Audio Research VT100 Mk II Stereo Power Amplifier 
Home Theater Power Amplifiers Stereo Amplifiers
Written by Bryan Southard   
Saturday, 01 July 2000

Introduction
The Audio Research VT100 Mk II is a 100 watt all tube, balanced stereo power amplifier which retails for $4995. It uses two matched pairs of 6550 output tubes per channel, and four 6922 twin triode tubes per channel. It also incorporates a fully regulated, 540-joule power supply, distributed between two separate, isolated output circuit boards, thus creating short signal paths and true "dual mono" operation back to the main power transformer.

The VT100 Mk II is a fully balanced amplifier, which offers both balanced and single ended connections. When using single ended inputs, shorting pins are inserted into the XLR connectors. There is a choice of 4 and 8 ohm speaker connections.

I was first taken by the overall look of the amp. I confess that I have had a fetish for the look of Audio Research gear for years. I just think AR gear looks cool. It has always looked rugged yet glamorously simple.

Setup takes just a few minutes. You are required to remove the top cover, (Audio Research supplies the screwdriver), remove the packaged tubes and install them into their correct locations. I then attached the removable power cord and we were in business.

Upon firing the amp up, I performed a ritual that I have often repeated. I turn out the lights and stare at the array of tubes through the top cover. To me there is nothing more beautiful about any audio gear than the look of powered-up tubes in a dimly lit room.

I originally auditioned the VT100 Mk I, but quickly had the modifications done to the amp to make it a Mk II. Without going into great depth, I will say that I found the improvements substantial. Rumors of any flaws, which might have existed in the Mk I version, were non-evident to me with the Mk II.

Several modifications were made. One of which was the installation of a new power supply, doubling the power storage capacity. They replaced existing caps with InfiniCaps, a modification previously offered separately to the Mk I. They also added a removable power cord, a fan to keep the chassis cool, and installed damping rings on the 6922 twin triodes thus lowering the overall noise floor of the amplifier. Overall, a fairly substantial upgrade by today’s standards.

One of my initial concerns about the VT100 Mk II was the power rating of the amp. I own a pair of Martin Logan SL3’s which are certainly not the hardest speaker to drive, yet far from the easiest either.

I fully planned to fire the amp up and let it run for the required break-in period prior to performing any critical listening. I sat down in my listening chair just to be sure that the speakers and all my cables were connected correctly and in phase. Three hours later I emerged from my listening room with an ear to ear grin.

For those of you that are interested in using the VT100 Mk II in your home theater systems, careful consideration of the amplifier(s) used to control the additional channels of your system is strongly recommended. Many manufacturers offer multi channel amplifiers for you comparison. For the best possible synergy between each channel of your theater, a comparable sounding amp would be recommended.

Sound
As I began to listen, one of the first things to grab me about the VT100 Mk II was how quiet the air about the amp was. I instantly felt that the noise floor had diminished. During quiet passages, I found information revealed in the music that I was previously unaware of. I also felt the absolute lack of grain. In addition, the effortless attack of the amp made it incredibly easy to listen to. I felt an ease of listening that I had never experienced to this level before.

The Audio Research VT100 Mk II has plenty of power to drive my Martin Logan’s, and for that matter most all speakers. When pushed, the VT100 Mk II held together remarkably. It consistently delivered clean, effortless power at most every listening level. While listening to Dave Matthews ‘So Much to Say’, from Crash, I marveled on the focus and bass control of the kick drum. Surprisingly, and contrary to popular tube folklore, which suggests that tubes can lack some of the deep focused bass that many solid state amplifiers deliver, you might be rudely awakened. Although perhaps not the final word in bass extension, the VT100 Mk II is sure to make you rethink the ancient tube myths.

My favorite byproduct of the amp remains the reproduction of mid range vocals. This amplifier has the ability to recreate the air responsible for the development of three dimensional images better than any component that I have heard. The effortless detail that surrounds the images is absolutely magical. While listening to Keb Mo’s ‘Momma, Where’s My Daddy’ from Just Like You, I had to occasionally remind myself that he was not in my room. His voice and guitar were so rich and full of body that I could practically feel his breath on my face.

The Downside
Although I found this amp to possess power much greater than what you would expect from a 100 watt amplifier, I would exercise caution depending on the efficiency of your speakers and the content of the music you listen to. Myself, I found the amplifier sufficiently drove my moderately inefficient speakers very adequately.

In addition, like all tube products, there is a tad more maintenance needed than with solid state. The tubes are estimated to last in the neighborhood of 2000 hours which means unless you are rich, you will be turning your amplifier on before listening, and off promptly after. What this means is that there is a slight premeditation of your listening habits required. I find a warm-up period of about 45 minutes, sufficient for this amp to sound its best. Replacement tubes from Audio Research retail for $518. If you are like me, I found this to be a non-issue after experiencing the benefits that this amp affords you. Also, tubes get hot and need sufficient airflow to stay cool. This almost certainly suggests an open rack or better yet, a stand.

Conclusion
I find the Audio Research VT100 Mk II to be a lesson in musical truth. This amplifier is infinitely transparent and capable of delivering the most natural musical reproduction I have yet heard. At $4995, although not a small chunk of change, this component feels like a bargain. This amplifier is your personal ticket to see your favorite artist anytime you wish.

For those considering a future amplifier purchase, do yourself a favor and give the VT100 Mk II a test drive, but before doing so, have your greenbacks ready. You are likely to have a hard time living without this amp.
Manufacturer Audio Research
Model VT100 Mk II Stereo Power Amplifier
Reviewer Bryan Southard





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