March 2001

Lamm Industries Model LL2 Line-Level Pre-Amplifier (Deluxe Version)
Review by Dick Olsher
Click here to e-mail reviewer

  Lamm Industries' Vladimir Shushurin is a man with a clear vision about audio design. His past research and experience has convinced him that there exists a limited number of circuit topologies suitable for creating truly high-end audio equipment. Sound quality, he says, can be largely predicted on the basis of how closely key measurements meet theoretical criteria of his models. To quote from a recent interview: "Time and practice have proven the almost complete correlation between the research results and sound quality of the equipment designed in accordance with my methods." Therefore, he does not conduct listening tests, and depends instead on the proper interpretation of measurement results to provide a picture of the sound quality. OK, Vladimir, who am I to argue with success. My past experience with his products has firmly established in my mind his design acumen and extraordinary facility with both tube and solid-state devices.

The LL2 line-stage is the only all-tube preamplifier in the Lamm Industries product lineup. Vladimir recognizes that the power supply is not an entity separate from the amplifier but forms an integral part of the signal path. It is the engine that drives the circuit. Therefore, it is not surprising, that the LL2 features full-wave vacuum tube rectification and a custom power transformer. I wish that more audiophiles would take a look under the hood of their amp or preamp. What they will likely find is a power supply based on 40-cent silicon rectifier diodes. Such diodes are noisy. As they switch on and off in concert with the line frequency, they generate high-frequency noise transients that are only partially filtered by the power supply's smoothing network. The sonic penalty is a coarser, grainier, musical tapestry. Tube smoothness can only be taken to the limit by avoiding any solid-state contamination of the signal path. A tube rectifier's usual drawback of higher internal resistance and thus a greater dynamic voltage drop is not a design issue in the context of a preamp with its minimal current demand. Use of tube rectifiers is a strong indicator of a designer's savvy and of ultimate sonic quality. Yet, they are rarely seen - even in the context of ultra high-end audio. One can only surmise ignorance, or worse, is at work at the highest echelons of audio design.

The Lamm Industries design philosophy embraces high-quality, minimal sonic signature, components and rigorous quality control. Use is made of military-grade Dale metal film resistors, Electrocube and Roederstein film capacitors, high-frequency switching grade Cornell Dubilier electrolytic capacitors, and selected vacuum tubes. A particular passion of Vladimir's is high-quality volume controls. You'll never find cheap potentiometers in his products. Separate left and right channel Alps stepped attenuators are used in the LL2. Sorry, there is no remote control. Not only will you have to get out of your seat to adjust levels, but you will also need to adjust each channel individually. I actually prefer such an arrangement to a stereo volume control followed by a balance pot. Products routinely undergo a 72-hour burn-in test, followed by the measurement of all essential parameters. If necessary adjustments are made at this stage. Finally, each product is auditioned in the reference sound system for at least two hours.

The LL2 is a full-featured line stage. It provides three inputs, one tape loop, two sets of outputs, a front-panel muting switch, and automatic mute at turn on/off. It is available in two versions: standard and deluxe. both of which utilize identical chassis, PC-board and parts. These versions are otherwise identical, except that in the deluxe version, the power supply energy storage is approximately twice as large, and film capacitors in critical paths are paralleled by high-quality polystyrene capacitors. There is no provision for adding a phono board, and at this time, a companion phono stage is not available.

A pair of dual triodes (12AU7 and 6DJ8) are used per channel for voltage amplification. The overall gain is about 18 dB, which is just fine in most system contexts. However, with digital sources, high-efficiency speakers and sensitive power amps, the volume controls could only be barely nudged from fully closed.

A word about looks. The LL2 was designed in the tradition of pro sound gear. As with all other products in the range, the LL2 does not make a visual statement. It will never be mistaken for vintage French or Italian gear. It simply goes about its business without attracting any attention, or distracting you the listener from its main reason for being; namely, to enjoy the music.

The Sound

Try making out surface features on a highly polished sphere. Its smooth topology makes it impossible to identify distinguishing marks. It will merely mirror whatever is in front of it. So it is with the LL2 - a preamp of supreme neutrality. There are no distinctive euphonic colorations. Its character is neither dark or bright sounding, and in the words of Goldie Locks, it sounds just right. So many inexpensive preamps sound bright and lively, giving an immediate sonic charge to any system. If you're into cheap thrills, the LL2 isn't the preamp for you. In fact, it sounds its best in the context of an expensive high-end system, where its strong suits shine most clearly.

Its most memorable performance was in the reference system, accompanied by the Wolcott Audio Presence amplifier and the Sound Lab A-1 full-range electrostatic loudspeakers. Keep in mind that the reference system has been hosting some of the world's elite, or should I say "rich and famous," preamplifiers for the past decade. Preamps costing as much as $20K have been here and have strutted their stuff to titillate my jaded ears. Amidst the decadence of the reference system, this cheapest link, costing even less than the cable, quickly established itself as a world-class contender. Control of musical transients was superb. Transient attack was unfolded with speed and precision. Neither was there any confusion about the decay portion of each transient. Individual instruments could be clearly resolved. - even in a complex tapestry of harmonics.

At the core of every great preamp exists a soulful heart, that infuses music with drama and dynamic tension. I have yet to hear a conventional solid-state preamp that could do that convincingly. Many years ago, when I lived in a state of audio sin, I owned a PS Audio solid-state preamp. In hindsight, it is easy to say that it sounded dreadfully lifeless. Dynamic shadings were squashed to the point where everything sounded like it was in slow motion. Tube preamps, in my experience, have a much easier time lighting a fire under the soundstage. The LL2 comes fully loaded with a responsive 5-speed transmission and dynamite under the hood. It'll take you to from 0 to 60 in a heartbeat. It allowed me to put on a good performance and totally enjoy the emotional fireworks. The sonic character did not change when the LL2 shifted into high gear. Harmonic and intermodulation distortion products rise with signal level, and with many preamps the effect is to muddy the purity of harmonic textures during dynamic passages. In contrast, the LL2 is capable of generating high drive voltages with minimal distortion, and its low output impedance guarantees compatibility with a wide range of interconnects and power amplifiers.

The treble range sounded open and airy, but harmonic textures were a touch soft in character. Because the preamp sits at the head of the amplification chain, its errors are subject to being magnified by the rest of the system. Hence, care in system building is till required. For example, this attribute could be a plus with either crisp sounding power amps or loudspeakers.

I hesitate to discuss the bass range of the LL2 as if it existed in a vacuum. Apparently, this aspect of its performance has garnered much praise elsewhere, and while I don't disagree with this assessment; I would also have to give credit in this respect to the associated power amp and loudspeaker. Preamps, in general, possess excellent bandwidth and very extended bass response. The LL2's -3 dB frequency in the bass is 1.5 Hz. That's very good, but probably not much different than that of a host of other preamps. Then how is it that preamps appear to influence bass quality, especially when the amp/speaker interface dominates bass response? The answer most likely is due to differences in preamp drive voltage linearity and output impedance. The LL2 excels in both regards. Its delivery of bass lines was well defined within the reference system, but I could easily detune bass tightness by changing the Wolcott's damping factor. With the amp's damping factor optimized, bass definition and impact were exemplary.

Tube preamps are well known for their ability to generate an expansive soundstage, with palpable spatial outlines. The LL2 did not disappoint in this regard, coaxing a soundstage of generous proportions from the speakers. Layering of the depth perspective was nicely done. Transparency, or the ability to clearly visualize the inner recesses of the soundstage was another strong suit. However, the width and depth perspectives were not as well fleshed out as with more expensive preamps (e.g., Air tight ATC-2). Meaning, that the LL2 was only realizing about 80% of what's possible in terms of dimensionality. Also, image focus was slightly diffused. These are minor blemishes, which may or may not matter to you, depending on how important imaging is on your list of priorities.

Conclusion

Considering its price point, the LL2 line stage's level of performance is nothing short of sensational. Its blend of tonal neutrality, speed, control, and harmonic purity add up to a sure recipe for musical excellence. It is capable of competing in the highest audiophile arena, while its slight spatial reticence and textural softness are easy to live with. It should readily integrate with a diverse range of systems. The LL2's ability to drive a variety of amps and exotic cables allows it to comfortably slip into an existing system without adverse complications. Let me take this opportunity to raise my glass in a toast: to Lamm Industries and Vladimir Shushurin for a job well done. Cheers!

Specifications

Rated Output Voltage (20Hz to 20 KHz): 1.0 Volts RMS

Voltage Gain: 17.92dB

Frequency Response: 20Hz to 400kHz

Slew Rate
Vout=28.8 Volts peak-to-peak of square-wave signal, F=10kHz: 41 Volts per microsecond

Rise Time:
Vout=28.8 Volts peak-to-peak of square wave signal, F=10kHz: 1 microsecond

Total Harmonic Distortion from 20Hz to 20KHz: Vout=2 Volts RMS: <0.03% 
Vout=30 Volts RMS: <1%

IM Distortion (60Hz: 7kHz 4:1) SMPTE: Vout=2 Volts RMS: <0.03%
Vout=30 Volts RMS: <1%

Input Sensitivity: 
Vout=1.0 Volts RMS: 0.127 Volts RMS

Input Impedance: 50 kOhms

Corrected Output Impedance: typically 250 Ohms

Noise:
Signal-to-noise ratio below 2 Volts RMS output, unweighted: better than 84dB

Operating Temperature: Operating temperature: -4 to +104 degrees Fahrenheit (-20 to +40 degrees Celsius) ambient.

Tube Complement:
V101 - 12AU7A (left channel, first amplification stage) 
V103 - 6DJ8 (left channel, second amplification stage)
V102 - 12AU7A (right channel, first amplification stage)
V104 - 6DJ8 (right channel, second amplification stage)
V105 - 6X4/6202 (full-wave voltage rectifier)

Power Consumption: typically 40 Watts

Burn-in Time at Factory: Minimum 72 hours

Dimensions: 4.5 x 19 x 15 (HxWxD in inches)

Unit weight: 20 lbs.

Shipping weight: 36 lbs.

Pricing: Standard version, $3990; deluxe version, $4290.
Warranty: Five years parts and labor.

Manufacturer

Lamm Industries, Inc.
2621 East 24th Street
Brooklyn, NY 11235

Voice: (718) 368-0181
Fax: (718) 368-0140
E-mail: lammaudio@juno.com
Website: www.lammindustries.com