January 1998

Cary Audio SLI-80 Integrated Amplifier

by John Stafford

I was quite interested in hearing more of the Cary line of amplifiers after the Montreal Hi-Fi show in February 1997 because I felt that the Cary/Verity room had some of the best sound of the show. I knew that Cary had some low-power integrated amps that could be classed as budget gear, so I called Audio Path, the Canadian distributor of Cary products, to see if I could get one in for review. It turns out that Cary had recently launched the SLI-80 integrated amplifier as an addition to their successful line of integrated tube amps, and Angie at Audio Path thought the new product deserved a listen. At $2,795 USD, the SLI-80 is not really in the budget zone, but I couldn't resist. Could you?

To my mind, tube amps are quite attractive, and the SLI-80 is no exception. The heft, materials, and components all spell quality. With a black anodized aluminum faceplate and chrome-plated stainless steel chassis, this amp is a thing of beauty, particularly when the exposed glowing tubes reflect off of the polished chassis. Remarks on the SLI-80's looks ranged from "someone's science experiment" to "a cute little city when the lights are out" to just plain "cool." There are no signs of corners being cut on this integrated amplifier. All parts fit extremely well, and there is point-to-point wiring throughout.

The SLI-80 is a minimalist design. From the front, there are three input selections labeled CD, Aux 1, and Aux 2. There is a single volume control and a balance control. The on/off switch has a standby mode which is good for warming the amp up and keeping it warm for extended periods for "instant" listening enjoyment. At the back are all high-quality gold-plated connections, and there are even RCA jacks for connecting a powered subwoofer. You could use this connection as a pre-out too, but for this kind of dough you're not likely to relegate the SLI-80 to line-level preamp duties. The only thing I found missing was a phono stage, a problem if you're into vinyl.

The SLI-80 is the big brother to the SLI-50, which runs at 50 watts ultralinear and 30 watts triode. With beefed-up transformers and output tubes, the SLI-80 runs at 80 watts ultralinear and 50 watts in triode mode using the Tesla KT88 output tubes. I was a little confused about the difference between ultralinear and triode mode, so here's the explanation, in English: The KT88 is a pentode tube that can give higher output and lower total distortion than a triode tube. So why run it in triode?? The reason is that the Cary runs in class AB and will operate in pure class A longer in triode than when it is set up to run in strict ultralinear. Also, many feel that the venerable 300B triode tube is the sweetest-sounding tube on the market and triode mode emulates the operation of a 300B.

Ignoring the numbers is sometimes considered a good thing, and the designers at Cary feel that triode mode is best. In fact, Cary ships the amp in triode configuration. Any change in operating mode has to be performed by a technician because it involves the removal or addition of two resistors, but the two options are available for those who feel a need for more power or better sound. I did all of my listening in triode mode and found the power to be quite adequate.

The SLI-80 uses a push-pull configuration. Huh? There are basically two ways to configure the output of an amplifier, be it tube or transistor: single-ended or push-pull. Push-pull uses pairs of tubes or transistors to boost the signal. Half of each pair boosts (or amplifies) the positive half of the audio signal, and the other half of each pair boosts the negative half of the signal. Single-ended amplifiers do not split the audio signal into positive and negative halves--the entire signal is amplified through one or more tubes or transistors. Think of it as a two-handled versus one-handled saw for cutting down a tree: two people (one on either side of the tree) are more powerful, but the one person doing all the work has more precision. There is an endless debate on the merits of single-ended and push-pull configurations, and I won't add to it at this point. Suffice it to say that the two camps are willing to give up a little of one characteristic of the sound to get more of another.

Tubes can sometimes be difficult to handle as far as bias adjustment goes. The bias adjustment on the SLI-80 is handled quite easily, although you will need a voltmeter that measures in millivolts. There are two jacks for measuring the level of each channel and there are controls beside the jacks to make adjustments, which are easily made using a flathead screwdriver. The recommended level is 80 millivolts.

Since the amp I received was the demo model, no break-in was required (other than an hour's warm-up) and that was immediately evident from the first time I listened. Equipment currently on hand in my system that shared time in the evaluation process includes: NAD 514 and Rega Planet CD players, Audio Alchemy DDE v1.2 DAC, PS Audio 4.6 preamp, Aragon 2004 power amp, Arcam Alpha 6 plus integrated amp, Triumph Signature speakers, Blue Circle BC83 Power Line Pillow, XLO Pro digital cable, Stager Sound interconnects, and Canare Quad Star speaker cables.

The SLI-80 is one of those nice-sounding amps that makes it hard to get past the beautiful midrange and general "tube sound" and really get a handle on what is happening. When I say "nice," I mean it as a high compliment. Very smooth mids and highs are the order of the day, and after a steady diet of budget transistors, it was a welcome change. This is one amp that you are not likely develop listening fatigue from in an hour or so.

I don't often refer to the term timbre when discussing equipment because I find the term rather vague. But when listening to stringed instruments with the SLI-80, timbre was the first word that came to mind. Whether it is the sweet sound of a violin or the mournful cry of a cello, to my ears, the SLI-80 captured the timbre of these instruments. In checking the dictionary definition of timbre, I came across a phrase that really hit home: "tone color." This definition, to me, captures the essence of timbre by suggesting that there is more to the sound of an instrument or vocal than just a bunch of measurements. It is a unique signature that when all other description fails, the correct timbre captures the "color" of the sound.

I found that the separation of instruments and vocals to be quite exceptional with the SLI-80. This is due to the good sense of air I found around each of the performers. With the beautiful mids, the correct timbre, and a good sense of separation, this amp excels at the acoustic end of the musical spectrum. I spent a lot more time listening to jazz, blues, and classical with this amp than I would normally.

Along with the nice tube sound came the other trappings of tube amplification. While the bottom end was, relatively speaking, well defined at low volume levels compared to some solid-state equipment, I found that at higher volumes the bottom end really lacked the slam and dynamics of transistors. This confirms to me the need for the subwoofer-out option. That is not to say the bottom end was cut off. Quite the contrary, it was well controlled and extended right through the volume spectrum. While this made for fabulous double-bass reproduction in jazz and blues, it made for a less driving rhythm in rock and pop (sorry, should I have said alternative music?). Also, after the first week or so I developed a sense that the highs were somewhat rolled off with rock and pop. Between these two characteristics the SLI-80 gave a less-exciting performance than I am accustomed to with this type of music.

Realizing that the bulk of my listening was done with components worth less than half the price of the SLI-80, I thought it was a worthwhile endeavor to put it into a system that would really put it through its paces. To that end, I made arrangements to listen to it with a VPI TNT Mk III turntable with a Benz Micro Glider cartridge, run through the phono stage of a Classe D7 preamp and into some ProAc Response 2 speakers (Cardas Twinlink and Hexlink cabling). For comparison purposes, a Blue Circle BC6 25-watt single-ended hybrid amplifier using the Classe for all preamp duties was also used. The $3750 BC6 is the little brother to the BC2 monoblocks that were reviewed by Doug Schneider in the January 1997 issue of SoundStage!. And more recently, the BC6 became Todd Warnke's new reference amplifier at that price point.

Even in this configuration it was hard to get past how "nice" the SLI-80 sounds, but I managed to wipe the smile off my face and get critical. It was with this very revealing equipment I noticed that while the SLI-80 had good air around the cymbals and snare drums, some etch was also present in the high end. Also, the detail and control in the bottom end was found to be a little wanting. This, however, was in comparison to an amp/preamp combination that costs double the price of the SLI-80.

It was during this listening session that I noticed how little the SLI-80 had to be attenuated to equalize to the BC6/Classe combo. In other words, I had to turn the volume way up on the SLI-80 to get the same sound level between the two. Further investigation lead me to discover that the gain at the preamp stage is only 15dB, as opposed to the 28dB gain with the Classe. One reason for this is that a lot of gain is not necessary with an integrated amplifier as there are no requirements to run long lengths of interconnect. It is also the case that you can run this amp at near full volume without wincing and running for the volume control. Bill Wright at Cary explained that they would rather have a wider practical volume spectrum than leave their customers with the illusion that there are gobs of power in reserve when the amplifier is already near clipping levels.

I also had an opportunity to play with VPI Magic Bricks and Black Diamond Racing Cones with this unit. Tube amps are susceptible to vibrations and other nasties, so tweaking is a natural extension of trying out a tube amp. While the SLI-80 was in the big rig, I tried the Magic Bricks. These are placed on top of the output transformers and provide load to reduce vibration. They are also said to have magnetic properties which help smooth out the performance of the transformers. What they did was help take that some glare off the highs and add a touch more control on the bottom end. The cones were tried in my system and the result was increased clarity and remarkably deeper soundstage. Be careful with cones and the like with this amp, however, as the weight of the unit made me uneasy about supporting the unit anywhere other than the location of the attached feet. Once the testing was done, I removed the cones because I was not comfortable that they were properly supporting the amp. I would recommend using cones or feet that screw into the location of the current feet of the SLI-80.

As with many debates in high-end audio as to whether or not one method or another is the better sounding, the whole integrated versus pre/power issue is really one of application. If there are advantages to one or the other, it is really a matter of how well those advantages are exploited that determines which way the sonic pendulum will swing--whether it's in favor or against that particular application of technology. In the case of the Cary line of integrated amplifiers, I feel they have managed to exploit advantages of a reduced signal path with fewer runs of interconnects and managed to minimize the interaction between the preamp and amplification circuitry. I quite often thought of the immediacy of the music, and I always related that to the elimination of the preamp-to-amp interconnect and RCAs.

Overall, I found the SLI-80 to be an exceptional performer with a stunning midrange. Is it tubey? You bet! This amp is not for those folks who are into big dynamics and bottom end unless you want to find a powered subwoofer to go with it. I would recommend it to those looking to keep it simple. If you're into jazz, blues, chamber music and other kinds of acoustic music, with a smattering of rock and pop thrown in, this amp may well be for you. If you're listening to a high percentage of rock, pop, techno and dance, you'll do well to steer clear. It is a refined performer for those audiophiles looking to keep their systems simple and reap the rewards of tube amplification, and at 50 watts a side, it will drive a pretty wide range of speakers to reasonable levels.

...John Stafford
stafford@soundstage.com

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