Cary Audio Design SLM-200 monoblock power amplifier
by Jonathan Scull
What would be the result, I wondered, if well-known single-ended aficionado Dennis Had of Cary Audio turned his attention to push-pull amplification? I pondered this question while perusing Cary's attractive color brochure at HI-FI '96 last June. The SLM-200 caught my eye: a 200W class-AB monoblock, 100W in triode mode (as delivered, dealer-selectable).
I looked closely and saw that the amplifier was stuffed with KT88s. Squinting, I could just make out that these KT88s were Golden Dragons. Upon inquiry, Dennis allowed in that aw-shucks North Carolina way of his, that, yes, in his opinion, the 200 was, after much work, indeed a fine-sounding amplifier. Raising his eyebrows meaningfully, he mentioned that it now came equipped with the new Teslovak™ KT88S, available from Penta Labs.
Slovakian Tube Doings
In due course – Carolina Standard Time – a pair of the big Cary monoblocks arrived. That is, one of them did. Our Man in Brown was evidently suffering from fits of the vapors--UPS misplaced the other amplifier deep within the bowels of the local depot, finally tracing and laying hands on it about a week later.
Both crates had obviously been much mauled by their Pre-Crustacean handlers. Unpacking the second amp, I noticed a scuff mark on its thick, attractive, gold-anodized faceplate. Then I heard from Dennis that they'd experienced a curious failure on some of the first batch of tubes delivered--including the ones we had, in fact. Of course.
The damage occurred when the shipping container was subject to Abrupt Handling by the atavistic drones of UPS. Unbelievably, a few tubes actually suffered from a shift--and actual displacement--of their internal frameworks. They were, as a result, prone to arc.
I identified two tubes that were sparking, for which Dennis immediately sent replacements, matched to the amp by serial number. While these were fine, a third KT88S acted up almost immediately afterward. It wouldn't flash during play, but when I switched from Standby to Operate it would arc and take down the tube fuse. And because there's only one tube fuse and one line fuse on the rear apron of each SLM-200, and only one bias control for all eight tubes, these babies require matched octets--that arcing KT88S resulted in a call from Steve Sanett at Penta Labs, who quickly supplied a second set of matched octets from the latest stock.1 (Penta offers a six month guarantee on the tubes, and has addressed the arcing problem by beefing up the nickel-alloy frame grid rods.)
Description: Monoblock tube power amplifier with class-AB1 push-pull output stage. Tube complement per side: two 6SN7, eight KT88. Output power: 100Wpc (20dBW) in triode mode or 200Wpc (23dBW) in ultralinear mode, dealer-selectable, both 20Hz-20kHz into 2,4,8 ohms with 3dB global feedback. Sensitivity: 700mV for full output Power consumption: 240W (Operate), 122W (Standby).
Dimensions: 12 l/4''W by 8 l/2'' H by 24" D. Weight: 75 lbs net, 100 lbs shipping.
Serial numbers of units reviewed: 960685/960686.
Price: $8995/pair. Approximate number of dealers: 63.
Manufacturer: Cary Audio Design, 111A Woodwinds Industrial Court, Cary, NC 27511. Tel: (919) 481-4494. Fax: (919) 460-3828.
I set the SLM-200s up on AudioPoints on top of a pair of small Michael Green TuningStands. Then I sprang a pair of Italian Bluenote Midas Tube Dampers around each pair of 6SN7s, and dropped a Shakti Stone on each of the power transformers.
The 200s looked handsome on the "Night Sky" finished stands. Their burnished gold faceplates (each sporting a retro green Magic Eye) were nicely set off by the stands' large brass footers and black corner posts. The amps looked like attractive, eager hunting dogs ready to spring on gilded feet.
The amps are decked out in what I'd describe as Classic Americana style -- they'd look at home in the Ralph Lauren emporium at 72nd and Madison. (I see green baize wallpaper hung with19th-century hunting scenes, the faint odors of old leather and Cuban cigars... )
You will observe from the photo that the SLM-200 adheres to contemporary Euro layout: not terribly wide, but fairly deep. The rear apron accommodates a standard IEC receptacle and the input RCA jack. There are also 2, 4, and 8 ohm binding-post pairs to choose from. On the rear two-thirds of the upper deck, the black power and output transformers are set in staggered arrangement, alternating with four cylindrical, black-sheathed power-supply storage capacitors (computer-grade electrolytics of 1500µF at 450V).
The eight KT88s are mounted on the front third of the amp; no tube cages are supplied. The top chassis cover plate features subtle graphics embellished with a typeface much like that found in dialog panels of silent films. Un hommage à la Belle Époque, as it were.
The Teslovak KT88Ses look muscular and purposeful ranked in two curving rows of four push-pull pairs. On the leading edge of the top plate are the On/Off and Standby/Operate toggles--heavy-duty, old-style switches that look and feel as if they'll last the lifetime of the amp. Standby drops the voltage to zero (with voltage potential of 250V but with no current capability) and keeps the filaments brightly lit (very cheery at night). The amps thus remain ready for listening at any time.
Normal operation from a cold start requires 30 seconds in Standby before going to "high boltage," as José Jimenez put it many eons ago. (Talk about politically incorrect... imagine a comic act like that today. My father thought Bill Dana was a scream.)
Full-power mode prods to life the gee-dad-it's-a-Wurlitzer green Magic Eye. This is a circular version of the indicator I recall from a mid-'50s Telefunken receiver in my parents' bedroom, beautifully finished in ivory and dark brown, with sexy rounded piano keys with which to select the frequency band. It had a captivating green tuning tube that closed in the middle when top dead center on a signal. The multicultural hubbub on the Telefunken's shortwave bands was fascinating; I had a sense that it was bringing me closer to something I couldn't then name. Perhaps an inkling of the Global Village to come? (Although rec.audio.destroy-all-subjectivists hardly seems a worthy flowering of the concept.)
Back to the Future: When the Magic Eye wraps around and touches itself (hoo-hah), the SLM-200 is pushing a full 100W in triode mode. As the green strakes overlap, you're into the amp's headroom (which seemed considerable, by the way). Dennis says the SLM-200 will do 130W in triode before hard clipping sets in. This never became an issue; there was, for the most part, more than enough power to drive the music to mind-numbing levels with the 87dB - sensitive Avalon Radians. If not sounding quite as macrodynamic and BIG as some of the solid-state boys manage, the Cary was nonetheless impressive.
The SLM-200 is built up of grain-oriented stainless steel, with a nickel-chrome-plated chassis optional. At a dense 75 lbs each, it feels as solid as the proverbial brick - when I threw the switch, the whole affair felt reassuringly hewn-of-a-piece. The amp features oil-filled coupling capacitors, 1% metal-film resistors, and point-to-point wiring.
It's true that there remain a few build compromises in comparison to the +$23k list price of the four-chassis pair of Jadis JA 200s that usually sit between the Avalons. To get picky, let's mention the transformer covers. On the Cary they're formed with a bent metal box and a somewhat déclassé spot-welded top-plate, which shows the seam. The Jadis is finished in much more elegant fashion. The point, of course, is how the Carys sound in comparison to the suave French monoblocks at a bit less than half their price.
Another minor annoyance was the rather soft, all-copper binding posts. I appreciate the fact that they were chosen for sonics, and I know that typical users won't change speaker cables at the same rapid-fire pace as do reviewers. But these connectors feature a post with a slice of its center section removed. They look like little copper tuning forks when seen from above. This way you won't strip the threads as, bug-eyed with anticipation, you rabidly screw down the terminals. If you do go too far, the two halves of the post deform toward each other. Should this occur, one need only to back off and use a screwdriver blade to separate the two halves of the post, then rethread the screw-down top and begin again.
Dennis Had prefers triode mode, and that's how the amps were supplied.
However, I recall cursing a mighty blue streak as I struggled to attach two unwieldy runs of Synergistic Resolution Reference and one run of their Signature No.2 for the bass. This proved impossible, as the 4 ohm post never fully recovered from its initial deformation. Tightening down on that tap was always a delicate operation. (And it's the 4 ohm tap that did the trick with the Radians.)
OTHER SYSTEM DOINGS
Bowing to outrageous fortune, I wired up an XLO Signature bi-wire pair, along with a third standard run for the bass. I also dropped in all-XLO line-level interconnect for The Perfect Connection contact-enhancement treatment that I reviewed in the March issue. Shortly thereafter, a freshly assembled bi-wire pair of Synergistic Rez Reference made an appearance, and life got easier. (They took forever to break in, however. Impatient audiophiles are advised to cultivate other pursuits.)
The Rez Reference/Signature No.2 speaker cable and Synergistic's Designer's Reference line-level lashup were used for best results throughout most of the test period. They proved clean, clear, transparent, extended, fast, and yet harmonically plush through the midband and highs. Their bass range was altogether above criticism. And what a huge and airy soundstage! They come as close to the Zen sense of not being there at all as any interconnect I've heard. Take a look at my sidebar conversation with Synergistic's Ted Denney regarding the build details of this mighty green stuff. I also used Ted's AC Master Couplers throughout the system.
A few other reviewerly details: I listened to the SLM-200s almost exclusively linked to the YBA 6 Chassis dual-mono-everything phono preamplifier. At $19k, the space-robbing 6 Chassis has proven over time to be utterly the reviewer's tool.
CD front-ends included the YBA CD1 Blue Laser, Forsell Air Bearing Transport and D/A, and Ensemble's Di-chrono duet. Digital setup was as described in some detail in last month's review of the YBA CD1.
Analog was not in play for the moment; my Forsell Air Force One had begun to show its age, and sat waiting for a little Swedish TLC from the factory.
I ADMIT IT - I'M BIASED!
The biasing scheme for the SLM-200 is a breeze. Cary supplies a pair of multimeter probe wires (positive and negative) terminated in a single phono jack, this to be inserted into the amp's rump while in Operate mode, with no signal applied. There's a screw adjuster next to the 1/4" jack with a knurled lockdown collar. Small movements of the screw produce dramatic shifts in bias current.
Dennis mentioned that he prefers a nice, bloomy sound at 280mA total DC bias current. At a slightly higher 300mA, I noticed that the sound became usefully tighter and more precise, but also rather too buttoned-down. 280mA did it for me. The operation is bog-simple - even a neophyte with four left thumbs will have no trouble getting it right. Only thing is, you need a multimeter that ranges to 400mA, and not all of them do. Radio Shack part #22-174A will do nicely, at $89.99 list price.
A few words about the unexpected circuit topology are in order. This is no run-of-the-mill push-pull amplifier. Actually, Dennis Had and company are having one over on us. Each SLM-200 monoblock is virtually two single-ended amplifiers.
I was impressed that Dennis didn't equivocate: He prefers triode mode, and that's how the amps were supplied. I thought the quick, transparent, reviewer-tight Avalon Radian HCs would benefit from what I'd characterize as triode's bloom factor, and this proved to be so.
On the first set of tubes, the SLM-200s sounded attractive, but without any remarkable distinguishing features, you might say. I did hear immediately that the KT88S, as implemented in the Carys, developed that special sense of corporeal 3-D virtual reality that only tubes seem to do.
The amps took a few days to leave grain and grittiness behind, never to return. In fact, from the lower midrange up, where had festered the dark and gritty stuff the sound opened up, illuminated and blooming in a wonderful, soul-satisfying manner.
I always begin by looking for that special sense of clarity and openness in the midrange and highs, so female vocals are where we begin. There is an embarrassment of riches of such recordings these days, many beautifully recorded and of high artistic purpose. Audiophiles should consider themselves quite lucky.
Speaking of which, the 24kt-gold PopeMusic release of Lori Lieberman's Home of Whispers(PM1005-2) has been growing on me like a fungus. This is a superb recording of wonderful, intensely personal music. Lieberman's sweet disposition keeps the unabashedly romantic from slipping into a bubbling cauldron of haute schmaltz.
Listening to "Something of My Own," I jotted the following: "At 1:49 the last few words hang sweetly in the air, followed by a light, shimmery bell. At track's end, the strings are fast and clear, the clarinet so tonal, the final bell chime sent a shiver down my spine." As Maynard G. Krebs put it so long ago, I got, like, all misty.
And that's key. As I grew to know the sound of the SLM-200s, I found that they regularly created musically emotive experiences. They were emotion-bearing, so to say. When the equipment brings the listener the poignancy of the work, I call it audio magic.
I hear you now: "Oh, Scull, it was your mood and Thanksgiving torpor. Or the Côte du Rhône from the night before. It's all in your mind!"
Quite. When you visit a gallery or a museum and peer at a work on display, isn't what happens... in your mind? Is that not its very purpose?
In that wonderful nonpareil manner, then, in which single-ended triodes deliver female vocals - in the way the Jadis JA 200s do, or the magnificent Wotans - we now have... the Cary SLM-200s.
You again: "Ah, he just loves everything with tubes."
Well, not everything. But we're not blasé about it, and that's the point. The SLM-200'sreached me in that special way that only the best equipment manages to. Once again, spoiled bastard that I am, this special audiophile magic was taking place - with apologies to Ed Sullivan - on our rilly big soundstage... with tubes.
More female vocals: I couldn't stay away from them. Grab Patti Smith's latest, Gone Again (Arista 18747-2). Here's my playlist: "Beneath the Southern Cross" (ineffable), "About a Boy" (for the sonic tricks at the beginning), "My Madrigal" (touching and soulful), "Wing" (I can feel it), "Ravens" (we're bounding the main and loving it), and finally Patti's heartfelt ode to her husband, the late Fred Sonic Smith, "Farewell Reel" (you'll plotz, it's so beautiful).
My notes: "I love this album. The phasey stuff at the beginning of 'About a Boy' - a bit Pink Floyd - like - is so... unstuck from the speakers. It occurs far forward in the ambient soundfield, floating free from her voice, which is set well back in the soundstage. She still sounds a bit digital. But with the Ensemalink, the YBA CD1 especially, or even the Forsell front-end, I don't mind. The power of the bass really sets up the piece. Oliver Ray's blarey guitar feedback, Smith's powerful, emotive voice positively velvet with inner detail in the midrange, soaring, meaningful, distinct, and corporeal back there behind the speakers. The amps lay everything out beautifully, even at loudest levels."
As I grooved maximally with Patti, a few thoughts percolated to the surface. I felt, at the end of the disc, quite close to her - like a friend, almost. As a listener, you, too, can be next to someone like Pam Smith. In fact, you may feel that you share her innermost thoughts and emotions. It's not like Patti's passing you on the street, preferring to remain anonymous and private. She's made this CD to express herself, after all. She's offering a part of herself to all of us who have the ear and the heart to enjoy her poetry and probing, powerful music.
And it's by way of a high-end system that you may make this journey of discovery. It can be shocking. It can take you places you've never imagined you could be. And that's what the great high-end search is all about.
I DID IT MY WAY...
For those of you wondering what the SLM-200s sound like on male vocals, let's turn to Frank Sinatra. Let me tell you, they were made for each other. Francis A. and Edward K (Reprise 1024-2) set up a soundstage as airy and bloomy as sin. Frank was set way back toward the rear; the soundstage was startlingly deep. The horns, acoustic bass, and trumpet were arrayed left and right, somewhat closer to the listener.
As I listened to this fab album, it occurred to me that the SLM-200s surged far beyond the somewhat limiting concept of layering, in the audiophile sense. The acoustic was always entirely viable and of a whole. There was a halo of air around each performer; the burnished horn sound, brass blattiness and all, filled my soul with musical contact of the third kind.
The remarkable ambience was supported by the SLM-200's ability to play LOUD with little apparent stress. The Chairperson sounded full-size, correct height, chestiness intact, countered by fast, extended, powerful trumpet riff's. The wraparound effect was startling. As was the dynamic "made you blink" startle factor - another hallmark of the SLM-200s' presentation.
The amps sounded subjectively fast transients on the Sinatra disc crackled with energy. In fact, they could sound a bit splashy at times, but never, how shall I say, unpleasantly or unmusically so. Those zippy leading-edge transients defined the acoustic wave billowing out to the boundaries of the soundstage before climbing the walls and falling back to fade into the noise floor, much like a wave against a rocky shore. (Yes, the SLM-200s did have a liquid presentation.) This acoustic presence and transparency were utterly defined by the 6 Chassis preamp, which does them better than any other preamp I have ever heard - clearly the result of YBA's fanatical attention to the very smallest of details.
Thinking to slip my classical hat on, I picked up Mozart's last two string quartets as performed by the Shanghai Quartet - another fine recording by John Eargle for Delos (DE 3192), recorded with the PrismSound AD-1 20-bit converter with Sennheiser and Neumann mikes. I applaud Delos for including a few pages of large-type Young People's Notes. This is so intelligent - involvement is the name of the game.
(Audiophiles! Be not alone in your listening rooms, eyes clamped shut, constipated with anxiety before your systems. Lighten up! The audio experience is so much more compelling when it engages your family and Significant Others. I am aghast at how solitary an experience some of you make this, while at the same time asking how to open the High End to the greater world of music lovers who know nothing of our divine pursuit. Exposure is the key, starting with your family and persons in your immediate vicinity. Socialize and share your passion.)
Ahem... where was I? Oh yes, Mozart. The Delos release isn't about pinpoint imaging, but rather concerns itself with re-creating the lovely resonant signatures of the instruments. As for me, you can keep your multimiked-to-hell Big Six productions; this recording is lovely, redolent with, yes, emotion-bearing harmonic richness.
The plush, fully developed tonal colors are just what's called for. The Shanghai's elegant, restrained musicianship suits the program material perfectly. (While no expert, my father surrounded my brothers and me with little else but Wolfgang during our formative years. With tubed electronics, no less. You probably guessed that.)
Once again, I noted a subjectively fast-sounding presentation. I keep coming back to "subjective" when describing the top octaves: As mentioned, the SLM-200s could sound a little splashy on cymbals, for example, at highest spls. This was surely part of the reason the amps sounded so quick.
In addition, over time I noted an ever-so-slight boxiness in the upper-midrange/lower-treble region. I was able to mitigate this effect with changes in front-end and cabling. Yet it was ever-present, if somehow... unobjectionable. It resulted in this region sounding lightly sweetened and a tad recessed, saved from airlessness by the tremendous dynamics on tap, and the stroked presence region just above.
And here is where we separate the sound of the amp from the sound of the power tubes. These slight upper-frequency anomalies were less in evidence when 10 matched pairs of Teslovak KT88S's were dropped into our Jadis amps. (The small artifact that remains may be crossover related.) Caveats abound, however, so see my "Adventures in Tubeland" sidebar, which details our Jadis / KT88 experience, as well as my interview with Penta Labs' Steve Sanett.
Now, about the bass. The high plate dissipation of the KT88s, combined with some mighty one transformers - never mind that they weren't hand-wound in France - made for formidable, powerful, room-energizing bass. Acoustic impact and slam were much in evidence.
For instance, I enjoy challenging audio systems with the beginning of track 2 on Spiritchaser, the relatively new Dead Can Dance album (4AD 46230-2; also available on LP from Music Direct, (800) 449-8333). After some initial mesmerizing sonic effects, there comes an insistent drumbeat that redefines the concept of power and drive as it relates to tautness. The incredible impact of these powerful strokes was tremendously real, very acoustic, seemingly without hi-fi artifice. And no bloat or overhang - a big plus with these amps. (It's worth noting that the follow-on vocals were beautifully illuminated, both in a reflective sense - lit 6om without, as it were - and combined with an essential dollop of light from within.)
Another interesting bass element could be heard when playing "Ravens," from Patti Smith's Gone Again, turned way up. My notes speak of HUGE drum strokes way down in the frequency range. Powerful, energizing waves of sound set up the larger acoustic ambience in a remarkable way. It billowed out at me, as much felt as heard.
The JA 200s, even when stuffed with KT88s, were simply not able to keep up with the SLM-200s in recovering this deep, room-filling bass. You can't have everything. [Sigh.] Then, too, when doing the bass, no tube amp can plaster me into the Ribbon Chair like the Forsell Statement can. (That giant among amps is back on its dual-mono feet again after I discovered an overlooked and much incinerated fuse that had, unbeknownst, brought our Statement game temporarily to an end.)
Let's consider "Too Rich for My Blood," from Patricia Barber's Cafe Blue CD (Premonition PREM 737-2). It proved an almost overwhelming sonic experience with the Cary's. The vocals are driven along by an astounding slam and pace in the bass. The drum line becomes more and more prominent toward the end of the piece as Barber's voice begins to trail off (in the megahertz range, it seems). Listening at high volume proved quite physical. The full, powerful, fast-paced drumbeats pressed me into my seat as if I were in a centrifuge. The countering cymbal licks cut through all razor-sharp and shimmery. The power and majesty of Barber's voice was truly awesome; the midrange textures to die for.
Now, while the SLM-200s managed to get a good grip on the Radians, things did get a mite untidy at the loud, driving climax of the Barber Aural Assault. I'm not complaining. It was too musically engaging, thrilling even, to utter any objections. If you're power-mad, order yours strapped for 200W.
The bass could sound a little small at low volumes on the tightly controlled Radians. When I cranked it up, however, and kicked some serious audiophile butt in the bass, it was just fantastic. Tight, pitch-differentiated, very deep, quite in control, meaty and powerful, and finally, ultimately, acoustic.
The sum of its many parts
There's an organic character to sound that tubes somehow or other seem to get better than silicon. And these superb amplifiers do an outstanding job of creating that blush of musical magic.
The SLM-200's sound is rooted in its superbly developed, lushly musical midrange. One almost takes for granted the midband's velvety textures and extraordinary detail The highs were always vivid, extended, and sweet as any recording called for. The bass of the KT88S, in conjunction with the unusual circuitry and some pretty slick transformer work, was altogether extraordinary for a tube amp. For any amp, for that matter. The dynamics on tap, from the deepest bass to the very top of the frequency range, were always startling. Altogether a most palpable and musically engaging presentation.
Bravo, Dennis - I'm glad your brochure caught my eye. I'll keep my more-than-twice-the-price Jadis JA 200s, thanks, but the SLM-200 really made me think about that decision. Recommended.
- Jonathan Scull
Following its warm-up/preconditioning, the Cary SLM-200 was typically hot for a tube amplifier. All of the measurements below were taken at the output tap corresponding to the load used (the 4 ohm tap was used for the simulated real-load measurements). The sample measured here was configured for triode operation, but for logistical purposes was sent directly to us by Cary Audio and was not one of the (similarly configured) pair auditioned in the review.
The input impedance of the Cary measured 129k ohms, the voltage gain into 8 ohms was 26.1dB. The output impedance was respectably low for a tube amplifier: at the 8 ohm taps, a high of 1.18 ohms at 20Hz and lkHz, and 1.09 ohms at 20kHz. At the 4 and 2 ohm taps, the output impedance at lkHz was 0.6 ohms and 0.37 ohms respectively.
The approximate maximum value of the Cary's DC offset was 4.6mV--it varied wildly, though largely remaining below this maximum. Signal/noise (unweighted red 1W into 8 ohms) measured 78dB over a 22Hz-22kHz bandwidth, 76.3dB lOHz-500kHz, and a low 98.6dB A-weighted. The SLM200 was noninverting, a positive-going impulse at the input remaining positive at the output.
Fig.1 shows the SLM-200's frequency response, which varies slightly with load at ultrasonic frequencies. The small but likely audible response variation with a simulated loudspeaker load, due to the amplifier's output impedance, may also be seen. The 10kHz squarewave response is shown in fig.2. There is a slight leading-edge overshoot followed by a damped ultrasonic oscillation. The same overshoot is visible on the lkHz squarewave (not shown).
The low-power THD+noise us frequency results are shown in fig.3. Except for a rise at low frequencies (in any event, below 1% above 20Hz), these are good results for a tube design. The plot of the small-signal distortion waveform at lkHz (fig.4) indicates that the distortion is heavily second-harmonic. (The result was very similar into 8 ohms and 2 ohms, not shown.)
Fig.5 shows the Cary's output spectrum reproducing 50Hz at 82W into 4 ohms. The result here is not exceptional, but not atypical for a tube amplifier. The two largest artifacts are the second harmonic at -34dB (2%) and the third at -48.8dB (about 0.4%). The very similar spectrum into our simulated loudspeaker load is not shown. The spectrum in fig.6 shows the IM distortion artifacts in response to a combined 19+20kHz signal at 20W into 8 ohms. This is the maximum power attainable with this signal prior to visible signs of clipping (the onset of clipping is quite mild, and difficult to see on an oscilloscope trace). Again, this is not a particularly distinctive result, but common in tube products. The lkHz difference IM is -37.3dB (about 1.5%), the 18kHz IM is -25.8dB (about 5%). The result for a similar power output into 4 ohms is reasonably similar, though the IM at lkHz is significantly lower (-50.5dB, or about 0.3%).
The percentage of THD+noise us output power curves for the Cary are shown in fig.7. The actual discrete clipping-point measurements at lkHz (in this case, we measured clipping at 3% THD+noise) were 123.2W (20.9dBW) into 8 ohms, 122W (17.9dBW) into 4 ohms, and 120.8W (14.8dBW) into 2 ohms. In all cases, the line voltage was 116V.
The measured performance of the Cary SLM-200 was not exceptional for amplifiers in general, but quite respectable for a high-powered, triode-configured tube design.
- Thomas J. Norton
©Stereophile Vol.20 No.5
Cary Audio SLM-200
In due course - Stereophile Standard time - I felt confident that once again I would have a smile on my face and joy in my heart with a Cary Audio amplifier review in the pages of Stereophile. (Hey, Bob Harley, I've done my homework on the [Audio Electronics] CD player... how about another review?!) In all sincerity, I am honored that Mr. Jonathan Scull opened his French doors for a Classic Carolina Comfort style of audio amplification. In my opinion the Cary SLM-200s represent a blend of single-ended velvet midrange, boundless imaging, and push-pull authority and slam.
If I may be so bold at this time I would like to speak briefly about a topic that is of grave concern to me about the high-end audio industry. I am appalled at the number of enthusiastic, music-loving audiophiles in this country that are being mistreated by unscrupulous audio retailers. On this end of the business, as a manufacturer, I have the opportunity to speak with audiophiles all over the country. Some of the narratives brought to my attention about the treatment from some retailers is appalling. Charging a fee to allow a prospective customer to audition equipment in his home. Checking a customer's credit limit on his credit card to ascertain if the customer should be allowed in certain show rooms. Refusal to issue a refund or a trial period if the equipment is not satisfactory. I mean the stories go on.
Fortunately, I believe this disgraceful and unethical behavior is associated with a small number of dealers, but it does cast a cloud of skepticism over the entire industry. My words of advice are simple: support your local specialty audio dealer, and beware of mail-order bargains. Make sure you have the privilege of an in-home audition, and ask if the dealer has a qualified service department for after-sale service. I believe the Cary family of dealers around the country will comply with these simple business standards.
Well I guess that's enough of my soap-box. I just love this industry and have a desire to share my passion.
Once again, thank you Jonathan Scull and Stereophile for your continued ethical reviewing practices and conduct as a professional publication. Oh... one last comment...YES, YES, Cary Audio Design does in fact build a complete line of push-pull amplifiers.
DENNIS J. HAD
President, Cary Audio Design, Inc.
1 I describe these tube doings not to cast aspersions on the well-intentioned gentlemen from Cary and Penta, nor to give anecdotal comfort to the tube-wary. Yes, it's true, you might feel an expensive amplifier like the SLM-200 should work perfectly right out of the box, no qualifications. (And mostly they do, Dennis Had would have you know.) But Penta stood behind their product and shipped replacement '88s our way doublequick. And there's nothing that would lead me to suppose they wouldn't do the same for you. After all most high-end companies stand or fall on their reputation for customer service.
Fig.1 Cary SLM-200, 8 ohm tap, frequency response at (from top to bottom at 20kHz): 1W into 8 ohms, 2W into 4 ohms and 2.83V into simulated speaker load (05dB/vertical did).
Fig.2 Cary SLM-200, small-signal lOkHz squarewave into 8 ohms
Fig.3 Cary SLM-200, THD+noise us frequency at prom top to bottom at 5kHz): 4W into 2 ohms, 2 ohm tap; 2W into 4 ohms, 4 ohm tap; 2W into simulated speaker load, 4 ohm tap; and 1W into 8 ohms, 8 ohm tap.
Fig.4 Cary SLM-200, 1 kHz waveform at 2W into 4 ohms (top); distortion and noise waveform with fundamental notched out (bottom, not to scale).
Fig.5 Cary SLM-200, 4 ohm tap, spectrum of 50Hz sinewave, DC- kHz, at 82W into 4 ohms (linear frequency scale).
Fig.6 Cary SLM-200, 8 ohm tap, HE intermodulation spectrum, DC-22kHz, 19+20kHz at 20W into 8 ohms (linear frequency scale).
Fig.7 Cary SLM-200, distortion (%) vs output power into (from bottom to top): 8 ohms, 8 ohm tap; 4 ohms, 4 ohm tap; and 2 ohms, 2 ohm tap.