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Ready, Set, Go…. Setting up and testing the INFRASUB-12 Pro was straightforward and enjoyable. The unit interfaced smoothly with my existing KRK 8” near field surround and stereo speaker setup, with a useful roll off point at 95hz; 3db down at 80hz. (Bag End makes no specific recommendations for what speakers to use but they DO have their own M6’s available to round out a complete 5.1/stereo system.) After some 20-600hz incremental sine-wave steps and level adjustment of my own listening space (a corner mix area, without parallel walls or major reflections), serious subjective testing began with levels similar to what had already been in place with an old brand-x subwoofer, toggling between the two initially to set overall levels and comfort, then eventually turning off the original subwoofer. The INFRASUB-12 Pro showed an immediate and dramatic change to what many will be used to hearing (or NOT hearing) with some less accurate subs already out there: tighter low end, smoother response (fewer hot spots as well) and a pant-leg rattling trip down to the lowest limits of human feeling…er…hearing. (See Sidebar 1) The low end roll off is selectable for 20 or 8 cycles, and while it’s tempting to want to hear all that “stuff” down there, I left it at 20 for the most part, getting a sense that the 8 cycle roll off was perhaps too much of a good thing for my mix area. Since most subs aren’t always visible or even hidden under the console, there’s a handy power-on indicator and Dynamic Filter active LED in a cute box (See Fig 2) that attaches to an XLR connector/cable. It can sit anywhere; probably on a meter bridge or between monitors to indicate that the unit is indeed on (trust me, you’ll know!) and when the unit may be running into an overload situation with the infrasonic levels below 40hz. This is a great tool alone, good to have when working on the low end of a mix, and deciding how much is too much. Putting it to work….. Having several live projects to mix and prep for broadcast, the INFRASUB-12 Pro went through some serious workouts, with everything from floor-rattling concert bass drum from a performance of Carmina Burana with the Chamber Orchestra of Philadelphia, captured live in the Kimmel Center’s Verizon Hall, to a punchy and low-down and thumpy double bass, from a live jazz date with the Randy Weston Trio, recorded in the same venue’s smaller and more intimate Perelman Theater, all done this past March, 2004. The INFRASUB-12 Pro delivered many surprises with clarity and brutal, unflinching honesty. Mixing down from the multitracks was a chance to re-evaluate and appreciate the value of good mic placement and choices between omni and cardioids. (Suddenly, it DOES make a difference what shows up down below!) Working with today’s high end digital resolution and no-excuse microphones like B&K 4006’s and Neumann KM 84’s, the Pro 12 shed new light on every microphone choice and the smallest amounts of track EQ selection. It was wonderful to roll off non-essential sub-bass from tracks that shouldn’t be adding to the muddle in the first place (soprano solo mics, children’s choir, bell-chimes, etc.) while allowing the full bodied punch of jazz and classical upright bass fiddles, with little or no tweaking. My mix/mastering software (Samplitude 7.2) allows for frequency-based summing to mono in stereo mixes (In most cases, usually everything below 150 Hz), and the INFRASUB-12 Pro served well for this purpose. The entire low end on each above-mentioned project came out tight, controlled, and predictable, with true portability to other listening systems. Our mixes done with the INFRASUB-12 Pro aired within days of the actual recording on our local NPR station, (Temple University. 90.1 FM in Philadelphia) They translated just the way I wanted, on everything I could get my hands on to monitor off the air. Not a bad way to keep one’s reference mixes current, and bass management skills honed! The bottom line….. There is really nothing quite like experiencing smooth overall bass response down to and below 20 cycles, with no slop, delay or smear. I USED to think my existing brand-x sub did a nice job, but it sags badly in comparison to the Bag End INFRASUB system. In revisiting many mixes of my own, there was lots of low end content between 20 and 40 cycles that would have otherwise been missed, perhaps even wasting power and bandwidth in some mixes without ever knowing it. It’s scary to think about what many of us are routinely missing, and what will become embarrassingly obvious as more and more systems like this gain acceptance. After demo’ing a few favorite commercial CD releases on the INFRASUB-12 PRO as well, it’s clear that many out there still mix with way too much kick and low end, thinking oomph makes up for a tighter bass or better mic positioning. There were also plenty of vocal plosives that were probably inaudible during mastering without a good sub, and the Pro 12 showed revealed them oh so wonderfully. There is an alarming difference between genres as well, making one wish for some kind of standard level for most bass low end. (Who wants to change subwoofer levels each time you change a CD?) From classical, jazz and pop, through rock and beyond, the differences in bass levels at the very low end are amazingly disparate. The Bag End Infrasonic Pro series is a very necessary step in the right direction; perhaps even setting a new standard. Anyone who’s serious about mastering and creating portable mixes needs one of these as a reference tool. (Not to mention how much fun they’ll have.) Many thanks to Jim Wischmeyer at Bag End for the technical info, and to Eddie Ciletti for feedback and ideas on subs, mics and tweaks. Additional Specs: The Low Down from Bag End: The INFRA series subwoofers boast a superior time domain performance, as stated by Bag End: The INFRA subwoofer maintains the bass energy in a tight packet, aligned with the upper range signal, providing a seamless musical connection with the main loudspeakers. This is achieved by making the system have a very wide, very flat frequency domain response. The INFRA driver is operated below resonance and flattened with an electrical boosting circuit, the INFRA dual integrator. Below resonance the INFRA system exhibits predictable, uniform response and reproduces each note with the same emphasis, reducing the influence of the resonances found in conventional above resonance bass systems. In addition, the use of a low pass filter is eliminated (and with it the associated long variable delay) and replaced with the INFRA dual integrator and its short uniform delay. The superior transient response of the INFRA subwoofer provides a greater body impact than a conventional subwoofer does, at all listening levels. RESPONSE DOWN TO 8 HERTZ:
While the INFRASUB-12 will reproduce 8 Hz, it is not audible nor does it have enough acoustical power to be felt. To achieve a flat response, full amplifier power is used at the lowest frequencies and very little (<1 watt) in the upper frequency range. The INFRA dual integrator provides the correct signal strength and amplifier power at each frequency. As the frequency is lowered the power and excursion required to maintain a flat acoustical response at high SPL become enormous and not practically attainable for a single driver system. Fortunately the improved phase response, one of the main benefits of an extended subsonic acoustical response, is preserved because the music content is typically not demanding high power subsonic reproduction. |
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BAG END INFRASUB-12 Pro (full review) 5.1 Management Powered Subwoofer System Reviewed by Joe Hannigan Bag End has been making speakers and subwoofers for quite a while now, creating their first sub in 1986 that went down to 30hz, and then an even lower 8hz version in 1990. (And, they were Tolkien-friendly long before it was hip to be a hobbit). |
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The specs: The new Infrasub-12 Pro (the smaller sib of two models: 12 and 18 inch powered subs, with a 21 inch version on the way soon) is a good fit for mid-line mastering/project studios and installations where space is a consideration, with a reasonable amount of power (400 watts continuous sine wave output) to handle all kinds of low end material, down to a user-selectable 20 or 8 hz. There are several improvements with the INFRASUB-12 Pro vs. the “Home” version (both models and complete specs viewable on their website at www.bagend.com). The Pro version allows better bass management than the traditional add-on subwoofer approach (channel .1) by accepting bass frequency content from the five surround speakers in a 5.1 system via balanced XLR inputs (A through E) and routing that mono-summed material to the sub. The passive crossovers then hi-pass the content back on out via another set of five balanced male XLR connectors (-3db@130hz/-6db@95hz). The result is better bass management that’s gaining acceptance by many in the 5.1 mixing community. There’s also a separate sub input (input F) with adjustable gain for systems that have already have LFE material generated, (a home receiver, or dedicated bass management out of the console, etc.) plus a -10 switch for even more flexibility with semi-pro gear. A phase reversal switch is a handy addition for proper alignment with the rest of the mixed signals, and there’s a separate level control for the infrasonic bass level as well. Thermal overload breakers protect the power amp in case of accidents or abuse, should things get REALY out of hand. A detachable power cord and removable black front grille round out the package. |
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What that little red light means….. DYNAMIC FILTER:
The Dynamic Filter circuit dynamically reduces the bass extension to prevent overload. It is inherent in the INFRA design that an overload condition will occur with the lowest notes first, as they require the greatest amount of amplifier power and driver excursion. In an overload condition the Dynamic Filter circuit will reduce the lowest frequencies to their maximum safe level while not affecting the bass content above the frequency that exceeded the threshold. The INFRASUB-12 Dynamic Filter threshold is not user adjustable. It has been factory set to 3 dB below the amplifier overload point. The maximum sine wave output power from the amplifier is 400 watts. With the Dynamic Filter detector engaged, the maximum sine wave output power is 200 watts. The full power of 400 watts or more is reserved and available for short duration impact. The Dynamic Filter is fundamentally different from the commonly used limiter which reduces the level of the entire sub woofer output, and is much more audible, when engaged. It is more natural not to hear the lowest frequencies and still hear the upper bass unaffected, as often there are sounds in nature without low bass content. It is not natural, and very noticeable, when the entire bass range limits to protect itself. When used in moderation the Dynamic Filter is very subtle and conceals very well the fact that it is working. When the system is turned up too far, the low bass is reduced to the point that only the upper bass is heard. If the user requires this much sound pressure, then more amplifiers and speakers are required to achieve the desired level along with the extended low frequency response. |