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KR Enterprise VT8000 MK monoblock power amplifier Manufacturer's Comment

Manufacturer's Comments

Editor: First of all, I would like to take this opportunity to thank Stereophile for permitting Mr. Michael Fremer to review our "top-of-the-line" monoblock amplifier, the VT8000 MK, and to visit our factory in Prague, Czech Republic.

Second, if I may, I would like to respond to a number of inexplicable points that have been raised by your test-bench results that may give erroneous ideas of our sound quality and design philosophy, despite Mr. Fremer's very enthusiastic audition.

My primary duty is to answer, point by point, the results of the curves…

KR Enterprise VT8000 MK monoblock power amplifier Michael Fremer returns

Michael Fremer returned to the VT8000 in December 1999 (Vol.22 No.12):

I've been reviewing audio gear for 13 years now, and never, never has the discrepancy between what I heard and what was measured been so great as it was with the KR Enterprise VT8000 MK monoblocks (Stereophile, November 1999). I didn't see the amps' disappointing measurements until the final review was faxed to me for fact-checking. I almost went into toxic shock. I am much more used to having John Atkinson or Tom Norton confirm what I heard; eg, the Audio Physic Virgo review, my first for Stereophile (September 1995…

KR Enterprise VT8000 MK monoblock power amplifier More Manufacturer's Comments

More Manufacturer's Comments

Editor: I am taking up my pen again to respond...to Mr. Fremer's...additional commentary in his "Analog Corner" feature, where he says, "I was extremely disappointed and surprised to read the discrepancy between the KR's claimed power (75W) and measured power (40W and lower, depending on load impedance and distortion)." From this statement, it is evident from Stereophile's technical testing, [that] we are still in the horse-and-buggy age. Those may have ran very well on plowed fields, but if there is a Ferrari, it certainly cannot give the same performance.…

Elements of Our Enthusiasm

At the end of August, we watched as the number of registered users in our online forums quickly ticked past the 10,000 mark. Ten thousand registered users! While it might prove interesting to learn just how that number breaks down into men and women, old and young, subjectivists and objectivists, or any of several other demographic and philosophical divides, that would only obscure the point: In our online forums, there are over 10,000 members who are eager to share their enthusiasm for music and hi-fi. What a beautiful thing!

Among the 10,000, there will doubtlessly be some who have…

Ayre KX-R line preamplifier

I can't think of a product that was as eagerly anticipated as was Ayre's KX-R preamplifier ($18,500). Following in the footsteps of Ayre's MX-R monoblock amplifier, a Stereophile 2007 Product of the Year, and milled, like the MX-R, from a 75-lb billet of aluminum, the KX-R also shares with its monoblock stablemate the Ayre ethos of zero feedback and fully balanced operation. But what really caused the buzz was the declaration by Ayre founder and chief designer Charles Hansen that the KX-R, with its use of a technology he calls Variable Gain Transconductance (VGT) to control the volume, would…

Ayre KX-R line preamplifier Page 2

Also, since the signal is not attenuated before entering the active circuitry, source components with extremely high outputs could have been problematic. "We had to do a fair amount of work to ameliorate this potential problem," Hansen said. "With a typical source of 2V to 4V balanced output, the distortion is around 0.001% to 0.002%. Increasing the input to 8V RMS, as some digital products produce, will bring the distortion up to around 0.008% to 0.01%."

Hansen chose to set the input impedance at a high 1M ohm per phase (2M ohms balanced). "You know how, when you load a moving-coil…

Ayre KX-R line preamplifier Page 3

I'll start with something that sounds simple: The KX-R was really quiet. (If this were a movie, somebody would have to say, "Yeah. Too quiet.") Aren't all audio components these days? Well, sure, but the KX-R, with an activated input selected and set to regular listening volume, was far more silent than the tomb. As Hansen said about the air, you don't notice it till it's gone.

Music sounded especially alive through the KX-R. I noticed this as much with the MF Nu-Vista 300 as I did with the MX-Rs. Want jump factor? The KX-R had it. John Atkinson kindly hand-delivered a CD-R containing…

Ayre KX-R line preamplifier Specifications

Sidebar 1: Specifications

Description: Solid-state, line-level preamplifier with remote control. Inputs: 4 single-ended (RCA), 4 balanced (XLR). Outputs: 2 balanced (XLR), 2 balanced tape. Input impedance: 2M ohms balanced (1M ohm/signal phase), 1M ohm single-ended. Gain: variable. Frequency range: DC–250kHz. Output impedance: 300 ohms balanced, 150 ohms single-ended. Power consumption: 36W, 65W maximum (when volume control operating).
Dimensions: 17.25" (438mm) W by 3.75" (95mm) H by 11.75" (29.2mm) D. Weight: 40 lbs (18.2kg).
Finishes: Silver; add $250 for black.
Serial Number…

Ayre KX-R line preamplifier Associated Equipment

Sidebar 2: Associated Equipment

Digital Sources: Ayre Acoustics C-5xe universal player, Simaudio Moon Evolution SuperNova CD player.
Preamplifiers: Conrad-Johnson ACT2 Series 2, Parasound Halo JC 2.
Power Amplifiers: Ayre Acoustics MX-R monoblocks, Musical Fidelity Nu-Vista 300.
Loudspeakers: Avalon Acoustics Indra, Thiel CS3.7, Wilson Audio Specialties WATT/Puppy 8.
Cables: Interconnect: AudioQuest William E. Lowe Reference, Stealth Indra & Nanofiber. Speaker: AudioQuest William E. Lowe Reference, Stealth Dream.
Accessories: Ayre L-5xe AC filter & Myrtle Blocks;…

Ayre KX-R line preamplifier Measurements

Sidebar 3: Measurements

I mainly used Stereophile's loaner sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com) to examine the Ayre KX-R preamplifier's measured performance.

The top setting of the volume control was an indicated "60" on the display, meaning that there are 61 steps. However, the preamplifier muted when the volume control was set to "60," "59" being the highest practicable setting (footnote 1). The KX-R offered just 0.53dB of gain for both balanced and unbalanced sources in this condition. Using the Setup…