Selected Equipment Reports

The Von Schweikert Research VR-4 Loudspeaker, The Klipsch KLF 20 Tower Series(tm) Loudspeaker & 300B Triode - Audio Electronics SE Tube Amplification

After seeing all the rave reviews for the Von Schweikert VR4 on the Internet recently, the Atlanta Audio Society invited Mr. Von Schweikert to present a program for us on Feb. 16, 1997. He accepted our offer and informed me that he was going to discuss crossover and driver design and give some practical examples of each as well as demonstrate the VR4 speaker. His presentation turned out to be very educational indeed, and changed my thinking about some key areas of speaker design (namely, the importance of time-aligned drivers and phase correct crossovers).

Von Schweikert discussed driver and crossover design as well as the importance of time alignment, phase correct crossovers and the importance of having consistent phase and amplitude on and off axis. One of his practical demonstrations was a small 2 way minimal baffle speaker with a sliding tweeter on a small box with a 5" midrange driver. He compared the sound with the tweeter flush with the front baffle; and then with the tweeters voice coil aligned with the midrange voice coil. The difference with pink noise was clearly audible. With the tweeter flush with the baffle the sound was brighter, with the highs more accentuated. He then demonstrated a 20 year old, small 3 way box speaker with phase correct 1st order crossovers. Of course with only 6 db per octave slopes, the drivers all overlapped considerably. To show how much overlap was occurring, he turned off 2 of the drivers with an outboard control box, and we heard what the remaining driver sounded like with J. Gordon Holt's voice. With the bass and midrange drivers turned off, it was amazing to all of us how much midrange information the tweeter picked up; Holt's voice was clearly identifiable, though rather high pitched and nasal sounding. With just the bass driver playing, his voice assumed a very resonant, chesty sound. Finally, the midrange driver alone was the most natural sounding of all with Holt's voice. After hearing this demonstration, it's a wonder to me why anyone would use 1st order crossovers, which cause severe overlap of the drivers which in turn, colors the sound. Then, to demonstrate the superiority of his own designed from scratch 5 1/4" woven carbon fiber midrange driver, he used it and several other high quality midrange drivers "in reverse" so to speak. He used them as microphones to pick up Dave Kersh's voice, with the idea that the transducer with the least coloration would also sound least colored used as a microphone, to pick up and transmit sound waves. It was very enlightening to hear the differences; one of the drivers sounded chesty and resonant, another bright and peaky, yet another seemed muffled. Vons Schweikert's proprietary midrange driver had the least colored sound. No off the shelf driver here; Von Schweikert has over 20 years of experience designing drivers and he designed the midrange driver from the ground up. A woven carbon fiber cone, a norsorex (actually sorbothane) surround, a specially designed voice coil and spider assembly, etc., all contribute to a very clean, very dynamic midrange driver. In fact, the dynamics and sound pressure capability of the VR4 was pretty amazing for reasonably sized speaker. The tweeter is an aluminum dome with a special rubber damping layer, to damp amusical vibrations. It produced very clean, extended highs without a bit of harshness or edge.

After the program, I asked Von Schweikert why so many speaker designers disdain time aligned drivers and phase correct (though not 1st order) crossovers. Apparently, there is substantial academic research that says time aligned drivers and phase correct crossovers are not audible with music. Von Schweikert said these studies were not complete and didn't go far enough. His own research shows that they are very important indeed. Apparently, Von Schweikert has been able to achieve a phase correct crossover without the deleterious effects of simple 1st order slopes, by cascading 1st order slopes. This approach gives steep rolloff characteristics, while preserving the phase integrity, and is an important part of the GAIN system. Of course, the midrange and tweeter in the VR4 are time-aligned, with a minimum baffle enclosure which gives a very widely dispersed sound field with correct amplitude and phase off axis as well as on.

The bottom line conclusion-? I'm no engineer, and the only way I can judge a speaker is by the sound itself; and the sound was sensational. A huge, deep, airy soundstage with pinpoint imaging and very wide dispersion. One could sit well off axis and still get a full coherent soundstage. Albert played 6 or so of his reference CDs, all of which showed off a particular aspect of the VR4. A recording of traditional Japanese instruments on Mapleshade showed how encredibly precise the imaging can be with a good recording. A recording of Copland's "Fanfare for the Common Man" on Delos developed a huge soundstage with tremendous depth and ambiance. The bass drum whacks had great weight and power, yet were very clean with no overhang. It was hard to believe that two 8" woofers per side were putting out this kind of powerful bass in a very large room (25'x 60'x 10'). Another recording, the audiophile favorite "Cantate Domino" on the Proprius label was astounding. The sense of ambiance wrapped around the whole listening area and actually put you in a cathedral. I've never heard such a huge soundstage with the depth and pinpoint imaging that this speaker has. A recording of a tenor voice (Jose Carreras, I believe) produced a very clean, natural sound with no sibilance, brightness or other artifacts frequently heard through other speakers. Just a tenor voice, seemingly suspended in space behind the speakers.

To sum up: Anyone considering a speaker at any price owes it to themselves to audition the VR4. It shows that state of the art performance is possible at a rational price. Several AAS members said it was the best sound they'd ever heard, and I concur. My only problem is figuring out how I'll pay for pair.

Greg Kelso

Associated equipment: Aragon 8008 amplifier, Audio Research SP15 preamp, Theta Pro Basic/Generation III.

Greg Kelso
Music Cataloging Unit
Technical Services
University of Georgia Libraries

The Legend Continues...
The Klipsch KLF 20 Tower Series(tm) Loudspeaker & Audio Electronics SE Tube Amplification

Klipsch may be considered un-hip and passed-on by audiophiles in the roaring 90's, yet those of us who have been around for awhile remember them well as a touchstone in audio long before today's big names were even conceived. I know of more than just a few seasoned devotee's that stand by their Klipsch's with a loving passion, especially the group fresh out of WW-II and Korea and their first exposure to hi-fi sound returning home in the 40 & 50's.. Prior to this time, quality sound was primarily enjoyed in theaters (compliments of Western Electric, RCA and others).

For Klipsch lovers, it's either all or nothing for them and they're not a bit phased by up-start audiophiles with their mystic tweaks and sterile digital bits 'n bytes. I've witnessed Klipsch devotee's confidently state: "I can hear what the musicians are doing just fine - thank you!" Counted among them are a host of low power tube amp kit builders young and old thirsting for high sensitivity/efficiency transducers and the excitement of big, open High Fidelity sound.

Deeply rooted in the early years of hi-fi Paul Klipsch stirred his innovative mind and those all around him and received the acclaimed AES Gold Medal. Serving as founder and chief designer at his namesake company for many years, Klipsch became and remains a "Brand Name" in audio and today. Offering a host of Home Theater A/V products including powered Subwoofers. Founding the company over 50 years past, in 1943 in Hope Arkansas, Klipsch is a legend in his own time for significant contributions in the world of development and application of high-sensitivity horn loudspeaker systems and enclosures. His "Folded Horns" are legends in their own right. Since the vast majority of amplifiers of the day were low power, Klipsch had to be creative in perfecting the highest sensitivity and widest response loudspeakers available. He did not have the luxury of arc-welding, multi-kilowatt power amps at his disposal to power energy soaking crossovers and drivers.

Today, ninety-four years young, Paul Klipsch maintains an office at the factory that he regularly visits. After passing ownership to family members such as Fred S. Klpisch, Chairman & CEO some years past, he still approves final design and testing of each model before it leaves the factory. If the remarkable performance of the KLF 20 Legend Tower Series loudspeaker described herein is any indication, his input is still valuable and appreciated.

As I embarked on this audio adventure, I must admit that from some long past experience with the Klipsch line (mostly the big corner horns), I was never crazy about the horn "sound". I had remembered a soundfield a bit too big and diffuse overall for my taste, lacking perceived focus and definition - not meeting that ideal "audiophile" sound. But 'oh in fairness, there was and remains something special about the Klipschorn midrange and upper registers, especially that of reproducing voices. Jazz singers are especially well treated of the 40's - 60's genre. That is; an ability to reveal vocal character with uncanny realism and intimacy. Novelty songs of this era are most appealing and fun. (A kit is available for Klipschorn owners to upgrade their crossovers to 90's component and sonic standards).

At the time of my introduction to horns in the 60's, I was a lot younger and swept up by the craze for so-called new generation, yet lesser efficiency loudspeaker designs. These, including an intriguing family of electrostatic/magnetic panel offerings from the US and abroad, including power-hogging dynamic driver and crossover designs (little did I know at the time, but the foundations of most of these "exotic" designs were laid down decades earlier). This supported by a host of new, big horsepower solid-state amps at the end of the tube days. Tubes and horns almost seemed laughable to the emerging "audiophile". Thinking these new offerings were the answer, finding sometimes yes, then 'oft times no.

Taking a look at the new KLF 20 Legend Tower, we find a 40" tall, 3-way, dual rear ported, bass reflex loudspeaker. It is positioned in the middle of a "Main Speaker" series, a family of products suitable for stereo audio or Home Theater-A/V systems. Beginning with the smaller KLF 10, 2-way ($599) and a larger KLF 30, 3-way ($1,799). All in the series are bass-reflex designs employing combinations of compression Tractrix and Exponential Horns, and pairs of dynamic woofers. A KLF C7 2-way center channel rounds out this family of higher-line loudspeakers. The KLF 20 retails for $1,499 per pair.

The KLF series and other Klipsch lines may be augmented by a series of five optional powered bass-reflex subwoofers. In my experience, the KLF 20's did not necessarily need subwoofer support for everyday listening unless you can't live without those gut rippling low Organ pedals. Versatility is the watchword for any successful audio company today and tomorrow if they expect to be around in the next Millennium. Seems that Klipsch has carefully thought this out and offers a variety of products to suit consumer preferences. After all, they have been at it awhile!

Over 30 models are offered in their colorful and well written brochures, including in-wall units ranging in price from $229 to $5,798, capped by the still popular classic Klipschorn, folded horn loudspeaker.

The KLF 20 sports 2, high efficiency/sensitivy horn-loaded compression drivers; one a 1.5" third generation Tractrix (midrange - with 90º x 60º coverage) and 1" Exponential (tweeter - with 90º x 40º coverage). A matched pair of 10" dynamic woofers with oversize magnet structures and poly type diaphragms serve the bass. The pair of large rear firing, wide flare ports are positioned near the floor of the cabinet to enhance bass performance. Crossover points are set at 750 Hz & 7 kHz. Two pair of standard, yet gold plated 5-way binding posts and robust jumper straps are fitted for bi-wiring/amping. Thankfully, the posts are mounted in a good sized opening positioned high enough up the cabinet to ease connecting larger, less flexible cables. Little design touches like these add to ease of use and owner satisfaction.

Overall dimensions are; 40.74" H x 12" w x 16" D and weigh 87 lbs. each. Fit and finish is first-rate furniture grade, with real wood Mahogany veneer in a sleek light oil finish that assumes a discrete and pleasing stance in the listening room. Cabinets appear extremely stiff, well braced, with scant vibrations to the touch even at higher power levels. The full length black grills are removable.

In brief for technophiles; Tractrix Horns(r) describe a hybrid curve of the opening or mouth into the base of which the compression driver fires. And you math geeks' I'm sure know what 'Exponential' indicates. We'll skip the science lessons today and move on to the music.

A wide variety of program material was employed. Of special note is KLF 20's conveyance of the human voice with an uncolored, uncontrived honesty that often goes to the heart of the music and the recording venue. As previously noted vocalists, especially female whether Jazz, Pop, or Operatic are conveyed with an uncanny realism. Vinyl from the golden '60's' are a special treat for the aficionado. Little if any added artifices or coloration's. Nor or large scale pieces shortchanged, if the impact of large orchestra, percussion or choruses move and involve me for hours, then the loudspeakers and source system is doing it's job. In this arena, the KLF 20's performed admirably.

The upper treble is extended just shy of being too sharp or etched. The whole time I auditioned the KLF 20's with a variety of solid-state and tube amps - and purpose tested at higher listening levels, I never detected breakup or objectionable behavior at either end of the frequency spectrum. There is little evidence of the thinness or "distant" nature imparted by horns (and associated crossovers) that I remember from times past. The extreme treble will harden a bit at higher levels, yet in my experience most any driver will behave as such when pushed, or when insufficient power is available. The low bass was always tight, well behaved - no flab or flop detected here. These providing a round, full conveyance of the lower registers. The woofers provide the required natural bass foundation without calling attention to itself. This is as it should be, as in a live performance - there when needed, yet without the "one note" character of lesser designs.

Our listening room is also a living room. Representing a real-world, family situation measuring 14' W x 18 L x 9' H, oak floored, plaster walls, fully furnished and 90% carpeted. Loudspeakers are usually placed on the long wall on either side of an archway that opens to similar configured yet somewhat smaller room. The KLF 20's were not particularly difficult to unpack or set-up at their robust but nor overwhelming weight of 86 lbs. each. They come with novel, convertible non-spiked and spiked feet. The non-spikes worked great for set-up. After minimum position tweaking, they ended up facing parallel approximately 6.5' feet apart, 15" from the wall and 10' from the listening position. This producing the best bass response and multi-dimensional soundstage in this particular room. Off axis listening was very good, with excellent driver integration and little if any lobing or beaming. I had several couches full of my informal panel of guest listeners over with side chairs to-boot, and nary a complaint of not hearing the full sonic picture.

Aural and handheld instrument evaluations of the KLF 20 in our (our - since it's spouse Joan's too) listening room with a variety of tracks from Sheffield Labs "My Disc" (10045-2-T) confirm and effective real-world response down to the low 30's as published. The high frequencies easily extended into the high teens with remarkable linearity, transition and coherence between the three sets of drivers. Published specs for this loudspeaker are; 34 Hz - 20 kHz ±3 dB.

The satisfying dynamic performance of the KLF 20's Legends should quickly cast aside audiophile reservations about lacking high-end attributes from a mainstream manufacturer. Sure, they're not the end all, do all in audio, but you'll be hard pressed to find a better value anywhere.

With the reemergence of low power, single-ended tube amplifiers, plus rethinking and refinements by a number horn based loudspeaker designers we have a match-case here that can open refreshing, high efficiency windows into the music. These designs are becoming more common at CES and Hi-Fi shows and garner a lot of attention.

I found the KLF 20 a pleasant suprise and offer first rate value in this world of super-kilobuck high-end lines that all to often don't satisfy as they should at their elevated prices. The kicker with some of these kilobuck system is all the time consuming expensive tweaking and equipment/accessory matching required to extract the best sound, further adding to the extreme cost.

Klipsch's have and continue to sell in the thousands to a new generation of Stereo and A/V fans with the famed "K-Horns" remaining the flagship of the line. This all while knocking on Millennium's door. With successful subsidiary manufacturing operations such as Pyle, apparently there is no end in sight for the Klipsch Corporation. They are to be truly congratulated for producing such a superior performing loudspeaker at a competitive price. Well worth inclusion in anyone's audition suite.

The source gear

I sourced the KLF 20's with a variety of solid-state and tube electronics which they handled with aplomb. Among them were; McCormack Audio's ADL-1 line stage/preamp, DNA-1 power amp and McCormack Signature Series integrated CD player. On the tube front a Cary Audio CAD-75Ia, 75 wpc, integrated, ultralinear push-pull amplifier provided yeoman duty. Each offering it's own effective musical statement but neither substantially altering the basic character of this loudspeaker. The KLF 20 does not appear to be especially amplifier sensitive.

Ever since the KLF 20's arrived and their versatile 100dB sensitivity, I was intrigued by the possibility of pairing them with a low-power, class 'A' SE amp(s), as were the two additional suppliers that quickly cooperated in providing equipment. Subsequently, the majority of the review settled on an ensemble consisting of a; Audio Electronics AE-One P dual-mono, line level preamp and SE-1 Signature SE Triode power amplifier boasting 7 watts of pure class 'A' power. These electronics are of special sonic merit and paired effectively with the McCormack Signature Series integrated CD player. This ensemble producing the best and sweetest overall sound, and just plain a lot of fun. The AE-1 and SE-1 were pre-assembled kits from the Cary NC factory and may be purchased in kit form for $599, and $699 respectively, priced a bit higher factory assembled. A matched set of 300B power tubes were provided by Western Electric's (Charles Whitener, President) Atlanta headquarters assigned to the SE-1 amplifier. The matched, serial numbered, 300B's are provided with original era replica packaging complete with, test curves and arrive in an impressive all wood, embossed, US made presentation case. At $800 for the matched pair, these tubes bespeak serious business and performed as such within the diminutive, yet superbly operating SE-1 amp. The AE-1 source preamp, replete with it's matched quad of new/old stock JAN 6SN7 (Philips) tubes was a smooth and sweet operator too. Each amplifier only occupied 14" W x 9" D of shelf, a relief for crowded racks. Their simple, quality no frills construction and quality, low parts count of both units is quite engaging. Real candidates when considering amplifiers of this type and price-point. The finely crafted 300B triodes are in a word - superlative, visually and sonically!

I must say when this system was warmed and cooking the KLF 20's reached new heights of realism and listener involvement. It's as if the synergy snapped inplace and those pure little 7 RMS watts shouted gimmie' more, all while sounding like a hundred watts or more with nary a stress or strain. Truly remarkable. I can't remember when I've had so much with an audio system, nor shared its enjoyment with fellow music loving audiophiles.

Expecting something special, I was still unprepared for the astonishing musicality offered up by this pair of remarkable, unfrilled, yet finely crafted pair of electronics. Even more remarkable at their affordable price points. A great pairing with the KLF 20's. Ideal for skinflint music lovers like me! I keep scratchin' my balding cranium. How can those NC boys do these 'kits" it for such competitive prices?

At this point, I don't give a whit about some forms of harmonic distortion endemic to SE operation. What I heard with the KLF 20's was music. And ain't this what we're seeking?

Chuck Bruce

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