On Other Ways to Woof…

By Bryan Geyer


JL Audo E-Sub e-110, 53 lbs.

“Hi-fi” is now in its 72nd year, and two channel stereo continues to be the dominant focus of those who enjoy music at home. Since the start, we’ve learned that good sound is best conveyed by utilizing different types of loudspeakers to reproduce select segments of the audible range—e.g., woofers for bass, tweeters for treble, maybe a mid-range driver too. More recently, we’ve also come to acknowledge that really deep bass (20 to 50Hz) might be that “bridge too far” for a traditional woofer. This prevails because the bottom bass is best achieved by using a relatively rigid, conically shaped driver + long, piston-like pumping strokes, whereas the upper bass needs a more compliant and responsive driver to effectively track rapid shifts in the 100 to 600Hz bass band. Big woofers that are tasked to cover both jobs simultaneously tend to sound muddy and sluggish, not “tight”. Or they might roll off, rather rapidly, below 40Hz.* The ideal solution is to gently separate the low bass from the main input by means of an external active (electronic) crossover network**. Start at a logical crossover point, preferably at some frequency that lies between 80Hz and 100Hz, and channel that bass, in progressively increasing doses, to independent self-powered subwoofers. The subs can then blend with the mains to create a uniform, phase-synchronized† wavefront that’s fully consistent with the source signal and capable of flat response to 30Hz before tapering to infrasonic cut-off. A low pass crossover latency of ~ one wavelength will naturally accrue due to the group delay inherent in this processing. The resulting time-of-arrival difference (10 to 12.5msec) falls well within the accepted fusion zone†† interval of ≤ 25msec when the subs and mains are equidistant. Cumulative delay will remain entirely within that boundary until the subs are spaced > 13 feet beyond the listener-to-main speaker radius. (E.g., if the mains are 10 feet away, keep the subs within 23 feet.) In view of this outcome there’s no need to consider digitally generated corrective timing (e.g., Mini-DSP, DEQX, et al), as any reasonable positioning of the subs will assure that net latency remains inaudible and within the verified fusion limit. Keep this purely analog stage exclusively analog!

Do verify (preferably by measurement) that the subs/mains are accurately phase-correlated, and that they are optimally balanced per the footnote† herein. Also confirm that both subs are placed inside the cited positioning radius. Minimize the allowed spacing when decor constraints permit. Just be aware that you have up to 13 feet available, free of significant performance compromise, if your preferred layout requires such separation.

External xover bypassed

This latter speaker system setup, wherein a pair of self-powered subwoofers handle the low bass while separate stereo main speakers handle the rest, can also yield other benefits. Consider…

Acoustics: The use of paired subwoofers can appreciably improve the overall room acoustics. Two subs, positioned in the front corners and flanked outside the mains, will propel a widely unified bass wavefront that’s approximately opposite in phase to the reflected back wall rebound. This will result in partial cancellation of that resonance, and it will mitigate the disruptive low frequency peaks/nulls that inevitably develop in home listening rooms. Improved clarity will result. Absorbent room treatment materials can also be of significant benefit, but the extra thick*† anechoic pads required to swallow low frequency reflections generally confines such stuff to man-cave environs.

Convenience: Big floor-standing full-range loudspeakers are not the sole solution anymore. Paired (or more) subwoofers, plus modest-sized mains, will present lots of layout freedom. Stand mounting the mains and spacing them several feet from the front wall will generally prove best, but a shelf mount†* is certainly feasible with a sealed enclosure; also with vented models if a port plug is utilized. (The plug will further benefit phase sync tuning.) Smaller main speakers are a lot easier to position (and live with) than big, dominant floor-standers, and subs like those in the JL Audio “E-Sub” series are easy to hide away in the front corners. You’ll like your options.

Bryan Geyer (April 16, 2020)

*There are very few full-range floor-standing loudspeaker systems with woofers that are able to match the performance of a good subwoofer at frequencies from 20Hz to 50Hz. Nearly all of the floor-standers sag from 40Hz down, which is not surprising, given the fact that they’re also expected to reach 600Hz to 1kHz or more. Conversely, good subs are intended purely for 20Hz to 100Hz bass, a demanding but restricted niche that they’re specifically designed to serve—and where they commonly excel.

**Refer “Optimizing Subwoofer Integration, Part 1”, at https://classicalcandor.blogspot.com/2019/02/optimizing-subwoofer-integration-part-1.html.

†Refer “On Optimizing Subwoofer Integration, Part 2”, at https://classicalcandor.blogspot.com/2019/03/optimizing-subwoofer-integration-part-2.html. This procedure details how to precisely (by measured means, with visual veracity) adjust the subwoofer’s input gain and phase angle controls to assure synchronous phase and optimal amplitude of the output at the prime listening position, at a designated crossover frequency. Both such adjustments are present on better subwoofers. (Lesser subs might substitute a simple 0˚-180˚ polarity inversion switch instead of fully variable phase angle adjustment, and that’s not acceptable. You’ll need a continuously variable 0˚ to 280˚ [as referred to 80Hz] control to assure optimal sub-to-mains phase sync.)

††The term “fusion zone” defines the accepted latency interval during which separate sounds (of near-equal amplitude) arrive close enough together to be perceived as the same sound. (Refer fusion zone, section 7.6.4 of Floyd Toole’s Sound Reproduction, 3rd edition [Routledge, 2018, ISBN 978-1-138-92136-8]). Note that this duration (cited therein as 30msec) is actually based on speech, which is regarded as a distinctly more stringent criteria than for music. Similar tests performed using Mozart compositions indicate that the fusion interval for music probably extends to 50msec or more (refer p.211-212 of Toole’s text). In this paper, I apply a maximum limit of 25msec (1/40th of a second) as the cited fusion zone interval; that’s quite conservative.

*†Absorbent padding will have to be ≥ 4 inches thick to have any appreciable effect in the lower bass region. Large drum-type “bass trap” canisters are also appropriate for managing low bass resonances, but their size and appearance is not compatible with most LR decor.

†*Shelf mounting of the main speakers against the front wall becomes somewhat more acceptable when they’re coupled with subwoofers because the most pervasive (most spherically propagated) lower bass frequencies have already been channeled to the subs. Setting a relatively high crossover point, i.e., 90 to 100Hz, can also help, but do verify that your subs are capable of relatively flat output to ~ 130Hz; some subs droop abruptly beyond 100Hz.


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Meet the Staff

Meet the Staff
John J. Puccio, Editor, Publisher, Reviewer

Understand, I'm just an everyday guy reacting to something I love. And I've been doing it for a very long time, my appreciation for classical music starting with the musical excerpts on The Big John and Sparkie radio show in the early Fifties and the purchase of my first recording, The 101 Strings Play the Classics, around 1956. In the late Sixties I began teaching high school English and Film Studies as well as becoming interested in hi-fi, my audio ambitions graduating me from a pair of AR-3 speakers to the Fulton J's recommended by The Stereophile's J. Gordon Holt. In the early Seventies, I began writing for a number of audio magazines, including Audio Excellence, Audio Forum, The Boston Audio Society Speaker, The American Record Guide, and from 1976 until 2008, The $ensible Sound, for which I served as Classical Music Editor.

Today, I'm retired from teaching and use a pair of bi-amped VMPS RM40s loudspeakers for my listening. In addition to writing the Classical Candor blog, I served as the Movie Review Editor for the Web site Movie Metropolis (formerly DVDTown) from 1997-2013. Music and movies. Life couldn't be better.
Karl W. Nehring, Contributing Reviewer

For more than 20 years I was the editor of The $ensible Sound magazine and a regular contributor to its classical review pages. I would not presume to present myself as some sort of expert on music, but I have a deep love for and appreciation of many types of music, "classical" especially, and have listened to thousands of recordings over the years, many of which still line the walls of my listening room (and occasionally spill onto the furniture and floor, much to the chagrin of my long-suffering wife). I have always taken the approach as a reviewer that what I am trying to do is simply to point out to readers that I have come across a recording that I have found of interest, a recording that I think they might appreciate my having pointed out to them. I suppose that sounds a bit simpleminded, but I know I appreciate reading reviews by others that do the same for me -- point out recordings that I think I might enjoy.

For readers who might be wondering about what kind of system I am using to do my listening, I should probably point out that I do a LOT of music listening and employ a variety of means to do so in a variety of environments, as I would imagine many music lovers also do. Starting at the more grandiose end of the scale, the system in which I do my most serious listening comprises an Arcam CDS50 CSD/SACD CD player, Goldpoint SA4 Passive Preamp, Legacy Audio PowerBloc2 amplifier, and a pair of Legacy Audio Focus SE loudspeakers. I also do a lot of listening while driving in my 2016 Acura RDX with its nice-sounding ELS Studio sound system through which I play CDs (the ones I especially like I rip to the Acura's hard drive so that I can listen to them whenever I want) or stream music through the system using my cell phone. For more casual listening at home when I am not in my listening room, I often stream music through the phone into a Vizio soundbar system that has remarkably nice sound for such a diminutive physical presence. And finally, at the least grandiose end of the scale, I have an Ultimate Ears Wonderboom Bluetooth speaker for those occasions where I am somewhere by myself without a sound system but in desperate need of a musical fix. I just can't imagine life without music and I am humbly grateful for the technology that enables us to enjoy it in so many wonderful ways.
Bryan Geyer, Technical Analyst

I initially embraced classical music in 1954 when I mistuned my car radio and heard the Heifetz recording of Mendelssohn's Violin Concerto. That inspired me to board the new "hi-fi" DIY bandwagon. In 1957 I joined one of the pioneer semiconductor makers and spent the next 32 years marketing transistors and microcircuits to military contractors. Home audio DIY projects remained a personal passion until 1989 when we created our own new photography equipment company. I later (2012) revived my interest in two channel audio when we "downsized" our life and determined that mini-monitors + paired subwoofers were a great way to mate fine music with the space constraints of condo living.

Visitors that view my technical papers on this site may wonder why they appear here, rather than on a site that features audio equipment reviews. My reason is that I tried the latter, and prefer to publish for people who actually want to listen to music; not to equipment. My focus is in describing what's technically beneficial to assure that the sound of the system will accurately replicate the source input signal (i. e. exhibit high accuracy) without inordinate cost and complexity. Conversely, most of the audiophiles of today strive to achieve sound that's euphonic, i.e. be personally satisfying. In essence, audiophiles seek sound that's consistent with their desire; the music is simply a test signal.

William (Bill) Heck, Contributing Reviewer

Among my early childhood memories are those of listening to my mother playing records (some even 78 rpm ones!) of both classical music and jazz tunes. I suppose that her love of music was transmitted genetically, and my interest was sustained by years of playing in rock bands – until I realized that this was no way to make a living. The interest in classical music was rekindled in grad school when the university FM station serving as background music for studying happened to play the Brahms First Symphony. As the work came to an end, it struck me forcibly that this was the most beautiful thing I had ever heard, and from that point on, I never looked back. This revelation was to the detriment of my studies, as I subsequently spent way too much time simply listening, but music has remained a significant part of my life. These days, although I still can tell a trumpet from a bassoon and a quarter note from a treble clef, I have to admit that I remain a nonexpert. But I do love music in general and classical music in particular, and I enjoy sharing both information and opinions about it.

The audiophile bug bit about the same time that I returned to that classical music. I’ve gone through plenty of equipment, brands from Audio Research to Yamaha, and the best of it has opened new audio insights. Along the way, I reviewed components, and occasionally recordings, for The $ensible Sound magazine. Recently I’ve rebuilt--I prefer to say reinvigorated--my audio system, with a Sangean FM HD tuner and (for the moment) an ancient Toshiba multi-format disk player serving as a transport, both feeding a NAD C 658 streaming preamp/DAC, which in turn connects to a Legacy Powerbloc2 amplifier driving my trusty Waveform Mach Solo speakers, supplemented by a Hsu Research ULS 15 Mk II subwoofer.

Mission Statement

It is the goal of Classical Candor to promote the enjoyment of classical music. Other forms of music come and go--minuets, waltzes, ragtime, blues, jazz, bebop, country-western, rock-'n'-roll, heavy metal, rap, and the rest--but classical music has been around for hundreds of years and will continue to be around for hundreds more. It's no accident that every major city in the world has one or more symphony orchestras.

When I was young, I heard it said that only intellectuals could appreciate classical music, that it required dedicated concentration to appreciate. Nonsense. I'm no intellectual, and I've always loved classical music. Anyone who's ever seen and enjoyed Disney's Fantasia or a Looney Tunes cartoon playing Rossini's William Tell Overture or Liszt's Hungarian Rhapsody No. 2 can attest to the power and joy of classical music, and that's just about everybody.

So, if Classical Candor can expand one's awareness of classical music and bring more joy to one's life, more power to it. It's done its job. --John J. Puccio

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Readers with polite, courteous, helpful letters may send them to classicalcandor@gmail.com

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"Their Master's Voice" by Michael Sowa

"Their Master's Voice" by Michael Sowa