MartinLogan Dynamo 1500X Subwoofer Review

Most people who are into high performance audio and audio equipment are familiar with the name MartinLogan. The company has been producing speakers for about 30 years and originally was primarily known for their range of large floor standing electrostatic speakers. However the brand has diversified quite a bit over the years to produce headphones, center channel and surround speakers and powered subwoofers. When I was asked to review MartinLogan’s Dynamo 1500X, the largest most powerful model in their Dynamo lineup, I visited the MartinLogan website to do a bit of reading up on it prior to receiving the review unit and was surprised to discover that they have no less than 8 subwoofer models in their current product range. As previously mentioned the Dynamo 1500X sits at the top of the Dynamo line but it falls in the upper middle of the entire MartinLogan subwoofer lineup as far as price and performance are concerned. Over the years I have had a few opportunities to hear various models of MartinLogan’s electrostatic speakers but this would be my first hands on encounter with one of their subwoofer offerings.

The Dynamo 1500X arrived in a moderate sized, heavy gauge, single layer cardboard box with the typical description and company logos on the sides. Weighing in at probably 60lbs and being a little more compact than expected the 1500X boxed up was rather lighter and more manageable to move than I am used to for a 15” subwoofer. Opening the box showed that the subwoofer and grille are both inside of bags and held by large shaped foam inserts at the top and bottom of the box. Other than the grill and the 1500X subwoofer itself the contents include, a set of spikes, a pair of right angle RCA cable adapters, a right angle power cord and the owner manual which is one of the more thorough and well written I have encountered.  The packaging was more than adequate considering the small stature and light weight of the system. Short of dropping the 1500X off of the back of a moving truck, I see very few situations where it would be damaged in shipping. A MartinLogan Perfect Bass Kit was also supplied and came in its own small box (The PBK system is shared with Paradigm who developed the system originally and it was evaluated as part of the Paradigm Signature Sub 2 review previously. Both Paradigm and MartinLogan are now under the ownership of ShoreView Industries so there is some sharing of R&D, technologies and manufacturing.). The PBK kit costs and additional $100 but includes a nice telescoping tri-pod stand, usb powered measurement microphone, the software cd, usb cables for connecting the microphone to the subwoofer and the operation manual, which again is well written. Out of the various manufacturer auto room equalization systems I have directly had experience with to date, the PBK system has been one of the best performing.

Unpacking the Dynamo 1500X was an easy affair and carrying it into the theater room from my garage was also no big deal thanks to the comparatively svelte exterior dimensions and 52lb mass. In fact I realized just how small it was after getting it into the theater room in the basement and moving a 100lb HSU VTF-15H I had been reviewing out of the way to make way for the 1500X. Despite both using 15” drivers the 1500X is less than half the size of the big HSU and weighs about half of the weight as well. As far as visual presentation goes this is a huge difference with the 1500X being about an order of magnitude less visually intrusive. To date the 1500X is the smallest powered sub housing a 15” driver that I have reviewed by far.

Design Overview

The Dynamo 1500X is a small sealed alignment utilizing a long throw 15” driver and an amplifier rated at 650 watts rms and 1300 watts short term. Other than the previously mentioned PBK system the 1500X does not employ a bunch of bells and whistles that some other subwoofers list as features but which may be of limited usefulness. The controls are simple and straight forward which I find refreshing. One unique feature that it does offer which I found to be rather interesting is an interchangeable foot system which allows the 1500X to be configured as either down firing or forward firing. The four feet are a molded black plastic that are L shaped and have a center screw which locks into the enclosure and a pair of pins which insert into the enclosure similar to how most grilles attach. There are 2 faces of the enclosure which have the mounting points for the feet, the face containing the driver and the amplifier panel. The feet can be screwed or unscrewed simply using a coin. The whole change takes less than 5 minutes. The 1500X comes configured for down firing which places the feet on the driver panel. In forward firing position the driver now fires horizontally and the amplifier is placed on the bottom. This is where all of the right angle connectors provided with the 1500X come into use as they will clear the floor easily. I like this option because there is little chance that your settings could be inadvertently changed since they would be under the subwoofer, however initially I had a concern about heat being trapped and building up in the amplifier, however after giving the 1500X some rather extreme workouts with various signal types the amp barely even got warm to the touch. The right angle connectors also help out with fitting the 1500X into tight places or up against walls. It would be nice if more manufacturers would provide a right angled power cord especially as this usually protrudes the furthest. After switching the feet a few times to see how this procedure worked I ended up leaving the 1500X in the down firing configuration for the rest of the time it was in my possession. The grille, which I test fitted on the subwoofer and then promptly put back in the packaging since I would be leaving the 1500X down firing, is constructed of molded plastic covered with the typical dark black grille fabric. To my eye the grille and plastic feet both failed to exude the same amount of quality as the rest of the subwoofer and components used. The grille felt very fragile and the feet also seemed like they could be broken without much force applied laterally. Now this probably won’t be an issue for most but on carpet you would not want to attempt to slide the 1500X on its feet as they could be seen to flex while doing so and I had visions of one cracking or becoming stuck in the threads. Otherwise the quality of finishing and components supplied with the 1500x was very good. The 1500X’s external dimensions measure just 18.3”x16.75”x17.6” in down firing configuration and 19.3”x16.75”x18” in front firing configuration so it shouldn’t be hard to fit into even tight spaces and won’t draw unneeded attention to itself.

The enclosure is available in only two finishes, the standard satin black finish of the review unit and a piano gloss black finish is available for a $300 upcharge. The standard finish on the review unit was well applied and heavy. I also noted that it seemed fairly durable as the review unit got a number of smudges which I found will wipe right off with a cloth and was also moved around a number of times. During transport to the outdoor test site it even knocked against a large metal ammo case in the back of the SUV due to an abrupt stop that was required and I thought for sure that there would be an ugly mark on the exterior, but once it was wiped with a bit of glass cleaner it left only a tiny little ding the size of a match head that could barely be seen up close. The 1500X is small with an unobtrusive and durable finish and it is well put together too. The 1500X looks good but at the end of the day it is still a basic black cube, so it didn’t exactly inflict me with pangs of longing to own it with its visual presentation.

Removing the 15” driver from the 1500X revealed it to be a well engineered if not massively powerful unit. The frame is a good looking cast aluminum design with under spider venting and with the flange cut into a square pattern. The driver mounts with a total of 12 large Allen head screws and is flush mounted into the baffle. The cone of the driver is a lightweight polypropylene which is suspended by a large rubber half roll surround and what looks like a pair of 6” diameter spiders. The motor is built with a pair of stacked ferrite magnets that are about 6” in diameter and ¾” thick. The top and bottom plates both appear to be about 8mm in thickness and the back plate has a small 0.5” diameter pole vent. The voice coil appears to be 2” diameter. When the driver was removed from the cabinet I noticed that there was a secondary small black wire that led to the drivers frame and went in under the spider landing. It turns out that this is a thermal sensing system which helps monitor and protect the driver from excessive heat buildup in the voice coil. As far as I know this system never came into effect while the 1500X was in my possession and I definitely was not delicate with it at times. Either that or it is very subtle in operation. 

MartinLogan Dynamo 1500X Driver

Once the driver was removed from the 1500X I could see that the amplifier was mounted inside of its own metal chassis which covered all of the internal components so I decided not to go to the trouble of removing the amplifier and then removing the covers over the amplifier. MartinLogan indicates that this is a 650 watt highly efficient Class D design and it includes a very basic set of controls with only gain, low pass and phase being user adjustable. The inputs are limited to a pair of RCA inputs and a single balanced XLR line which is nice. A trigger input and the input for the PBK system complete the connection scheme. This is plenty of control and connection options to blend the 1500X into the majority of systems. In use the amplifier certainly seemed to have plenty of power for the driver and even during the ground plane measurement session with pure test signals the amplifier barely got warm to the touch.

MartinLogan Dynamo 1500X Amplifier

The cabinet of the Dynamo 1500X appears to be constructed of ¾” medium density fiberboard with the baffle built of slightly thicker material. The roughly cabinet features a cross brace which ties the 4 panels not housing the amplifier or driver together and also is generously lined with thick damping material on both of the sides and top of the cabinet. The result of this is a well damped and dead cabinet with little resonance or panel vibration in the subwoofers range of operation. Both the driver and amplifier are flush mounted and the cabinet features a small 1/4” round over on each edge. The basic satin black finish was evenly and thickly applied and durable. The component quality and construction of the 1500X is very good with the exception of the grille and feet which seem a little flimsy for a subwoofer of this price.

MartinLogan Dynamo 1500X Cabinet