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post #1 of 190 Old 04-26-2012, 03:35 PM - Thread Starter
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Introduction
The subject of this review is the Simply Sound Audio Rumba 12. The Rumba 12 is an acoustic suspension subwoofer with a 12", front-firing driver. It measures exactly 16" cubed -- 16"x16"x16" -- and weighs a staggering 75 pounds.

The amp is rated at 500 watts, but there's no indication if that's RMS or peak. There is no quoted frequency response on the website or in the manual. Simply Sound Audio offers a 2 year warranty on the amp and driver, as well as a 30 day in home trial. The Rumba 12 is designed and manufactured entirely in the USA.

Ordering
The review unit was supplied to me by the manufacturer, so I didn't go through the normal ordering process. Simply Sound Audio is a typical ID (Internet Direct) company though, meaning the only place to purchase them is directly from the manufacturer.


Unboxing
The unit came single boxed, but it was thicker cardboard then most I've seen. The sub was enclosed in a cloth bag, and suspended by a thick block of dense foam at each corner. Accessories include high quality carpet spikes with discs for hardwood floors, as well as a CD that contains the documentation. There is no printed copy of the manual included. The CD is somewhat unique, because it seems few companies supply those anymore.


Initial Impressions
The documentation could use a bit of attention. The owners manual seems to cover a lot, at first, but realistically doesn't give enough information about the Rumba 12 itself, especially some of the controls and options on the amp. For example, there's a toggle switch for Slope with settings for 12dB or 24dB, yet nowhere in the manual is it listed. I know what it's for, but I'll bet others don't. That's a nice feature to have, but it should be documented.

There's also a 2nd manual strictly for the PEQ (Parametric EQualizer). That one does a pretty good job of explaining what a PEQ is and how to use it, but there's really no need for that to be an entirely separate document. Both should probably be combined into a single PDF file.

One of the first things you notice about the Rumba 12 is just how heavy the thing is. When I saw it listed as 75 pounds on their website I figured that had to be a generous assessment, but it turns out to be spot on; I weighed the review unit and it is indeed 75 pounds. The thing is built like a tank, with 1" MDF for the front and back panels, and .75" for the rest. It passes the 'knuckle rap test' with ease.

The build quality is excellent. The finish is a satin black lacquer, which is applied in multiple coats. Except for a tiny chip the size of a pen point in the bottom right corner the paint was smooth and even. The thing feels rock solid. Most of the screws were properly tightened, with only two on the driver and two on the amp needing maybe 1/4 turn.

Strangely, the Rumba 12 looks better in person then the pictures would lead you to believe. I say strangely because the photo's posted on-line were taken by a professional photographer. What they fail to adequately reveal is the detail in the cabinet design. For example, the side panels have this very slight angle cut along the entire edge which gives it a refined look, yet that's somehow not fully captured by the pictures. Another unique design feature is that the side panels are taller then the front and rear panels (.5" total, .25" each on the top and bottom). This gives a singular impression unlike any other sub I've seen. I consider that a good thing personally, because it's certainly not your typical black square box sub. It's apparent Simply Sound Audio wanted to differentiate the Rumba 12 from the rest of the pack, and I think they succeeded.

One thing I'm still up in the air about is the fact there's no grill. I happen to prefer a grill - to me it gives the overall appearance of a more finished look. With the Rumba 12 it's not even an option. However, I have to admit that I derived an unexpected amount of enjoyment seeing the driver do it's work. This thing is an absolute beast, and watching it pound away was quite interesting.

The amp has somewhat of an industrial appearance, and could perhaps benefit from a bit more refinement. The markings for the various dials and switches silkscreened on the back plate are small and not terribly distinctive. The dials only show the extremes too -- the highest and lowest setting -- which makes minor adjustments challenging at times. Each dial does have a blue insert which enables you to clearly see what direction it's pointing in at least. The RCA input connector didn't feel as solid as the line level in connectors, but it wasn't flimsy either.

There's a large toroidal transformer bolted to the bottom of the cabinet. That's a nice feature, and uncommon for a sub in this price range. The amp generates little heat; no matter how hard I pushed the Rumba 12 neither the back plate nor transformer ever got more than warm. The Parametric Equalizer is also not something many subs costing what the Rumba 12 does include. It's an excellent way to tailor the sub to your exact room needs. The range of adjustment is phenomenal too, providing a full 24dB total of boost or cut (from -12 to +12). That's far more generous then most PEQ's provide. Finally, there's a toggle switch that allows you to select either a 12dB or 24dB slope for the cutoff. Generally speaking, acoustic suspension designs -- like the Rumba 12 -- tend to have a gradual decline in their output when they start to reach their limits. Bass reflex, on the other hand, tend to drop off far more rapidly. This switch allows you to tailor that behavior to your specific liking or need, which is a seldom seen option.

I had mixed results with the standby feature. Often times it simply would not go into standby mode, staying on no matter how long the receiver had been shut off. There was never an issue with it coming out of standby; as soon as I turned on the receiver the Rumba 12 would instantly wake up, without any hesitation. It also seemed particularly sensitive to a ground loop issue with my cable system. The standby timer is 40 minutes too, which seems rather long to me.

The driver is truly something to behold. It's the living embodiment of the word "over-built"; it weighs a staggering 32 pounds. There's a massive butyl rubber surround that feels very stiff, which is not only glued to the cone -- like every other driver -- it's stitched to it as well. The motor is enormous, with huge double stacked magnets and a bump-out to allow extended voice coil travel. It's attached to a cast aluminum frame that appears to be powdercoated. The voice coil itself is vented at the rear, with an outsized 1.25" vent, along with multiple vent holes between the base of the frame and magnet. It's hard to imagine anyone overheating this driver. The tinsel leads are woven into the spider, and there's what resembles some type of glass fibers impregnated into the very stiff pulp-based cone material. There's no question it's been engineered for the long haul.

I do have a few concerns about the driver though. The more excursion it's capable of the more potential there is for distortion. I didn't really hear anything untoward, which I suspect was partially due to the fact that the cabinet and driver are top notch, but it's something to consider. Another thing is the driver is secured to the cabinet using wood screws. For a driver this heavy and powerful t-nuts or inserts would probably be more appropriate. None of the screws came loose during the evaluation, so my concern may be unwarranted, but for a driver this heavy I would rather not have wood screws securing it.

The cabinet is stuffed with 10 ounces of polyfill, which has a story behind it (more on that later). Attention to detail is everywhere. For example, the plate amp fits perfectly into the cabinet cutout; I don't think there's even a 64th of an inch gap between it and the cabinet at any spot. There's an internal shelf brace that has a hole drilled in it for the speaker wires to pass through, so they're secured. The brace also has chamfered edges, similar to what the side panels have. Who does that? Who takes the time to design and build finishing details like that in a spot where 99% of the population will never even see them? To me that says good things about a company if they're willing to go to that length.


Setup
Hooking up the Rumba 12 is straightforward; plug in the RCA cable from your receiver to the LFE input and plug in the power. There are the ubiquitous left and right line level inputs but there's no summing function if you use them both, so the LFE input is the preferred method. That input also bypasses the Rumba 12's own crossover.

Next you set the gain, or volume, for the amp itself. I found the Rumba 12 had to be set on the "hot" side in order to match my other speakers properly. To get everything fully integrated I added +2dB to the subwoofer setting on my receiver, as well as drop my other channels by -2dB. Doing that will often limit the subwoofers headroom -- meaning it can't ultimately play as loud -- but I didn't notice a limitation during the evaluation. I found even with that the Rumba 12 was able to play pretty loud without struggling.

The phase is of the variable kind -- not just 0 or 180 degrees -- so you have complete flexibility on how you want to set it. Next you have to decide on how to set the slope, either 12dB or 24dB. There's probably no need to set it to anything other then 12dB though, since this is an acoustic suspension sub. Then comes the PEQ.

The Rumba 12's PEQ has three things that need to configured; the frequency you want to boost or cut, the level (amount of boost or cut to apply) and the "width". The latter setting is used to determine how much of the surrounding frequencies are affected by the first two settings. To disable the PEQ entirely just set the level to 0dB, which essentially negates the other two setting in the process. Without using a meter these adjustments will have to be set by ear, so you may be tempted to ignore them entirely, but that wouldn't necessarily be the best choice. A PEQ allows you to tailor the Rumba 12 for your specific home theater, which can provide a lot of benefits if done properly.


Listening
My living room is 13x17x8 (1768 CF), so it's not terribly large. The main seating position is approximately 11 feet from the subwoofer. Normally I do all my testing after the unit has been broken in for at least 15 hours, but in this case I waited for about 25 instead. That seemed prudent, given the stiffness of the drivers surround. It turned out to be a wise choice, because it did take longer then average for the Rumba 12 to fully break in.

When you look at the size of this sub, and couple that with the fact it's acoustic suspension, you initially think it might have some shortcomings in output and/or extension. Then you glance over at that imposing driver and think maybe it won't be too bad. Don't let the size deceive you; as it turns out, the Rumba 12 is one very powerful little subwoofer.

I found it to have a flat, neutral sound, without much, if anything, in the way of embellishment. To me this is the perfect way for a subwoofer -- or any speaker, for that matter -- to function. All I want to hear is what's on the soundtrack, and nothing else. Acoustic suspension designs seem more prone to behaving in this manner, which I suppose is partially why I've gravitated towards them for as long as I can remember. When the bass track was not a prominent part of the source material the Rumba 12 stayed in the background. When something more demanding was called for it came to life and pumped out deep bass.

The Rumba 12 has good dynamics, and sufficient headroom to allow all but the most demanding scenes to be played at an elevated volume level. Could I get it to bottom out? Yes, I was able to exhaust the drivers prodigious amount of travel; playing something like WOTW's, or select tracks off the Bass Mekanik CD at high volume, could induce slight mechanical noise. However, the Rumba 12 behaved perfectly when used under normal circumstances. Essentially, I didn't bump into it's limits unless I was trying to find them. Up until that point the sound was clear and powerful. Using the frequency sweeps on the Bass Mekanik CD I was able to get strong output down to 25Hz. By the time I got to 20Hz it had pretty much run out of steam, which is not at all unexpected given the price/size/configuration of the Rumba 12 (the PEQ was disabled during the frequency sweeps).

Attack and decay seemed particularly quick, making music hit fast and hard. Some of my reference CD's were played at a higher volume then I normally use for testing because the sound was so rich and powerful I just couldn't help myself. There was enough detail and articulation that I would classify the Rumba 12 as a musical subwoofer, not a designation I bestow lightly (I tend to be a bit picky in that regard). It doesn't quite have the accuracy to handle the more nuanced music, and lacks a slight bit of definition in general, but for the genres I listen to it did very well. I used 80Hz and 100Hz as a crossover point at various times and found it handled both with equal aplomb.

The owners manual states the preferable installation method is to forgo the carpet spikes and place the sub directly on the floor. This is so "The Rumba 12 will take advantage of physics and room acoustics together to provide deep pressurization as well as that tactile and tuneful response we love in our bass systems". The manual goes on to say "Generally speaking, do not use the supplied spikes. RUMBA 12’s work on the principle of the driver in a high-pressure sealed zone that directly couples it to the floor. Spiking the RUMBA 12 will decouple the woofer from the floor, which will lean out the bass response. If the floor is an older, very springy floor, spikes can be useful in reducing the influence of the RUMBA 12 on the floor".

I tried it myself -- placing the sub directly on the carpet, without the spikes -- but chose not to leave it that way. I must have one of those "springy" floors they referred to because there was too much resonance for my liking. I got a bit of additional tactile feel, but the droning was more then I wanted. Anyone buying the Rumba 12 should probably try it themselves though, in case their environment provides different results.


Movies/TV
I'm not prone to watching at "reference level", so my assessments should be considered in that regard. I run each test scene twice; once while seated in my normal listening position, and then a second time while sitting on the floor a few feet from the subwoofer. This allows me to hear it as I normally would, yet still affords me the opportunity to determine if it's straining even the slightest bit. Both tests are run at the same volume level.

Like most people I have specific DVD's I use when testing subwoofers. A few of my favorites are Lord of the Rings: Fellowship of the Ring, Collateral and Avatar. Recently added to my repertoire are scenes from 10,000 BC, and the quintessential ULF (ultra low frequency) torture test; War of the Worlds. Each individual test is listed in the format of Movie: Scene.


Lord of the Rings: Bridge of Khazad Doom - There is an ultra low frequency rumble in portions of this scene, as well as significant amounts of impact generated by numerous structures crumbling. For a subwoofer to handle all of that properly it needs to be precise and capable of reaching very deep, otherwise a lot of it comes across as nothing more than annoying resonance. The Rumba 12 handled it all in stride.

With a subwoofer that lacks precision the aforementioned rumble merely bombinates, but that was not the case here; it was reproduced clearly and accurately. There was a little loss of definition if the volume was turned up high, but it only started to occur when it was far louder then I would listen under normal circumstances.

As some of the structures start to collapse you have a blending of sounds, some pretty low some not so much. The Rumba 12 had no problem reproducing anything that was occurring, and portrayed all the effects with the correct amount of emphasis.

My favorite part of this scene to play around with is the Balrog's roar. There's an instance when you see it for the first time that I just love to crank way up. He jumps out of a cavern and lands right behind the Fellowship with a thud, and then lets out a fire-breathing roar. I enjoy seeing how loud I can play that part, because when the volume goes up it just sounds cool. The Rumba 12 did a great job, and handled the volume with relative ease. The huge reverberations created when the Balrog's feet hit the ground as he chases after the Fellowship came through with a pronounced impact.


Collateral: Club Fever - This disc has the option of using DTS or DD for audio, but I only test with DTS. In general I've found DTS encoding has a bit of additional low bass and an overall greater depth to the soundtrack, so I've decided to use that exclusively for testing.

Although this scene doesn't contain a tremendous amount of LFE information it does have a driving musical soundtrack and over-emphasized gun sounds. The music portion I've found can cause trouble for a subwoofer because it does tend to drown out the voice track in certain spots, especially if it lacks clarity and speed. Because of that articulation is crucial. The Rumba 12 didn't even break a sweat with this one.

The club music was about as clear as I've ever heard, even with the crossover set at 100Hz (actually, it sounded better at 100Hz then 80Hz). Voices were not drowned out in the slightest, and the magniloquent gunfire was rendered to perfection.


Avatar: Assault on Home Tree - For those familiar with the movie this scene has low frequencies, ultra low frequencies, explosions, gunfire, voices and enough other things going on to provide a good test of virtually every component in your system. The Rumba 12 had no problems with this scene either.

As the gunships approach Home Tree you can almost feel the underlying intensity. The roar of their engines, the sound of the rockets being launched, the impact of each explosion, the crackling of the massive roots as the tree begins to list, and all the way to the point where it's toppled and crashes into the ground the low frequency reproduction was spot on.

The Rumba 12 handled this scene so effortlessly that I tried a few others, namely Battle for Pandora, Fall of the Heroes and Eywa. All of these additional scenes were delivered with the same ease and grace.


War of the Worlds: The Machine Emerges - The archetype... perhaps the most recognized subwoofer test scene of all time comes from a movie that's about 7 years old. The depth and volume of bass that occurs during a several minute span is simply amazing. If you want to see what your sub is capable of this scene can certainly be used as a barometer. With subterranean vibrations, exploding pavement and collapsing buildings you have ultra low, low and mid-bass frequencies pouring out of your subwoofer. One of the most punishing combinations there is, and an excellent way to really push something to the brink. As in the case of Collateral, the DTS audio track is used for this scene. For the most part the Rumba 12 did exceedingly well, only straining as the volume rose to substantial levels.

At a normal listening level, or even slightly elevated, the sound effects were rich and powerful. This was the only test scene that made the door of my hallway closet rattle. The individual elements -- buckling pavement, collapsing buildings, etc. -- each have their own individual sound profile, and all were presented accurately. So engrossing was it that I tried another two scenes; Heat-Ray and At The Window. Both exhibited the same degree of clarity and impact, and only when I really cranked up the volume did I get the driver to protest. Even then it was only apparent when sitting within a few feet of the subwoofer. In my normal listening position it wasn't really evident.


10,000 BC: Mammoth Hunt - During this scene there's either ultra low bass or mid-bass, with very little in between it seems. However, I've found this to be a good way of determining how a sub performs with nuances while being pushed hard. If it's struggling to hit the very low notes then the mid-bass suffers, and will come across as a jumbled mess (lacking in detail). If it can hit the low notes, but isn't articulate, then it tends to sound "thick" or "heavy", losing most of it's distinction. When portrayed correctly though, the really deep bass is what makes this scene. The Rumba 12 did a wonderful job here.

In the prelude leading up to the stampede the mammoths are simply milling about, but each earth-rattling thud from their massive feet is supposed to be felt as much as heard. When the stampede begins you then have dozens of raging mammoths running to escape. In order for this scene to work properly your subwoofer must be able to produce a tangible sensation of the ground shaking all around you. I sat there enthralled as this little subwoofer made that all come to life. It seems implausible to me that something of this size could produce such a corporeal impression, but it did. I actually played this scene multiple times, because I couldn't believe what I was feeling coursing through my chair.


Music
I use a combination of lossy and lossless material -- MP3's and CD's -- to see how musical a subwoofer is, and in both instances the Rumba 12 shocked me with how well it performed.

My first test is always Johnny Lang's CD Lie To Me. The mix is beautifully done, and the simplicity of the music means you can easily focus in on nuances. The detail from the Rumba 12 was impeccable, even as I started to crank the volume. And crank it I did, all the way up to "that's starting to hurt my ears" level. Yet the Rumba 12 kept pace, without ever once breaking stride. On virtually every type of music I sampled the results were the same; the precision and speed hardly ever faltered.

I don't have any pipe organ music to use for testing, but I did pick up a copy of Bass Mekanik. For those unfamiliar with this "music" (and I do use that term loosely)... it's essentially the source material people use to show off their car audio systems at those SPL (volume) contests. Consisting of nothing more than ridiculous electronic music, it has little value save for one; it contains some very deep bass. I hammered the Rumba 12 mercilessly with this CD and it kept it's composure on all but the deepest notes. Excessive volume could undo it's poise, as you would expect, but in order to unnerve this thing the volume had to be higher then any $550 subwoofer should be expected to play, especially when you consider the depth of bass in these songs.


After pounding the Rumba 12 for several hours -- with movies, music, test tracks, and various sound effects (rocket launches, fireworks displays, locomotives, etc.) -- the amp was nothing more then warm. Knowing that the toroidal transformer is attached to the bottom panel I felt around their as well, but even that wasn't hot. I have never punished a subwoofer like I have this one so I expected a lot more heat, but it just never materialized.


Support
The support provided by Simply Sound Audio can be summed up in a single word; exemplary. The reality is this company is a one man operation, and the guy who does it all is named Murrel Gray. Almost everyone who owns an MFW 15 subwoofer is already familiar with Murrel, so it's not like he hasn't already proven himself. Building his own line of subwoofers seems to be a natural extension to what he already does. A perfect example of the support you get would be the polyfill situation I alluded to earlier.

While doing the critical listening portion of my evaluation I noticed what seemed like a little overhang, a slow response on occasion, which could make the sound a bit "thick". Users of ported subs will often hear something like this -- which is commonly referred to as 'group delay' in that case -- but sealed subs don't generally have such an issue. Part of my normal process is to take the subwoofer apart so I can see how it's built, and also to get some pictures of the driver, amp, cabinet internals, etc. When I did that with the Rumba 12 I noticed there was very little damping material being used (turns out it was 2 ounces). That seemed insufficient to me, so I contacted Murrel to discuss it with him.

Now, when I say "contacted Murrel" it usually means by phone. Why? It's his preferred method of doing support. That's not to say he doesn't respond to emails -- because he does -- it's just that he would much rather speak over the phone (to the extent that his home page actually contains his phone number). In this day and age that's exceedingly rare. After speaking with him for a while, and explaining what I found/felt, we hung up. I figured that was the end of it; I'd provide some feedback and he would take it under advisement. What happened next was anything but that...

The next night I get an email from Murrel that has all kinds of graphs in it. Each one showed the frequency response with a different amount of polyfill damping, from 0 ounces to 16 ounces in 2 ounce increments. That must have consumed several hours to gather that type of data. Based upon that we decided 10 ounces would be the ideal amount, so all future subs will come with that much in them. Very uncommon to get that level of response and commitment from any company, but that's not where this story ends.

The next day I get another email, this time from FedEx. Simply Sound Audio is sending me 10 ounces of polyfill so I can stuff the evaluation unit with the same amount that we deemed ideal. I considered that excellent customer service, but did you think Murrel was done yet? Think again. Two days after the FedEx email I get yet another message, this time with a link to a 450 meg HD video file. It's a 7 minute video he took of what the frequency response graph looks like in real time while watching a movie. But that's not all; along with the perpetual graphs being displayed on his laptop there's also an oscilloscope hooked up so I can directly compare the signal to the output! He wanted to show me just how clean and accurate the sound was now that the unit had 10 ounces of polyfill. Who on earth goes to that extent to support their products? Simply incredible...

The difference between 2 ounces and 10 ounces is actually palpable; the driver moves less frenetically when it's being pushed, it starts and stops faster and has a slightly more detailed sound overall. Because of the testing he did all future Rumba 12's will have 10 ounces of stuffing, so everyone will benefit from it.

This wasn't a one-shot deal either. Every single time I spoke with him on the phone he was the same way; courteous, polite and very helpful. To be honest, it was the rare call that was less then 20 minutes. He's just a very personable guy.


Conclusion
Sometimes the Conclusion section of the review is the easiest part to write, because some overriding thought or theme is constantly evident. That's what happened in the case of the Rumba 12. I kept finding myself thinking "is this guy making any money on these subwoofers?". He must work on some pretty slim margins, that's for sure. I have some experience in the DIY area, and have been integral with the design of subwoofers myself, so I have more then a passing familiarity with what goes on 'behind the scenes'.

Without question, the driver being used is high-end. It's hard to imagine the unit cost isn't somewhere in the vicinity of $200 each. And the amp, with 500 watts, a toroidal transformer and PEQ? It has to be around the same price as the driver. What about the enclosure? The materials being used, the level of detail in the panel cuts, the amount of craftsmanship to construct them, coupled with a multi-layer lacquer paint job means they have to be at least $100 each. Of course there's always the ancillaries, like wire, screws, damping material, spiked feet, and the like. What about packaging? Boxes, foam, cloth bags - they all cost money as well. And that's to say nothing of the value of Murrels time to build them. Even if you price things conservatively it adds up to be around $500. For a subwoofer that sells for $550? Like I said, how does this guy make any money?

The bottom line is the Rumba 12 represents an extraordinary value. For those looking at a small acoustic suspension subwoofer this one should be at the top of your list. The output is clear, articulate, deep and powerful. It's all wrapped up in a nicely designed and styled enclosure that feels as though it was hewn from a piece of granite. With support that's second to none -- along with an amazing price/performance ratio -- the few flaws it does have are pretty easy to overlook.


For those interested in my subjective assessment it's that the Simply Sound Audio Rumba 12 is highly recommended.
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post #2 of 190 Old 04-26-2012, 04:10 PM
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Wow! that was a well written review of a product that seems like a great value! So who's gonna be the first to pick one up?
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post #3 of 190 Old 04-26-2012, 04:13 PM
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Thanks! Terrific review.

Any idea how it compares with the SVS SB12?

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post #4 of 190 Old 04-26-2012, 04:38 PM
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Great review Jim! That must have taken a while.
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post #5 of 190 Old 04-26-2012, 04:46 PM
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That FR graph is pretty impressive. Nice review!

 

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post #6 of 190 Old 04-26-2012, 04:57 PM
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Jim

Thank you for all of your time and hard work. I am already working on some of the things that were issues. I just spoke to the amp designer and I will be changing the auto circuit to a shorter time. All the amps are pulled and will be in the shop tomorrow morning. So shipments may be delayed a few days.

If anyone has questions please feel free to contact me!

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post #7 of 190 Old 04-26-2012, 05:09 PM - Thread Starter
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Thanks guys. I really do appreciate the comments.

The reviews do take me quite a while because I'm very particular how I go about them. Seems like the more I do the longer they become too.

I've never had the opportunity to hear an SB12 -- which is probably a direct competitor to the Rumba 12 -- so I can't really say how they compare. I can tell you it's better then the Emotiva Ultra 12 I had, and I loved that little subwoofer. The Rumba has it beat though. One thing I don't know if I ever fully divulged is how I do my assessments, so perhaps it's time to clarify that...

All of my assertions in a review -- every single one of them -- is relative to the price of the unit. What would be a glowing comment for a $200 subwoofer might be mediocre for a $600 one, strictly because I would expect more from the latter. I've seen far too many reviews that had a comment such as "this subwoofer is not as good as Product X, but that costs 3 times as much". Well, duh; if it's 300% more then it d@mn well better have an advantage! I always considered that disingenuous, like a backhanded compliment. I do my best to make sure all my comments are in line with what something costs. If the Rumba 12 cost $1000 then my comments wouldn't have been so positive, but for $550 it's really hard to beat.

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post #8 of 190 Old 04-26-2012, 05:29 PM
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Quote:
Originally Posted by JimWilson View Post

I've never had the opportunity to hear an SB12 -- which is probably a direct competitor to the Rumba 12 -- so I can't really say how they compare. I can tell you it's better then the Emotiva Ultra 12 I had, and I loved that little subwoofer. The Rumba has it beat though.

lol, I have the ultra 12 xD. With all seriousness though, the rumba is $550 (+ shipping). The emo was about $330-$430 (free shipping) which completely justifies it's performance. If the rumba wasn't a better subwoofer, I'd be concerned. Nevertheless, looking forward to some comparisons between the rumba vs competitors. Epik Legend and FV12 are more in its price range, and have quite substantial output down to 20hz. These would be good for comparison.

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post #9 of 190 Old 04-26-2012, 06:02 PM - Thread Starter
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Originally Posted by Khaos View Post

Nevertheless, looking forward to some comparisons between the rumba vs competitors. Epik Legend and FV12 are more in its price range, and have quite substantial output down to 20hz. These would be good for comparison.

Those aren't really it's competitors though; the SVS SB12 and Emotiva X-Ref 12 would be. Essentially, small acoustic suspension subs with a 12" driver are more in line with the Rumba. I'd like to see a direct comparison between the three of them myself.

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post #10 of 190 Old 04-26-2012, 06:07 PM
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Great review!
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post #11 of 190 Old 04-26-2012, 06:12 PM
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Originally Posted by JimWilson View Post

Those aren't really it's competitors though; the SVS SB12 and Emotiva X-Ref 12 would be. Essentially, small acoustic suspension subs with a 12" driver are more in line with the Rumba. I'd like to see a direct comparison between the three of them myself.

True for the FV12, but the Epik is sealed (and its width is an inch less), so I'd still consider the Epik something to compare to. To each his own though. xP

Your comparison to the ultra 12 has really perked my interest. I already assume low output extension is much better on the rumba 12, but as far as sound quality goes how would you compare them?

Thanks.

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post #12 of 190 Old 04-26-2012, 06:37 PM
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Wow, what a great review, Jim. Thanks for taking your time doing this review. How does the Rumba compare to the XTZ that you kept after reviewing it? Thanks again.
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post #13 of 190 Old 04-26-2012, 06:45 PM
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Congrats Murrel.

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Congrats Murrel.

Thanks Hugh!

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post #15 of 190 Old 04-26-2012, 07:01 PM - Thread Starter
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Originally Posted by Khaos View Post

Your comparison to the ultra 12 has really perked my interest. I already assume low output extension is much better on the rumba 12, but as far as sound quality goes how would you compare them?

The Ultra 12 started to lose output when test tones below 30Hz were run, and by the time it hit 25Hz that was pretty much the end of the line. The Rumba beat that by about 5dB; it hit 25Hz with some authority, but by 20Hz it had run out of steam.

Sound quality I would probably give the nod to the Ultra 12. It had a bit more finesse, making it a little cleaner. For someone who listens mostly to music the Ultra 12 would more then likely win out. For those who watch more movies and TV, or are perhaps 50/50 TV music, then the Rumba would be the better alternative. The Rumba also has the PEQ, so you can tame a peak or fill in a null. You can't do that with the Ultra 12.

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Originally Posted by JimWilson View Post

The Ultra 12 started... Ultra 12.

True, the EQ features are pretty nice. I'm 90%-95% music (gaming being my only exception where low extension matters), so happy to hear my Ultra 12 is no slouch.

Thanks again. xP

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Originally Posted by tvuong View Post

Wow, what a great review, Jim. Thanks for taking your time doing this review. How does the Rumba compare to the XTZ that you kept after reviewing it?

There's another chapter to the XTZ story; I actually traded in the 99 W10.16 (10") for a 99 W12.16 (12"). Why? Because I get upgrade-itis just like everybody else!

You can tune the XTZ subwoofer using port bungs and EQ boost switches. I had been using the W10.16 with everything set for the most extension, because I don't really listen all that loud when I'm not doing an evaluation. What I was finding is that when I did watch something like WOTW, Tron: Legacy, etc. I could get the driver to complain if I did want to add some volume, like when demoing it for someone. And while it did definitely kick some butt, I wasn't feeling enough rumble in my bu... chair. My chair!

Since it was only a few months old I contacted XTZ to see if they would be amenable to a trade in, and they were. I got a pretty good deal too, so I went for the 12" version instead. Now I can tune it for "neutral", to gain the extra definition, yet still get some rumble. So, back to the original question...

If the XTZ is run acoustic suspension -- both ports blocked -- I would say the Rumba will outperform it. Change it to full extension and the XTZ wins, but the SQ drops a little. So in some respects it's a draw. The XTZ cabinet is very stout too, but the Rumba still weighs more.

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post #18 of 190 Old 04-26-2012, 07:51 PM
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Just a update on the amp specs in the Rumba 12. It is 500 watts RMS and has a 880 watt peak rating.

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post #19 of 190 Old 04-26-2012, 09:20 PM
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Thanks Jim. A side question, can you tell me the timeframe of the movies, WOTW, LOTR, Avatar, 10,000BC where you test subs? I have an HTPC with these movies in mkv formats that do not have chapters skip. I like to see how my sub performs on these scenes. Thanks.
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post #20 of 190 Old 04-27-2012, 03:05 AM
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Great job Jim!!

I read the whole thing. Very well written. Are you sure this is not your full time job?

Almost makes me want to buy 1. Hopefully they'll come out with a ported model.
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Originally Posted by jproy13 View Post

Great job Jim!!

I read the whole thing. Very well written. Are you sure this is not your full time job?

Almost makes me want to buy 1. Hopefully they'll come out with a ported model.

Stay tuned!



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Murrel,
I understand that you have another sub in the work (ported one as you seem to reveal). Do you know the size of the driver and the over all dimension of this future sub? Thanks.
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post #23 of 190 Old 04-27-2012, 06:33 AM
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^^^
yes, do tell
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post #24 of 190 Old 04-27-2012, 06:34 AM - Thread Starter
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Originally Posted by jproy13 View Post

Great job Jim!!

I read the whole thing. Very well written. Are you sure this is not your full time job?

Thank you for the kind words.

I'm in the computer field actually, but in a more senior technical position so I do have to communicate with the people who wear fancy suits and expensive shoes. In that realm an extended vocabulary has proven advantageous. To some extent, even back in school, I've had a certain fascination with the English language. It's perhaps the most convoluted of them all, but can be eloquent as well. I have no formal training as a writer though (or reviewer, for that matter). I'm just tenacious.

The way this is starting to go I might have to figure out a way to make some $$ from it. I have my next test unit already breaking in as we speak, and another on the way to me now. There are 5 others I'm trying line up after these 2, so if it all works out I'll have 7 more to do. Guess I'll be busy the rest of this year...

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^^
As I mentioned in other thread, you do deserve some $$$ for spending lots of your time reviewing them.
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post #26 of 190 Old 04-27-2012, 08:06 AM - Thread Starter
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^^
As I mentioned in other thread, you do deserve some $$$ for spending lots of your time reviewing them.

I could sure use a business manager. Care to volunteer? I'd give you a cut of whatever I earn...

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Murrel,
I understand that you have another sub in the work (ported one as you seem to reveal). Do you know the size of the driver and the over all dimension of this future sub? Thanks.

tvuong,

It will use the same cabinet as the Rumba, the same amp as the Rumba (different eq curve) it is an opposed twin 8 with a down firing port. The cabinet will set on a raised matching base.

It is not much of a secret as I have posted some pictures of the test cabinet on my FB page. The amp plate in the test cabinet is much larger and will not be used in the final product.

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post #28 of 190 Old 04-27-2012, 08:35 AM
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Introduction
The subject of this review is the Simply Sound Audio Rumba 12. The Rumba 12 is an acoustic suspension subwoofer with a 12", front-firing driver. It measures exactly 16" cubed -- 16"x16"x16" -- and weighs a staggering 75 pounds.

The amp is rated at 500 watts, but there's no indication if that's RMS or peak. There is no quoted frequency response on the website or in the manual. Simply Sound Audio offers a 2 year warranty on the amp and driver, as well as a 30 day in home trial. The Rumba 12 is designed and manufactured entirely in the USA.

Ordering
The review unit was supplied to me by the manufacturer, so I didn't go through the normal ordering process. Simply Sound Audio is a typical ID (Internet Direct) company though, meaning the only place to purchase them is directly from the manufacturer.


Unboxing
The unit came single boxed, but it was thicker cardboard then most I've seen. The sub was enclosed in a cloth bag, and suspended by a thick block of dense foam at each corner. Accessories include high quality carpet spikes with discs for hardwood floors, as well as a CD that contains the documentation. There is no printed copy of the manual included. The CD is somewhat unique, because it seems few companies supply those anymore.


Initial Impressions
The documentation could use a bit of attention. The owners manual seems to cover a lot, at first, but realistically doesn't give enough information about the Rumba 12 itself, especially some of the controls and options on the amp. For example, there's a toggle switch for Slope with settings for 12dB or 24dB, yet nowhere in the manual is it listed. I know what it's for, but I'll bet others don't. That's a nice feature to have, but it should be documented.

There's also a 2nd manual strictly for the PEQ (Parametric EQualizer). That one does a pretty good job of explaining what a PEQ is and how to use it, but there's really no need for that to be an entirely separate document. Both should probably be combined into a single PDF file.

One of the first things you notice about the Rumba 12 is just how heavy the darn thing is. When I saw it listed as 75 pounds on their website I figured that had to be a generous assessment, but it turns out to be spot on; I weighed the review unit and it is indeed 75 pounds. The thing is built like a tank, with 1" MDF for the front and back panels, and .75" for the rest. It passes the 'knuckle rap test' with ease.

The build quality is excellent. The finish is a satin black lacquer, which is applied in multiple coats. Except for a tiny chip the size of a pen point in the bottom right corner the paint was smooth and even. The thing feels rock solid. Most of the screws were properly tightened, with only two on the driver and two on the amp needing maybe 1/4 turn.

Strangely, the Rumba 12 looks better in person then the pictures would lead you to believe. I say strangely because the photo's posted on-line were taken by a professional photographer. What they fail to adequately reveal is the detail in the cabinet design. For example, the side panels have this very slight angle cut along the entire edge which gives it a refined look, yet that's somehow not fully captured by the pictures. Another unique design feature is that the side panels are taller then the front and rear panels (.5" total, .25" each on the top and bottom). This gives a singular impression unlike any other sub I've seen. I consider that a good thing personally, because it's certainly not your typical black square box sub. It's apparent Simply Sound Audio wanted to differentiate the Rumba 12 from the rest of the pack, and I think they succeeded.

One thing I'm still up in the air about is the fact there's no grill. I happen to prefer a grill - to me it gives the overall appearance of a more finished look. With the Rumba 12 it's not even an option though. However, I have to admit that I did derive an unexpected amount of amusement from watching the driver do it's work. This thing is an absolute beast, and watching it pound away was quite interesting.

The amp has somewhat of an industrial appearance, and could perhaps benefit from a bit more refinement. The markings for the various dials and switches silkscreened on the back plate are small and not terribly distinctive. The dials only show the extremes too -- the highest and lowest setting -- which makes minor adjustments challenging at times. Each dial does have a blue insert which enables you to clearly see what direction it's pointing in at least. The RCA input connector didn't feel as solid as the line level in connectors, but it wasn't flimsy either.

There's a large toroidal transformer bolted to the bottom of the cabinet. That's a nice feature, and uncommon for a sub in this price range. The amp generates little heat; no matter how hard I pushed the Rumba 12 neither the back plate nor transformer ever got more than warm. The Parametric Equalizer is also not something many subs costing what the Rumba 12 does include. It's an excellent way to tailor the sub to your exact room needs. The range of adjustment is phenomenal too, providing a full 24dB total of boost or cut (from -12 to +12). That's far more generous then most PEQ's provide. Finally, there's a toggle switch that allows you to select either a 12dB or 24dB slope for the cutoff. Generally speaking, acoustic suspension designs -- like the Rumba 12 -- tend to have a gradual decline in their output when they start to reach their limits. Bass reflex, on the other hand, tend to drop off far more rapidly. This switch allows you to tailor that behavior to your specific liking or need, which is a seldom seen option.

I had mixed results with the standby feature. Often times it simply would not go into standby mode, staying on no matter how long the receiver had been shut off. There was never an issue with it coming out of standby; as soon as I turned on the receiver the Rumba 12 would instantly wake up, without any hesitation. It also seemed particularly sensitive to a ground loop issue with my cable system. The standby timer is 40 minutes too, which seems rather long to me.

The driver is truly something to behold. It's the living embodiment of the word "over-built"; it weighs a staggering 32 pounds. There's a massive butyl rubber surround that feels very stiff, which is not only glued to the cone -- like every other driver -- it's stitched to it as well. The motor is enormous, with huge double stacked magnets and a bump-out to allow extended voice coil travel. It's attached to a cast aluminum frame that appears to be powdercoated. The voice coil itself is vented at the rear, with an outsized 1.25" vent, along with multiple vent holes between the base of the frame and magnet. It's hard to imagine anyone overheating this driver. The tinsel leads are woven into the spider, and there's what resembles some type of glass fibers impregnated into the very stiff pulp-based cone material. There's no question it's been engineered for the long haul.

I do have a few concerns about the driver though. The more excursion it's capable of the more potential there is for distortion. I didn't really hear anything untoward, which I suspect was partially due to the fact that the cabinet and driver are top notch, but it's something to consider. Another thing is the driver is secured to the cabinet using wood screws. For a driver this heavy and powerful t-nuts or inserts would probably be more appropriate. None of the screws came loose during the evaluation, so my concern may be unwarranted, but for a driver this heavy I would rather not have wood screws securing it.

The cabinet is stuffed with 10 ounces of polyfill, which has a story behind it (more on that later). Attention to detail is everywhere. For example, the plate amp fits perfectly into the cabinet cutout; I don't think there's even a 64th of an inch gap between it and the cabinet at any spot. There's an internal shelf brace that has a hole drilled in it for the speaker wires to pass through, so they're secured. The brace also has chamfered edges, similar to what the side panels have. Who does that? Who takes the time to design and build finishing details like that in a spot where 99% of the population will never even see them? To me that says good things about a company if they're willing to go to that length.


Setup
Hooking up the Rumba 12 is straightforward; plug in the RCA cable from your receiver to the LFE input and plug in the power. There are the ubiquitous left and right line level inputs but there's no summing function if you use them both, so the LFE input is the preferred method. That input also bypasses the Rumba 12's own crossover.

Next you set the gain, or volume, for the amp itself. I found the Rumba 12 had to be set on the "hot" side in order to match my other speakers properly. To get everything fully integrated I added +2dB to the subwoofer setting on my receiver, as well as drop my other channels by -2dB. Doing that will often limit the subwoofers headroom -- meaning it can't ultimately play as loud -- but I didn't notice a limitation during the evaluation. I found even with that the Rumba 12 was able to play pretty loud without struggling.

The phase is of the variable kind -- not just 0 or 180 degrees -- so you have complete flexibility on how you want to set it. Next you have to decide on how to set the slope, either 12dB or 24dB. There's probably no need to set it to anything other then 12dB though, since this is an acoustic suspension sub. Then comes the PEQ.

The Rumba 12's PEQ has three things that need to configured; the frequency you want to boost or cut, the level (amount of boost or cut to apply) and the "width". The latter setting is used to determine how much of the surrounding frequencies are affected by the first two settings. To disable the PEQ entirely just set the level to 0dB, which essentially negates the other two setting in the process. Without using a meter these adjustments will have to be set by ear, so you may be tempted to ignore them entirely, but that wouldn't necessarily be the best choice. A PEQ allows you to tailor the Rumba 12 for your specific home theater, which can provide a lot of benefits if done properly.


Listening
My living room is 13x17x8 (1768 CF), so it's not terribly large. The main seating position is approximately 11 feet from the subwoofer. Normally I do all my testing after the unit has been broken in for at least 15 hours, but in this case I waited for about 25 instead. That seemed prudent, given the stiffness of the drivers surround. It turned out to be a wise choice, because it did take longer then average for the Rumba 12 to fully break in.

When you look at the size of this sub, and couple that with the fact it's acoustic suspension, you initially think it might have some shortcomings in output and/or extension. Then you glance over at that imposing driver and think maybe it won't be too bad. Don't let the size deceive you; as it turns out, the Rumba 12 is one very powerful little subwoofer.

I found it to have a flat, neutral sound, without much, if anything, in the way of embellishment. To me this is the perfect way for a subwoofer -- or any speaker, for that matter -- to function. All I want to hear is what's on the soundtrack, and nothing else. Acoustic suspension designs seem more prone to behaving in this manner, which I suppose is partially why I've gravitated towards them for as long as I can remember. When the bass track was not a prominent part of the source material the Rumba 12 stayed in the background. When something more demanding was called for it came to life and pumped out deep bass.

The Rumba 12 has good dynamics, and sufficient headroom to allow all but the most demanding scenes to be played at an elevated volume level. Could I get it to bottom out? Yes, I was able to exhaust the drivers prodigious amount of travel; playing something like WOTW's, or select tracks off the Bass Mekanik CD at high volume, could induce slight mechanical noise. However, the Rumba 12 behaved perfectly when used under normal circumstances. Essentially, I didn't bump into it's limits unless I was trying to find them. Up until that point the sound was clear and powerful. Using the frequency sweeps on the Bass Mekanik CD I was able to get strong output down to 25Hz. By the time I got to 20Hz it had pretty much run out of steam, which is not at all unexpected given the price/size/configuration of the Rumba 12 (the PEQ was disabled during the frequency sweeps).

Attack and decay seemed particularly quick, making music hit fast and hard. Some of my reference CD's were played at a higher volume then I normally use for testing because the sound was so rich and powerful I just couldn't help myself. There was enough detail and articulation that I would classify the Rumba 12 as a musical subwoofer, not a designation I bestow lightly (I tend to be a bit picky in that regard). It doesn't quite have the accuracy to handle the more nuanced music, and lacks a slight bit of definition in general, but for the genres I listen to it did very well. I used 80Hz and 100Hz as a crossover point at various times and found it handled both with equal aplomb.

The owners manual states the preferable installation method is to forgo the carpet spikes and place the sub directly on the floor. This is so "The Rumba 12 will take advantage of physics and room acoustics together to provide deep pressurization as well as that tactile and tuneful response we love in our bass systems". The manual goes on to say "Generally speaking, do not use the supplied spikes. RUMBA 12's work on the principle of the driver in a high-pressure sealed zone that directly couples it to the floor. Spiking the RUMBA 12 will decouple the woofer from the floor, which will lean out the bass response. If the floor is an older, very springy floor, spikes can be useful in reducing the influence of the RUMBA 12 on the floor".

I tried it myself -- placing the sub directly on the carpet, without the spikes -- but chose not to leave it that way. I must have one of those "springy" floors they referred to because there was too much resonance for my liking. I got a bit of additional tactile feel, but the droning was more then I wanted. Anyone buying the Rumba 12 should probably try it themselves though, in case their environment provides different results.


Movies/TV
I'm not prone to watching at "reference level", so my assessments should be considered in that regard. I run each test scene twice; once while seated in my normal listening position, and then a second time while sitting on the floor a few feet from the subwoofer. This allows me to hear it as I normally would, yet still affords me the opportunity to determine if it's straining even the slightest bit. Both tests are run at the same volume level.

Like most people I have specific DVD's I use when testing subwoofers. A few of my favorites are Lord of the Rings: Fellowship of the Ring, Collateral and Avatar. Recently added to my repertoire are scenes from 10,000 BC, and the quintessential ULF (ultra low frequency) "torture test"; War of the Worlds. Each individual test is listed in the format of Movie: Scene.


Lord of the Rings: Bridge of Khazad Doom - There is an ultra low frequency rumble in portions of this scene, as well as significant amounts of impact generated by numerous structures crumbling. For a subwoofer to handle all of that properly it needs to be precise and capable of reaching very deep, otherwise a lot of it comes across as nothing more than annoying resonance. The Rumba 12 handled it all in stride.

With a subwoofer that lacks precision the aforementioned rumble merely bombinates, but that was not the case here; it was reproduced clearly and accurately. There was a little loss of definition if the volume was turned up high, but it only started to occur when it was far louder then I would listen under normal circumstances.

As some of the structures start to collapse you have a blending of sounds, some pretty low some not so much. The Rumba 12 had no problem reproducing anything that was occurring, and portrayed all the effects with the correct amount of emphasis.

My favorite part of this scene to play around with is the Balrog's roar. There's an instance when you see it for the first time that I just love to crank way up. He jumps out of a cavern and lands right behind the Fellowship with a thud, and then lets out a fire-breathing roar. I enjoy seeing how loud I can play that part, because when the volume goes up it just sounds cool. The Rumba 12 did a great job, and handled the volume with relative ease. Even the huge impacts created when the Balrog's feet hit the ground as he chases after the Fellowship came through with a nice impact.


Collateral: Club Fever - This disc has the option of using DTS or DD for audio, but I only test with DTS. In general I've found DTS encoding has a bit of additional low bass and an overall greater depth to the soundtrack, so I've decided to use that exclusively for testing.

Although this scene doesn't contain a tremendous amount of LFE information it does have a driving musical soundtrack and over-emphasized gun sounds. The music portion I've found can cause trouble for a subwoofer because it does tend to drown out the voice track in certain spots, especially if it lacks clarity and speed. Because of that articulation is crucial. The Rumba 12 didn't even break a sweat with this one.

The club music was about as clear as I've ever heard, even with the crossover set at 100Hz (actually, it sounded better at 100Hz then 80Hz). Voices were not drowned out in the slightest, and the magniloquent gunfire was rendered to perfection.


Avatar: Assault on Home Tree - For those familiar with the movie this scene has low frequencies, ultra low frequencies, explosions, gunfire, voices and enough other things going on to provide a good test of virtually every component in your system. The Rumba 12 had no problems with this scene either.

As the gunships approach Home Tree you can almost feel the underlying intensity. The roar of their engines, the sound of the rockets being launched, the impact of each explosion, the crackling of the massive roots as the tree begins to list, and all the way to the point where it's toppled and crashes into the ground the low frequency reproduction was spot on.

The Rumba 12 handled this scene so effortlessly that I tried a few others, namely Battle for Pandora, Fall of the Heroes and Eywa. All of these additional scenes were delivered with the same ease and grace.


War of the Worlds: The Machine Emerges - The archetype... perhaps the most recognized subwoofer test scene of all time comes from a movie that's about 7 years old. The depth and volume of bass that occurs during a several minute span is simply amazing. If you want to see what your sub is capable of this scene can certainly be used as a barometer. With subterranean vibrations, exploding pavement and collapsing buildings you have ultra low, low and mid-bass frequencies pouring out of your subwoofer. One of the most punishing combinations there is, and an excellent way to really push something to the brink. As in the case of Collateral, the DTS audio track is used for this scene. For the most part the Rumba 12 did exceedingly well, only straining as the volume rose to substantial levels.

At a normal listening level, or even slightly elevated, the sound effects were rich and powerful. This was the only test scene that made the door of my hallway closet rattle. The individual elements -- buckling pavement, collapsing buildings, etc. -- each have their own individual sound profile, and all were presented accurately. So engrossing was it that I tried another two scenes; Heat-Ray and At The Window. Both exhibited the same degree of clarity and impact, and only when I really cranked up the volume did I get the driver to protest. Even then it was only apparent when sitting within a few feet of the subwoofer. In my normal listening position it wasn't really evident.


10,000 BC: Mammoth Hunt - During this scene there's either ultra low bass or mid-bass, with very little in between it seems. However, I've found this to be a good way of determining how a sub performs with nuances while being pushed hard. If it's struggling to hit the very low notes then the mid-bass suffers, and will come across as a jumbled mess (lacking in detail). If it can hit the low notes, but isn't articulate, then it tends to sound "thick" or "heavy", losing most of it's distinction. When portrayed correctly though, the really deep bass is what makes this scene. The Rumba 12 did a wonderful job here.

In the prelude leading up to the stampede the mammoths are simply milling about, but each earth-rattling thud from their massive feet is supposed to be felt as much as heard. When the stampede begins you then have dozens of raging mammoths running to escape. In order for this scene to work properly your subwoofer must be able to produce a tangible sensation of the ground shaking all around you. I sat there enthralled as this little subwoofer made that all come to life. It seems implausible to me that something of this size could produce such a corporeal impression, but it did. I actually played this scene multiple times, because I couldn't believe what I was feeling coursing through my chair.


Music
I use a combination of lossy and lossless material -- MP3's and CD's -- to see how musical a subwoofer is, and in both instances the Rumba 12 shocked me with how well it performed.

My first test is always Johnny Lang's CD Lie To Me. The mix is beautifully done, and the simplicity of the music means you can easily focus in on nuances. The detail from the Rumba 12 was impeccable, even as I started to crank the volume. And crank it I did, all the way up to "that's starting to hurt my ears" level. Yet the Rumba 12 kept pace, without ever once breaking stride. On virtually every type of music I sampled the results were the same; the precision and speed hardly ever faltered.

I don't have any pipe organ music to use for testing, but I did pick up a copy of Bass Mekanik. For those unfamiliar with this "music" (and I do use that term loosely)... it's essentially the source material people use to show off their car audio systems at those SPL (volume) contests. Consisting of nothing more than ridiculous electronic music, it has little value save for one; it contains some very deep bass. I hammered the Rumba 12 mercilessly with this CD and it kept it's composure on all but the deepest notes. Excessive volume could undo it's poise, as you would expect, but in order to unnerve this thing the volume had to be higher then any $550 subwoofer should be expected to play, especially when you consider the depth of bass in these songs.


After pounding the Rumba 12 for several hours -- with movies, music, test tracks, and various sound effects (rocket launches, fireworks displays, locomotives, etc.) -- the amp was nothing more then warm. Knowing that the toroidal transformer is attached to the bottom panel I felt around their as well, but even that wasn't hot. I have never punished a subwoofer like I have this one so I expected a lot more heat, but it just never materialized.


Support
The support provided by Simply Sound Audio can be summed up in a single word; exemplary. The reality is this company is essentially a one man operation, and the guy who does it all is named Murrel Gray. Almost everyone who owns an MFW 15 subwoofer is already familiar with Murrel, so it's not like he hasn't already proven himself. Building his own line of subwoofers seems to be a natural extension to what he already does. A perfect example of the support you get would be the polyfill situation I alluded to earlier.

While doing the critical listening portion of my evaluation I noticed what seemed like a little overhang, a slow response on occasion, which could make the sound a bit "thick". Users of ported subs will often hear something like this -- which is commonly referred to as 'group delay' in that case -- but sealed subs don't generally have such an issue. Part of my normal process is to take the subwoofer apart so I can see how it's built, and also to get some pictures of the driver, amp, cabinet internals, etc. When I did that with the Rumba 12 I noticed there was very little damping material being used (turns out it was 2 ounces). That seemed insufficient to me, so I contacted Murrel to discuss it with him.

Now, when I say "contacted Murrel" it usually means by phone. Why? It's his preferred method of doing support. That's not to say he doesn't respond to emails -- because he does -- it's just that he would much rather speak over the phone (to the extent that his home page actually contains his phone number). In this day and age that's exceedingly rare. After speaking with him for a while, and explaining what I found/felt, we hung up. I figured that was the end of it; I'd provide some feedback and he would take it under advisement. What happened next was anything but that...

The next night I get an email from Murrel that has all kinds of graphs in it. Each one showed the frequency response with a different amount of polyfill damping, from 0 ounces to 16 ounces in 2 ounce increments. That must have consumed several hours to gather that type of data. Based upon that we decided 10 ounces would be the ideal amount, so all future subs will come with that much in them. Very uncommon to get that level of response and commitment from any company, but that's not where this story ends.

The next day I get another email, this time from FedEx. Simply Sound Audio is sending me 10 ounces of polyfill so I can stuff the evaluation unit with the same amount that we deemed ideal. I considered that excellent customer service, but did you think Murrel was done yet? Think again. Two days after the FedEx email I get yet another message, this time with a link to a 450 meg HD video file. It's a 7 minute video he took of what the frequency response graph looks like in real time while watching a movie. But that's not all; along with the perpetual graphs being displayed on his laptop there's also an oscilloscope hooked up so I can directly compare the signal to the output! He wanted to show me just how clean and accurate the sound was now that the unit had 10 ounces of polyfill. Who on earth goes to that extent to support their products? Simply incredible...

The difference between 2 ounces and 10 ounces is actually palpable; the driver moves less frenetically when it's being pushed, it starts and stops faster and has a slightly more detailed sound overall. Because of the testing he did all future Rumba 12's will have 10 ounces of stuffing, so everyone will benefit from it.

This wasn't a one-shot deal either. Every single time I spoke with him on the phone he was the same way; courteous, polite and very helpful. To be honest, it was the rare call that was less then 20 minutes. He's just a very personable guy.


Conclusion
Sometimes the Conclusion section of the review is the easiest part to write, because some overriding thought or theme is constantly evident. That's what happened in the case of the Rumba 12. I kept finding myself thinking "is this guy making any money on these subwoofers?". He must work on some pretty slim margins, that's for sure. I have some experience in the DIY area, and have been integral with the design of subwoofers myself, so I have more then a passing familiarity with what goes on 'behind the scenes'.

Without question, the driver being used is high-end. It's hard to imagine the unit cost isn't somewhere in the vicinity of $200 each. And the amp, with 500 watts, a toroidal transformer and PEQ? It has to be around the same price as the driver. What about the enclosure? The materials being used, the level of detail in the panel cuts, the amount of craftsmanship to construct them, coupled with a multi-layer lacquer paint job means they have to be at least $100 each. Of course there's always the ancillaries, like wire, screws, damping material, spiked feet, and the like. What about packaging? Boxes, foam, cloth bags - they all cost money as well. And that's to say nothing of the value of Murrels time to build them. Even if you price things conservatively it adds up to be around $500. For a subwoofer that sells for $550? Like I said, how does this guy make any money?

The bottom line is the Rumba 12 represents an extraordinary value. For those looking at a small acoustic suspension subwoofer this one should be at the top of your list. The output is clear, articulate, deep and powerful. It's all wrapped up in a nicely designed and styled enclosure that feels as though it was hewn from a piece of granite. With support that's second to none -- along with an amazing price/performance ratio -- the few flaws it does have are pretty easy to overlook.


For those interested in my subjective assessment it's that the Simply Sound Audio Rumba 12 is highly recommended.


I want to see more pics of the amp.....

That driver is built like a tank! Stitched Cone! Bolted down spider!

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post #29 of 190 Old 04-27-2012, 08:41 AM
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Hello Nick!

The amp is the same design as the V3 amp. Different transformer, curve and the EQ section is added.

More pictures here: http://www.5280fotos.com/SSA

Thanks to my friend Bobbi Turner

Murrel

Murrel J Gray
 

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post #30 of 190 Old 04-27-2012, 08:51 AM
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Quote:
Originally Posted by murrel View Post

Hello Nick!

The amp is the same design as the V3 amp. Different transformer, curve and the EQ section is added.

More pictures here: http://www.5280fotos.com/SSA

Thanks to my friend Bobbi Turner

Murrel

Cool! Thanks!

I see you added a magic black box!

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