Introduction

In today’s economy, good value in audio is more important than ever. To that end SVSound (SVS) has created a line of subwoofers that address every possible need in home theater and music listening without breaking the budget. I recently spent some quality time with their big box model, the PB12-Plus. This superbly-built sub includes quality amplification, a sweet-sounding 12-inch driver and plenty of adjustability. I would venture to say that most bass issues can be resolved with the PB12’s tuning and EQ controls.

The component that most affects the “feel” of your home theater and music listening experience is the subwoofer. To this end SVSound (SVS) has created a line of subs that addresses every need. If you want volume, they can do that. If you want a sub that plays low, they can do that. If you want a sub that doesn’t take up too much room, they can do that too. The subject of this review, the PB12-Plus is definitely not the latter! This 12-inch box model is one of the largest and heaviest subs I’ve ever seen! Fortunately its price is not large. After spending some quality time with this beautifully made product, I found the price/performance ratio to be quite favorable.

Many subs will play loud and low but not many will do so with control and finesse. Once sound becomes non-directional, precision and clarity are what separate average subs from exceptional ones. Not only does the build quality affect this but adjustability does too. Most subs don’t have the necessary controls to solve standing wave issues which cause peaks and nulls in the frequency response. You are left to adjust your room by adding bass traps or moving the sub to different locations. SVS has overcome this challenge by including controls for parametric EQ and a slick tunable port system with corresponding subsonic filters.

Design and Build Quality

My review unit arrived via freight strapped to a pallet. This is one big sub and heavy too. The ship weight was over 150 pounds! The packing quality was exemplary. The carton had nary a scratch on it. Unpacking revealed dense, flexible foam and a cloth bag to protect the sub’s high-quality finish. One word of warning; this sucker is slippery! I strongly suggest moving the sub on the included pallet. I could not get a good grip otherwise. The side panels are very smooth and the cloth bag is no help. After a strong friend helped me up two flights of stairs to my theater, I was ready to dive in.

Did I mention this sub was big? After placing it in my usual position between the left main and center channel speakers I stepped back. This thing really dominates the room! Granted, my room is small but the front of the cabinet extended out further than the front of my left tower speaker. The sides are finished in a wood veneer that SVS calls Rosenut, a medium red color. They also offer a lighter Oak color and Piano Gloss Black. No matter what the finish, the front and top of the cabinet are a textured black. It’s a high-quality finish that does not pick up reflections in a darkened theater room. The wood sides transition to the textured black with a gentle curve and a perfect seam. This is one fine cabinet that puts many more-expensive subs to shame. It’s also one of the most solid subs I’ve encountered. Rapping on the sides or top you can barely tell the box is hollow! Construction is 1-inch MDF all around with 1½-inch for the front baffle. The feet consist of six removable rubber cones. They work equally well on carpet or hard floors. They can also be swapped out for alternative feet or spikes without creating any air leaks in the cabinet.

The 12-inch driver is designed and made by SVS. The cone is a fiberglass composite which is sewn and glued to a large rubber surround. The SVS logo is silk-screened in the center. The sub looks good with the grill off but I put it on for all my tests. The curved and perforated grill is quite substantial. It’s all metal with and attaches with strong magnets. There was absolutely no rattling at any time. This is the best magnetic grill I have yet seen. Below the driver are three flared ports. By default, they are open but three foam port plugs are included to block one or all of them for different tunings; more on this later.

At the rear is a 525-watt BASH amplifier. This is a high-quality amp and was designed exclusively for SVS. Inputs and outputs include left and right RCA and speaker-level binding posts. There are no XLR jacks. As I said earlier, the controls are extensive. In addition to Gain, there are infinitely variable Crossover and Phase dials. The crossover can be disabled with a switch. There is also an Auto/On switch. Set to Auto, the sub turns on whenever a signal is detected. It will stay on for several minutes if the signal stops. I used the Auto mode and the sub never shut down during any of my listening. If you want to leave the sub on 24/7, you can use the On mode. The other controls are for the Subsonic Filter and Parametric EQ features. I’ll discuss them in the next section.

Setup

Subwoofer Operating Modes

There are three choices here: 20 Hz tuning with all ports open, 16 Hz with one port blocked, and Sealed with all ports blocked. There is also a 25 Hz setting on the amp, which can also be used with all ports open, and simply starts to filter the response a bit higher in the pass band to help compensate for smaller rooms which exhibit excessive amounts of low-end gain. I measured the 20, 16 and Sealed tunings for comparison. The graph below (fig. 1) shows the effects. This is the raw subwoofer response before any EQ or low pass filtering from the AV receiver. The effects of the three tunings can clearly be seen. Sealed mode rolls off smoothly at 40Hz, 16Hz mode stays relatively flat to 16Hz and 20Hz rolls off a bit more sharply at 20Hz.

Red Trace – Sealed
Blue Trace – 16Hz one port blocked
Green Trace – 20Hz no ports blocked
These are raw measurements with the test tones sent directly
to the sub and measured from the listening position.

Parametric Equalizer Control

I wanted to see the effects of the parametric EQ so I did some additional measurements. The three controls are Frequency (20-80Hz), Level and Q. Frequency controls the center point of the frequency range you want to adjust, Level controls the amount of cut, and Q controls the width of the change on either side of the target frequency. Like most PEQ controls, the level control is cut-only, as boosting nulls is never recommended and can result in subwoofer overload and amplifier damage. As the term literally implies, the higher Q setting produces a narrower control bandwidth (Low = wide, High = narrow). Once you understand the terminology, it’s easy to tame frequency response peaks.

In order to use the PEQ control effectively, you will need to plot the frequency response of the subwoofer. You will have to use an SPL meter and discrete test tones (supplied by SVS or available from other on-line sources). An even better choice is Room EQ Wizard. This free software is available from the Home Theater Shack website (www.hometheatershack.com). With a soundcard equipped laptop and a Radio Shack SPL meter, you can graph your room response with reasonable accuracy and see exactly what your sub is doing.

One thing that makes using this control tricky is the Frequency dial is not marked with any numbers between 20 and 80Hz (12 o’clock is 50Hz). This makes zeroing in on the target frequency a trial-and-error affair. When you’re trying to tame a room peak, it may take several measurements before you achieve the right combination of settings. It also would be nice if there were more than one band available. Still, having this level of flexibility at this price point really sets the PB12-Plus apart from the competition.

Since my room response was decent to begin with I simply changed the controls in order to illustrate the different response curve (fig. 2).

The red trace shows the uncorrected response. The blue trace shows the effect of setting the Frequency to around 30Hz, the Level to max and the Q to low. The green trace shows the Q set to high. Notice the difference in the bandwidth of the correction.

In-Room Equalized Measurements

Since I have Audyssey MultiEQ XT available in my Onkyo TX-805 receiver, I wanted to see what effect it would have on the sub’s in-room frequency response. On the SVS, I disabled the PEQ control, set the subwoofer gain at the half-way point, disabled the low pass filter, and then ran the Audyssey setup for each operating mode in my usual six measurement positions. After completing the auto-setup I changed the main speaker size to small and set the crossover to 80Hz. The sub was measured with the mains disconnected. The results were quite nice as you can see from the below graphs. Red traces are with Audyssey on, blue traces are uncorrected.

In Use

This is a lot of sub for my relatively small theater, so I thought it best to throttle things back a bit at the beginning, and I started with Sealed mode. I blocked all three ports with the included plugs and turned the subsonic filter dial to the Sealed setting. All listening was done in this mode with one exception noted below.

Eagle Eye (Blu-ray, Dolby TrueHD)
This action thriller is a series of high-adrenaline chase scenes woven into an interesting plot about cyber-terrorism and artificial intelligence; loads of fun. The musical score is of very high quality with impressive depth and a wide soundstage. The PB12-Plus really expanded the musical dynamics of the score providing extra impact to low strings, percussion, timpani notes and brass sounds. Sound effects took on an equally expansive quality. The sound of a helicopter’s beating blades was especially powerful. During one scene our heroes are driving a Porsche Cayenne SUV through city streets. The crescendo of its V8 engine had all the thunderous effect of a NASCAR racer.

Dark Knight (Blu-ray, Dolby TrueHD)
This film has a very strong LFE track. The sub is used heavily in pretty much every scene that doesn’t have dialog. Car crashes, explosions, gunfire, you name it. It all came across loud and clear. I could feel every tremor coming through the back of my heavily upholstered chair. It was like having a motion simulator! I couldn’t believe the sub was operating in sealed mode. There was no apparent lower limit and every sound effect was rendered with the utmost precision. The only way it could have sounded any better is if my room were larger. This sub wouldn’t break a sweat in a room twice the size.

Since this title made the most use of LFE of my selections, I went back and listened to several scenes using the sub’s 20Hz all ports open tuning. The net result was a huge increase in the lowest frequencies but a slight loss of detail. I believe this to be purely a function of my room and not the sub. There just wasn’t enough space for the sub to breath in this mode. The lower frequencies were very loud and clean but the precision I enjoyed in the sealed mode just wasn’t there. I would recommend this mode for larger rooms.

Philadelphia Orchestra, works for organ and orchestra (Super Audio CD)
This superb recording was made recently to inaugurate the new organ in Philadelphia’s Verizon Hall, the home of the Philadelphia Orchestra. The album includes pieces by Samuel Barber, Francis Poulenc and Camille Saint-Saëns. To test the subs ability to blend with my Axiom speakers, I set all the crossovers to 80Hz. As with the Blu-ray selections, this really opened up the soundstage nicely. The hall ambience could really be heard and felt. The organ’s pedal tones had amazing depth and clarity and were truly enveloping. At no point was the sub stressed producing the organ’s lowest notes. The fast-moving passages were also rendered with excellent detail and accuracy. The timpani and low brass sections of the orchestra benefited too. It really brought those instruments forward during the louder parts.

Jazz Knights, At First Light (CD)
This recording was made by colleagues of mine and as such, I have a unique perspective as I have heard this excellent big band play live many times. The Jazz Knights are made up of some of the best young jazz musicians of today and the quality of this CD is right in line with their excellent performance. I tried several different crossover configurations to put more or less bass into the sub. No matter what, the PB12-Plus blended seamlessly with my mains. The string bass had just the right sound being neither too bloated nor too meek. Drum hits were equally crisp and balanced. This sub really captured the detail present in this high-quality recording. This sub would be a great match for smaller main speakers because of its ability to blend well and render the area between 60 and 120Hz with such precision.

Conclusions

The SVS PB12-Plus is truly a chameleon among subwoofers. It can play loud; it can play soft and everywhere in between. It can play as well up high as it does down low, a quality many subs lack. Its multiple port tunings and parametric EQ mean it can work well in any room with any speaker system. Its build quality is on par with the most expensive products available and it looks great too. I’d have to say SVS has hit this one out of the park.

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