Innovations: Genelec W371A Adaptive Woofer System

As the world of audio production continues to evolve, with work happening in increasingly smaller spaces, the Genelec W371A Adaptive Woofer System takes a new direction in offering close- and midfield high-SPL, high-accuracy monitoring. The goal is to offer large main-monitor performance in a freestanding package.

The W371A serves as a lower-frequency monitor extension system for Genelec’s The Ones coaxial Smart Active Series of monitoring products. It shouldn’t be thought of as just a subwoofer, although part of its function is to in fact reproduce lower frequencies down to 20 Hz. However, because it features two LF drivers capable of reproducing their own bandpasses, the W371A turns the three-way Ones monitor into a five-way playback system. It connects in a one-to-one arrangement with the monitor it is paired to. As a result, two W371As are required for stereo and three would be needed for an L-C-R arrangement.

When considering LF reproduction in smaller spaces, we often see a multitude of challenges in obtaining linear frequency responses. Over the years, Genelec has visited hundreds of control rooms and performed room calibrations. Observations revealed that even after calibration, notches in the frequency responses were prevalent below 1 kHz, with the strongest notching occurring below 250 Hz.

In looking at the cutaway picture of the W371, we see an upper front-firing 14-inch driver and a 12-inch lower rear-firing driver. Note that the upper driver sits in a sealed enclosure, while the lower driver is ported. It is important to remember that any driver will yield a differing frequency response depending on its location in the room. The fact that the W371 has multiple drivers, operating either independently or in unison in different locations, adds tremendous value in obtaining as linear a response as possible.

The bullet list below defines the primary uses of each driver.

Lower rear driver:

• 12-inch unit handles lowest frequencies, making use of room gain due to closer proximity to boundaries
• Vented to avoid excessive driver excursion/distortion and higher amplifier requirements
• High displacement capability

Upper front driver:

• 14-inch unit can provide enough volume displacement alone (no real need for port)
• Sealed solution provides cleaner phase response—easier for directivity optimization
• Easier to produce cleaner output at higher frequencies

The W371A is part of the Genelec’s Smart Active Monitoring (SAM) lineup, which means it contains a core DSP module that facilitates all filtering, crossover, level and phase coherency in order to properly integrate to the room and seamlessly match itself to the monitor paired to it. The Genelec Loudspeaker Manager (GLM) gives the user the control bits to oversee the tasks, review the results, and give options for further adjustments. Each driver in the W371A has a 400W Genelec-designed Class D amplifier connected to it. Analog and Digital AES inputs and outputs are also incorporated into a rear-mounted amp panel, along with the power and Cat 5 for GLM control.

Among the many powerful attributes of the W371 are the five different calibration modes. Each offers a different calibration algorithm and should be objectively and subjectively evaluated in many and varied types of listening environments, be it a music studio, mastering suite, production suite or high-end stereo playback in the home. GLM allows for easy control and measurements, as well as quick recall of each.

The Complementary Mode makes use of each driver independently. Each driver is independently swept and calibrated and linearized, with the crossover between the lower and upper drivers automatically determined by the algorithm. The user is given a range selection when assigning a crossover point to the main monitor as high as 300 Hz. This mode effectively makes the Woofer Stand system a five-way system.

In Continuous Directivity Mode, both drivers are swept at the same time, with timing and phase relationships determining the directivity match and crossover assignment to the main monitor on top of it.

Each of the Back Wall, Side, and Floor Reflection Reduction Modes assigns unique filters for each algorithm to reduce the first order reflection by up to 12 dB. Both drivers are swept at the same time, and the user can select the Lowpass/Highpass crossover filter range to the main monitor much like in the Complementary mode.

GLM Woofer Stand Calibration

The actual calibration process is divided into two parts. First, the main monitor on each stand is calibrated. Due to GLM’s flexibility, we suggest the user first make a Group of the just the main monitors. He or she can then duplicate the Group and then add in the Woofer Stands. Either way, once the main monitor is calibrated, the calibration values are automatically stored into them and used as a reference for the actual Woofer Calibration.

The user then selects the mode of operation as well as selecting the crossover range to the main monitors. Then, by double-clicking the microphone icon, the second part of the calibration sweeps are emitted from the upper woofer, the lower woofer (for Complementary and in unison for the other modes) and the previous calibrated or duplicated main monitor. The process continues for the second channel. Calculation times vary depending on computer platform, but typically run around 1.5 minutes per channel.

These screen shots show the frequency response as well as level and time of flight for one W371 with an 8351B SAM Studio Monitor paired to it. Frequencies below 200 Hz are graphed with 1/12th octave weighting and above 200 Hz 1/6th octave weighting. Contained in each channel’s system info is the name of the device, the firmware revision, the model it is paired with, the Calibration Mode, the selected crossover frequency, the objective system flatness and the correlation to the other channel. (Figure 2)

After calibration, the user has additional filters to subjectively alter the EQ LF/HF balance between the Woofer Stand and the paired monitor, as well as four additional notch filters to customize further. (Figure 3)

The W371A Adaptive Woofer System is a truly unique product, designed specifically to seamlessly complement Genelec’s 8341, 8351 and 8361 monitors and, in conjunction with these models, create a series of full-range monitoring solutions with unrivaled neutrality and supreme levels of control over directivity and the effects of room acoustics. For the first time ever, studios can experience all the benefits of a large main monitor, but with the freedom to locate this freestanding system in optimal positions within the control room, even providing the option to switch between nearfield and main monitors without image shifting.

Genelec • www.genelec.com