Solid State Preamp Reviews

The Iris's build quality is very good at the price, with metal-film resistors and what appear to be polypropylene capacitors used in critical locations. The main power supply consists of an LM317/337 voltage regulator pair, following two 2200µF reservoir caps, which provides regulated and smoothed ±16V rails, though local decoupling is provided for each channel of the phono and line stage with electrolytics bypassed with plastic-film capacitors. All the integrated circuits used are socketed, for easy replacement, and, with the exception of the Tape, Mono, and EPL switching, the lack of mechanical parts in the signal path should give a long, trouble-free life.

The Sound
Hafler's Iris served general preamplifier duties in my system for eight weeks or so; I also used it as the preamplifier in the blind power-amplifier listening tests that Will Hammond and I carried out at the Bay Area High End Hi-Fi Show in April. First impressions of the Iris's phono section were of a lightish tonal balance, rather dry-sounding when compared with the much more expensive PV9 and Vendetta preamplifiers. The low bass didn't seem as extended as I expected, and the upper bass was a little fat. This latter characteristic added a useful degree of bloom to orchestral music—the bottom strings of the soothsayer's harp at the introduction to "Vysehrad" from the Berglund/Dresden Staatskapelle Má Vlast (SLS 5151) literally purred (footnote 2).

When the Hafler was compared directly with the PS Audio 4.6/M-500 combination, the more expensive preamp excelled at the presentation of recorded space. On "Tip of My Tongue," from John Hiatt's classic Bring the Family (A&M SP5158), Jim Keltner's drums were set much farther back via the PS. In addition, the Hafler presented Hiatt's voice with too dry a tonality. This is not to say that the music failed to communicate: the Iris is definitely a contender, but the PS goes just that essential bit further.

On Ronnie Scott's tenor sax solo on "The Look of Love" from Casino Royale, again the PS enabled you to hear the artificial reverberation just that bit clearer, allowing the instrument to be better defined in space. One puzzle here was that the Hafler presented Dusty Springfield's voice as being definitely higher than the PS. (I have no idea why that should be, nor indeed how electronics can produce a three-dimensional effect from one-dimensional recorded data that synthesizes an illusory two-dimensional image. Any hypotheses, all you psycho-acousticians?)

When it came to piano recordings, things were not so clearcut between the two solid-state preamps. Listening to the superb Nojima Liszt album on Reference Recordings (RR-25), the Hafler was better at presenting the body of the tone while the PS emphasized the leading edges and the sound of the hammers. This surprised me—my previous auditioning had led me to expect the opposite. The Hafler piano was usefully fuller in the left-hand registers. The preamp's dry nature, however, meant that it fared less well when string instruments entered the picture. David Abel's Guarnerius was just a little too rosiny, even "whispy," on his Wilson Audio recording of the Beethoven Op.96 violin sonata (W-8315). It has to be admitted that neither of these preamps can rival the phono section of the $3000 Conrad-Johnson PV9 when it comes to the optimum presentation of string-instrument tone.

All the above comparisons were made with the PS Audio used in its Straightwire mode, where the wipers of the volume control are fed directly to the output sockets. To make a fairer comparison between the PS and the Iris, I repeated a number of tests with the PS's line stage in circuit, readjusting the levels accordingly. Now things were much closer, the PS sound becoming a little sibilant. It still wasn't as dry as the Iris, however, the Hafler still diminishing somehow the contribution of recorded ambience.

The Hafler's line stage is fundamentally relatively neutral, which is one of the reasons why I decided to use it for the Hi-Fi Show tests. This is in itself quite an achievement for an inexpensive preamplifier. Continued bypass testing under more familiar conditions, however, convinced me that it, too, was a little on the dry side. Listening to Peter McGrath's recording of a Byrd mass for Harmonia Mundi USA (HMC 905182) revealed the singers to be in a slightly smaller acoustic space than via the Line Drive alone. Careful listening to the Flim & The BB's "Tricycle" track (from Tricycle, DMP CD-443) revealed the delicate ambient shroud on the opening piano eighth-notes to be diminished. But the effect in absolute terms was small—bypass testing is almost too revealing of such effects—and such great all-digital recordings such as the new Roger Norrington "original-instruments" Berlioz Symphonie Fantastique (EMI Reflexe CDC 749541 2) didn't lose too much of their bloom.

Tonally, my own master tapes revealed the Hafler's line stage consistently to add a degree of HF whispiness to violin tone, very similar to the sound of the phono stage but to a lesser degree. Again, the upper bass region seemed a little less clear than the reference straight-wire position, accentuating the second-harmonic rich nature of the bass guitar spectrum. From analogous experience with other preamplifier designs, this is the kind of problem generally solved by stiffening up the power supply, but that, of course, is always an expensive solution and would put the Iris into a completely different price category.

How about the ultimate resolution of the Iris's line stage? My standard test is to use the Gluck "Dance of the Blessed Spirits" track on the HFN/RR Test CD. This was recorded in a recital hall in London's Kensington region, where a small half-shell behind the stage helped ensure that the sound of the piano was consistently hooty in the midrange. Ivor Humphreys demonstrates the ability to get a wonderfully creamy tone from his flute (a 19th-century wood and silver Rudall Carte, I seem to remember), particularly with the first half of the track, recorded with crossed Coles 4038 ribbon mikes. For me, however, the purpose of the track is that it started to rain heavily as the recording took place. Usually, you can hear that there is some kind of undifferentiated pinkish noise in the background, but with the most revealing components and systems, you can actually hear the gentle sound of rain striking the auditorium's glass roof—from CD, no less! Did the Iris line stage pass this test? No, but it certainly came close, which is very good performance at the price. Again, however, the sound became a little drier and whispy in tonal quality.

Finally, I must say that I found the "analog" remote control wonderful. The advantages offered by the ability to fine-tune listening level and channel balance in such a straightforward manner from the listening chair can't be sufficiently stressed, in my opinion. Given my druthers, I would have liked to have an absolute-phase switch on the remote, though it is hard to see from the schematic how that could be achieved. The only drawback to the remote is that it can't somehow be locked out. Those with children should get in the habit of checking that the remote has not been set to some crazy volume setting before pressing Play on their CD player.

I had a disturbing experience when using the Iris at the Bay Area Show: I had set the volume to zero with the front-panel control before one of the question-and-answer sessions. A question then came up from the floor concerning high-frequency hearing loss. I thought that the best way to answer this question would be to play some HF tones from CD to see how many of the audience could and how many couldn't hear each one. On went the CD, I punched in the track number, and reeled back in horror as the VTL power amplifiers pumped out 300W of 16kHz sinewave. Before I could dive for the mute button, the B&W 801s' protection circuits cut in—thank goodness: changing tweeters in mid-public demonstration would not be my first choice of occupation—and we all lived to hear another day (apart from the people in the front row who had neat little holes drilled in their foreheads).

What had happened? The Iris remote had been placed on top of one of the speakers where someone had inadvertently twiddled the volume knob to maximum. If you cast your eyes back to my description of how the Iris works, you will recall that operating the remote volume or balance controls transfers control to the remote, deactivating the front-panel settings: I thought the preamp was fully down, as indicated by the front-panel knob; the preamp was set to full gain, as indicated by the remote knob which, of course, I couldn't see. To avoid this problem, the Iris has a front-panel green LED which illuminates when it has control. Under the stress of the show, I hadn't noticed that this had gone out when I fired up the CD player.

Conclusion
Although it does have more of an editorializing nature than the best preamplifiers around, in its basic $650 configuration the Hafler Iris represents good value for money, offering as it does a reasonably neutral line stage and a very low-noise MC phono stage. I have to say that it is bested sonically by the most expensive version of the PS Audio 4.6, but that is perhaps an unfair comparison as the PS approaches twice the basic Hafler's price.

The least expensive version of the PS competes head-on, however, with the fully remote-controllable Iris. Here the comparison hinges on whether you would want to own a conventional preamp with an excellent phono stage and the ability (in its passive Straightwire mode) to get a fundamentally neutral sound from CD but perhaps at the expense of overall dynamics, or opt for one of the most convenient-to-use preamps around, also possessing a good phono stage and a line stage offering the same performance standard as the PS, at the expense of a less deep delineation of soundstage depth and a drier, slightly more HF-prominent presentation of CD sound. The choice is yours, but I can confidently recommend the Iris preamplifier in Class D of Stereophile's "Recommended Components" listing—it is a fundamentally musical performer at an affordable price.

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Footnote 2: Disturbed by my advocacy of this particular recording, Will Hammond, late of Radio KPFK's "In-Fidelity" program in Los Angeles, recently sent me a copy of the 1960 Supraphon recording with Vaclav Talich conducting the Czech Philharmonic, released here on Parliament PLP 111. "That'll show what a conductor with the music in his blood can do!" he rumbled. Well, yes, Will, point taken, but the Supraphon sound is so thin. I'll continue to recommend the Berglund for those who need the best of analog sound.