SVS PB12-Plus DSP Subwoofer Introduction

THE SVS PB12-Plus DSP is a self-powered front-loaded vented subwoofer featuring a proprietary 12" long throw driver and 800 watt amplifier with single knob DSP implemented control over filtering, equalization and compression functions. Weighing in at 125lbs+ and costing slightly under $1400, it's no lightweight, and requires more than a little bit of real estate.  From its ungodly output capabilities, true 20Hz extension, and ability to play clean and distortion free, the PB12-Plus DSP has truly earned the right to be called a "subwoofer". 

Read our review to understand why this product earned the Audioholics coveted 2010 Product of the Year award in the subwoofer category.

Product Overview

According to SV Sound, the PB12-Plus DSP was designed with the following features and engineering philosophy: “flat, deep, clean, linear, and dynamic”. It is a vented bass reflex design (with Sealed mode available) with sufficient cabinet volume for maximally flat alignment without resorting to excessive EQ boost. The large cabinet volume also improves sensitivity and deep bass efficiency, thus reducing amplifier power requirements. The PB12-Plus DSP employs triple ports with high cross-sectional area for reduced chuffing to help lower both distortion and port air-flow compression. Variable tuning with 20 Hz/16 Hz/Sealed modes is present to satisfy a wide range of room sizes and applications.  The 800 watt (continuous power rating) DSP controlled amplifier has a single feature controller with digital read-out for all subwoofer functions for enhanced ease-of-use and utility. The DSP power/compressor/limiter settings are designed to control audible overdrive artifacts above Fb in each bass reflex tuning mode. 

To elaborate more on the tuning modes; the 20 Hz mode is maximally flat while the16 Hz mode is slightly overdamped, which complements available room gain in a mid-size room. (Meaning composite power response of sub and mid-sized room are essentially flat). The sealed mode features a 2nd order roll-off and no HPF within the pass band for enhanced transient response and excellent coupling with room gain in smaller rooms. 

The 12” high performance, long-stroke, FEA-optimized woofer is designed for high output and low distortion. Suspension geometry and VC length prevents bottoming of VC against the back-plate. 

The PB12P Plus DSP subwoofer is designed to pass CEA-2010 at max drive levels at all test frequencies (20 – 63 Hz) within intended pass-band in both bass reflex tuning modes.  This sub is designed for high bandwidth linearity with respect to distortion-limited output to ensure excellent clean output capability in the 16-32 Hz octave where most subwoofers traditionally struggle. 

The Driver (Subwoofer)

Many many years ago when we first started using Santoprene in the speaker business as a surround material, we had a great many problems in reliably gluing it to the cones.  Foams, or cloths were never a problem, but rubber or Santoprene (a mixture of rubber and polypropylene) was another story.  The first time I had seen it stitched to the cone, I had one of those Homer Simpson like “DOOH”, why didn't I think of that moments.  Turns out that the nice thing about stitching the surround to the cone, while really expensive, is that it is the best possible way to guarantee the edge will NEVER tear free of separate from the cone.  That might not sound important unless you have actually been in the room when it happened to a speaker you owned.  Now not having taken apart the driver or been inside the factory to get a look at the assembly process, I can't speak to all aspects of the driver construction and quality.  What I can tell you is this much.  Anybody who goes to this extreme to prevent a glue bond failure is not going to be taking any shortcuts in making the best driver they know how to.

The Amplifier

While I have no bones with the amplifier performance, I did get a little frustrated trying to operate the amplifier with only one knob, which handles several functions.  This is not an uncommon approach with DSP, as all the settings are software based, not hardware based, so you do not turn a potentiometer (volume control) to reach the value, you simply dial in the number and the software does the calculation.  Just tell it what function to do, and then select the value.  While ALL the other amplifiers used had dedicated knobs for each function, being software controlled the SVS amp required you to tap the single control knob like a mouse (twice fast) for it to go between functions.  At first I found it frustrating.  Frankly, I don't care for having to guess what the programmer wanted to do, and I am not one of those folks who can pick up an Iphone and just start using it.  Everyone else at Audioholics thinks I am not too hip, and they may be right.  SV Sound has an online PDF format manual for those wanting to find out about using the products, so I guess I am complaining for being old and lazy. Seeing as how I have been around subwoofers for 20 plus years, I have no patience for these kind of ergonomics.  I am old school and I want a knob for every function!  I guess I will have to cope.

If you are comfortable with this kind of control, you will not find any issues with the parts efficient and completely digital SVS approach.  In all, it took me about 4-5 minutes of playing around to get it, and that is without cracking the manual open.  If you read through it, it should be very easy to set up.  An advantage of the SVS approach is that their amplifier has a user selectable low pass filter with adjustable frequency and slope (12 or 24dB per octave) at the touch of the button.  The amplifier also has a high pass filter for the line level outputs with the same frequency and slope selections as the low pass filter.  This will allow the user to implement a true crossover (for both frequency and slope) between the satellite speakers and the subwoofer for 2-channel applications.  The amplifier also includes a digital delay on the line level outputs to compensate for the latency of an external subwoofer equalizer, so that the subwoofer and the speakers can be time-aligned in 2-channel applications.  These aren't features any of the other amps could boast about in our subwoofer shootout comparison. 

My listening tests were performed at 24dB per octave low pass filter (LPF) settings.  I find when you use a high cutoff frequency for the sub, it is necessary and advisable to use the higher roll-off rates. Those who will complain about the phase issues resulting from higher order filters have not spent much time measuring phase with a microphone.  In truth the phase issues of having the subwoofer a large distance apart from the main front left and right speakers far outweigh the issue of phase shift and time delay caused by the electronic filters used.  While the higher roll-off rates in filters may come with some small artifacts, they offer the benefit of having less overlap and therefore reduce the chance of out of phase acoustical behavior between the subwoofer and satellite speakers.  That problematic band where both the satellites (or main speakers) and the subwoofer(s) overlap is called (in filter speak) the transition band.  Having built and measured hundreds if not thousands of crossovers, my feeling is minimize the overlap, and to hell with the electronic delay.  Since most of the sound reaching your ears has bounced off several surfaces on its way to your ear, our ear-brain mechanism is accustomed to integrating the sounds that reach it over tens of milliseconds. First order filters can claim perfect transient behavior and time domain addition, but few systems are built to avoid the problems that first order (6dB/octave) filters create.  We recommend bypassing the LPF of the PB12-Plus DSP in favor of the LPF in your A/V receiver/processor.  If your A/V receiver doesn't have  a 24dB/octave LPF filter, then use the SV Sound LPF filter instead.

For those of you new to bass management systems, Gene Dellasala has written some excellent articles on this topic, which can be found here:

Hometheater Multiple Subwoofer & Setup Guide

Bass Management Basics - Settings Made Simple

Basic Subwoofer Setup Guide Not for Dummies