POSITIVE FEEDBACK ONLINE - ISSUE 24
as reviewed by John Mazur
The frustration of being an audiophile is that your system is only as good as your last reference component. Frustrating, too, is the fact that many of us do not have enough local resources to evaluate audio equipment. When, at an early point in the hobby, you try to figure out your biases and tastes, the complexities of equipment synergy make it painfully evident how maddening this hobby can be. Along the way, however, something happens to change your perspective, and you discover what you really need from your system.
I discovered what I needed about ten years ago, when I replaced my Audio Research LS-3 line stage with a Spectral DMC 10 preamp. I was using a Musical Design D75 solid-state amp, and my system just came alive when I installed the DMC 10. It had more explosive dynamics, better pace, more image density, and gave me more overall enjoyment. The trouble occurred when I tried to get more of what was being served up by that system. To chase that goal, I tried to build the system around the preamp, but it didn't happen.
The Artemis LA-1 line stage has some interesting things going for it. John Atwood of One Electron has created a conservative design that is built to last many years. According to the owner's manual, "Experience has shown that the best audio quality is achieved with the minimum number of active parts in the signal path. Each amplifying device has its own transfer characteristic and when these are multiplied together in a complex design, the result is an overall transfer characteristic with high-order distortion products—the worst sounding ones." To extract the best possible sound, Atwood used high-quality parts, point-to-point wiring, and innovative parts implementation in key locations in the signal path.
The LA-1's gain stage employs one 5687 dual triode for each channel. Atwood chose the 5687 for its low resistance and excellent linearity. The low plate resistance of the tube allows it to drive heavy loads without the use of a cathode follower to buffer the load. The gain stage employs a high-quality Lundahl C-core inductor instead of the more common plate resistor. This allows the choke to essentially become a perfect current source, allowing the triode to operate into an infinite-resistance load, which provides the lowest distortion. Because the inductor is an energy-storage device, the plate voltage is able to swing 100 percent above the B+ plate supply voltage. This allows a lower B+ supply voltage to be used, while doubling the headroom. The output of the LA-1 is over 40 volts rms before clipping occurs. Only 4 dB of feedback is used to stabilize the gain and make the frequency response less sensitive to loading. The manufacturer claims that the LA-1 can drive loads as low as 8 Kohms and still meet specifications, allowing it to be used with low-input-impedance solid state amplifiers.
The power supply for each channel has MOSFET source followers that serve as low-gain regulators, eliminating any coupling that might occur between the two channels through the power supply. The topology provides good regulation without the transistor sound of high-gain op amp regulators. Protection resistors and diodes are used to prevent damage to the MOSFETs. A DC heater supply for the tube filaments permits the use of tubes that would produce too much hum if AC voltages were used. A soft-start is used for powering up the filaments, which delays high voltage application to the plate circuit, extending tube life.
The LA-1 uses another unique design feature called Cool-Swap. This circuit lets the tubes run cooler, extending tube life even further. Because the 5687 tube employs a split filament, it can run from either a 6.3 or 12.6-volt supply. This permits only half of the heater to be used. The result is that the unused half becomes a spare, and when it comes time to replace the worn tubes, the two 5687s are swapped between channels, and the previously unused sections are brought into use. Another benefit of this configuration is reduced crosstalk between channels, since only one tube is designated for each channel.
The LA-1 has a business-like appearance look that reminds me of the well-built instruments in a university research department. It looks handsome and utilitarian rather than flashy. Operation is straightforward. The large volume control dominates the front panel is a stepped attenuator with 24 settings. Below the volume control is a smaller input selector switch for up to five sources. To the right and left of the input selector switch are the balance controls, one for each channel. I would be willing to buy John Atwood a nice dinner for including that feature. So many designers do away with the balance controls in the interest of purity, but it is self-defeating. To the left side of the volume control is the power switch with its associated indicator, and to the right is the mono switch with its LED. The rear panel has five input jacks and two output jacks, all RCA. An IEC power connector, grounding lug, and fuse holder complete the rear panel.
Putting the LA-1 into my rack brought some nice surprises. Real estate in my rack is precious because it only has three shelves, and the LA-1 didn't take up the full width of a shelf. I especially liked the feel of the stepped attenuator. Its smooth yet positive action reminded me of my GAS Thaedra. When I flipped up the tiny on/off switch, the soft start sequence began and the power indicator glowed red for forty seconds. The muting relay then announced itself, and the LA-1 was ready to go. I hooked it up to the First Watt F1 amp and fed it with a Marantz SA-11S1 SACD player, using both DNM and Virtual Dynamics David cables.
At first, the LA-1 did not sound noteworthy, so I let it run continuously for a little more than a week. When I listened to it after the run-in, it sounded better, but still fell short of my expectations. With the help of Charlie Santmire's crew at The Sound Environment, I was able to try some different interconnects, and found that the LA-1 sounded best with a shielded cable between it and the amp—the sound was now more natural. I let everything run continuously for two more days, using my FM tuner. At one point, my wife asked me what the applause was. When I told her it came from the stereo, she was surprised, and my daughter mentioned that earlier in the day, she had thought someone was downstairs talking. My curiosity was aroused, and I went to hear for myself. I could tell that the sound was special as soon as I started down the stairs. There was a natural flow and ease that made the music more compelling. As I walked into the dark listening room, it felt like I was going into an underground jazz club. I was anxious to sit down, become part of the scene, and not miss a moment of the performance.
What I heard through the tuner was more dramatic than before, with better dynamics. The music had a bounce that I had not previously experienced. When I switched to CD, Nickel Creek's first release had that same drama, and it sounded like the performers were on stage in front of me. Loud sounds seemed louder, but not forced or electronic. Soft sounds were softer as well, and everything in between seemed to have a more natural dynamic scale. The only way I can describe what the LA-1 was doing is to say that it had a more dynamic linearity. Its clarity and speed also scored points. I could hear more of the acoustic environment in which the recording was made. The corners of the soundstage were better defined, and I could hear more of the decay of notes as they disappeared into darkness. The LA-1's whiter sound seemed to illuminate the soundstage better, and reminded me of the Audio Research Classic 60 tube amp I owned years ago. I could hear virtually no noise coming from the Artemis, which may explain why I was able to hear so far down into the mix.
The bass was better defined. Instruments had better separation. Strings and vocals had better texture and harmonics. On the Nickel Creek CD, it was easier to hear the pick on the guitar strings. The starts and stops on the mandolin were more pronounced. I could precisely hear singer Sara Watkins' intimate relationship with the microphone. On the Patience Higgins Live in Harlem CD on Mapleshade, I could hear the telephone ringing more clearly in the background, to the point that it became annoying. The drummer's cymbal work was more apparent, and more enjoyable. The background conversation on the second track made me feel that I was a witness to an occasion in which everyone in attendance was thoroughly enjoying themselves. Drum work was delineated to the point that I could hear the tightness of the skins. I didn't however, hear the roundness of the drum itself, as I was used to hearing with the Mini Max. I didn't care. I—along with everyone else in the club—was having such a good time.
I could follow instrumental lines with more ease. I was better able to hear the percussionist's work on the congas. I could now hear the manipulation of the reed and mouthpiece on the saxophone. The squeak on the cymbal in the second track was more noticeable. Bass was better defined and fuller, without bloat. There was that telephone ringing again. The piano was more full-bodied, giving it more of a place in the set. I could understand Higgins' announcements much better than I could before. The performance had more coherence. Everything sounded more natural. The LA-1 did not have the lush, wet sound that some tube components deliver. Instead, the music had speed, along with harmonics and fullness. Listening to Live in Harlem through the LA-1 was like listening to National Public Radio's Toast of the Nation program on New Year's Eve, when they broadcast live feeds from jazz performances across the country. The music sounded more spontaneous.
I put on another great Mapleshade recording from Pierre Sprey, The C-Nuts, a raucous, jazz/swing session. I was able to hear a larger space in the front of my listening room. Pace and timing were more engaging, with better transient attack. The interplay between the musicians was more noticeable. The LA-1's articulation was a strength that kept showing up on vocals. I was better able to understand the lyrics. Cymbals again sounded more natural. I even paused the player to go to my son's drum kit and tap the cymbals for comparison. Although this was a stark reminder of how far we still have to go to reproduce the sound of cymbals, the LA-1 provided a measure of improvement.
I don't often listen to Patricia Barber, but listening to Modern Cool through the Artemis gave a better front-to-back perspective. Barber's voice sounded darker and huskier, and was more dramatic relief against the background. The midrange had more presence. I stayed glued in my seat, wanting to hear all that the LA-1 was revealing. Barber's voice had a foreboding sound that gave it more suspense. I was also able to hear the studio musicians more clearly, and better understand their contribution to the music. I felt I should listen to Patricia Barber more often.
What use is audio equipment if it can't play rock music? This has been a big consideration of mine since I cast off my planar speakers. On Creed's album, Human Clay, the guitars on "What If" emanated in space much better. With better delineation, the drumming was more intense. Scott Stapp's singing had better focus. The beginning of the fourth track startled me with its suddenness. I was also able to hear talking in the background that had gone unnoticed before. The system had more drive than I was used to hearing with rock music. The compression used in the recording was less obvious and objectionable. The drums on "Never Die" sounded much better. On "Wash Away Those Years," the fading bass line had much more focus and energy, and the desired effect was much more apparent.
I tried using the LA-1 with other amplifiers. With the Eastern Electric M520 integrated amp, I wasn't able to eliminate a noise that sounded like tube rush, whether I used the pre-in jack or connected the LA-1 through a source input. Changing cables didn't help either. My ATI 1502 solid-state amp was also a no-go, because the Euro-nanny speaker connections were too large to hold the banana connectors, and to rub salt in the wound, the plastic covers over the connections were too small to allow me use spades. The Golden Tube Audio SE-40 totally destroyed the quickness and fleet-footed quality of the LA-1. The GAS Ampzilla was a surprise when partnered with the LA-1. The sound was fast, and had more fullness, but was just a tad electronic. Still, the fact that the Ampzilla fared so well with the LA-1 was testament to the thirty-year-old design.
Lord knows how many preamplifiers I have had in my systems over the years. I have tried tube and solid-state units, passive and active, domestic brands and imports, and everything in between. The Artemis Labs LA-1 line stage left an impression on me that was hard to shake. I felt so much more connected to the music because of the dynamic drive and clarity that the LA-1 gave to my system. The ability to listen further into the performances was captivating. The partnership of the First Watt F1 with the LA-1 left me little to want. Both components are lightning fast, with super-low noise floors. While the Mini Max is no slouch (and is a screaming bargain), the LA-1 provided even more magic. The system synergy could be felt as well as heard. I had a more emotional connection with the music, with better imaging to boot. The LA-1 brought so much to the table that the experience had me filling out the warranty card. This is one for the ages. John Mazur