Loth-X JI-300 Integrated 300B Amplifier

Loth-X JI-300 Integrated 300B Amplifier


Constantine Soo

26 May 2003


Type: Vacuum tube single-ended stereo integrated amplifier
Inputs: 5 (RCA, line only)
Power Output: 8 Watts per channel at 8 Ohms
Output Taps: 8 and 16 Ohm (available with 4 and 8 Ohm taps)
Input Impedance: 10k Ohm
Tube Complement: 300Bx2, 5965×2, 5687×2
Dimensions: 15.5W x 13.5D x 9H (inch)
Weight: 49 lbs
Price: $15,000

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

Loth-X is a German-owned international enterprise with operations in countries such as South Korea and Singapore. They design and manufacture complete high-end audio systems including turntables, amplifiers, speakers and cables. Quoting from the company’s website, Loth-X’s expressed goal is ” … to create products far beyond the norm which would satisfy the dreams of the world’s most dedicated and discriminating audiophiles.”

Manufactured in the high-tech sector of democratic South Korea, the JI-300 is one of three amplification products from Loth-X, the other two being the $30,000 Silbatone C-102 preamplifier and the $100,000 Silbatone 300 SEL power amplifier. At $15,000 (MSRP) the JI-300 is currently the company’s lowest priced product offering. 

Loth-X is a purveyor of 300B-based single-ended tube amplification. They are of the opinion that AC’s high impedance characteristics and the electromagnetic and radio frequency interference (RFI) rampant in many conventional power supplies are the limiting factors in the triode method’s frequency extension. To combat this, the company engineered a battery-operated power supply system for the cost-no-object C-102 and 300 SEL Silbatone’s, whereas the JI-300 is given an advanced, rectifier-less, AC-based power supply that the company claims to have an impedance fifty times lower than conventional ones, providing “high speed energy delivery on transients.” In other words, the JI-300’s power supply characteristics approach that of a battery-operated one, supposedly. 

The JI-300’s output transformers are of a special custom design with silver clad copper foil wound for superior linearity and extended frequency response, in addition to custom wire-wound resistors, oil capacitors and specially designed Silbatone silver mica unit. The attenuator is a $300 custom broadcast grade unit made by Tokyo Ko-On. Loth-X believes that parts quality defines its products’ musicality, and claims that the complement of exotic parts in the JI-300 is a result of extensive auditions and research, and is not available on any other amplifiers in the world. The JI-300 biases its tubes automatically. Last but not least, the JI-300 features “soft-start” in which the output tubes are charged one minute after the unit is powered-on, a process that supposedly eradicates harmful surges created by the onslaught of power-on from reaching the delicate 300Bs.

The JI-300’s full aluminum chassis is precision machined from a solid aluminum stock, and the two super-large front control dials are milled out of solid aluminum with ball bearings. With the exception of the back and bottom of the unit, there is not a single screw or removable panel on the front, top or sides of the chassis, and the seemingly impenetrable transformer housing appears to have been unconventionally fitted from under the chassis prior to final assembly. The amplifier’s super-imposing feet are part of the chassis. The front feet are spaced outward to the two front corners as an integral part of the front support columns, similar to the Wadia arrangement. The rear feet are spaced closer together and are directly beneath the transformers.

The two Western Electric 300B output tubes do not emanate the same degree of heat as those in Audio Note’s Quest monoblocks that I reviewed in 2001. Instead, it was the transformer housing that was the major heat-generating section. It was consistently too hot to lay hands on for more than 10 seconds especially after five hours of operation. According to Loth-X’s U.S. importer, Joe Roberts, the all-aluminum chassis functions as a heat sink to dissipate heat from internal components. Loth-X also claims that the JI-300 incorporates specially designed circuits for maintenance of output tube stability in extended operating conditions. 

Compared to all the equipment that has ever graced my system, the all-aluminum Loth-X JI-300, with its sheer metalwork elegance and magnificence, and the singular sky-blue power light and the illustrious large-dial control knobs on the front panel, is an audio version of a supermodel. 

Loth-X’s drive in creating the JI-300 is best illustrated in an e-mail message from Roberts:

“It seems everybody out there is repackaging the same old circuits into a $10,000 box with a thick faceplate. This is precisely where Loth-X wanted to do something different.”


The 47 Lab Flatfish and Progression digital system chaired the first half of the audition period using the Audio Note AN-V digital cable. During the second half, the Flatfish would serve as the reference transport transmitting data to the Audio Note DAC 5 Special via Audio Note’s Sogon digital cable. Two ISO’s, a medical-grade AC power isolation device, were used to provide extra isolation for the rest of the audio system from the digital equipment. The 94.5 dB/8 Ohm Audio Note AN-E SEC Silver served as primary loudspeakers. Virtual Dynamics’ Nite interconnects, power cords and speaker cable supported the first half of the review and were later replaced by Audio Note’s Sogon interconnects, AN-Vx interconnects and SPx speaker cables. Reviews on the cables are underway. 

The JI-300’s low input sensitivity was reminiscent of my experience in using the 47 Laboratory 4706 Gaincard S Dual Mono Integrated Amplifier, as I had to turn the volume on both integrated amplifiers up to 1 or 2 o’clock for serious listening. The good news is the volume increments of the JI-300’s Tokyo Ko-On attenuator were so finely divided that each step was small enough to allow for highly optimized settings. 

Though produced in the mid 80’s, the Windham Hill Records Sampler ’84 [Windham Hill Records WD-1035] contains some of the most aural and evocative tunes from the label. Capturing the abundance of spatial cues from the 2nd track, “Liberty Bell”, as relayed by the 47 Lab Flatfish CD transport and the Audio Note DAC 5 Special, the JI-300 compelled the Audio Note AN-E SEC Silver Loudspeakers to project vast spatial proximities of instruments with acute location of onstage activities. The Loth-X also complemented the AN speaker’s prowess in tonal definition, as snare drum rhythms had ample downward energy and acoustic foundations that distinguished it effortlessly from the synchronized electric bass. Then, the hover trumpet’s fluidic and reverberating sheen narrated beauty and serenity profoundly in one part, and courage and determination in the other. 

Tonality of the piano played by Martha Argerich in her 1999 reading of Chopin’s “Piano Concerto No. 1 in E minor Op. 11” [Accord ACD 100-2] was the most resolute via the JI-300, as droplets of the piano’s tones emerged and traversed in mesmerizing beauty amidst a backdrop of the grand and lively, yet tender Sinfonia Varsovia, conducted by Alexandre Rabinovitch. Dynamic contrasts of the solo instrument and the accompanying Polish ensemble rose both concurrently and sharply in communal partnership with each other. Whereas the JI-300 endowed the piano, even during climactic passages, with exquisite presence and adequate dynamic contrast to that of the orchestra, lesser amplification would cast ambiguity on both the piano and the ensemble. Argerich’s touch presented a convincing smoothness on top of a firm stance that would probably have amazed Chopin himself. 

In presenting orchestrations of higher complexity and larger scale, such as a 1993 re-release of the 1985 recording of Dvorak’s Symphony No. 9 [Deutsche Grammophon “Karajan Gold” 439 009-2], the JI-300 produced competent, sweeping textural delicacy, capturing the renowned virtuosity of individual players within the Berlin Philharmonic. They propelled their respective sections into a masterful unity. As the Loth-X differentiated and presented the virtuosity of individual players, it also harnessed rampant dynamics and involving spectral coherency from the ensemble as a whole. It diligently captured the collective, dynamic walls of sound that were overwhelmingly lifelike, thus conveying Maestro von Karajan’s artistic vision. Through the Loth-X-induced Audio Note speaker, the aggregated orchestra seemed to relinquish individual musicians and transformed them into the perfect music communion medium.

With a fusion of sonority and transients as relayed by the JI-300, one can’t help but be immersed in the vividness of sound and the efficacious impact, enabling gradual submergence into the spirit of the performance. While performances by many other ensembles with various conductors often exhibit indulgence in the name of artistic spontaneity that distracts and dismays me, Maestro von Karajan and the Berlin Philharmonic’s fusion of artistic visions in this reading of the “New World Symphony” towers above all others in its disciplinary and virtuosotic brilliance.

The Loth-X JI-300 was also able to impart highly articulate sonic textures amidst a wide dynamic range from the AN speakers in their rendition of DMP’s 1987 CD, “Thom Rotella Band” [DMP CD-460]. In portraying the pure percussive session of track 10, “Little Chubby”, the triode integrated amplifier injected dynamic agility and acute responsiveness in testimony of this diaphragm-crushing drumming feast. Among the other 13 tracks, the instantaneously memorable melodies of “Patti Cake”, “Come Down Easy”, and others feature a resounding acoustic guitar solo in coiling arrangements alongside a highly supportive ensemble. Via the triode amplifier, the dynamic transients and tonal texturing of the guitar had definitive clarity, while the accompaniment of the band had a dynamically compelling and spatially expansive presentation atypical of the dynamically deprived 300B camp. 

Playing U2’s 1991 Achtung Baby [Island 314-510 347-2] revealed a fiery spirit within JI-300. As effective as the output tubes were in communicating distinctive instruments, the JI-300, as a whole, produced outstanding dimensionality amidst acute percussions and a variety of intertwining instrumentation. The decisive tonalities and steadfast soundstaging of the Loth-X JI-300 promoted the CD’s listenability in my system.

Other Considerations

Although the 8 Wpc JI-300 induced impressive bottom end performance while driving the 82 dB/8 Ohm Celestion SL700, the amplifier did not fully induce the reference minimonitor’s signature dynamics as completely as the powerful, solid-state Linn Klimax Twin. Yet, complementing the Celestion’s transiently dynamic, tonally sophisticated, and stereophonically impressive character, the JI-300 endowed the transducer with appreciable gains in sonic coherence, evoking unprecedented tonality and soundstage believability.

Although this Loth-X/Celestion combo met my volume demand at a 2 o’clock volume position, the JI-300’s modest output could not satisfy the insatiable Celestion beyond that, as dynamic compression began to set in. Yet, during those extended listening sessions, I reckon some will find higher volume rather unnecessary, when the presentation had already been eminently musical, and the sound tremendously satisfying.

While both the AN and Celestion speakers exhibited significant sonic betterment in dimensionality and tonality with the JI-300, the 104db/8 Ohm 1993 Klipschorn benefited relatively little from the $15,000 amplifier. Instrument localizations from the K-horn received improved delineation, and reverberations became a little more pronounced. Likewise, the horn speaker’s tonal depiction improved only marginally. 

Having witnessed wholesale improvements from the AN and Celestion speakers with the Loth-X JI-300, my assessment of the K-horn dilemma thus leaned unfavorably against the horn speaker. On the other hand, the K-horn’s past association with amplification such as the Audio Note M3 preamplifier, Quest monoblocks, Monarchy Audio SM70 (stereo and mono), 47 Lab Gaincard S, Decware SE84C monoblocks and Linn Klimax Twin, suggested that the horn speaker is not summarily inert to improvement upstream. Therefore, I must admit to the possibility that my continuous, prolonged exposure to systems of exceptional tonal finesse has finally instilled a heightened tonal preference and sensibility in me accordingly.


In preparation of this review, a most resolute digital source plus a transducer of exceptional caliber were commissioned to gauge the Loth-X JI-300 Integrated 300B Amplifier’s potential. The induced complex and vivid tonalities, summarily dimensional spatiality and capable dynamics beseeched me with alarm at my forgiving viewpoint and my long-standing, unreserved favoritism and preference towards speakers of less capable tonalities that are otherwise peerless in rekindling lifelike dynamics. 

In driving the 82 dB/8 Ohm Celestion SL700 minimonitors, the single-chassis JI-300 demonstrated a drive capability curiously more substantial than the Audio Note Quest monoblocks. And as supported by the upstream Audio Note DAC 5 Special and showcased by the incredibly resolute AN-E SEC Silver downstream, the Loth-X JI-300 Integrated 300B Amplifier demonstrated agile transient, immaculate spatiality and above all, a sonorous tonal aptitude that proved to be worthy of the Loth-X heritage. More importantly, the Loth-X’s explicit transients and expeditious dynamics represented a far cry from most 300B designs’ dynamic deprivation, and its special rectifier-less high-tech power supply with silver foil-wound transformer was undoubtedly of exceptional sustenance and vigor. 

The Loth-X JI-300’s responsiveness in depicting the rise and fall of delicate transients was incomparable among tube amplifiers, and its tonal disposition invoked spectacular complexity in conveyance of textural realism, permeated nonetheless by a sparkling delicacy. This level of sonic excellence set the stage for the JI-300 to showcase its spectral coherency in the incredibly resolute and wholesome portrayals of instruments, consequently reinforcing instrument dimensionality in purveyance of sonic realism. Armed with such level of musicality, the Loth-X’s consistently prevailing and revealing spatiality from each recording authenticated a most exquisite audiophile experience. 

In both conception and implementation, the Loth-X JI-300 integrated amplifier is a brilliant accomplishment in the concordant incorporations of a customized pre-amplification stage and high-quality power amplification, showcased by an advanced power management system. The absence of a solid-state fortified drive capability in the Loth-X JI-300 only serves to testify the caliber of the integrated 300B as of the highest among its kind in design and engineering-a quintessential tour de force of the tube camp. Following the emergence of the likes of its Silbatone siblings, the JI-300 represents Loth-X’s efforts in creating a less expensive product that will, nevertheless, not tarnish the mark’s priceless reputation. In transcendence of the WE 300B’s typical application, Loth-X also succeeded in emancipating inherent limitations of the decades-old design, by developing a power supply system that is an industry first. Let’s hope that Loth-X can adapt this innovation to amplifiers costing much less.

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