Tube Preamp Reviews

The most startling aspect of the Jadis's performance was how it re-created the dynamic range of live music. Whether it was a solo instrument such as Taj Mahal's National steel-bodied guitar (Recycling the Blues & Other Related Stuff, Columbia 31605) erupting in full force from soft to loud, or a full orchestra revving up in a crescendo of orgasmic proportions, the energy release was sudden and startingly real—volcanic, if you will. I never felt that the Jadis was holding back or blunting the power and rise-time of orchestral peaks. I've never heard a preamp so convincingly delineate the dynamic range from soft to very loud. I was confident at all times that the Jadis was releasing 100% of what the program material had to offer.

Where the Jadis wove its magic most effectively, and where its dynamics mattered most to me, was in its portrayal of solo instruments. The dramatic bite of a soloist immersed in the ambience of a sympathetic hall was beautifully conjured up within the confines of the soundstage. The bloom of the spatial outlines, the modulation of a singer's chest, together with the sudden release of breath, were all captured with a realism that approached that of live music. The shock of hearing Lesley's voice reproduced on "Jazz Me" (Lesley, ViTaL Records) with almost its full dynamic range intact—essentially as I had heard it in the recording studio—still reverberates through my psyche.

The illusion of live was greatly facilitated by the JPL not only because of its inherent sense of dynamic gradation, but also because of its soundstage transparency and mastery over the elements of spatial resolution. The sense of transparency was so strong that at times I felt as though the Starship Enterprise's Scottie had beamed me right into the original performance space. That, together with incisive spatial outlines, liquid phrasing, and purity of harmonic textures, helped me transcend the reality of the situation. The seemingly empty space between and behind the A-1s was now populated by phantom musicians.

It takes some mental gymnastics to involve body and soul in so blatant an illusion and to allow the music to communicate effectively. The Jadis was able again and again to establish a blend of aural cues that allowed me to be teleported into the essence of the music. Image outlines were palpably focused. Massed voices were naturally resolvable, without the smearing or blending of spatial detail so common to a host of preamps.

The degree of spatial focus, and to a lesser extent the liquidity of harmonic textures, turned out to be functions of the brand of tube used. (Of course I had to experiment. Does a bear poop in the woods?) Victor Goldstein of Fanfare International was kind enough to provide me with genuine Telefunken and Siemens 12AX7s, and samples of a special run of Yugo 12AX7s per Jadis specs. I also tried a number of Chinese 12AX7s, including the Golden Dragons; to top off the fun and games, I included some 5751s from my own secret stash.

The preamp appeared to be voiced around the stock Yugo tubes, as none of the Chinese tubes worked well—at least as a direct substitution for the gain stages (the two tubes closest to the front panel). All of the Chinese tubes sounded bright and somewhat coarse through the upper midrange. By comparison, the stock tubes sounded smoother and quite a bit darker. Some have accused the JPL of being colored on this basis alone. The Jadis/Yugo specials were smoother, sweeter, and more romantic yet. My favorite 12AX7 turned out to be the Siemens. Victor told me not to bother trying to hunt these down, as he'd bought out the whole lot of what are new original stock (NOS). With the Siemens (Victor only sent a pair, so I left the cathode follower alone), the presentation was gorgeously detailed, yet effortless, with a flair for harmonic purity.

However, none of the 12AX7s, including the Siemens, yielded as tightly focused a presentation as my gold-pin Sylvania 5751s—at least before the arrival of the Ensemble TubeSox. Understand that the 5751 (sadly long out of production) has a lower mu than a 12AX7 (70 vs 100), and as such does not represent a direct substitution for a 12AX7. Gain and possibly circuit feedback may be affected. I say "may" because modern 12AX7s have had a hard time meeting their mu spec anyway. Being lower in microphonics typically gives the 5751 a sonic advantage which translates into cleaner and sweeter harmonic textures and less spatial fuzz. Note, however, that not all 5751s are born alike. Most past production was churned out by General Electric (selected samples are fine), the rest by RCA (usually not as rugged or as clean-sounding) and Sylvania (in my experience, the best-sounding).

With the arrival of the Ensemble TubeSox, matters changed considerably. Slipping the Sox over the Siemens tubes instantly snapped the soundstage into much tighter focus. So attired, the Siemens took on the spatial precision of a 5751 while retaining its inherently lush harmonic voicing through the midrange. The ultimate tube complement I settled on included the Siemens for the gain stages and a Golden Dragon 12AX7 for the cathode follower. That's right—without the Golden Dragon, the extreme treble lost air and sounded a bit closed-in.

The next best tube makeup that is readily available would include the Jadis-branded Yugo 12AX7s but replacing the standard output follower with a Golden Dragon 12AX7. I should emphasize that imaging precision suffered with the stock tubes, as did tonality through the upper octaves. Harmonic textures were a bit darker and shut-in compared with the real thing.

As far as resolution of detail, there was plenty. The JPL poured forth low-level detail with the sparkle and naturalness of a mountain spring. None of this information was artificial, as is often the case with an overly etched and bright preamp, where detail is zinged out with sufficient ferocity to singe one's eyebrows. The JPL did not hammer out detail synthetically, but resolved it the old-fashioned way: by clearly enunciating transients, quick attack followed by tightly controlled decay. It was possible to delineate the decay portion of transients all the way down into the noise floor of the recording. This greatly enhanced the sense of being there.

Bass performance was dependent on the choice of partnering power amp. However, even under the best of circumstances, deep bass extension failed to match that of the FET-10/e line stage. There was plenty of punch and kick-ass intensity on display, but deep bass information below 40Hz just wasn't retrieved as well. There was no difficulty in controlling the mid- and upper-bass regions. James Leary's solo on "Summertime" (on the Lesley album) was as tight and defined as I'd heard it in the Studio. James's unusually sure and expressive fingering really digs down. None of this is lost on the JPL. It resolved bass detail as well as any solid-state preamp I've heard. But it buried transistorized wonders in its ability to project the authentic size and weight of, say, cello or double bass. The fundamental range of these instruments was fleshed out with lifelike tonality.

A point of reference
Because the Audio Research LS-2 line-level preamp has been highly touted in the press, including a rave review from our own Bob Harley, I very much wanted to pit the Jadis against it. Being a known quantity, the LS-2 would provide a reference point by which to judge the Jadis's sound quality and value.

Prying the LS-2 out of Bob's hands wasn't easy. Finally, a window of opportunity opened. Bob was off for a week in Japan, and consented to ship me the unit for a quick listen. At last the two did battle.

Although I felt the LS-2 to be an excellent value at its price point, it was also clearly outclassed by the JPL. For starters, the LS-2 veiled the soundstage, reducing the sensation of being able to see far into the hall. It also failed to delineate spatial outlines as convincingly as the Jadis. Image outlines lacked either the 3-D palpability or the precision of focus afforded by the Jadis, proving fuzzier and more difficult to resolve through the LS-2.

The upper mids and lower treble were grainier and not as sweet as with the Jadis, especially in the upper registers of soprano voice. The Jadis navigated this whole range with much cleaner and purer harmonic textures. Treble transients were comparatively smeared through the LS-2, the JPL doing a much better job of caressing and unfolding transient attack and decay.

Finally, the LS-2 could not match the JPL's verve. The LS-2 blunted the release of energy, robbing the music of some of its dramatic intensity. I know that all of this sounds bad for the LS-2, but I emphasize that, on an absolute scale, the LS-2 is a very good line stage. It just suffers in comparison with a unit as sonically supreme as the JPL.

Cosmic Don, a good friend and a human being in touch with the great spirits that roam the cosmos, happened to be present for one of these shootout sessions. He liked the LS-2, but after hearing what the JPL could do, he nodded his head wisely, his arms thrust forward, and laid bare his gut feelings. Don is a man of few words, but they cut right to the core of the matter. Don felt that the JPL was simply more informative and spatially much crisper. Since Don is never wrong in such matters, I could only nod my head in agreement.

The only challenge to the Jadis I know of comes from the CAT SL-1. From my experience with the CAT's line-stage section, I judge it to be competitive with the JPL, but not quite the JPL's equal in propelling dynamics forward from soft to very loud. Neither is the CAT, in my estimation, as vivid in its portrayal of the soundstage.

Final thoughts
Merci and bravo, Jadis. I've waited a lifetime for a product like the JPL. For all the sonic happiness it's given me, I am sincerely grateful.

If ever I scale Mount Olympus, I'm sure that the JPL will be there, in the company of the Gods Themselves, crazy or not. This is one of those rare products guaranteed to dramatically improve your system. Be prepared for a dynamic eruption that will nudge you much closer to the illusion of live music.