Paradigm Signature Sub 2 Subwoofer Review

Paradigm Sub 2 Introduction

Paradigm is a name that is probably familiar to most audio enthusiasts as a manufacturer of bookshelf and floor standing speakers, center channels and subwoofers. Over the last 25 years Paradigm has stuck to a core model of offering audio related products that are well engineered, subjectively pleasing to the ear and reasonably priced. Today Paradigm has a broad range of products and full speaker lines at a couple of different price points. At the top of the heap is the Signature series, which offers a few subwoofer models to choose from including the Signature Sub 2, which is the subject of note for this review. Sitting at the very top of the Paradigm subwoofer mountain the Sub 2 is in many ways a statement level product and the $8,999 msrp certainly suggests that it is, being the single most expensive product in the Paradigm catalog or that Paradigm has ever produced to my knowledge. However for that rather substantial sum of money the Sub 2 delivers an almost comical amount of hardware that on the surface sounds like it sprouted from some bass obsessed teenagers dreams, including specs like: Six 10” drivers, a total motor assembly weight of over 150 lbs, an amplifier that needs a 240v line to develop its full peak output of 9,000 watts short term and an unpacked weight of 230lbs. Firepower is obviously not in short supply here. But can all of this hardware be turned into accurate sound reproduction with equal parts finesse and bludgeoning force if needed, the veritable iron fist in a velvet glove? Read on…

Unpacking and Initial Thoughts

The Paradigm Signature Sub 2, being a very expensive and heavy piece of equipment, was delivered via a freight carrier and arrived wrapped and strapped to a large pallet with the small box containing the PBK kit (Perfect Bass Kit) riding on top. The shipping documentation listed a shipping weight of 310 lbs. Needless to say the box itself is very large and a full sized pallet will not fit through most domestic door frames. This necessitated removing the main box from the pallet prior to bringing it into the house. Additionally I have a couple of steps to go up to enter the doorway so the act of getting the Sub 2 into the house took some amount of effort from a couple people in concert, one of which was the delivery driver who seemed curious as to just what sort of “speaker” was this big and heavy. Either that or he was simply feeling sorry for us. Once we had the Sub 2 to the door it wasn’t too hard to slide it on in. The box just barely squeezes through a regular sized door frame. Since this unit came directly from Paradigm I am not sure what arrangements would be made when purchasing through an authorized dealer, but I assume that there would be some after sale support to get it into the home and in place in your room. A single person job it is not.

After getting the Sub 2 into the house and having a moment of reflection I set about reading the unpacking instructions furnished by Paradigm, which were attached to the top of the box and boldly labeled ATTENTION! READ FIRST. The instructions were not that different from most other large subwoofers. Open the top and then tilt the box over onto the top using the plastic handles integrated into it. Lift the box up and off of the subwoofer, remove packing materials, plastic wrapping, accessories, etc. This leaves the Sub 2 sitting on two large pieces of thick foam cut to fit over the cabinet bottom and protect it. At this point you tilt the Sub 2 slightly so that one of its three feet is off of the floor and remove the foam piece from under that foot then repeat for the other two until it is sitting on the floor. Obviously due to the weight of the Sub 2 you would want to unpack it as close to your final placement for it as possible. The packaging and materials used are robust and high quality. This coupled with the freight shipping ensure that there is little chance of a Sub 2 sustaining damage during shipping. Other than the Sub 2 itself, contained in the package were: Two owner manuals, one in French and one in English, the power cords, one for 120v and the other for 240v operation, threaded adjustable feet for the Sub 2, the PBK kit, etc.

Once the Sub 2 was sitting alone and I had my first chance to inspect it in person I was immediately given the impression of very high quality. All of the joints were tight, the grills were solidly attached and the piano gloss black finish of the review unit was simply stunning. The cabinet exterior was mirror polished and very deep to such an extent that you could easily see distortion free reflections in it. Additionally the unusual hexagon shape, the large milled aluminum amplifier plate and the nicely contoured top and bottom panels which blend into the grilles and amplifier offer a somewhat more exotic than usual profile for a subwoofer. I was also a little surprised at the size of the Sub 2. After viewing the size of the outer box and feeling the weight I expected the Sub 2 to be somewhat bigger than it actually is once unpacked. In person it is much smaller than you would think and one compact, massive slab of speaker. To be sure it is no shoebox subwoofer but it is no giant either. It is actually smaller in volume and with less of a footprint than some other subwoofers that I have reviewed lately.

Paradigm Signature Sub 2 Subwoofer Design Overview

The Signature Sub 2 is a sealed subwoofer system utilizing no less than six heavy duty 10” drivers in an unusual hexagonal shaped enclosure and a host of technologies developed by Paradigm’s Advanced Research Center (PARC) over the course of a few years. The drivers are arranged in a radial fashion on three of the enclosures six sides in vertical groups of two drivers to a side. This provides the benefit of cancelling the vibrations that otherwise would be imparted into the cabinet by the movement of the driver cones. This cancellation occurs due to the opposing forces from the other drivers in this type of arrangement. In a conventional driver layout at high output levels the driver can start to vibrate or physically shake the cabinet due to its movement. This has nothing to do with the actual sound waves emitted by a subwoofer and is a result of the physical mass of the driver moving assembly vibrating back and forth rapidly. In effect it acts like a shaker weight attached to the enclosure. The Sub 2 design cancels out these forces which is especially important with six high power long excursion drivers all active in one small enclosure. An internal amplifier of unusually high output capabilities provides the motivation for all of those drivers and occupies the entirety of a fourth side of the hexagon enclosure. The amplifier is rated at a titanic 4500w rms when connected to a 240v line, has internal DSP which is set by Paradigm to contour and shape the response of the Sub 2 and also has a USB port for connection of a computer for use with Paradigm’s PBK kit, which is included. The Perfect Bass Kit is Paradigm’s own crack at developing an automatic correction for the effect of a rooms acoustics on the subwoofers output as delivered to the listening position. More on that later…

The Sub 2 owner manual, PBK manual and quick start guide are all very detailed and much more thorough than the average literature, even going so far as to get into some basic theory on room placement and system integration. In particular the owner manual provides a lot of background information on the design and engineering that went into the Signature Sub 2 and Sub 1, including notes on the drivers, amplifier, exploded views and internal shots of the cabinets, major components, etc. It is obvious that Paradigm are proud of these units and the engineering that went into them as most companies do not provide this type of detailed information even for their flagship products.

Usually I will partly disassemble the subwoofers as part of a review in order to assess the design further and check the quality of the internal cabinetry and components, but Paradigm literature notes that the grilles for the Sub 2 are non removable due to the extreme power of the Sub 2 and for safety reasons involving the amplifier design. Additionally there are a lot of nice pictures and renderings of the internal workings and components used in the Sub 2 such that there really wasn’t a need to do this since Paradigm has already provided most of this information and plenty of product pictures. That being the case and since I couldn’t help myself, I decided that I would still go ahead and have a look inside of the Sub 2 with Paradigm’s blessing.

The 10” drivers used in the Sub 2 are very robust and individually would be impressive in most other company’s subwoofers. The motor is a very large roughly 8” diameter affair utilizing 3 large ferrite magnets stacked on top of each other and attached to a proprietary heavily vented and open cast aluminum frame which Paradigm calls AVS or Airflow Ventilation System. The motor also has a large diameter pole vent with a mildly bumped back plate and a couple of small diameter holes for gap venting. Additionally the pole vent has a large aluminum heat sink, which probably also doubles as a demodulation circuit, mounted inside of it which is a first in my experience. The motor assembly for each driver is listed as 25.2 lbs which puts the individual driver weight at about 30lbs. With six drivers all crammed into the single enclosure you can easily see where the 230 lb mass of the Sub 2 comes from. That is 180 lbs worth of drivers! The voice coil is a 10 layer, aluminum wire on a 3” Nomex former with a long wind for extra excursion. The leads for the driver voice coils do not connect to terminals on the driver frame from the area near the spiders as is usual with most bass drivers. Instead the leads exit the driver from inside the former out of the pole vent. The cones are a mineral filled polypropylene with reinforcement ribs molded into them for extra stiffness. The stiff suspension consists of a large half roll FEA optimized thermoplastic foam surround and a pair of large diameter spiders. This is a heavy duty and likely somewhat expensive driver to produce and there are not one, not two, but six of these in each Sub 2.

         

Paradigm Sub 2 Driver

The amplifier of the Sub 2 is a very high end piece that is not your typical plate amp. First off there is the obvious which is the extra high power rating of 4500 watt rms and 9000 watt peak, which is closer to the types of power levels seen more commonly in professional touring power amplifiers rather than the plate amps in commercial subwoofers. Paradigm calls the patented topology used in the Sub 2 amplifier Ultra-Class-D and indicate that it has a very high efficiency of around 95%. It is a transformer-less design utilizing PFC to regulate a 400v bus which the bridged class D amplifier is powered from. PFC or power factor correction in very simplistic terms allows the amplifier to draw current from the wall more efficiently and throughout the entire ac cycle instead of only during the peaks of the waveform. This helps boost the amplifier efficiency and also can help the amplifier produce maximum power when operating from sagging or dirty AC lines. Again this is a feature normally found in touring grade professional amplifiers. The Sub 2 amplifier also has Universal Input Voltage which allows it to be connected to voltages between 108 and 265 volts. In order to get the full continuous output from the amplifier it should be connected to a 240v line. The rating is 3000 watts continuous if connected to a standard 120v line. The amplifier’s continuous output is limited when operating from 120v in an effort to avoid tripping the breaker. A cord set for each voltage is provided. Interestingly both have a ground pin but the actual socket on the amplifier has no ground pin. This is because the amplifier is double insulated. Being that the amplifier operates in a non isolated manner the driver voice coils have the same potential as the AC line voltage and this is the reason for the non-removable grilles. In practice the difference between operating on one voltage versus the other would not be noticeable until the extra power is needed when the Sub 2 amplifier is asked to produce maximum continuous power into low impedances for extended duration. Auto on/off, thermal and short circuit protections, a soft clipping circuit and 12v trigger on/off are employed as well. The amplifier also has internal DSP processing but this is configured by Paradigm at the factory and not user accessible. The amplifier provides a left and right unbalanced RCA style input, a balanced XLR input, USB input for connecting to a computer for running PBK and a 12v trigger input. Input sensitivity, phase adjustment and low pass crossover are the only controls provided.

         

Paradigm Sub 2 Back Panel

The hexagon enclosure used for the Sub 2 appears to be made of 1” thick MDF throughout with the top and bottom panels perhaps being slightly thicker material. After removing the grilles and a couple of the drivers to examine the internal workings, a thick shelf brace across the middle of the cabinet in between the drivers could be seen which ties all of the enclosure corners together. It has a couple of strategically placed windows to allow the total enclosure to still appear as one air space to the drivers. Additionally there is a large 2”x2” brace extending through the center of the enclosure which ties together and braces the top and bottom panels. There is also plenty of dampening fiber inside of the enclosure in between the drivers and on the panel surfaces. This is one rock solid and inert enclosure. As mentioned previously the piano gloss black finish was visually stunning and befitting of a product of this caliber. Internally all of the enclosure surfaces are sprayed with a matte black paint. The grilles are heavy duty and not just cloth but are actually constructed of wood frames with perforated steel grilles which are then covered in black fabric.

Once I could see the internals of the Sub 2 it became apparent just how compact and full of hardware the cabinet is. It is literally cram packed as you can see in the pictures below. The effective volume of air seen by the drivers must only be a couple of cubic feet in total. The driver motors are only about an inch from touching each other or the center brace and the amplifier itself takes up a good amount of room as well and sprouts a ridiculous amount of wires to feed the six drivers. The driver motors are in such close proximity to each other that when you mount one the magnetic field from the other motors tries to twist or push away the motor of the driver in your hands and this despite the 30lb driver weight. That said the attention to detail and logical layout that is apparent on the outside of the Sub 2 also extends to the inside of the enclosure as each driver has a set of terminals anchored in the cabinet behind it with quick disconnect spade connectors. The leads from the amp can be secured in place with only a short lead from the drivers to the terminal. If a driver somehow got dropped or otherwise yanked during removal it will not yank on the leads from the amplifier or at the voice coil since the leads are anchored into the back of the motor heat sink as well. Not that any Sub 2 owners should be delving hands on into the guts of their multi thousand dollar bass maker, especially since it will void your warranty and all. I don’t want to give anyone that impression, but it shows that the Sub 2’s designers were paying attention even to the internals on their products.

          

Interior View at Paradigm Sub 2 Internals

One thing that puzzled me slightly was the lack of casters in the Sub 2’s included accessories. The Sub 2 has three feet built into the bottom of the enclosure which also happen to have a nice big threaded hole. With the odd shape, the relatively small size, massive weight, beautiful finish and only three feet, maneuvering the Sub 2 when you have to can be a tricky affair as you try to protect the finish and grille cloth while dealing with its bulk. It also makes leveraging it onto a furniture dolly, or using a 2 wheel dolly a little dicey. As soon as I could see that there were threaded holes that I could use for a set of wheels I made a run to the hardware store for a set. Simply screwing in a couple of casters and rolling it around when needed sure made life easier. Paradigm probably rightly assumes that most users will only ever move it into position once or maybe twice. I’m not so lucky. I can only assume that Paradigm put those threaded holes in the bottom for just such a purpose.

As can be seen the Paradigm Sub 2 build and components quality is through the roof. It is even evident in little things like the screws and small bits of hardware used which are of higher than average quality as well. Even the inside of the grilles, which are not meant to ever be seen by the end user, are over built and nicely finished. The amplifier is a cut above any other commercial plate amp I’ve yet seen attached to a subwoofer both in power and sophistication. There are other subwoofer manufacturers who have drivers of similar quality but they use one or perhaps two of them at the most, while the Sub 2 is shoehorning no less than six of them in. The finishing quality and packaging quality are the very best I have seen to date as well. It is a very expensive subwoofer but the build, finishing and component quality are certainly in line with that big sticker.

Paradigm’s Perfect Bass Kit

As part of the purchase price of the Signature Sub 2 Paradigm includes their PBK kit which is an auto equalization system developed by Paradigm that helps counteract the effects of a room’s acoustics and smooth out the subwoofer response in the room and at the listening position. These types of auto EQ systems are growing more popular of late with many manufacturers starting to incorporate their own version into their products. Paradigm’s PBK comes in a small light weight box, separate from the Sub 2 itself, that contains product literature, user manual, quick start guide, software disc and multiple smaller boxes containing a usb powered microphone, microphone tri-pod stand and a couple of usb cables. Running the PBK routine is very straight forward and involves: Placing the subwoofer, installing the PBK software onto a computer with two available usb ports, connecting both the Sub 2 and microphone via the supplied usb cables, placing the microphone at the primary listening position and starting the auto routine. At which point all you need do is occasionally move the microphone to a new position in between measurements. After the minimum amount of measurements are gathered, or you decide that enough have been done, the system will calculate the EQ corrections needed, import them into the subwoofer and display the results. These can then be saved to your computer for recall later. The whole process is very simple and takes less than 20 minutes. The results in my room are shown below and indicate that I have a dip at 30Hz, a peak near 40Hz and another dip near 65Hz. After measuring many subwoofers in this placement, none of this was a surprise to me. The raw response of the Sub 2 as delivered to the microphone is the red line on the first graph below and the purple is the expected outcome after PBK’s equalization is applied. I also decided to do a couple of before and after measurements with my own rig to see how closely they correlated with the PBK reported results. This is presented in the second graph below.

Paradigm Signature Sub 2 PBK measurement

Paradigm Signature Sub 2 before and after PBK measurement

The two results match up rather well despite the different software, resolutions and graph scales. All of the major response features both dips and nulls are present on both measurements. The important point of this is that before running PBK the Sub 2 response was +/-5.7dB, or an 11.4dB total window from 20-150Hz. After running the PBK routine the response was flattened into a much tighter +/-3.4dB and now fits into a 6.8dB total window over the same frequency range. The measured result after running through the PBK routine is a large improvement that should result in audibly smoother, more uniform bass and indicates that running PBK can have a big effect on your Paradigm subwoofers performance, especially if you are not the type of person who manually measures and equalizes your system yourself.

Paradigm Signature Sub 2 Subwoofer Review Listening Session

For all of the listening sessions the Paradigm Sub 2 was placed in the front right corner of the room about 4 inches from the walls. This places the subwoofer a little over 4 meters from the primary listening position. I have determined this to be the best available single subwoofer placement in the room for most units. The Sub 2 was connected to one of the 240v outlets normally occupied by a KPA2400 amplifier and this ac voltage was used for the duration of its stay. Paradigms PBK routine was run on the Sub 2 first to allow it to adapt the subwoofer response to the room. This was followed by Audyssey auto EQ being run on the system to allow it to further integrate the Sub 2 and flatten the response, which was then followed by a check and recalibration of the subwoofer and speaker levels prior to the listening sessions. Paradigm recommends running PBK prior to any other EQ or system optimization in the literature supplied with the Sub 2. For all listening the Sub 2’s internal low pass filter was bypassed in favor of a 125Hz setting inside of the Onkyo PR-SC886P.

Listening Impressions: Various Artists, Movies and Formats

This part of the review will be a little different from normal. Reason being that Paradigm sent the Sub 2 way back in 2011 before the holidays and instead of the week or two that I usually have to get acquainted with and listen to a subwoofer I was lucky enough to have the Sub 2 as the part of my home theater for about 3 months. The reasons for this length of time were part, timing, part scheduling, life events, weather, you name it. Thankfully Paradigm was very patient and only inquired once every few weeks and they never rushed the review process. A good chunk of my time spent with the Sub 2 was critical in depth listening with notes using material of every stripe. Other times it was just casual enjoyment without focusing in on what the Sub 2 itself was doing. Since I had an extended amount of listening to the Sub 2 and used such a wide range of materials I’m just going to give my final impression mixed in with some specific notes from various sessions.

The first thing that I did once the Sub 2 was fired up in my system was connect my i-pod, which only has uncompressed .wav files loaded on it, and run through a bunch of favorite tracks at a moderate volume which have bass that I enjoy for one reason or another, old Beastie Boys, some Victor Wooten, Pink Floyd, etc…Over the duration of time that I listened to the Sub 2 I would occasionally go back and listen to just pure music in between movies and sporting events. The first couple of times that I listened with the Sub 2 involved, nothing immediately jumped out at me, or bowled me over and nor did I expect it to. This not what a subwoofer should do if it is integrated and level matched well. What eventually became apparent was that the bass lines just seemed to be there in a nonchalant manner and presented without coloration. If the kick drum was heavy so was the Sub 2’s contribution. If the track was mixed lean it stayed lean just as it should. On dense tracks such as those contained on Strapping Young Lads The New Black album, which has quick double kick flurries and occasional blast beats interspersed with frantic bass guitar runs and the occasional 808 like drop bass effect, the Sub 2 was completely unfazed even at volume levels that were starting to get uncomfortable to be in the same room with. Even at those levels everything was clear and uncongested sounding. One track on this record in particular, “Almost Again”, has drummer Gene Hoglan throwing in the occasional drop bass effect into his double bass patterns before adding in floor toms to the previously already over the top verse drum beat. On most systems you might not notice the floor toms being thrown into the beat on this section of song as there is so much going on already and they do not have a lot of top end attack. The Sub 2 clearly maintained separation of this material such that the floor tom fundamentals were readily apparent over the kick drum pattern and bass guitar. On VAST’s “Music for the People” album which is moody pop rock the low register of piano and bass guitar were satisfyingly smooth and the drums were presented with a lot of weight to them and a dark analog warmth which is how they are mixed on most of the tracks. On a track titled “Take Me with You” from a different album there is virtually no bass until a huge bass drum drops into the song at about 1:54 in. I believe it is centered at around 40Hz or maybe slightly lower but it sounds like it is coming from a mountain in the distance and has a lot of sustain and impact. It is not particularly taxing but I love the way that it sounds on a dynamic system. I cranked the Sub 2 way up for this and it did not disappoint generating a huge percussive slam. Other fodder served up to the sub 2 included everything from Animals as Leaders and Loreena McKennit to Neil Young and Cypress Hill. Slow booming rap bass, quick bass guitar runs, fast kick drum patterns, piano, deep male voice and I even threw some pipe organ in there. The big Paradigm was impressive with all of it and would only call attention to itself when the material demanded it. One of the concert blu-rays enjoyed was Michael Jackson’s “This Is It”. If you haven’t seen this movie it is primarily behind the scenes footage and rehearsal’s during the build up to what was billed as his final tour and contains a really well mixed low frequency range during many of the bigger rehearsal sequences that only gets that much better with a subwoofer like the Sub 2. Even if you aren’t a fan it is worth a watch just for the smooth low end mix and skill of the backing musicians. I had only seen this once previously and had forgotten just how good the bass mix was but the Sub 2 reminded me in short order with big, punchy and clear bottom end that made me want to reach for the remote and increase the volume every couple of minutes, which I did quite a bit. Awesome.

As is customary I also enjoyed a couple of movies with subwoofer crippling bass in order to gauge how the Sub 2 would deal with loud playback of this material in a fairly demanding room. For this I decided to go straight for the big guns starting with Steven Spielberg’s 2005 adaptation of “War of the Worlds”. Despite being released quite a few years ago this is still one of the most demanding if not THE most demanding movie soundtrack available and has simply punishing bass in a number of scenes. Suspect number two was Dreamworks “How to Train Your Dragon”, an animated children’s film about a bungling young Viking that just happens to have an insanely bombastic mix as well. The thought behind using this material is that this is about the most demanding material that any subwoofer will ever see, so if the Sub 2 does well here then it should have the headroom and in some cases protections built in to deal with anything else Hollywood is likely to send down the pipe. Considering the massive amount of testosterone the Signature Sub 2 brings on deck with it, I had a hunch that cutting it loose on these big action flicks aught to be entertaining to say the least. I was not disappointed. With a little apprehension I started War of the Worlds with a master volume of -12 from theater reference, which may not seem that high, but I can assure you that the majority of single subwoofers will utterly crumple at that playback level of this soundtrack in my system. Not Paradigm’s Sub 2. The first scene with notable bass is during the lightening storm which is very low frequency such that most subwoofers skip it entirely. The Sub 2 sent a good sized tactile pulse through the furniture and floor which was impressive and tells me that the Sub 2 has response that extends very low in frequency with substantial power. During the pods emerge scene the Sub 2 produced room shuddering bass with impressive authority, shaking the couch and floor both. When the giant alien ship goes on the rampage and starts laser beaming people and houses the bass shifts a little higher in frequency to the 25-35Hz range at very loud levels. This is the section where most subwoofers would be over driven and the Sub 2 just cranked the bass out while sounding like it was completely in control the whole time. Again on the highway bridge collapse I listened for any sign that the Sub 2 was distorting or into the limiter but it was difficult to tell because it sounded like a bridge had just collapsed! This performance on extremely demanding material was about the point that the Sub 2’s output capabilities started to sink in. About a week later was when I finally had a chance to watch “How to Train Your Dragon”. I used the same volume level as used with War of the Worlds and again the Sub 2 seemed to have no problem at all with the myriad explosions, thumps and loud booms present in the soundtrack. This film also has a lot of very low frequency content below 20Hz and again it was readily apparent that the Sub 2 has deep extension producing what I like to refer to as the push or shove effect, which is where the bass is so low in frequency that it barely registers with your ears but you get a tactile or physical sensation of it on your body or through the furniture. It is a subtle effect that is a little eerie at first experience, but it takes a subwoofer or sub system with deep extension and a lot of headroom to pull this off. Apparently the Sub 2 qualifies. At the very end of “How to Train Your Dragon” there is a climactic battle with the uber dragon that results in a loud, rumbling, thud of epic proportions. The Sub 2 pulled out all of the stops and provided a powerful room shaking shudder befitting of the action on screen.

Over the next month or so I continued to use the Sub 2 and enjoy its contribution with a wide variety of material. Not once did it do anything other than a fantastic job. With high quality music and movies it was always neutral and never sounded anything other than composed. I do not know if its limits were ever found with either of the two big bass flicks that were used but if they were, I could not tell. I never heard any noises of overload or anything like that. The fact that all of that clean output comes from such a good looking and reasonably sized enclosure is the cherry on top. Also I did briefly put a glass of beer on the subwoofer while I was watching “This Is It” and there was barely a ripple even though the sub was cranking out an impressive amount of bass at times. I was a little sad when the time came and the Sub 2 was finally boxed up and sent back to Paradigm. I would be proud to have one or three in my system.

Paradigm Signature Sub 2 Subwoofer Review Meaurements and Analysis

Configuration for Measurements

The Paradigm Signature Sub 2 subwoofer was measured outdoors sitting on the ground with the M30 microphone placed 2 meters from and pointed directly at one of the blank panels of the cabinet with four of the six drivers pointed toward the microphone in a V shape and the final two firing backwards away from the microphone. The XLR input was used, the internal low pass filter was disabled, the phase was set to 0 and the subwoofer volume was set to its center detent. The PBK equalization curve used to flatten the in room response was deleted from its memory. The Sub 2 was connected to a 240v ac line for all of the testing unless specifically noted that the measurement was taken using 120v ac power. All tests were conducted in this configuration, except for those tests purposely conducted to examine the effects of the built in functions, different cabinet orientations, or different operational modes.

The overall approach to this testing along with the equipment and software used is outlined in the article here.

Powered Subwoofer Testing Outline and Procedures Overview

additional recommended reading: How to Interpret Audioholics Subwoofer Measurement Report

Editorial Note on Enclosure Orientation for Outdoor Measurements:

When measuring subwoofers for performance such as CEA2010 maximum short term output in an outdoor environment, in order to have an accurate comparison of data in a fair manner each DUT should have as much of its energy directed at and as close to the specified distance from, the microphone element as possible. For subwoofers with multiple points of radiation such as those having ports that fire from the opposite side of the enclosure, or drivers on multiple sides of the enclosure, it is impossible to direct all of the radiation towards the microphone and minimize the difference in distance. In room there are boundaries that constrain and reflect the output back toward the listener from these multiple points of radiation. Outdoors in quarter space there are no close boundaries other than the ground. This causes the output to be under represented when measured from any single point in space around a subwoofer having the radiating elements separated as compared to a subwoofer using the same radiating elements placed all on one panel which can then be directed towards the microphone. Technically there is no difference in total energy from the two approaches only distribution of it depending on where you are in proximity to it. That being the case there is a need to develop a compensation file for subwoofers such as Paradigm’s Signature Sub 2 which has drivers firing from three opposed faces on the enclosure such that no matter how it is oriented there will always be drivers firing away from the microphone. Additionally the Sub 2’s drivers all operate over the entire effective range of the subwoofer unlike a port or passive radiator. Measuring from a greater distance from the subwoofer helps to equalize for the differing distances from the major points of radiation to the microphone. In order to ascertain the correct amount of compensation to add to correctly represent the Sub 2’s output SPL a series of measurements are taken at various distances of 1 meter, 2 meters, 4 meters and 10 meters, using the same drive level and compared with the change in SPL that should occur due to the inverse square law. Measuring at 10 meters (roughly 32.8ft) allows for much better integration of the Sub 2’s output from the various drivers since a difference of less than a meter to the microphone causes a negligible difference to the total SPL at that distance. This is then compared to the 2 meter measurement and what the 10 meter measurement indicates that the 2 meter measurement should show according to the predictable drop off in SPL of the inverse square law. The difference then becomes the compensation file.

 

 Paradigm Signature Sub 2: Output Compensation

 

Outdoor Groundplane Measurements & Analysis

 

Paradigm Signature Sub 2: Basic Response

Above is the basic response measurement of the Sub 2 with the internal low pass filter defeated. Overall this is an extremely extended and impressively flat response which fits within +/-3dB from 13-240Hz. 13Hz is an extremely deep -3dB point in a quasi anechoic setting especially for a sealed alignment. The -10dB points are at 11.1Hz on the low end and 285Hz on the top end respectively. The Sub 2 should be able to be effectively crossed over as high as 180Hz if such an extended range were needed to integrate with small, bass shy mains perhaps. This might be an unlikely scenario but it is nice to have the bandwidth available to do so if needed.

 

Paradigm Signature Sub 2: Effect of Low and High Pass Filter Settings

Above is the effect of various settings of the Sub 2’s low pass filter on its upper bass response. These were taken with the filter bypassed and at the minimum, maximum, 11 o’clock and 1 o’clock positions on the dial. These correspond to about 40Hz, 50Hz, 80Hz and 120Hz acoustically. The Sub 2 exhibits a text book 4^th order LR roll off.

 

Paradigm Signature Sub 2: Waterfall Decay

 

Paradigm Signature Sub 2: Group Delay

The response of the Signature Sub 2 in the time domain shows no area of concern, never breaking even1 cycle of delay. The waterfall plot is free from any ringing and shows a rapid 30dB drop in energy which is exactly the type of thing you would want to see indicating a well damped response with a clean decay. There is a slight increase in energy below 25Hz due to the boost EQ being employed to extend the response but it is at very deep frequencies and not enough to be of any concern at all.

 

Paradigm Signature Sub 2: Long Term Output Compression

Above are the results of the output compression test for the Sub 2. It maintains the very deeply extended basic response shape up until the nominally 100dB output sweep. By the nominally 105dB level there is starting to be some output limiting below 20Hz. By the 110dB nominal output sweep it is obvious that the limiting circuit is intervening heavily, limiting the deep bass output at which point the response shape below 30Hz has changed by a large amount. Increasing the level a further 5dB resulted in the Sub 2 abruptly muting a few seconds into the measurement. When this happened I was worried that a fuse had blown in the amplifier or that something else had happened in the amplifier. After a few tense minutes the Sub 2’s amplifier reset and resumed operation. Luckily it was only a protection circuit inside of the amplifier that muted the output. To say that I was relieved is an understatement. After this occurred I was a little more careful with the input levels sent to the Sub 2. Remember that 13Hz extension that was mentioned earlier? The Sub 2 has incredibly deep extension but its relatively modestly sized sealed enclosure implies that it also requires a very large amount of deep bass boosting to accomplish it. This combined with the very high output levels being asked from it resulted in a monumental amount of power being asked from the amplifier which resulted in it protecting itself. The Sub 2 with its six long throw drivers and brutally powerful amplifier is in a much better position than most to be able to handle the increased load but even it will eventually succumb to physics. This was the only event of note encountered with the Sub 2 during the entire review process. It was run very hard in actual use during the listening sessions and this protection never triggered, so it is very unlikely to occur with real world use and signals.

Note on Output Compression Testing: This is by far the most demanding measurement type conducted on the subwoofers and will reveal any issues with overload, port compression, port noise, driver distress, creaks, rattles, buzzes, clipping, etc. Additionally this is outdoors with the subwoofer operating alone with no nearby walls or objects to vibrate and no upper frequency content from other speakers that would normally help to cover up or mask any objectionable noises from the subwoofer in a typical room. Any sort of audible distress or issues with the subwoofer will be readily apparent in this environment.

During the high power sine wave sweeps the Sub 2 behaved as well as one could hope and never sounded distressed or overdriven. There were no cabinet or panel resonances noted and the drivers while driven to large excursions in the low bass range never seemed to be out of control. Even at the very loudest levels there were no discernable buzzes, rattles, resonances, or other spurious noises. Being a sealed system there is no possibility of port noise either. The Sub 2’s force cancelling design and distribution of the amplifier power amongst six drivers coupled with a rock solidly constructed enclosure combine to give it among the quietest at the limit operation I’ve encountered. Judging from what I observed despite the humongous power reserves of the Sub 2’s amplifier it is still an amp limited design and as such it will go into protection before the drivers are driven to audible distortion. The Sub 2 simply refused to make an offensive noise.

 

Paradigm Signature Sub 2: Output Compression Magnitude

Above we have another way of looking at the previous results which shows only the amount of output compression occurring. Here we can see that the Sub 2 has virtually no compression up to and through the 100dB nominal sweep level. Further increases in level indicate that the subwoofer is into the limiter in the sub bass frequencies and give an indication as to the shape and placement of the equalization used to extend the Sub 2’s response. It appears that the boost is centered at 14Hz and is probably at least 12dB which is a substantial amount. 12dB of boost corresponds to 16 times the power needed from the amplifier. The negligible amount of compression apparent above 40Hz indicates that there is likely a large amount of headroom still available there.

 

Paradigm Signature Sub 2: Connected to 120v versus 240v AC

Above we have a comparison of the Sub 2 when connected to a 240v versus 120v line. Paradigm’s literature on the Sub 2 indicates that the amplifiers long term output is limited when on 120v service so as to avoid potential tripping of the breaker and that for maximum output and headroom a 240V line is recommended. In order to test this out the Sub 2 was measured both on 240v and 120v service. The graph above shows that there is essentially no distinction in the Sub 2’s performance when using it with either voltage well within its limits. This is the bottom two traces on the graph. However the 240v line does allow 2 or 3dB greater long term SPL if you drive the Sub 2 to its limits as shown in the top two traces on the graph where you can see that on the 120v service the Sub 2’s deep bass output limit is a couple of decibels lower. This is just as Paradigm claims. To make a long story short there was some performance advantages to the higher voltage line but they really only take effect if you are running the Sub 2 at the edges of its very considerable limits. Otherwise it performs virtually the same on either voltage.

 

Paradigm Signature Sub 2: Total Harmonic Distortion

 

Paradigm Signature Sub 2: 110dB Sweep Distortion by Component

Total harmonic distortion and distortion by harmonic component testing reveals that the Signature Sub 2 has very low distortion above 35Hz well below 10% and less than 5% THD above 40Hz. In the deep bass the distortion increases smoothly as is usual with sealed enclosures where all of the output comes from driver displacement. Still the THD stays below 15% until under 20Hz. Once again the effects of the deep bass boosting can be seen in the distortion results near 14Hz. Even though the distortion below 16Hz may seem high the Sub 2 never sounded distressed or distorted to the ear. The make-up of the THD is primarily 2^nd and 3^rd harmonics which are not as offensive as higher order over tones. Overall this is a good showing for a sealed subwoofer especially considering the amount of actual output capability below 30Hz.

 

Paradigm Signature Sub 2: CEA2010 2 Meter Groundplane RMS Results

 

Paradigm Signature Sub 2: CEA2010 2 Meter Groundplane RMS Comparison 120v / 240v

CEA2010 Results

As expected the CEA-2010 maximum short term distortion limited output results are impressive with over 120dB recorded at 50Hz and above. In the sub bass frequencies the six 10” drivers and amplifier combine for some heavy lifting with just shy of 100dB of maximum peak output at 12.5Hz and almost 97dB at 10Hz. Remember this is a quasi anechoic outdoor result. In room with the help of pressure vessel gain, output in these bands could easily be boosted by 10dB or more. The Sub 2 is amplifier limited at every band above 16Hz and is 3^rd harmonic distortion limited below 20Hz. More important than the output at any one band is the overall headroom that is available across the entire bandwidth. Not to mention that this sort of output is produced from a unit not much physically bigger than many companies vented 12” offerings. The Sub 2 was CEA-2010 tested while operating from both a 120v and 240v line. 240v operation offered about 1-1.5dB more output below 25Hz and slightly less distortion. Higher up in frequency the output advantage was only about 0.5dB in favor of the higher voltage operation.

Paradigm Signature Sub 2 Subwoofer Review Conclusion

Paradigm has produced a tour de force with the Signature Sub 2. It is overall the highest performing and most thoroughly impressive subwoofer that I have encountered. The msrp of $8,999 is undoubtedly a large chunk of cash but with the amount of development, technology and hardware packed into each Sub 2 coupled with the attention to detail, high tech look, beautiful finish and high performance, that big sticker starts to look more reasonable. The performance basics are well covered with a linear response, deep extension, low distortion and plenty of headroom. Additionally Paradigms PBK system is probably the best example of an automatic equalization system that I have used to date. It made a measurable and clearly audible improvement in response smoothness in my room. I was also pleasantly surprised at the basic control scheme and lack of filler features of limited usefullness on the Sub 2. The result is a subwoofer that is surprisingly easy to integrate and set-up. I had it dialed in in about an hour and a half, at which point it sounded very good indeed. Wall shaking power is on tap at will as the Sub 2 clearly demonstrated with a couple of big time performances on movie night. Obtaining useful extension and output down to the 10Hz range is not out of the question with this subwoofer. Likewise with two channel music there is plenty of headroom to serve up near live output levels. But the kicker is that no matter how hard the Sub 2 is pushed the output is always well controlled and lacking in significant coloration. You are more likely to run into issues with objects vibrating due to the Sub 2’s output in your listening space. That sort of neutrality coupled with lots of headroom goes a long way towards making the foundation of any material sound its best. The Sub 2 simply performed magnificently no matter what I happened to be listening to. One other unanticipated attribute of the Sub 2 that I noticed was that it always started a conversation whenever one of my friends or family would be over and see it for the first time where they would ask what it was or “how does that one sound”? Most of my friends have seen so many speakers come through my house that they barely get a second glance or draw a comment anymore. Not the Sub 2, it invariably received comments and questions. Paradigm’s Signature Sub 2 is undoubtedly one of the most impressively engineered powered subwoofers on the market today. If this fine subwoofer is within your financial means you would be remiss to not give it an audition.

The Paradigm Signature Sub 2 receives the Audioholics Bassaholic Extreme Room rating, which means that this sub is recommended as maintaining adequate headroom in rooms or spaces of 5,000 cubic feet or greater and/or for users who usually listen at high volume levels. For further information in how we make these recommendations see the full article here.

See: Audioholics Subwoofer Room Size Rating Protocol

 

Paradigm Signature Sub 2 Review
Paradigm Electronics Inc.

Paradigm.com
Customer Support: (905)696-2845
MSRP: $8,999

 

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
Fit and Finish
Ergonomics & Usability
Features
Dynamic Range
Performance
Value