September 2001

KR Enterprise Antares Amplifier
Review By Bill Roberts

  Why on earth would someone pay five grand for a pair of vacuum tubes that are 65 years old and untested? Simply put, to get that final electron of music out of their system and to feel chill bumps all over their body and hair standing on the back of their neck in total musical involvement which Single ended triode amplifiers can do. Mind you, eight watts is not a great deal of power but it is enough to tease the senses and boggle the mind. Enter Ricardo Kron.

What if you could get more power from a 300B and keep the whole thing in class A configuration and use only one tube per channel? There is an answer. Drive 550 or more volts through the KR300BXLS tube and heat sink the devil out of it. Now we are talking about 14 watts of 300B power with a tube that has 65 watts of plate dissipation and 32 cathodes! Kron calls it the Vacuum transducer. It is a mixture of the brute 300BXLS tube and pounds of aluminum wrapped around it.

The 300BXLS is a remarkable tube and is a drop in replacement for most 300B applications. If your amplifier does not have the extra voltage that the 300BXLS can accept then it will simply behave as an eight watt 300B tube. KR has a very in depth write-up of this tube on the Welborne Labs website.

Upon receiving the Antares, loaded by fork truck into my sport utility vehicle, it is packaged in a wooden crate with rope handles screwed together and secured in thick shock absorbent foam. Unit arrived in perfect condition due to the superior packaging. The unit is very robust and solid while construction is absolutely stunning. Black Power transformer housing, black output transformers (2) and heat sink unit (vacuum transducer) appear around the two KR 300 BXLS vacuum tubes. A chromed base plate, side panels in black with fins and spiked feet with platforms (3) round out the units' superb construction. Built like a battleship in my opinion. A LED (light emitting diode signals protection cycle in red for the first 35 seconds of turn on and then turns green upon stability of the entire circuitry mounted on the front panel right.

I mentioned before how the Antares is packaged. We are talking about a very large wooden crate, rope handles and yes, this amplifier is "only" 14 watts per channel weighing a mighty 105.1 lbs.! We are talking serious build here with most of the weight in power and output transformers, which are Kron design. What a beast! Hefting this amplifier out of the crate takes serious Kahunas!

Preliminaries

The test unit for this review has been to industry shows for display and did not need time to break in. After a few hours of use the unit was rock solid. I will take this time to mention that the KR Antares does not come with a power cord. Speaking of cables, I used several different types of loudspeaker cables and each cable gave the merit that cable has. My favorite loudspeaker cable is per Jon Risch design of cross-connected 89259 twisted double coax and can be seen by clicking here. The Antares has high quality five-way binding posts virtually any loudspeaker cable will install easily.

Upon turn-on, the front panel LED is red, followed by stabilizing the tubes and 35 seconds later the LED turns green. There is no audible noise when this happens. This amplifier is quiet. Dead quiet. No noise heard from the loudspeakers or the amplifier itself. "Scary quiet". Many times I have had to look at the front panel to see if it was on.

Now On To The Sound!

The first selection I listened to was Electric light Orchestras Greatest Hits. This is a CD I purchased back in 1987, not a new re-mastering job. Oh my my... the cellos. Gosh, never heard them so dynamic and intact. Where did all of that come from? Imaging is needle point tight. Sound is crisp, large, smooth, sweet, soft, punchy, fat, clean, fatigue free... all at the same time. Wow! This is some serious sound here. I played the entire CD and mastering cues between different studios are very apparent. Mistakes in mastering are right there. This amplifier is allowing me to hear about 8 notches deeper into the mix than previously heard.

Sticking to CD's, next comes a favorite reference of mine. The Bob James CD, Hands Down contains the track "Spunky". It's always been a vinyl reference for me, though this time on CD. What amazed me on this one is the seamless transitions of the instruments. It sounds like each instrument has a specially tuned speaker system designed around that particular sound. Decays in bells during loud passages last forever. This I have yet to hear on any system at any price. Usually they are lost amongst the bass or blurred slightly during the loud passages and masked. Not here. This gave me serious goosebumps. I actually yelled, YES!!! Brought tears to my eyes. Now this my friends is what high-end audio is all about. Total emotion. Even though the music is studio-based multi-track recordings, the engineers that worked on the mixes may not have heard it this good. The really did their job on the balance. Uncanny. As a recording studio engineer myself, I know what I am referring to here.

Jazz Time

In my biography I state that jazz is my forte'. From studio open mic jazz to live hall performances, nothing to me is a satisfying as being able to duplicate the live event as close to possible in my listening room. Acoustic grand piano, string bass, brushes on a well tuned drum kit, tenor or alto sax... This is where the Michelins meet the road.

I am blown away by these dynamics. Never hard or harsh, just right there or right over there. Literally as perfect as I have heard. We are talking about crystal clear transparency in the bass all the way up. Seamless and solid is the word for it. After about 150 hours of listening the best description I could use to describe what this amplifier is doing is virtually nothing at all. The Antares takes the input signal and makes it larger to drive speakers. That is all I want an amplifier to do. Nothing else. Measurement wise, as there is test gear here, I get virtually the same reading with or without the loudspeaker connected. Once you start exceeding 20 watts the waveform shapes will change because you are simply running out of available power. Yes there is a limit of course. If you need this performance and you need a very few more dB, KR enterprises offers essentially the same amplifier in mono block form but be prepared to spend well over $10,000 dollars each unit. I simply have found no program material, commercial or professional that strains this amplifier without it really being just too loud for the room. I find for dynamic integrity, reasonable efficiency loudspeakers and moderate room size with Class A tube amplifiers is simply so much more musical than units marketed to "heat the loudspeaker cable" as I say.

You most definitely need a really serious high fidelity pre-amplifier to get the best from the Antares... or use no pre-amplifier at all per se. The best results were from a heavy modified McIntosh C-26 solid state unit. Let's just say that less than 20% of it is stock Mc.

Vinylly

I simply cannot put this into proper words, those who do not have a vinyl setup in their system are missing out. This is serious sound and the Antares deserves the finest vinyl setup you can afford. Sky's the limit here folks... and then some. I simply cannot get enough listening time in. You will have your albums out rediscovering old favorites with goosebumps a-plenty.

Reasons For My High Ratings

Any rating beyond 90 is exceptional performance at any price. Above 95 we are splitting hair. A rating of 96 on one factor and 97 on another gets down to long term feel in direct comparisons with other products that may perform in one area at super high quality. It is difficult to explain the difference between a 96 or a 97 simply because there is room for improvement in any Art or Science. I will say that a rating above 93 is very difficult to outperform. Basically there are some areas where more performance I believe can be obtained in the future and it may exist now. In some areas I find this amplifier cannot be beat. As sure as I am sitting here, one area may be excelled by some piece of equipment somewhere but by no means are these high scores baseless and without top merit. I think it will be a difficult task to outperform this amplifier in these areas and I am considering these performance scores within the classification and the topography of this kind of circuit, plus the price range this unit is offered. Surly there is (possibly) an $80,000 dollar amp out there than could (possibly) give this level of performance and maybe a shade better in some areas and with more power. From a pure value/performance perspective, it would be a very tall order for any manufacture to use this type of technology and achieve this level of performance in a ready built delivered plug and play unit.

Regardless, here is a list which I think the manufacture could work toward improvements but that would come with an added price. The covers for the output transformers are solid as a brick. They are similar to solid chunks of steel. I like that but the cover for the power transformer needs to be of heavier gauge steel, especially the top of it in my opinion. You rap it with your knuckles and it sounds like a hollow can. Looks-wise, I personally like the way it looks. I did have another audio buddy come over and he did not. You will have to decide this for yourself. My buddy loved the sound.

As for the vacuum transducer pod. Inside this pod houses the 300BXLS vacuum tubes in ten large anodized aluminum heat sinks with a finned top cover and base. This unit runs very hot. It will burn you if you touch it more than 0.25 seconds! Small children must be kept at bay. This can cause injury if carelessness is allowed around this amplifier. This amplifier was not intended to have children around it. They must be warned that it is very hot and do not touch.

The tubes have a 2 year warranty on them and should give about 20,000 hours of continuous use. The tubes sell at this time for $475 per matched pair. I am going on others' data here and I personally would have a spare set stored for future use. The 32 cathode 300BXLS is a unique tube. Unique to KR enterprises and their distributors. I really don't know what would happen if they quit making them as the Antares uses higher voltages than a standard 300B is specified.

Conclusion

Besides those observations above, everything about this amplifier is of genuine extreme high quality and performance. This is the ultimate value and affordable expression of SET Class A, no negative feedback, bang for the buck in a finished complete amplifier package. If you buy one, you will be very pleased with its performance within its wattage classification. I simply find no fault in the performance in this price range. I am so spoiled by it that now I must finance the purchase. I love it!!

Specifications

Dual Mono Amplifier Operating in Class A 
Load Impedance: 4.8 Ohm (2 Channels) 
Sinus Output: 14 W RMS by two channels
Music Output: < 50 watts 
Distortion: 0
Bandwidth: 12 Hz - 35 KHz (-2dB) 
Input Sensitivity: 1 volt 
Input Impedance: 100 KOhm 
Negative Feedback: 0 
A.C. Power: 100/230 volts 
Maximum Power Consumption: 250 VA
Dimension: 53 x 36 x 26 cm 
Weight: 48 Kg
Price: $5,100

Company Information

KR Enterprise sro
Nademlejnska 600/1
CZ 198 00 Praha
Czech Republic
Voice/Fax: (+42) 02 830228
Website: www.kraudio.cz 
E-Mail: kr.enterprise@worldonline.cz

United States Distributor:

KR Audio USA
8390 E. Via De Ventura
F110-194
Scottsdale, Arizona 85258

Voice: (888) 593-8488
E-mail: info@kraudiousa.com
Website: www.kraudiousa.com