

'Bass Resolution test' (Chesky Jazz and Audiophile tests Vol2; Chesky; JD68)

All subs were easily able to deliver the required SPLs for these tracks. The ACI Force was able to plumb into greater depths, rendered each transient attack with requisite speed, the decay was without overhang and nary a hint of underdamped resonances. She is my reference for good reason.

Even without the SOS activated, the Rocket ULW-10 seemed to hold it 舗 s own in terms of speed to address transient attacks and was a bit shy in note depth. But it faltered in aspects of boominess and unwanted resonances. The peaks were rattling miscellaneous loose items around my room, and would make any SPL-bound teen piqued with envy.

With the SOS turned on (see Figure1) it was like I was listening to a completely different subwoofer. The peak at about 40hz was nicely suppressed, yielding a much flatter response and the measured improvement was also an audible one. The presentation was quite musical, and the boom and resonances were drastically reduced. Only in direct comparison to the Force did the ULW-10 seem a bit recessed and lacking in depth.

The Velodyne did not fare as well in this comparison, even when compared to the ULW-10 with the SOS turned off. This speaks quite well for the ULW-10, considering it only costs $50 more than the Velodyne.

On the plus side we have good extension, minimal unwanted resonances, fairly fast transient response, an exquisite finish, nicely appointed controls, small footprint and of course, the outstanding SOS feature.

Negatives? Well, on an absolute scale I would say that the musical performance and low-frequency extension did not match that of my reference units. But to expect a $500 subwoofer to meet either of those standards would be 舰 well, asinine to say the least.

On a more realistic scale, considering the price point I cannot think of any significant issues with this unit. Barring, a minor issue of a bit more flexibility on the input options, leaves me with nothing to kvetch about. Well done.