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Positive Feedback ISSUE
as reviewed by Bryan Gladstone, Mark Katz, and Dave Clark
My dear friends and family: As you know, I have been gone for several weeks now, leaving behind home, career, friends, and family, but I will not look back. Living on the lam is difficult. It is a lonely, solitary life, but I will never return home. There comes a time when a man must stand up for what he believes, so I will continue running.
I believe that I have successfully evaded the police, for now, but government authorities are only a minor concern. Infidels track me day and night from audioMUSINGS and Joule Electra. These two loosely-affiliated groups share interest in my capture, for I have stolen the Joule Electra Stargate monoblock amplifiers. They were loaned to me for review, but when asked to return them, I could not. You see, their owners speak of these amplifiers in terms such as "transformer-coupled", "class-A," and "parallel single ended," but this only shows how little they understand. Never have they mentioned love, art, beauty, or romance. They could never care for these amps the way I canthe way they deserve. Therefore, I have taken them.
Before receiving the Stargates, I thought I knew what to expect from low-powered, single-ended amplifiers. Having heard many, I expected a glorious, euphonic midrange lacking in bass and dynamics, the perfect amp if you listen to chorales or string quartets. But I listen to rock, jazz, and full orchestra, so the first thing to do was to to see what these 50-watt amps could really do. It turned out that the low power of the Stargates did represent my largest complaint, but not to nearly the degree I expected. When played loud, the Stargates exhibited some compression, but only on crescendos. At all other times, the Stargates are impressively dynamicnot impressive for low-powered tube amps, but just plain impressive. My Conrad Johnson Premier 11A lacks the very bottom octave compared to a powerful solid state amp. The Stargates seem to lose still another octave. The tympanis in Jascha Horensteins Dvorak Ninth on Chesky lack the gut-busting punch that a big solid state amp can produce. In normal listening, though, I never missed it. Despite the lack of low-end punch, the Stargates have a warm and full-bodied low end that gives enough weight to underpin even a full orchestra.
In the treble, an area in which both my ProAcs and I are extremely sensitive, the Stargates really shine. The high end through the Joules reaches stratospheric frequencies without any hint of sizzle or distortion. Cymbals shimmer beautifully, and the overtones of strings and human voices are perfectly proportioned, never revealing even a hint of fatiguing stridency. This wonderful, subtle upper end also translates into air and ambience in spades. The Stargates let an orchestra play from within whatever hall the event took place. They reveal a wonderful sense of enveloping space, depth, and reverb that is superb in its ability to put the listener into the original recording space.
The Stargates have an ultra-quiet background from which their dynamic "aliveness" emerges. Leading edges of transients appear explosively and completely free of any grain. Trailing edges and reverb tails fall off smoothly until they gracefully disappear into empty space. The Joules sound much more like a musical instrument than an electronic device. Although I didnt notice any grain or distortion removed when I switched to the Stargates, they definitely deliver more detail and delicacy than the CJ. This added detail emerges from darkness, uncluttered by system noise or by other elements in the mix. I constantly heard new details unmasked in recordings Ive heard dozens of times. Even very slight sounds become clearly defined and hold their own space in the soundfield.
A few times I thought I detected just a hint of honkiness in the midrange through the Stargates. Soon, however, another recording would prove me wrong. Ive yet to discover if certain recordings reveal an anomaly in the Stargates or if the amps reveal something in those recordings that Ive never noticed. Finally, and most importantly to me, the Stargates have a sensual and romantic gentleness. Through the Joules, Alison Krauss thin, nasal, and sometimes shrill voice becomes so sweet you want to reach into the soundstage and hug her. Music through the Stargates just has a "rightness" that makes me sink happily into my overstuffed couch and sigh with joy. It should be mentioned that the Stargates take a long time to warm up. Although they sound pretty good after half an hour, they dont really bloom until they have been running for closer to an hour.
Im a big-picture kind of guy, always trying to see the forest through the trees, and this is what makes the Stargates such a pleasure. I like these amps so much that I find it difficult to describe or criticize any single aspect of their performance. What they do best is create an extremely lifelike presentation while making no glaring errors to ruin the illusion. The Stargates dont better my CJ in every regard. For sheer power and dynamics, my Premier 11A beats up on the Joules, although this is probably not a fair comparison given their power specs.
Any complaints I have about the Stargates are subtractive. Their faults are ones of omission rather than audible slaps in the face. Some very fine amps, especially solid state ones, are capable of digging very deeply into the details of a recording. Often, though, they leave me feeling as if Im listening for musical errors or edits in a recording studio rather than to an artistic performance. The Stargates get the subtle details and microdynamics right without adding any significant coloration. With just a touch of tube "glow," the Stargates produced an unbelievably lifelike recreation of the recorded event without giving the feeling of looking through a magnifying glass. Soundstaging, timbre, timing, dynamics, and delicacy come through, putting flesh and bone back into a two-dimensional recording. Performers have never sounded so alive in my living room as when played through the Stargates.
I am traveling on foot now, after a chase with authorities forced me to ditch my car in the Arizona desert. At forty-five pounds apiece, carrying the Joule Electras makes for a difficult journey. They are built as solidly as any amps Ive encountered. Setting them up in a new location each evening is a breeze using their large, clear LED readout and pushbuttons to bias each tube. At only thirty watts, the Joule Electra Stargates are not the perfect amp for everyone, but they should not be limited to only chamber music. The Stargates achieve the elusive combination of transparency and subtlety without giving up any boogie. They are both analytical and highly musical, making almost any material thrown at them sound wonderful.
So, to my
friends and family, I say goodbye. Do not feel sorry for me. Although my days are long and
dangerous, my nights are filled with lovely music. I will miss you all,
Ive just had the pleasure of spending about a month with the Joule Electra Stargate amplifiers. When Dave Clark mentioned Joule Electra, I naturally thought of the output-transformer-less amps that Id heard sound so good at hi-fi shows, most recently with Merlin speakers. However, these thirty-watt, forty-five-pound monoblock amps are not OTLs, but parallel single-ended devices, each using a pair of the industrial looking, nipple-topped Russian 6C33CB tubes that Joule has used in their recent OTLs. I first suspected that the Stargates werent OTLs when I lifted them. The transformers are heavy! The amps have multiple output transformer taps to accommodate speakers with impedances of 4, 8, and 16 ohms.
What can you do with a mere thirty watts? Plenty! Think of them as single-ended amps for medium efficiency, relatively flat-impedance speakers. You wont need horns with 100 dB-per-watt-plus efficiency ratings. I wouldnt recommend them for speakers with large impedance dips, but theyll do fine with many speakers where eight-watt 300B amps would not. I first tried them with JM Labs Mezzo Utopia speakers, Kora Triode preamp, Museatex Bidat DAC, and CEC TL-1 transport. Cabling was Kimber 8TC shotgun from amps to speaker, and Goertz Quartz triode for the electronics. The amps were plugged into the wall, the supporting electronics into a Power Wedge 116 II. The amps are quiet, without excessive hiss or hum, a good sign.
Now for some listening! The delicacy and tonality of strings and woodwinds were the first thing I noticed, compared to the borrowed Clayton M70s I currently use, though dynamics were more restrained on piano. Switching from the four-ohm to the eight-ohm taps seemed to improve everything, surprising for a speaker nominally rated at four ohms. The music was more dynamic and detailed. I spent some time testing out an old McIntosh MR78 tuner, and enjoyed listening to the local classical station, feeling this setup worked nicely. On CDs, the J.S. Bach Concerto in D Minor for Two Violins on Harmonia Mundi, a CD I recommend for an excellent period performance, was very successful. The Stargates did justice to the violins. The Bach Coffee Cantata, on Dorian, also fared well, with the voices having the proper texture and well balanced with the harpsichord and orchestra. These are not fat or syrupy-sounding amps. The Telarc CD of the Firebird Suite was more of a mixed bag, with the closing bass drum less explosive than Im used to and the early deep bass notes minimal. Overall, though, the orchestra sounded very realistic. The midbass was presented with fair control but the deep bass was not, as evidenced by Reference Recordings Rutter Requiem. Voices were superb, but the deep organ bass notes were diminished or absent. There was a great sense of space and ambience. I think that thirty watts is the least amount of power that Id consider with these speakers.
Then I moved the Stargates to a more modest system: the floorstanding Tannoy Saturn S8 speakers (eight-inch dual-concentric mid/tweeter and eight-inch woofer), prototype KSS tubed preamp, and Pioneer 701 Laser Disc/CD player. Though the speakers are nominally rated at six ohms, I tended to listen with the eight-ohm tap. These speakers are not in the same league as the much pricier JM Labs, but they are forgiving enough for a video system with some audio use, and are easier to drive than the Mezzo Utopias. Dynamics were better. The comparison amp in this system is a Music Reference RM10, which I feel is a more realistic price match.
The Naum Starkman Chopin Polonaise on the Pope Music label is a no-holds-barred dynamic test for any system. Pope captured the contrast of tone and dynamics of classical "power" piano, and the notes are explosive at times. The Stargates audibly clipped on the louder notes of this piece with the Mezzo Utopias, and I expected them to do so on the Tannoys, as this had occurred with my eight-watt 300B SE amps and my twelve-or-so watt SE EL34-based amp. They did not, maintaining composure at moderate levels and not clipping until the volume was turned up past where I would normally listen. I didnt have to keep the volume low, waiting for a dissonant clipped note.All of my comments on their sound with the JM Labs apply, except that there was more apparent energy and not as refined a midrange or treble.
Mahlers Des Knaben Wunderhorn, performed by Dietrich Fischer-Dieskau and the Berlin Philharmonic on a Sony Classical sampler, is a gem. The first-rate singing has lively orchestral accompaniment, and this track is a good test for baritone, orchestra, and the percussion section. While the energy of the crashing cymbals seemed a bit less than with the push/ pull RM10, in all other respects the performance seemed more powerful. The triangle sounded more realistic, the brass more blatty, and the baritone had greater presence and immediacy. My 300B SE amps simply cant render the performance of this piece on these speakers.
The Stargate amps are easy to set up and bias with the help of the manual. As with all tube amps, experiment with which tap works best for a given speaker. I tended to prefer the 8-ohm tap. From the upper bass on up they are excellent amps. Midbass is fairly well defined, but low bass is diminished. Their sound is clear, detailed, and dimensional, with sweet extended treble and a hint of warmth. They are not harsh or artificially edgy. According to the advertising material that came with the amp, Joule also makes a push/pull version with 40 watts per channel. Perhaps a biamped system with the push/pull Stargate for the bass and the SE Stargate for the mid/treble would get the best of both worlds? The Joule Electra Stargate amps are a great way to get single-ended "magic" without owning exotic high-efficiency speakers. Mark Katz
The Stargate is the first foray into conventional amplifier design for Joule Electra, which is well known for its OTL amps. The Stargate is nonetheless unconventional in its featuring of the 6C33CB output tube (two per channelthese are monoblocks, by the way) putting it firmly in the camp of amplifiers that use a freak-of-nature-tube from some Flash Gordon episode. The 6C33CB has a low plate resistance, which means, first, that the transformer primary requires very few turns, and second, that one can use very large wire. This results in an extremely large current-carrying capability. Additionally, the Stargates output transformer weighs more than 20 pounds and the two 6C33CBs have been biased at 200 milliamps each, allowing for a dissipation of 80 watts in the primary core. This all results in an amplifier rather heavy for its sizeso lift with the legs. The Stargate can be configured to output either 40 watts as a push-pull class A amplifier or 30 watts running in single-ended triode. The units we received were the 40-watters, based on the speakers belonging to the audioMUSINGS writers involved in this review.
The Stargates are more utilitarian in appearance than earlier Joule Electra amplifiers. They feature black metal cases with no hint of glitter and sparkle, and little resemblance to the wood-encased, furniture-quality OTLs Judd Barber is known for. Easy to set up and use, the Stargates worked wonderfully for several weeks on my 94dB 8-ohm Reimer Tetons, which, even with the SET-friendly load and Diaural-series crossover, present a butt-load of drivers for any amplifier to controlespecially one of lowish power. Each Teton features four 8 ¾-inch woofers in two isobaric chambers, two 5 ½-inch midrange drivers, and one 1 1/8-inch tweeter, and offer a frequency range of 18Hz to 20kHz. Like I said, this is a fair amount of magnets and cones to work in a speaker, and one, when complemented just right, can really put out a whole wagonful of music.
I have had a rather varied group of amplifiers here in recent years, from low-powered SETs to medium-powered integrateds to high-powered tube, solid state, and hybrid amps. Some of these amps made the Tetons sound slow or weak, some made them sing. When mated to the Stargates, the Tetons sang with astounding beauty. They did not have the authority and slam of the 100-watt class A Claytons, but did remarkably well. The Stargates were amazingly clean, fast, and detailed, but never dry or sterile. Being sweet and as dynamic as all get-out, these amps reminded me of the girl next door, that while possessing an innocent demeanor with the face of an angel, could whip the living daylights out of any boy on the block. And doing so with a grin on her face that let you know you both were enjoying it! Sweet, yes. Quiet and demure, definitely not. I loved every minute of my limited time with these amps, never once feeling guilty for cheating on my Claytons. The Stargates were just too much fun to listen to, and sounded just marvelous on anything I threw at them.
But what should an amp sound like? Well, it shouldnt sound like anything at all really. What should happen is that the amplifier should amplify the signal from the preamplifier all the while "reacting" harmoniously with the speaker, cabling, and components upstream with as little if any sonic character of its own being thrown into the mix. Which is not to say that amplifiers will not have their own "sound", its just that the better they are, the more they should sound alike. Sure one can go find tube amps that sound like tubeswarm, rich and full-bodied at the expense of speed, clarity and "neutrality," and solid state amplifiers that sound like, well, they just sound bad. To put it another way, unless one just has to have a particular "sound" to work witha speaker that has a particular "sound" to match their perception of music having a particular "sound"an amplifier should simply pass the signal pure and simple.
In this sense, the Stargates were a very happy match to my system. In fact, they reminded me in many ways of the Claytons, except they were a tad leaner, a smidgen faster, and a few clicks less dynamic, with less bass slam. The fun factor was the same, though. In many ways they also reminded me of the almost-twice-as-powerful Naked Truth Callas, a 70-watt OTL Fast, clean, and musically powerful, the Callas were highly recommended back in Issue 11. Both amps are as neutral from the midrange up as any other amplifier I have heardincluding the Claytons, which tend to be a bit darker, warmer, and, well, more tube-like. Which is right? Go figure. The Stargates treble is light, airy, and well extended, with nary a trace of grit nor grain. For a 40-watt amp, the bass was fast, clean, and considerably more powerful than it had any right to be. They werent as deep and powerful as the Claytons, but apples to oranges.
The only real
problem I had with the Stargates was the fact that they are 40 watts, and thus had a
tendency to run out of steam with my speakers. More good watts is MUCH better than less
good watts, particularly with respect to dynamics, slam, and a sense of ease. While the
40-watt Stargates were extremely musical, the 100-watt Claytons were a couple more levels
up the ladder. If Jud could just make the Stargates as 100-watters, wed really be
cooking. Highly recommended.
Interview with Judd Barber of Joule Electra
Terry Rossen: Why and when did you get started in this business?
Barber: Joule Electra was born when a good friend of mine, Carter Asbill, moved
back to the
My first project was a preamp, and I really didnt realize that this was one of the hardest pieces of audio equipment to design and build. I drew up schematics for three basic designs, and predictably the first was quite complicated, the second was simpler, and the third was the simplest. To make a long story short, the third sounded the best by far. One of the most difficult things to learn was that the parts needed to break in before good sonics could be achieved. After hearing Carter comment I cant listen to it several times as I tried to develop the production version of the preamp, we discovered that good sound required burning in. We began the test marketing of the first LA-100 preamp in June 1992, and realized that we had a product with great potential.
Terry: What separates your products and designs from the competition?
Jud: The third simple design for the preamp was based on the Mu Follower circuit showcased in Glass Audio and explored in great detail by Alan Kimmel. This circuit was such a sonic success that all our products utilize variations of that original circuit. Among the unique design and construction characteristics of the LA-100 are circuit boards that I describe as construction boards. Virtually all the components in the signal path are connected together with their own wire on pads. There are no traces in the signal. For example, two resistors and a capacitor all terminate at one point on one pad and their leads are twisted together. It would not be necessary to solder many of these sites at all, but then we dont tempt fate.
Terry: Why did you choose the materials that you use in your designs? How many products do you manufacture, and what are their sonic characteristics?
Jud: We were not too original in picking parts, but relied on picking ones we knew were very good, like Holco resistors, MIT caps, Noble pots, Cardas Hardware, and New Old Stock tubes. The circuits were tuned to meet our sonic requirements, using acoustic music and auditioning by trained musicians. Carter is a professional violinist and has the golden ears on which we relied. Using these basic principles, Joule Electra now manufactures preamps, transformer-coupled amps, OTLs, and phono stages, all using the Mu Follower circuit and NOS tubes. The amplifiers all use the Mu circuit configured as a differential amplifier. They are probably the only commercial products being manufactured today that use this topology, which accounts in major part for their success.
Terry: Why do we need another high end audio manufacturer?
Jud: Why do I feel we need another preamp or amplifier manufacturer in the high end marketplace? The answer is quite simple. While I started designing and building speakers in the mid-eighties, I failed to come up with designs that were consistently better than Dunlavy, Celestion, B&W, and others, so I gave it up. The Joule Electra electronics are another story. I still prefer the sound of the Joules, together or in part, to any other competing products. The Joule Electra motto is The Only Thing That Matters Is The Sound.