MartinLogan Dynamo 600X and Dynamo 1600X Subwoofer Review

Five years ago, the MartinLogan Dynamo 1500X left us impressed with its slick looks and high performance for its reasonable size in our review. However, time has passed, and other manufacturers have brought some very tough competitors to market since then. In response to a fierce marketplace, MartinLogan has revamped their Dynamo subwoofer series and has added ingredients that not only keep up with the competition but jumps a step ahead. This summer MartinLogan unveiled their new Dynamo subs which Audioholics was lucky enough to be present at in their unveiling (MartinLogan Revamps Dynamo Subwoofers). As promised in our preview article, here is a full review of two of the new Dynamo subwoofers: the 600X and the 1600X.

The 600X is the successor to the Dynamo 500. It is a relatively small ported 10”. The 1600X is the successor to the 1500X as the flagship of the series, a powerful sealed 15”. MartinLogan sent us these two particular subs so we could see both ends of the Dynamo’s design spectrum. We will look at what MartinLogan brings to us from the very affordable end of their Dynamo subs to the top of the line. We were impressed by what we saw at MartinLogan’s launch event in our preview, but let’s see what they have really delivered now that we have time to really dig in these subwoofers…

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MartinLogan Dynamo Subwoofer Series Overview & Comparison YouTube Discussion

Packing and Appearance

The Dynamo subs arrived in robust cardboard boxes that were sealed using heavy-duty staples. Both subs were packed with two large foam sandwich pieces that gave them a good amount of clearance from the box walls. The subs were wrapped in a cotton sleeve to protect them from moisture and scuffing during transit. Underneath the packing were two minimalist-styled subwoofers that had a smooth satin black finish. If the look of a subwoofer could ever be described as sophisticated, this would be it. Some subwoofers try to hide the fact that they are just a driver and amp in a box by angling or curving the cabinet and rounding the edges, but the Dynamo subwoofers embrace their boxiness with a modernist flair.

Dynamo 600X (left) and 1600X (right)

The 600X is a smooth, smallish cube with an approximately 14” edge length on all sides. The 1600X, in its down-firing configuration, is similar but with an approximately 18” edge length. The key to their style is the simple, unbroken symmetry of their cube shape. Despite their boxiness, they are very clean and understated, and these qualities would allow them to fit in nearly any decor. They are nice enough that they will not be aesthetically displeasing if they are placed in the open, but they are so austere that they would easily vanish from notice if tucked away in a corner. Their satin black finishes make them disappear in low-light conditions. There is a very small and simple MartinLogan badge on the exterior that announces that they are not just a box; they are objects that have purpose. One thing to note is that the 1600X’s finish is finer than the 600X’s finish, which is a bit more textured.

 

Dynamo 1600X (left) and 600X (right)

The 1600X’s enclosure can be converted from down-firing to front-firing by relocating the feet (as seen in our YouTube video). In a clever bit of engineering, the down-firing feet slots are also the grille guides in its front-firing orientation. The 1600X definitely has a lot more personality with an exposed cone in its front-firing orientation. The cone is quite pretty by subwoofer standards, and I would never hide it were I the owner. It is sleek and stylish with the MartinLogan logo etched in its inverted dustcap. The Dynamo subwoofers use inverted surrounds, and I am conflicted as to whether they look better than typical bulbous surrounds; they don’t look as muscular but they do look a bit more elegant. With the grille on, the 1600X looks rather plain. I would only use the grille when it’s needed to protect the cone.

Dynamo 1600X in front-firing orientation with grille(left) and without grille (right)

Design Analysis

Before we get into the analysis of the physical designs of the Dynamo 600X and 1600X, let's talk about one of the chief features touted by MartinLogan for the Dynamo series, which is their ‘cord-cutting.’ I am using the phrase ‘cord-cutting’ here to mean that nearly all of the usual means of controlling a subwoofer can be done wirelessly. Some subwoofers have wireless receivers, and some subs have smartphone app control, but how many subs support both of those and also an app for automated room correction? Even the wireless signal receiver that is supported by the Dynamo subwoofers gets powered by the subwoofer’s onboard electronics, so the receiver does not even have to be connected to a power outlet. The only wire that the Dynamo subs absolutely need is the power cord, but surely MartinLogan’s engineers are researching a way to jettison that last physical tether as we speak.

 

Control screens for MartinLogan’s Subwoofer Control App (above two and lower right)

Let’s dig into the wireless features by first discussing the subwoofer control app. The plate amp for the 600X and 1600X has only a volume knob as a physical means of control. MartinLogan has allocated all other controls of the Dynamo subwoofers to a smartphone app that is compatible with iOS and Android devices. The ‘MartinLogan Sub Control App’ has all of the conventional control functionality of regular panel controls and a few neat features that are well outside the ability of typical subwoofers. The MartinLogan Sub Control App can control the volume, low-pass filters, phase, low-frequency boost (that can adjust the 20-30 Hz region by +/-10 dB) and can access preset listening modes. One unique and useful feature of the MartinLogan Sub Control App is the ability to run a tone sweep from 20 Hz to 120 Hz that allows the user to pause and hold the tone at any frequency in this range. This feature allows the user to identify points of audible rattling and vibrations in-room. This has always been such a pervasive problem with low-frequency reproduction that it's difficult to believe this is the first time we have seen a subwoofer to include a feature like this (although we are told that the MartinLogan BalancedForce 212 and 210 subwoofers have this feature). The MartinLogan Sub Control App can control a multitude of subs independently. The App also has helpful explanations for every control so the user isn’t forced to refer back to the manual to understand every aspect that can be changed.

 

Instruction screens for the Anthem ARC Mobile App (above two and lower right)

Another cord-cut function is automated room correction equalization in the form of the ARC Mobile App. Audioholics previewed the Anthem ARC Mobile App with good results. ARC is the highly-regarded room correction equalization software developed by the audio electronics manufacturer Anthem, and the ARC Mobile App brings that equalization functionality to Android and iOS devices. For ARC-enabled speakers such as MartinLogan’s new Dynamo subwoofers, ARC Mobile uses the microphone of the iOS or Android device to record the frequency response of the subwoofer in-room. ARC’s algorithm then forms a correction curve which is sent to the subwoofer for a more linear and smoother sound at the listening position. Since low-frequencies are the band that is most dramatically affected by room acoustics, this can be particularly helpful in gaining an even, neutral response. The ARC Mobile App makes it simple to EQ troublesome room modes that are the plague of subwoofer frequency bands, and no wired components are needed to use it.

The new Dynamo subwoofers (excluding the Dynamo 400) are compatible with MartinLogan’s SWT-X Wireless Subwoofer System (which is sold separately) so that the subwoofers do not need a physical wire for the signal. Omitting the need for the signal cable can greatly increase the availability of potential placements for the sub, and since the placement of the subwoofer is so critical in getting a good sound from it, this can be a very significant assist in sound quality. The SWT-X Wireless System uses 2.4 GHz dynamic frequency selection and error correction. The receiver end of the SWT-X system is powered by the subwoofer itself and so does not need to be plugged into a power outlet. The SWT-X Wireless Subwoofer System has a 50-foot range, so it should be able to handle any conventional domestic room size without problem.

Now let’s talk about the design of the individual subwoofers under review, and we will begin with the 600X. The 600X uses a 10” driver in a down-firing, vented cabinet with a 1.25” x 7.5” slot port. The cabinet uses 1” MDF for the front baffle and ¾” MDF for side panels that all add up to a 14” cube enclosure. When we take a peek inside the cabinet, we see a healthy amount of stuffing for damping, and one interesting thing we see is the length and construction of the slot port. The port stretches all along the length of the interior of the cabinet for a 180-degree turn so that the inner port opening faces the same direction as the outer port opening. This is a good use of spatial economy of the interior of the cabinet because otherwise MartinLogan would have had to settle for either a relatively high tuning point for a large diameter but short depth port, or lower output and turbulence for a port tuned to a lower frequency which would force it to be narrow. It also acts as some internal bracing to help reinforce the cabinet. The 180-degree angle turn of the 600X’s slot port certainly raises the manufacturing cost of the enclosure, but it shows that MartinLogan wanted to optimize performance for the 600X and so used a smart design choice that necessitated more construction effort.

 

The 600X uses a 120-watt RMS class-D amplifier. For physical signal inputs, it can accommodate RCA inputs as left and right/ LFE, and also take speaker-level inputs with banana-plug inserts. The 600X also accommodates the SWT-X wireless input as well. There are other 10” subwoofers out there that boast more powerful amplifiers, but 120 watts is still a healthy quantity of power depending on the driver, and a greater factor than sheer wattage is how efficiently the driver uses those watts. A driver with a heavy moving mass will soak up tons of power without offering a big return on that energy investment, but a more sensitive driver can make every watt count. The driver that the 600X uses looks to have a moving mass on the lighter side and so is likely quite efficient. From a glance, it would appear to be a design of a higher sensitivity that would capitalize on a modest amount of energy. It uses a light but stiff polypropylene cone on what looks like a 1” to 1.5” diameter voice coil/former in an overhung topology. The permanent magnet is a 1” thick, 5” diameter ferrite disc which should be sufficient to throw the cone around with ease. The basket is stamped steel perforated with holes. The backplate is bumped out for larger excursions and also has a vented pole piece. The cone uses an inverted surround that MartinLogan claims can help reduce turbulence between the cone and floor when in a down-firing orientation, although I think that typically isn’t a serious problem unless there is not much clearance between the cone and floor, which doesn’t seem to be the case here since the 600X’s feet gives the down-firing cone plenty of space. 

 

The 1600X is a sealed 18” cube enclosure with a 1 ¾” thick MDF front baffle and ¾” side panels. There are two interior braces that reinforce the cabinet at perpendicular angles and a good amount of stuffing inside the enclosure. It uses a 900-watt RMS class-D amplifier, which makes it one of the more powerful amps among 15” subwoofers. It has RCA inputs, speaker-level inputs, and an XLR input, along with built-in support of the SWT-X wireless adapter, so it can accommodate a wide range of system connectivity. The 1600X driver is a formidable 15” that uses a wicked-looking cast aluminum basket under its sleek polypropylene cone. The motor system is an overhung design comprised of two 1” x 6” ferrite slugs over a 2” diameter voice coil/ former and a vented pole piece. It is a very pretty driver!

  

MartinLogan 15" Bass Driver from the 1600X Subwoofer

Both the 600X and 1600X use similar feet, however the 1600X’s feet can easily be converted from a rubber end to a spiked tip. The advantage of this is that spiked feet will not leave impressions or marks on carpeted flooring, and rubber will not scratch hard floor surfaces, so the user can choose what best suits their situation by simply pulling off the lower end of the feet. As was mentioned before, the 1600X can be converted from a down-firing woofer to front-firing by simply removing the feet on the woofer side and installing them on the amp side of the sub, which is a simple process. Also, like was said before, the 1600X comes with a grille that can be installed in the feet inserts when in a front-firing orientation. The grille actually offers some physical protection for the cone as well; it is not just a piece of fabric draped over a frame. In the 1600X grille, the fabric is draped over a perforated plastic shield that could feasibly block a solid object headed toward the cone.

   

MartinLogan 600X feet (left) and 1600X spiked feet (right)

Listening Sessions

The best placement for a single sub in my room gives me a relatively flat response for an un-EQ’d single subwoofer, with a window of +/- 4 dB from 25 Hz to 100 Hz with no broad dips in important ranges. This location trades low-end room gain for a relatively flat response, a worthwhile trade for my tastes. The receiver used was a Pioneer Elite SC-55 and speakers were Paradigm Premier 800F towers and Premier 500C center channel speaker (reviews of those speakers will be forthcoming), and the crossover was used mostly at 80 Hz. I set the Dynamo subwoofers up in a manner where I could easily switch back and forth between them, and also in placements right next to each other to minimize the difference of the acoustic effects of the room between them.

As always, I will note here that since room acoustics have a huge effect on low frequencies, the way these subwoofers sound in my room at my listening position is not necessarily going to be the way they sound anywhere else for anyone else, so readers would do well to keep that in mind, and not just for this subwoofer in this review, but for any subwoofer in any review.

Music Listening

One of the first albums that I listened to using the Dynamo subwoofers was the DVD Audio recording 'Bach: Organ Spectacular" on the Teldec label and performed by Ton Koopman. This recording, released in 2001, is a selection of famous works by Bach played on the Christian Muller Organ in the Grote Kerk in Leeuwarden which is considered one of the most beautiful sounding baroque organs in the Netherlands (according to Wikipedia). Any recording of Bach's works on such a massive pipe organ is bound to have plenty of content that digs well into subwoofer frequency bands, and a DVD Audio disc by Teldec is bound to be a very high-fidelity recording of such an event. While this recording had deep digging notes, it wasn't as thunderous as some other pipe organ recordings I have heard, especially of Toccata and Fugue in D Minor which can have teeth-rattling levels of bass when the sound engineer gets carried away. Alternating between the 600X and 1600X, I felt both sounded natural. They blended well with the rest of the system and were authoritative enough to keep up with the Paradigm 800F towers for this recording. I would guess that a pipe organ recording with more amped up bass could expose the limitations of the 600X in the face of the 800F tower speakers, but this recording did not push the subwoofers that hard. What this recording demonstrated to me was that both of these subwoofers were able to provide a solid bass foundation to the music without making their presence known as subwoofers—in other words, they disappeared as gear and simply turned into music, which is exactly what a subwoofer should do in a recording like this.

Another album of acoustically recorded music that I listened to was 'Planet Drum' by Mickey Hart. This album provides a nice contrast to the sustained pipe organ notes of 'Bach: Organ Spectacular' in that its instrumentation, outside of vocals, is almost entirely percussive and so is full of quick attacks and rapid decays. This album brings together a group of percussionists from different parts of the world as an experiment to see what rhythms would emerge and makes for a good subjective test of a sound system's transient response, especially that of subwoofers, since many of these drums are tuned deep enough to take real advantage of subwoofer playback. The track 'Temple Caves' uses a bass drum that has such a low fundamental frequency that it sounds like it was made with a synthesizer.  While both the 600X and 1600X subwoofers could reproduce 'Temple Caves' with force, the 1600X did seem to capture the deeper end of that powerful drum with more definition and more potency. That is not surprising, of course, given that the 1600X uses a much larger driver and a more powerful amplifier. None of the other tracks were able to bring out a significant difference between these subs, although I imagine that at high enough playback levels, the 600X would tap out much sooner than the 1600X. Both subwoofers were able to render the various percussive instruments of this album with a convincing punch for the levels that I listened to this album at, however, I did not crank it to extremely loud levels. I didn't sense any overhang or lingering bass sound, and the Dynamo subs were able to play back this album with very good control and a sharp transient response.

An album that I listened to which was a complete 180-degree turn from Planet Drum was Steve Roach’s 2013 release, ‘Possible Planet.’ ‘Possible Planet’ is a very strange album that was composed and performed entirely on analog synthesizers without any exterior control devices such as keyboards or MIDI trackers. It was created only by knob control directly on the synth modules themselves and suggests a primitive alien environment. As such, it is purely a soundscape, albeit one with progression. With an absence of traditional notation, the sounds are long and drawn out, with very gradual attacks and decays. Low-frequency content on this album is plentiful, with guttural sweeps, distant drones, and subterranean rumbling throughout its duration. The bass is richly textured; sometimes it is very prominent and other times it is subtle, but it saturates the running time of the album. A lesser performing subwoofer might miss the subtler moments of bass or overdo the more powerful low-frequency passages thereby detracting from the delicate soundscape created by Steve Roach. Thankfully this was not to be with the Dynamo subwoofers. The 600X and 1600X both gave a lucid and well-defined low-frequency foundation to Roach’s mysterious musical creation. This sonic world was realized with a vivid clarity on this sound system, and the Dynamo subwoofers were an integral part of that. Both subs proved to be adept in rendering the low frequencies of the bizarre landscape that Steve Roach paints in ‘Possible Planet,’ and I wouldn’t say one performed especially better than the other in my time with this album, although it’s possible that the differences would become more obvious at higher loudness levels.

In order to see the limits of the Dynamo sub’s dynamic range, I threw in something which has bass that is non-stop and never subtle; it was time for some Drum’N’Bass music. The album I turned to was Limewax’s ‘Scars on the Horizon,’ a brutal 2007 album that has wall-to-wall ferocious breakbeats, pounding bass lines, and searing atmospherics. This is an album that demands to be played loudly, which is exactly what I intended to do. First up, the 600X. I started at a modest volume level and continued to raise it until the sub just wasn’t getting any louder. The 600X was able to get loud, and it reached a powerful and punchy sound, but only just. When pushed to its limits, it did manage to capture the kind of energy I would want from an album like ‘Scars on the Horizon,’ but its dynamic range ended where I normally like to start with this kind of music. However, I’m not saying I was disappointed; the 600X performed well for its design and met my expectation for what it could do. The 1600X’s turn came next, and it proved to be on a whole other level (more like two or three levels). I kept on increasing the volume, and the 1600X scaled with the rising loudness until it was at jarring levels. I had placed it in a near-field position, right behind my listening position, and it blurred my vision every time a bass note hit. It vibrated my entire sofa. The mid-bass power of this subwoofer exceeded my expectations. It was a truly tactile, palpable bass experience. Its violence perfectly matched the fierce music, and even though it shook the room, the 1600X never lost a good sense of pitch definition. It was a well-mannered monster; it will tear a person up but do it with surgical precision. Listening to the ‘Scars on the Horizon’ on the Dynamo 1600X at very high loudness levels left me bruised and battered, and I loved every second of it!

Movie Watching

One movie that I thought should be able to give any sub a real workout is the 2015 disaster epic ‘San Andreas’ with Dwayne Johnson. The title alone would be enough to clue people in as to its suitability as subwoofer demo material; it's a movie about a big earthquake! Structures crumble, the ground shudders and cracks open, and a tsunami even strikes a city shoreline, so subwoofers are given plenty to feast on. I watched this one at a relatively loud level using the 1600X. The 1600X did a great job in recreating the non-stop chaos in ‘San Andreas.’ One thing I like about this movie is that the carnage starts early and continues throughout the movie, which is better than spending on hour on characterization and buildup before getting down to the mayhem as was the formula in the 70’s disaster movies. The 1600X let us know what it could do early on in the Hoover Dam scene where it left a positively visceral impact (not to spoil the movie for any readers who have not seen it, but Hoover Dam plus earthquake movie... well, you do the math). San Francisco collapsed with a resounding intensity that vibrated my seat. This subwoofer has punch to spare, and I am not sure that I pushed it to its limits, even at the spirited volume levels that I watched it at. Of course, being a sealed sub, it will not take long to reach its limits in deep bass, but in mid-bass, the 1600X shows itself to be a true powerhouse. Contrary to popular belief, much of the bass energy in a movie like ‘San Andreas’ lay in mid-bass ranges, so doubtlessly the 1600X will capture most of what is there, and with the dynamic range to do justice to the roaring bass in that frequency band as well.

Another movie with plentiful bass that I used to evaluate these sub was the 2012 action sequel ‘The Expendables 2.’ With a cast that includes Stallone, Schwarzenegger, Jason Statham, Bruce Willis, Chuck Norris, Van Damme, etc., this film is overflowing with testosterone so of course the sound mix is going to be bass-heavy. It’s the kind of movie where every gunshot is exaggerated with a low-frequency ‘whoomp!’ and even the orchestral score is punched up with bass drums and heavy brass. I mostly used the 600X for the duration of this movie to give it a chance to shine. For the most part, the 600X was able to keep up very well for a sub of its size. Motorcycles growled with vigor, explosions roared, and every kick and punch had a massive meaty thump that no one in real life would survive if anything had connected with their bodies sounding like that. In some passages, I cranked the movie loud to see where the 600X’s limits lay, and after a certain point is simply stopped getting louder. The sound became compressed as softer low-frequency sounds gained loudness while loud low-frequency sounds did not. A 10” driver with a 120-watt amp is going to have its limits, but it was impressive what the 600X could do even with its comparatively modest specifications. The 600X gave ‘Expendables 2’ a solid foundation, and I was surprised at how much bass it could belt out. I mostly didn’t miss the larger subwoofers that I was accustomed to. 

MartinLogan Dynamo 600X and Dynamo 1600X Subwoofer Measurements and Analysis

The MartinLogan Dynamo 600X and 1600X were tested using ground plane measurements with the microphone at a 2-meter distance in an open setting with well over 100 feet from the nearest large structure. The subs were tested with woofer and port side facing the microphone for the 600X and woofer side facing the microphone for the 1600X. The subwoofer’s gain was set to maximum, phase was set to 0, and the low pass filter was left off. The weather was recorded at 61°F and 71% humidity.

  

Frequency responses for the modes of the Dynamo 600X and 1600X subwoofers 

The above graphs depict the frequency responses for the Dynamo 600X and 1600X subwoofers for their available modes. We can see that the ‘Music’ mode has a nicely flat response where the ‘Movie’ mode places more of an emphasis on lower frequencies. The ‘Movie’ mode boosts the range from 30 Hz to 70 Hz which can come in handy for those who want to put more weight in effects sounds. Using the Dynamo subs in the ‘Movie’ mode should give them more ‘growl.’ Those who would rather have accuracy would be advised to use the ‘Music’ mode. The ‘Night’ mode filters out a lot of deep bass output. This mode is intended to be the ‘considerate’ mode when listening to content at night but not wanting to bother other people within the same household or apartment complex. This response shape makes sense because deep bass is what travels through walls and obstacles most easily and what will be heard most readily in any nearby rooms. The ‘Night’ mode curve in the 600X graph does not even reach the same amplitude as the other curves because there is a dynamic range limiter that prevents it from getting louder after a certain point. That point wasn’t reached in the 1600X graph but it is apparent in the 600X graph. You can turn up the gain but the subwoofer will not get louder once that limit is reached. This is another good idea for users who want some bass but don’t want to bother other people.

Something else to note about these responses is the high-frequency extension out to 200 Hz. This is good for those who might want to use a higher-than-normal 80 Hz crossover frequency, and there are multiple scenarios where that is useful. It’s especially useful for the 600X, since a small subwoofer like that is more likely to be paired with small satellite speakers, and small satellite speakers don’t normally have any bass extension below 100 Hz. Using an 80 Hz crossover frequency with speakers that roll off above 100 Hz will leave a gap in the bass response, but not every small sub can make the stretch past 80 Hz, especially when they are using heavy cones for a lower resonant frequency.  

  

Audioholics CEA-2010 Measurement Data for MartinLogan 600X (left) and 1600X (right)

The above CEA-2010 measurements are short-term bursts that show the subwoofer’s clean peak SPL before heavy distortion sets in. Our measurements have been referenced to 2-meter RMS, which is 9 dB down from the standard requirement for the measurements to be shown at 1-meter peak. However most publicly available CEA-2010 measurements are shown at 2-meter RMS, so we followed that convention. Standard test frequencies lower than what is shown on these graphs indicates that the subs were not able to produce a passing score at those frequencies, e.g., the 600X was not able to produce passing results at 16 Hz and lower.

The 600X puts up a good showing for a small subwoofer. This is by far the smallest subwoofer this reviewer has ever tested, yet it can manage 100 dB at 31.5 Hz. It hits over 105 dB from 50 Hz to 100 Hz and does so with relatively low distortion levels. It is clear from the distortion levels that MartinLogan has placed limiters in the amp to prevent the subwoofer from beating itself to death or producing gross amounts of distortion. The SPL readings plus the distortion levels comprise a solid measurement set, and this isn’t a surprise to anyone who has heard what this feisty little guy can do. It might not be in the heavy-weight SPL class of subwoofers, but among the welterweights, it is a real bruiser.

The 1600X’s performance is indicative of a different set of performance targets. In low bass, a significant quantity of distortion is permitted, but it does have some output capability in deep bass regions. It’s clear from the very powerful mid-bass but somewhat tetchy deep bass maximum output capability that the driver does not have a tremendously long-throw but does have higher sensitivity and lighter weight. While the distortion quantities look high at 31.5 Hz and below, it should be remembered that this is around the maximum output capability of this sub, and by taking the gain down by just a few dB dramatically reduces distortion. The driver here is being pushed way past its linear operational range which is easy to do with a sealed subwoofer in deep bass. We will get a better look at its distortion behavior at nominal levels in our distortion graphs of long-term tones.

At 40 Hz and above the 1600X is an output monster. Its 50 Hz and 63 Hz CEA-2010 burst measurements sets a new record for output among subs that I have reviewed. Distortion in the range is quite low too. The 1600X is a mid-bass monster, and these measurements show how hard it can punch in this frequency band. 118 dB in this frequency range is a savage thing to experience; I can’t recommend it enough. Those who like bass-heavy music at high output levels would enjoy the dynamic range offered here. 

  

Dynamo 600X (left) and 1600X (right) long-term output compression 

Testing for long-term output compression was done by first conducting a 20-second sweep tone where 50 Hz hit 90 dB with the subwoofer 2 meters from the microphone. We then conduct further 20-second sweeps by raising the gain by 5 dB until no more output could be wrung out of the subwoofer. These tests show us the long-term continuous headroom that these subwoofers are capable of. In these measurements, we can see the 600X puts out a respectable performance showing, exceeding 100 dB at 35 Hz and above and even touching 105 dB from 50 Hz to 80 Hz. That is a very good showing from a petite, modestly-priced cube subwoofer. The 1600X is a different matter entirely. Its output advantage hovers around a 9 dB to 11 dB difference. This roughly equates to three to nearly four times the output of the 600X. This is about proportionate to the price difference. The 1600X exceeds 110 dB from 35 Hz to 200 Hz and even hits 115 dB from 50 Hz to 90 Hz. Those kinds of output levels give it a very tactile sensation when driven to those extremes. One extra advantage that the 1600X holds over the 600X is that its sealed design allows it to have deep bass output below 20 Hz. In smaller rooms, pressure vessel gain can give a disproportionate boost to low frequencies where there is some output in that region, and the 1600X is better positioned to produce that kind of deep frequency room gain.

MartinLogan Dynamo 600X and 1600X Total Harmonic Distortion per output level (note: the 1600X graph dips down to 10 Hz whereas the 600X graph stops at 20 Hz.

Before jumping to conclusions about the distortion quantities shown here, read below paragraphs to learn why the 1600X’s graph is extended and the significance of these distortion shown here) 

The above graphs show the corresponding total harmonic distortion to the long-term output graphs. Essentially, they depict how linear the subwoofer remains for the corresponding drive level seen in the long-term sweeps. The quantity being measured is how much of the subwoofer’s output is distortion and is shown here as a percentage.

One aspect about the above graphs that need to be stressed is they are aren’t comparable to each other: the X-axis needs to be closely looked at. In the graph for the 600X, I have cut off the X-axis at 20 Hz, so it is only showing the frequency range from 20 Hz and above. I have allowed the graph for the 1600X to go down to 10 Hz. So at a glance, it looks like the 1600X has a lot more distortion, but the truth is very different. I cut off the X-axis at 20 Hz in the 600X graph, because the 600X had so little deep bass output that the noise floor actually constituted a substantial portion of what was recorded as distortion, and so it looked like the 600X had a lot more distortion at low drive levels than at higher drive levels. Of course, the opposite is true, because distortion is being shown here as a percentage, and the noise floor is going to constitute a greater percentage of the overall recorded sound at low output levels versus higher output levels. The 1600X doesn’t have this problem because it is generating significantly more energy at every drive level and every frequency, so its own output greatly outweighs the noise floor below 20 Hz.

Nonetheless, the 600X is a very clean performing sub. At its highest drive levels, it can’t really be pushed too much beyond 10% THD above 20 Hz. Distortion below 20 Hz does not matter for it so much since output rapidly drops off. Sometimes subwoofer manufacturers will allow a great deal of distortion from their smaller subwoofers; they try to wring as much output as possible from them since smaller subwoofers will be inherently output-limited. MartinLogan clearly does not subscribe to that design goal. Linear behavior was very much in their minds in the design of the 600X. The 90 and 95 dB sweeps don’t even pierce 5% THD until under 25 Hz. Those who need a smaller-sized subwoofer but do not want to give up accuracy or linearity would do well to give the Dynamo 600X a close look.

Regarding the 1600X, while it looks like it distorts more than the 600X from just glancing at these graphs, the viewer must keep in mind the output levels at which this distortion is occurring. In reality, the 1600X produces considerably cleaner bass than the 600X for most of the subwoofer frequency band. What the higher quantities of distortion in the 1600X graph are telling us is that the 1600X can be pushed to more distortion than the 600X from around 40 Hz to 20 Hz. Below 20 Hz, the 600X is not producing any meaningful bass sound, and what little sound it is producing is almost entirely distortion, as it is with most other ported subwoofers below their port tuning frequency. When the 1600X is pushed hard in deep frequencies, it will run into distortion, however, decibel-for-decibel, the 1600X is mostly generating cleaner bass than the 600X. At 90 dB test tone, it hovers around 1% THD from 40 Hz and above, and at the 95 dB test tone, it barely pokes its head above 2% for that same range. That is some of the cleanest bass I have ever measured, and it is far below any audible threshold. 

It should also be mentioned here that while I absolutely throttled both subs and pushed them to their limits during testing, I was not able to make them bottom out, so they appear to be well-protected from being driven into self-destruction. That can give the user a nice sense of security for the moments where they want to show off the subwoofers in demos to friends or just want to see how far these things can go. Of course, it is not advisable to run them really hard all the time, since that would considerably shorten their lifespan, but it’s nice to know that driving the subs hard once in a while will not kill them.

Component Harmonics of the Dynamo 600X and 1600X  (note: the 1600X graph dips down to 10 Hz whereas the 600X graph stops at 20 Hz. This makes the 600X appear to have less distortion relative to the 1600X than it actually does if the X-axis range is not considered) 

The above graphs depict measurements of the constituent harmonics from the long-term output sweeps and are what the total harmonic distortion measurements are composed of for the 2nd and 3rd harmonics. These individual harmonics can give us a clue as to what might be the cause of some quirk or non-linearity. We are only showing the 2nd and 3rd here because they more or less reflect the higher even-order and odd-order behaviors, although higher-order harmonics will likely not be as abundant in quantity as the 2nd and 3rd harmonics.

Examining the 600X’s results, we see that there is far more even-order distortion than odd-order, and this indicates some non-linearity that is only affecting one direction of the cone’s travel. Port artifacts can do this, as well as tension in the suspension that inhibits one direction of excursion more than the other, but given the shape of the curves, the steady rise in the distortion, and the relatively even amount over the entire frequency band, this even-order distortion looks to be the product of induction effects. Induction in loudspeaker drivers is when the changing magnetic field from the movement of the voice coil next to the stationary permanent magnet causes a counter-current that can interfere with the initial current thereby inhibiting linear motion that is faithful to the source signal. The good news here is that even-order distortions are more difficult to audibly detect than odd-order distortions, and there isn’t enough distortion here to worry about. This is a surprisingly clean subwoofer given its size. As was mentioned before, many small subs can be pushed hard in order to squeeze out as much loudness as possible, but MartinLogan has wisely not taken that tack.

The 1600X looks to also have some induction effects present in the even-order harmonic distortion, but, as with the 600X, they are in very modest quantities outside of high drive levels in deep bass. We can see that 3rd-order harmonic distortion really takes off above the 110 dB tone sweep below 30 Hz. This is likely the driver’s voice coil blowing past the top-plate gap where the magnetic field is very tightly controlled. Once outside of this region of control, the moving mass of the driver isn’t able to react as tightly to changing swings in the signal voltage and runs into heavy distortion. The 1600X driver is not an extremely long-throw driver, and this has advantages as well as disadvantages. A disadvantage is that it doesn’t really produce deep bass really well on its own. It can produce deep bass cleanly, but only up to a limited point. An advantage of this design is that long-throw drivers tend to be heavy which limits their mid-bass output. The 1600X banks on its lightweight design to produce prodigious amounts of mid-bass. Most distortion in the mid-bass region is even-order as well, so what little distortion is generated in that region is of a relatively harmless type, not that those quantities would be audible in that range to begin with.

 

MartinLogan Dynamo 600X and 1600X group delay 

Group delay is the measurement of how much time it takes for individual frequency bands of an input signal to be produced by the speaker. It can indicate that some frequency components are developing slower than others or are taking longer to decay. It is generally thought that 1.5 sound cycles are needed for group delay to be audible at bass frequencies, although there is an argument that group delay should remain under 20 ms to be completely unnoticeable, but that is likely meant for mid and upper bass frequencies. Both the 600X and 1600X boast very good metrics here. The 600X stays well below 1 cycle or 20 ms until very deep bass where it is beyond audibility. The 1600X never pierces 1 cycle and doesn’t go over 20 ms until 30 Hz. There is a rise in group delay below 30 Hz in the 1600X measurement that is evidence of a high-pass filter, but it is well beneath any audible threshold. The bass in both subwoofers decays very quickly. Evidently, MartinLogan was very concerned with time-domain issues and sought to engineer a subwoofer that would be free of any stored energy, and on this count, they have done a stellar job. Any boominess or sluggish bass sound from a system with these subwoofers would be attributable entirely to acoustic conditions that the subs are being used in, and not the Dynamo subs themselves.

  

Examples of the effect of the 20-30 Hz Level Adjust Control 

One of the controls on the Dynamo’s subwoofer control app is an adjustment to the 20-30 Hz region. This control raises or lowers the response in the 20-30 Hz frequency band. For the curious, I have included some measurements that demonstrate its behavior. It is essentially a parametric level adjust with a fixed frequency and it does raise and lower the low-end response, but its Q is wide enough to have a considerable impact outside of the 20-30 Hz region. It is useful for either boosting or reducing low-frequency output to the user’s taste.

Conclusion

The original Dynamo subwoofers were an enormous success for MartinLogan, and I can now understand why. MartinLogan takes a practical, accessible approach to subwoofer design. Many of my past reviews were of subwoofers that were very large, and they needed to be in order to chase the very deep frequency output that was their performance targets. The reality is that these large sizes make them impractical for a large percentage of audio shoppers. Most people do not want their living space to revolve around audio gear; they want good sound, but they do not want to give up the floor space to something that is as big as a piece of furniture that only produces bass sound. Such people are called normal people, and sometimes we audio enthusiasts forget that more can be done in a living space than merely setting it up to listen to an aural recreation of an event somewhere else.

The Dynamo subwoofers may not be the deepest digging subs out there, but they do capture much of the recorded bass content of movies and music. They do so cleanly as well; the 600X generally doesn’t produce much distortion in its operational range, and the 1600X doesn’t produce much distortion above 40 Hz, although it is capable of producing some distortion below 40 Hz when pushed hard. However, every sealed subwoofer will behave similarly unless it has very strict filters which dramatically limits deep bass output. And while the 1600X can be pushed into distorting in deep frequencies, it is protected from overdriving itself into any harm. When size is taken into consideration, both the 600X and 1600X tout some very good performance numbers. As was mentioned before, the 1600X is an output monster at 40 Hz and above, and it nets a ‘Large’ room rating in Audioholic’s Bassaholic room rating, meaning it should be able to handle room sizes from 3,000 to 5,000 cubic feet. The 600X merits a ‘Medium’ room size rating, so it should be able to handle 1,500 to 3,000 cubic foot room sizes. It’s worth mentioning here that the 1600X majorly outperforms its predecessor, the 1500X, when their measurements are compared (Dynamo 1500X review measurements).

But performance is only one part of the story of MartinLogan’s new Dynamo subwoofers. Their plethora of wireless features is also a big selling point of these subwoofers. MartinLogan’s subwoofer apps make fine-tuning the sub easy. The user does not have to fiddle around with a bunch of cryptic knobs on the back panel to make adjustments to the subwoofer; it is all done from a smartphone app that has accessible explanations for each of the myriad of controls. The ARC Mobile App was also easy to run and very clear in its instructions. It didn’t really do much more for me than trim a minor peak at 40 Hz, but at least it was smart enough not to attempt to fill in any nulls. And while I didn’t use the SWT-X Wireless Subwoofer System, I like knowing that I can get wireless signal transmission without needing an additional power output plug. The Dynamo subs aren’t really plug’n’play devices any more than any other subwoofer, but what is nice about them is that once you plug them in, most of the setup is done from your sofa, where you can hear the results of setting changes in real time at your listening position, instead of hunched over the sub while trying to dial it in.

The Dynamo subwoofer’s clean appearance also has a lot to do with its practicality. These are subs that do not draw attention to themselves and therefore can fit in nearly any decor. The satin black finish is tasteful and the cabinet is simple, so while these subs would be a perfect fit in modern interior decor, they aren’t likely to clash with traditional home styling either. Another aspect of their practicality is their reasonable weight. At 35 lbs. for the 600X and 57 lbs. for the 1600X, these are subwoofers that almost any healthy adult can lift up and carry without much problem. As a subwoofer reviewer, it’s been a while since I have had such easily movable subwoofers, so I can especially appreciate that!

I am guessing that MartinLogan is going to continue their winning streak with these new Dynamo subwoofers. They sound great, they can be integrated into any system and any room, they are a breeze to set up and dial-in, and they are not exorbitantly expensive. I think those who want a subwoofer in their living room but have to compromise on the size of the sub for other household occupants are going to be pleasantly surprised by the performance of the 600X. I also think those who end up with a 1600X will be shocked at the sheer amount of punch it has for such a modest-looking piece of audio gear. This generation of Dynamo subwoofers is clearly a major leap over the previous generation in every respect; I know it will be years until the next generation, but I am already eagerly looking forward to where MartinLogan goes from here based on the terrific work that they have done on these subwoofers.

The scores below reflect both the Dynamo 600X and the Dynamo1600X, although the 600X scored slightly lower in the bass response and performance category.

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Bass Extension
Bass Accuracy
Build Quality
Ergonomics & Usability
Features
Dynamic Range
Fit and Finish
Performance
Value