Krell Power: A Visit to the Laboratory of Doctor Morbius

Author's Note: It was January 1986. I flew from London to Las Vegas for the Consumer Electronics Show, following which I drove to Santa Fe, NM with Stereophile's then-owner/publisher Larry Archibald to talk about my leaving British magazine Hi-Fi News & Record Review magazine to join Stereophile. After discussing my future role at the magazine, I flew to Chicago to discuss an alternative idea, starting my own audio magazine, with a potential investor. (An idea that fell by the wayside the more I considered Stereophile's potential.) And what happened next, when I flew out of Chicago? That is the subject of this article, which was originally published in the April 1986 issue of HFN/RR, along with my CES report. It is reprinted here with the kind permission of that magazine's editor, Paul Miller.—John Atkinson

The only one who knows this ounce of words is just a token
Is he who has a tongue to tell, but must remain unspoken.
—Moondog, 1968

The Lockheed 1011 sits dormant on the ground at Chicago's O'Hare airport. "We have a little light bulb problem here" drawls the pilot in the approved Right Stuff manner. "We don't know if it's the bulb or what, we'll let you know."

Time passes. I eat an apple. The plane's TV screens show Carole Burnett being professionally funny. More time passes. My unlimited mileage, four-stop, air ticket was costing TWA rather more than the £88 it had cost Hi-Fi News & Record Review magazine [($127 in 1986)], but maybe this is how they make up for it. The previous day, for example, there had not been a plane available for my flight from New Mexico to Chicago. A week before that the only flight to Las Vegas I could get a seat on had arrived in that fair town at midnight. And I missed the start of the Consumer Electronics Show.

More time passes.

486krell.1203dagintAt last the pilot announces that the bulb has been changed and we lazily take off an hour late, destination New York. I was hoping eventually to arrive in Milford, Connecticut, to be exposed to Dan D'Agostino's latest thinking on Krell power. I have to admit to feeling just a wee bit apprehensive as the bus winds its way up Interstate 95 through the New York suburbs. My review of the Krell PAM-3 preamplifier in the January issue of HFN/RR could have been interpreted as saying that although the solid-state Krell was undoubtedly a world-class preamp, when the chips were down I would have to admit to a preference for the similarly priced Audio Research SP-10. Yes, the latter uses valves, with all the relationship complexities that that implies, but we're talking ultimate sound quality here, not component longevity.

"That's okay," says Dan, when he meets me off the bus, "You're not too deaf. At least you didn't prefer Conrad-Johnson! Let's go eat."

We eat. Spinach pizza. Heavy duty. We also drink. A Californian Chardonnay from Russian River Valley. I'm too tired to do it justice, but I drink several glasses in order to get to know it better. We don't listen to Dan's system, which is just as well, considering the rapidly mellowing out of my psyche due to the Remy Martin with which I follow the Chardonnay.

The next day, it is time to get serious. We drive to the Krell factory in the company's Chevy van, Dan's Carrera not being a winter's car. (The Chevy doesn't have quite the feel of the Porsche—I can't imagine it being heavily featured in Miami Vice.) Over the noise of the van, Dan brings me up to date on what's been happening at Krell. The KSA-50 has been revised a little, the latest version incorporating the output relay first used in the KSA-100. A rear panel key-switch converts the amp into a mono bridged amplifier, capable of giving 200 class-A watts into 8 ohms—a hefty subwoofer amplifier, for those who believe in subwoofers. (I am afraid that this is a subject on which I maintain a firm agnosticism. I've yet to hear a system that doesn't get worse with a subwoofer. More is not necessarily better.)

The back panel facilities may have been updated, but the front panel (and those for the rest of the Krell range) gets a facelift. The blue-anodised finish has been getting more and more unpredictable from batch to batch—Quad owners will be familiar with the feeling of shock they get when they see a 405 amplifier with a totally different heatsink hue. Blue is still on offer, but the main finish is now a subdued grey coloration, a surface treatment previously only used for jet engine turbine bearings. (Dan's chief engineer Scott attacked a PAM-5 front panel with one of those sharp steel probes so beloved by dentists to show me that the finish is inviolably hard—a Krell owner, I almost fainted!)

The main business of the day, however, was to talk about Dan's "Reference" amplifier, which is being launched in Japan this month. In a way it is a parallel launch to the Mark Levinson No.20. Both are cost-no-object high power monoblocks aimed mainly at the Japanese market, but Dan feels that the Krell Reference will set the pace. He regards it as a statement in modern solid-state amplifier design, the most advanced devices used in the best possible way: "It won't be an amplifier, it will be a non-amplifier."

The Reference will have a killer power supply, fully regulated—"even the wires"—with the equivalent of 600,000µF reservoir capacitance, and will have two toroidal transformers, one for the positive rails and one for the negative. The amplifier will be "intelligent" in that when turned on it will carry out a series of checks on its operating points and conditions, including checking the loudspeaker impedance, and only allow a signal through when ready. A display panel will show the status condition, something Dan thinks the Japanese would just "Krell" over. The Reference amp will be all-balanced, from input to output, and a balanced version of the KRS-1A preamplifier on the way.


At the time of my visit, Dan and his henchmen had still to assemble the prototype Reference, the signal-handling circuits still being bread-boarded, the chassis still a handful of raw aluminium heatsinks, and the logic circuitry existing mainly in Dan's notebook. The power supply did exist, however, and that afternoon's task for Dan, Scott and new hand Will was to assemble two samples of a Krell 200W mono power amp with the Reference psu grafted on. Heart of the supply are two 2kVA toroidal transformers,—these will be 4kVA in production—with 6 ×40,000µF caps.)

There was some doubt if the conventional KMA-200 boards would survive being turned with the new supply, even with its slow-start circuitry, and, indeed, the first amplifier lasted but a few seconds before biting the big one, a power transistor case emitting a farewell plume of blue smoke.

We walked back to the smoking ruin from the other side of the lab where we had suddenly found ourselves—there's a lot of stored energy in a big amplifier like this. Dan, of course, had had the presence of mind to pull the mains lead out on his way to safety, and Scott started to dismantle all of the neat wiring that he'd spent the afternoon installing. Dan and Will fired up the second amplifier without a problem, other than some diode noise breakthrough due to a grounding problem.

It was interesting to see how Dan sets the bias of his class-A designs. A current probe clamps the lead from one of the reservoir cap banks and the 1kHz current waveform at full power into 8ohms is monitored on a 'scope; the standing bias is then adjusted for the best current sinewave, with additional checks at 20kHz and above, with a final check on THD. (It's an alarming proposition to be standing next to a power amplifier pumping out upwards of 300W at 100kHz—lesser amplifiers have been known to break!)


Time passes.

Scott and Will have installed new output transistors in the first beast, and after ascertaining that it can survive being turned on, it is time for music. We carry the monsters into Dan's listening room at the factory where an unsuspecting pair of Apogee Duettas are waiting. James Newton Howard is slipped on the Oracle/Syrinx/Koetsu player, the volume control on a coupling capacitor-less PAM-3—more on that later—is cranked up, and my God, that bass drum is tight as a nut. The amp is really kicking the Duettas' bass panels around and although the speakers have a more forward presentation of the soundstage than the Scintillas, there is still depth way behind the wall of the room.

We bundle the amplifiers into the van and trundle off to Dan's house for some serious music. Now those who missed Ken Kessler's write-up on Dan's record player 18 months or so back should be warned that this man does nothing by halves. Front-end is a Goldmund Studio fitted with a Koetsu Red Signature, which feeds a Krell dual mono, quadruple power supply, KRS-1A preamplifier. This, like the PAM-3 in the factory and future preamp production, has nary a coupling capacitor in the signal path. Instead, active circuitry—"Not a servo!" says Dan—looks after the DC conditions. A three-way active crossover follows the preamp, which in turn is followed by the amplifiers, a truly righteous combination of KMA-100 mono amplifiers for the mid and treble ribbons of the seven foot Apogees and KMA-200s for the bass panels.


The supercharged 200 watters are hooked up to the woofers and we warm up with a couple of glasses of Glenmorangie. (I have mine on the rocks—this is America after all!) Thick steaks are accompanied by a 1978 Napa Valley Cabernet Sauvignon; pudding is, well, indecent. It is a chocolate cake bought at the local fresh fish shop. (You'll have to work that one out.) I was in severe danger of chocolating out, of succumbing to chocolate overload! Is it time to listen to music? It is.

And what track to play first other than Joan Armatrading's "Willow." Dum. Da da dum. Da de dum. O-oh Yes! The glass of Remy clutched in my hand starts to overheat. Dan's wife and business partner Rondi puts on more Armatrading, "Unlucky." Drums hit me in the face. Robert Palmer follows with "Frankie and Johnny." I am thinking that this is almost like live music.

I have no choice, I reach for the live album of all time, Little Feat's Waiting for Columbus in the Mobile Fidelity recut. Little Feat, the band that played with time the way others play with Dinky Toys.

The band are in the dressing room getting charged/changed: "Join the band, people oh come on and join the band." I get an adrenalin rush—"Oh oh oh oh oh oh oh"—as the band run through the tunnel onto the stage.

The atmosphere of the auditorium fills Dan's living room. "Ladies and gentlemen, please welcome...F... FFFFF... E... EEEEE... A... AAAAA... T... TTTTT, Little Feat."

The audience roars. Cowbell, then Ken Gradney's powerhouse bass swoops under Lowell George's and Paul Barrere's chopped guitars into "Fat Man In The Bathtub"—"Juanita, my sweet Juanita, what are you up to?"—around 115dB, I reckon, my sweet Tequila!

Almost unbelievably, the white magic of live rock is working on a domestic system.

Some domestic system!

Little Feat run off stage at the end of their set and things get little cooler with Gil Scott Heron's Reflections. I reflect that this is just with a pair of amplifiers cooked up that afternoon to drive the bass. The Japanese are not going to know what's hit them!

We end with Bobby Caldwell's Clouds on the TK label, a singer with the kind of sky-high tenor voice you only hear from black Americans—until Dan tells me he's white—the classic Moondog album from 1968—trust one of the best CBS classical albums from that era to have been taped by rock engineers—and as I can't find any Larry Graham, the glorious Brothers Johnson"s "Get the Funk Out Ma Face."

I funked out—and off.


James Newton Howard & Friends: Sheffield Lab LAB23
Joan Armatrading: Show Some Emotion A&M 68433
Joan Armatrading: Walk Under Ladders A&M AMLH 64876
Robert Palmer: Clues Island ILPS 9595
Little Feat: Waiting for Columbus Mobile Fidelity MFSL 2-013
Gil Scott Reflections Arista SPARTY 1180
Bobby Caldwell: Clouds TK8804
The Brothers Johnson: Look Out for #1 A&M SP 4567
Moondog: Moondog CBS 63906

Bogolu Haranath's picture

Those Apogee speakers would be hard to drive by either Audio Research or conrad-johnson :-) .......

Bogolu Haranath's picture

RAAL probably could design speakers like those Apogees :-) .......

Bogolu Haranath's picture

RAAL should try to make them more sensitive than 80 db like the Duetta was :-) ........

Zarathustra's picture

I know about a guy that drives his Apogee Apogee with a pair of Audio Research D250's directly like the Krells and Mark Levinson ML-2 can do.

Metalhead's picture

with apologies to Mr. D'Agostino I will take the Conrad Johnson please.

Bogolu Haranath's picture

After eating that spinach pizza JA1 became a 'strong man' like Popeye :-) .........

tonykaz's picture

Oh my, I wonder if it's more true than we imagine or imagined?

Krell's first Amplifiers were beautiful with those Gold plated screw fasteners and "Show-off" Power to Authoritatively drive any loudspeaker.

How many Front Covers did Krell accumulate?

Krell was one of the most desirable Lines for Dealers ( like me ) to carry. ( I couldn't carry it because Krell needed the Gramaphone & Rick Howard ( Detroit's Big Show'y Dealer ) and I was a measly Front-End Phono-Arm-Cartridge type tweaky dealer.

About then, RedBook 16/44.1 was shoving 33.3 aside, CD players were costing $1000.00, I was migrating back to my Transportation Industry Origins ( whilst working Class Americans got their last pay increase 5 years previously -- and still haven't increased one iota ).

Mr.D'Augostino is still making the gaudiest "Show-off" gear out there , he seems like the Dolly Parton of Audio and it seemed his henchmen kicked him out of his own company ( which is exactly what happens when two ( of three ) business partners squeeze out an owner ).

Tony in N.H.

ps. I admired the Krell gear but preferred Electrocomaniet

Bogolu Haranath's picture

AD, who usually likes tube equipment, liked the sound quality of Electrocompaniet AW400 amps :-) ........

Strat56's picture

... still not less than once per week, on car stereo, on office stereo, on my listening room, and... on my strats

antonmb's picture

...but after a couple of Glen Morangies, a bottle of cab, and a glass or two of Remy, the sense of realism I experience from my system is also greatly enhanced.