Loth-X BS1 2-way Bookshelf Speaker

Loth-X BS1 2-way Bookshelf Speaker


Constantine Soo

23 August 2002


Type: 2-way, bass reflex (Single-Wiring only)
Tweeter: 1-inch cloth with magnetic fluid (for ambience only)
Main driver: 6-inch Loth-X paper cone and cloth surround with shielding
Frequency Range: 55 Hz – 20k Hz
Efficiency: 94 dB/2.83 V/m
Impedance: 8 Ohm
Dimensions: 200 mm W × 295 mm D× 400 mm H 
Weight: 10 kg each
Price: $599 a pair
Finishes: Cherry 
Warranty: 5 years 

Loth-X America 
PO Box 4550
Austin, TX 78765
Telephone: 512-467-0323
Website: www.lothxonline.com

Minimonitors have become significant products nowadays, beginning back with the advent of the Rogers LS3/5A. Although they possess space-saving, non-intrusive appeal to both the audiophile and his/her aesthetically driven spouse, these advantages are quite often offset unfortunately by an equally uncompromising need for individualized system matching to exploit the speaker’s full potential. 

The subject of this review, the $599 Loth-X BS1, is the smallest among eight models of progressively larger, crossover-less, single-driver, high efficiency loudspeakers from Loth-X, named after Mr. Lothar Sanders, its managing director, culminating in the $20,000 a pair, back horn loaded monolithic BARD. Whereas the floor standing models employ the proprietary Stamm Full Range Drive Unit created by designer Mr. Stefan Stamm, the bookshelf BS1 and its two upper models are equipped with the Ion-series, specially impregnated paper cones to maintain lightness and stiffness. The 6-inch paper/cloth main driver for the BS1 is magnetically shielded and extends upward to around 45 kHz, at which point an 1-inch ferro-fluid cooled, cloth tweeter picks up the higher band via a single capacitor which is not linked to the main driver.

With dimensions similar to those of the Celestion SL700, the Loth-X BS1 is a little deeper and is made entirely of wood with the large, core section sandwiched between two side panels. Construction is sturdy and the wood is sanded into a fine polish. Bass augmentation is provided via a front-loaded rectangular port. 

Putting the BS1 on my Celestion SL700’s original 24-inch Aerolam speaker stands resulted in the achievement of a parallel height of the ambience tweeter to my ear. With the main driver situated far below the horizontal axis from my listening level, I reused the same arrangement for listening to my Celestion SL700, in which the stands were raised by bricks by another 3-inches. This elevated the BS1’s main driver to near my ear-level, with the tweeter firing just slightly above my ears. The BS1’s performed well whether in a nearfield or conventional, domestic listening environment. While its dispersion patterns were not overly excessive, an optimum between maximization of soundstaging and minimization of reflections for the listening position 9 feet away was reached by placing the BS1’s 5 feet away from the back wall, 3 feet away from side walls, and 52 inches apart from each other. Finally, the speakers were toed-in two-thirds towards me. 

Amplifications was the $6,500 50 Wpc integrated solid-state 47 Laboratory Gaincard S. The following power amplifiers were also used for comparisons: the $2,800 185 Wpc solid-state McCormack Power Drive DNA-1 Deluxe and the $3,450 125 Wpc tube Music Reference RM9 II. The $6,000 Audio Note M3 was the preamp when either the McCormack or the Music Reference was in use. Although the BS1’s 94dB 8-Ohm sensitivity hardly requires muscular amplifiers, Decware’s 5 Wpc stereo SE84C was inadequate as constant and severe dynamic compressions persisted. Cardas Quadlink 5C speaker cables and Granite Audio #470 interconnects were used throughout.


Where the recording quality was high, the BS1’s sonic presentation was big and immediate, inducing a full-bodied sound to voices and instruments. Evgeny Kissin’s Chopin – 24 Preludes, Sonata NO. 2, Polonaise, Op. 53″ [RCA Victor 09026-63535-2] possesses sonics worthy of an audiophile’s choosing and did not sound diminished or small-scaled. To my surprise, the BS1 gave a tonally accurate rendition of the piano’s overtone, accompanied by undaunted dynamics befitting a horn speaker. Driven by the 50 Wpc Gaincard, the BS1 was capable of such unexpected loudness that I actually had to adjust the volume downward twice during the fist listening. With the Loth-X’s bottom-end deficiency, I was surprised at how well it portrayed piano timbres.

A change for something even better, there was dimensionality and immediacy from female jazz vocalist, Ayako Hosokawa’s lamenting in “Bridge Over Troubled Water” from “The Famous Sound of three blind mice,” [JVC XRCD TBM-XR-9001], and the vividness of Ms Hosokawa’s voice intertwined with the supple smoothness of the double bass. Injecting a keen sense of delicacy and intimacy, these aspects of this small-scale, audiophile jazz presentation validated the BS1 again, especially in light of its affordability. 

Likewise in “Summertime,” a live session produced by Keith Johnson for the Sheffield/XLO Test & Burn-in CD [Sheffield Lab 10041-2-T], which has excellent soundstage definition and tonal realism, the BS1 captured the lyricism of the French Horn with adequate sheen. Though indisputably in need of more precision, dimensionality and microdynamics, the BS1 was nevertheless able to retain clarity in instrument separation and tonality, with a dynamic ease representative of drivers with no crossover. 

Retrospectively, more than any musical tracks, the overlapping voices of Sheffield Lab’s Doug Sax and Roger Skoff in track 5, “Walkaround”, was less resolute and the test track represented an uncalled-for infinitesimal examination of the Loth-X’s microdynamics and imaging limits. Putting a $599 pair of speakers through this test also represented a shot of wishful thinking on my part, which was not totally unfounded considering the somewhat inflated optimism generated from my earlier sessions.

On bottom-end performance, the BS1 showed an expected lightness of double bass from both CDs, and hence led to less-defined renditions of that instrument therefore. In addition, the perceived bass output sounded rather light in comparison to the speaker’s specified 55 Hz, and I thought the small cabinet was the limiting factor in preventing the BS1 from rolling out more information in the low frequency region. Reproduction of the lowest octave of instruments may be augmented by putting the speakers closer to corners, or by integrating them into a smaller room. 

Choice of speaker cable also played a decisive role on certain CDs. The BS1’s midranges had such dynamic ease that excessive energy could be released, blemishing a listening session. A trusted cable for all my existing speakers, my Cardas Quadlink 5C enhanced the upper midrange from the BS1 that was rather sibilant to my ears. Soprano Dame Montserrat Caballe’s vocal line “Ah, fors’e lui: Sempre libera” from Verdi’s “La Traviata,” on Opera’s Greatest Love Songs [RCA Victor Red Seal 09026-61886-2] carried a glorious radiance albeit intermittently audible midrange artifacts.

The Cardas also induced spectral imbalance and ringing from the BS1 on less optimized piano recordings such as a 1965 rendition of Beethoven’s Sonatas on The Originals, Ludwig Van Beethoven, Sonaten No. 8 “Pathetique”, No. 14 “Moonlight”, No. 21 “Waldstein”, No. 23 “Appassionata” [Deutsche Grammophon 447 404-2]. Wilhelm Kempf, the legendary German classical pianist’s otherwise consistently insightful reading via my other speakers, was not only plagued by high note sibilance and midrange muddling via the Loth-X, but was also afflicted by resonance-induced distortions. While my reference minimonitor, Celestion SL700, was able to hold its composure during the same passages with aplomb and still proceed to deliver a fulfilling performance, the BS1’s presentation had an unmistakable congestion, negating the crucial open sound. Having heard the BS1 under much better terms, I believe it wasn’t a major resolution issue but rather one of refinement. 

This is an irony existing only at both ends of the equipment quality spectrum. With the SL700 belonging to the vast category of medium-priced, core audiophile products, and the BS1 of the budget-priced category, readers can expect the refinement from the exotic product to reveal all in balanced details, while the limitations of such ability in many budget products can parch the simple listening pleasure.

Changing speaker cable to the less expensive and less sensitive Tara Labs Phase II TFA Return alleviated the symptom considerably. Although it did not match the Cardas’s dimensionality and textural refinement, neither did the Tara Labs hinder the BS1’s dynamic ease and background information conveyance, sounding just a little reserved in tonality, thus serving the BS1 very well.

With the Tara Labs Phase II TFA Return, getting down with the latest compilation of disco-queen Donna Summer’s Greatest Hits [Mercury 314 558 795-2] complimented the BS1’s potentials. The 45-rpm single version of “Hot Stuff” sounded coherent and lively, albeit with intermittent depletions of microdynamics. Via the BS1, while the recording was not of the same caliber in vocal resolution as the JVC XRCD, the Loth-X was always depicting Donna Summer at center stage unwaveringly and reproduced the up’s and down’s of Summer’s very powerful singing aptly.

Playing Richard Strauss’ chamber music, “Sonata No. 1” from Richard Strauss Sonatinen for 16 woodwinds [DG BMG D112472], the BS1 sounded sophisticated and zealous. The woodwinds sounded lively and swift, with good image and textural definition. The musical presentation consisted of woodwind instruments with mild dynamic demands, allowing this chamber music to represent a most rewarding coupling of music to the Loth-X.

In reproducing complex, large-scale orchestral performances, like “Shostakovich Symphony No. 10” from Karajan Gold [DG 439 036-2 or BMG D118283], medium volume settings enabled the Loth-X to sound large with expeditious transients and punchy dynamics. However, my attempt at squeezing more wholesome dynamics and tonalities from the BS1 with an increase of the volume affected a uniform aggressiveness, which I believe was an indication that it was buckling under my demand to have it behave like my other, larger speakers within the same space.


Progressively, we are setting our expectations from minimonitors higher and higher. Their ability to play loud without strain becomes absolutely essential. 

In reality, minimonitors will work to an exceeding excellence if certain conditions are present to facilitate a full exploitation of their potentials. These conditions include appropriate room dimensions, proper listening height, meticulous positioning and compatible amplification. Optimized, a reference-class minimonitor in a proper setup could exert tidal dynamics, captivating dimensionalities and sonorous tonalities. My Celestion SL700, which is renowned for refinements in dimensionality and tonality, and its tenacious appetite for substantial amplification, is able to perform breathtakingly in an average-sized room. Some minimonitors, however, regardless of dynamic capabilities, must be pampered in smaller rooms. In my opinion, the Loth-X BS1 is such a speaker.

I also exerted additional expectations on the modest BS1 by using amplification well beyond its league, as the BS1’s abilities in conveying what is upstream of it became supremely important. Had similarly priced budget gear been available to me, I might have imposed fairer expectations. Nonetheless, the BS1 was exploited under uncommon circumstances, and having considered its limitations, its fortés are sweepingly exciting for just $599.

For example, the 47 Laboratory Gaincard S induced in the Loth-X mild dynamics, refined top-end and a detailed but relatively soft midrange. On the other hand, the all-tube amplification of M3 and the 125 Wpc EL34-based Music Reference RM9 II power amp charged the BS1 in producing dimensionality, lively dynamics and a host of complex tonalities. Alternatively, the 185 Wpc McCormack DNA-1 Deluxe offered a bland and less detailed midrange and slightly recessed top-end, though it did induced the most defined bottom-end of the four amplifiers used. In addition, my 6-month experience in using the 300B Audio Note Quest monoblocks might have overly realigned my sonic priorities to the favor of a prominent midrange.

Therefore, matching the BS1 to amplifiers with moderate outputs, such as the Gaincard S, was more befitting of the speaker’s comfortable operating zones than either the overly powerful Music Reference or McCormack ever contributed. 

In spite of my $3,200 Celestion SL700’s wholesale superiority over the Loth-X BS1’s, their $599 MSRP houses a high cost advantage for its efficiency, fundamentally sound dynamics and full-fledged tonalities. Incapable of supporting double-bass conveyance and the soundstage specificity of the Celestion, a dampened BS1 nevertheless sounded confident and mature, making prolonged listening sessions highly enjoyable. Adding a powered subwoofer will compliment the BS1 undoubtedly, an option well worth any audiophiles’ considerations. 

While there is the widely accepted wisdom of allocating more funds on speakers over anything, an initial investment of more than $599 for a pair of bookshelf speakers in a budget system may no longer be necessary. Although I believe no audiophile can resist the temptation of progressing onwards with more exotic loudspeakers, for the purpose of music replay, the BS1 is a good starting point. 

While the Loth-X was of modest disposition, I believe audiophiles will be amazed at its potential when fed from competent upstream components. This is particularly indicative of the potentials of BS1’s bigger brothers. I wouldn’t be surprised to see readers taking it into their main audio system after hearing what it is capable of in their dormitory or secondary system.

The $599 Loth-X BS1 is a cost effective execution of a proven technology. While many audiophiles will understandably seek out more complex, mainstream and costlier products, experienced listeners will appreciate and recognize instantly the feasts this affordable speaker achieves. While it is unlikely any reader would choose a $6,500 amplifier (47 Lab Gaincard S) or $9,450 system (Audio Note M3 + Music Reference RM9 II) to drive the $599 Loth-X as I did, the BS1’s ability at conveying the distinct characteristics of varying amplification speaks volume of its potentials. The BS1 may just as well bring you a fresh and revelatory experience and open up a whole sleuth of options for you.

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