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Positive Feedback ISSUE 9
as reviewed by Robert H. Levi
I've always liked tube amps. That said, there are a lot of things about tube amps I dislike:
1. They are big, heavy, and fragile.
2. They are critical in the areas of speaker impedance matching, damping factor specificity, and are usually underpowered, with insufficient headroom.
3. Their designers do not think about the needs of the consumer.
4. They mostly use the same old tube types which have been around since 1957, except that the modern manufacturing of these good-ol'-boy tubes is hit and miss.
5. They are overpriced.
6. They require expertise on the part of the audiophile for biasing and other adjustments, some of which may be dangerous.
Wouldn't it be wonderful if I could tell you that I've found a tube amp that did not have these problems? If you can live with a $5000 price tag (less than a boatload of tube exotica offered by other amp manufacturers), I'm listening to your new amp right now!
I was wondering when someone would design a serious amp using KT90s, not just two per channel, as Jadis and Manley have done. The E.A.R. 890 instead uses four of these powerhouse tubes per channel, in a circuit that maximizes their capabilities. Issued for the first time in 1990, the KT90, which is made by EI in Yugoslavia, is a derivative of the 6KG6 TV sweep tube which was then modified several times to be compatible with the 6550 and its variants. The KT99 is a select version of this tube. The EI factory was not damaged during the war, and produces large quantities of these reliable tubes. With a temperament and power similar to that of the famed Genalex KT88, the KT90 has been waiting patiently for a designer to maximize its design parameters and produce a great-sounding, powerful amp. The day has finally arrived. The Tim de Paravicini-designed E.A.R. 890 is now available, and it is a masterful, melodious triumph!
The 890 uses four KT90s per channel in a pure class A, push-pull design, to achieve a stated 70 watts continuous power per channel. The damping factor is over 30, high for a tube amp. The story continues, and so does the power, beyond 70 watts. I tried the 890 with Avalon Eidolons, which are 87 dB efficient, and it made clipping mincemeat out of an ARC VT 100 II with four 6550s per channel. The 890 refused to clip. I substituted it for a pair of Pass X 600s, which are 600 watts per channel, and it drove the speakers 95% as hard. Overall detail was improved by a factor of two. I heard nuances never revealed by the Pass, and the jump factor of a more real presentation was astounding. We have something new here for audiophiles, and it is 100% tube powered from E.A.R.
How about some more good news? The 890 weighs only 60 pounds, and is a compact 16 by 16 inches, with lots of beautiful chrome on its faceplate and trim. It features balanced and single-ended operation, easy-to-get-to binding posts, a convenient, front-mounted, and lighted power switch, a switch for mono bridging, and automatic biasing for the output tubes, which do not need to be matched. Plus, it has dual volume controls that are easy to reach. The IEC connector lets you experiment with power cords, plus it's totally quiet and only slightly warm in operation. I settled on a Tara Decade power cord after experimenting with Kimber 10 Gold, RSC Air 1, and Powerstrings. The Decade sounded musically right, though I have no idea whythe amp will change voice perceptively with different cords, so experiment. It was connected to the Pass X1 preamp using Soundstring interconnects in balanced operation, and to the Eidolons with Soundstring speaker cables. The amp was plugged into the Power Wing power conditioner.
Listening to the Bach Goldberg Variations with Glen Gould on SACD, Gould's humming has never, ever been clearer, and the piano was palpable. If you cherish realistic piano, this SACD played on the 890 is perfection. I heard natural, powerful piano sound between my speakers, with no dryness. I've never heard a piano sound better in my system.
Try the Hovhannes SACD on Telarc for spectacular stage width. The right-to-left spread was the sonic equal of my monoblock amps, with BETTER imaging and depth. The violin sound was delicate and layered, not syrupy or liquid, just smooth, smooth, smooth, and suggestively real. There was no hint of compression at high volume. In fact, the 890 has more apparent headroom than any 6550 or EL34 design I've run across in the last 45 years. It does not tease you like single-ended designs, which choke just when the music gets going, unless you are running horns or the like. This amp is surely a cousin of the Eveready bunnyit just keeps going. It will clip, but rarely and gracefully. You find yourself thinking, "Did that clip? Well, maybe, maybe not."
Miles Davis, in the SACD reissue of Kind of Blue, told the tale. The horns sounded natural and blatty, with very strong focus and texture. Coltrane's sax was so realistic. The imaging specificity was top notch, and the textures were analog-like and natural. This amp has excellent bass control. Its tightness and power was almost equal to that of my Pass solid state monoblocks, perhaps not quite as room shattering, but damn close. Its increased definition extends to the lowest octaves. The 890 bass is defined, in a way not only unusual but unique among tube designs.
Do you like air and space? You'll love this amp. Try the Lauridsen Lux Aeterna CD, and you're at the concert. This recording will give you goosebumps. Its microdynamics are special, and its choral sound it just is. I have never heard anything like it on the Eidolons. The music breathes with melody and sweetness. There is utter smoothness at all frequencies. No emphasis is apparent from lowest bass to the very top octaves. There is no discernable coloration; in fact I have never heard a tube amp with less coloration. The Pass 600s have more. The 890's sound is empty of artifacts, and it is ultra quiet. Its grainless quality reminds me of great OTL designs.
Tube rolling is the sport of audiophile kings. No audio guru is worth his golden eared opinion unless tube brands are swapped. The EAR 890 uses 8 KT 90's made by only one company in the world nothing to do here. The small signal tubes, two 12AX7's and two 6AQ8's are very important triodes in the front end of the amp and replacement with great NOS types may be very exciting. Currently, the amp is shipped with tubes unmarked as to country of origin or manufacturer. They are, instead, elegantly imprinted in brilliant gold leaf logo, "DP," and look quite jewel like on inspection. Sonically, as reported, the sound is state of the art. If one could improve on this exalted performance level, we might just see heaven.
Focusing on the 12AX7's, we substituted the renowned Mullard NOS tubes. The results were mixed. The midrange became bloomy and the bottom end unfocussed and less detailed. This was no improvement.
Next we tried the famous Telefunken's. The sound became too lean in the midrange and thin on the bottom, a bit strident as well.
Next we tried the EI Gold Pin Special Edition. These were beautiful tubes to behold. The sound was closer to stock, but a bit two dimensional and slightly strident. They were certainly usable, but not as musical and winning as the "DP" labeled tubes.
Lastly, we tried GE 5751's which, in my experience, are excellent NOS tubes from the 1970's. They had a delicious rich midrange in the circuit with a very traditional tube sound, but when all was said and done, they ruined the truly precise musical nature of the amp. Back went the "DP" tubes, and back came the state of the art sound that just bowled us over. I plan to get a case of these "DP" branded tubes for future use from the EAR distributor. No joke, from 15-20000hz these tubes are clean, delicate, powerful, linear, quiet and ultra detailed beyond the finest NOS 12AX7's we have ever used!
I'm going to wrap this up so you can get on the web and research this giant-killer amplifier for yourself. It's the best tube amp I have listened to in my system! It is cost effective, powerful, maximally tuneful, user friendly, and you need only one chassis. It has new-think incorporated within its KT90 tube choice, and it's seductively musical. It works with inefficient, 4-ohm speakers like the Eidolons, and will probably power anything on the planet, from horns to electrostats to multi-driver designs, with musical authority. Plus, any normal audiophile can lift it without dastardly results. I not only recommend it, I'm buying the review sample to prove to my Positive Feedback friends that I stand behind my reviews! I highly recommend the E.A.R. 890 amplifier. It is class A+ in my audiophile domain, and my new tube reference. Robert H. Levi