Audio by Van Alstine Fet Valve EC Preamplifier/Omega III 440hc Amplifier

High Performance Review, Autumn, 1995

By John Gatski

Hybrid transparency

I first got to know Frank Van Alstine, president and chief designer of Audio by Van Alstine, in 1994 when I arranged a kit building project using his well-known Super Pas Three and Super 70i modification kits for a Dynaco amp-preamp tandem. The project was being done for a pro trade magazine, and the builder and I quickly became familiar with Van Alstine's personal service and dedication to quality. We were impressed.

Those same assets also remained evident during the listening/user evaluations of two new Van Alstine products: the Omega III 440hc active feedback power amplifier and the Fet Valve EC (Enhanced Capability) preamplifier.

As with most of Van Alstine's new products, these two are based on the building block system. The Omega III amplifier versions are all the same design and use the same cover and chassis but have different power ratings. The Fet Valve EC preamp uses the same box as AVA's top-of-the line solid-state preamp, but it uses the patented Fet Valve hybrid vacuum tube design. A smaller and less expensive version, the Fet Valve SL preamplifier, uses the same circuits but has no tone controls.

The Fet Valve EC Preamp

Priced at $1279 with the optional phono card, the Fet Valve EC preamp offers a lot of bells and whistles. It reminds me of the functionality of older preamps such as the Dynaco PAS and PAT series with all the control flexibility they offered. The features include precision-stepped volume and balance controls, tone controls (switchable in or out), separate mono/stereo channel switches, high filter, switchable external processor loop, mute switch and built in high quality headphone amplifier.

Although it can be argued about whether including tone controls and other features audibly affect sound quality, they do not bother me if care is taken to ensure audio integrity. And as the listening part of my evaluation bears out, these controls did not affect the sound when I switched them.

The preamp has plenty of hookup capability that should appeal to home theater users, multicomponent hi-fi enthusiasts and those who are input hungry. Included are jacks for CD, tuner, VCR, three auxiliaries, phono/special (the latter used as an auxiliary if phono card is not installed), two tape loops and an EPL loop. The preamp also has two sets of output jacks. All jacks are gold plated.

The overall look and finish of the exterior is very good, but the preamp is not as slick-looking as some others I have seen. But hey, beauty is in the eye of the beholder.

The reason I wanted to sample the Van Alstine preamp was its hybrid tube/solid-state design. There are plenty of hybrid designs out there, but Van Alstine said his patented design makes the Fet Valve EC the most transparent preamp"he has ever designed.

The design combines tube and solid-state in the same stages inside the overall gain loops. Van Alstine described the circuit: The input circuits are triode vacuum tube, the pre-driver circuits are compound hybrid vacuum tube power MOSFET - Fet Valve transimpedance amplifiers, and the output is power MOSFET." According to Van Alstine the hybrid design avoids having the tube section directly driving real-world loads but instead uses the tube for voltage amplification only, all current and load drive being handled by the power MOSFETs.

Inside, the Fet Valve EC preamp is busy but very tidy, and the wiring is exceptionally neat. Power is supplied by a solid-state circuit, complete with a shielded, high-current toroidal transformer. The four tubes are high-grade, hand-selected Chinese 12AX7As. Two tubes are used in the overall preamp stage and the other two for the optional phono stage that my unit was supplied with. Van Alstine preamp specs include 10 Hz - 40 kHz bandwidth, less than 0.02 percent distortion and 100 dB signal-to-noise ratio (line). The switches and controls are gold contact and should provide years of noise-free, reliable operation. Dimensions include a 17-inch width to accommodate all the controls and connections.

The Omega III 440hc Amp

The Omega III 440hc active feedback amplifier at $1399 is 220 watts per channel with distortion listed at less than 0.01 percent from 20 Hz to 20 kHz and a flat large signal frequency response extending to nearly 500 kHz. Measuring 17" wide by 7" high by 13" deep, the amp is your standard-issue black box look with anodized metal and a simple on/off rocker switch on the front. Weight is 39 pounds. On the back are RCA input jacks and speaker binding posts. A large heat sink is located on the rear. There are also vent holes on the top and rear panels.

Inside, the MOSFET amp features a circuit with no overall feedback, but feedback does exist, according to Van Alstine, in a &quotunique"active and buffered powered feedback loop that is electrically and thermally matched to the active input parameters. The result is smoother, quicker, tighter and more detailed audio without the solid-state artifacts, Van Alstine claims.

Internal components include twelve big die heavy duty TO-3 power MOSFET devices, toroidal power supply and the input and output circuits. The power supply section is bottom plate mounted near the front and the input/output section is horizontally mounted on the back wall. The ample box has a lot of extra space, which is good thermal news for the internal components. Heat should not be a problem (and was not during my evaluation).

In Use

I paired the Omega III 440hc with the Fet Valve EC preamp and then paired them separately with other preamps and amps, including a Legacy high-current amplifier, conrad-johnson PF2L preamp, and a Van Alstine-modified Dynaco PAS, the Super Pas Three. Source gear included Denon DCD-1015 CD player and Luxman turntable with AudioTechnica AT-ML150 cartridge.

Van Alstine said he had burned in both units before shipping them to me, so the only warm-up was about 15-20 minutes each day. The amp was relatively quiet during turn-on; the preamp is very quiet since the tubes take a few seconds to warm up. All preamp controls were quiet and smooth-feeling and the switches were noise-free as well.

When I tapped the top of the preamp, with no source playing, there was a very slight ping from the right channel - a microphonic tube easily remedied by swapping another tube. Also, with a source playing, but the volume all the way down, I still heard the music faintly on the left channel. Again no big deal.

Ergonomically, the Fet Valve EC preamp is busy, but all controls were easy to use. The tone controls did not have a drastic effect on bass or treble. The treble seemed to be centered at about 10 kHz or higher. The filter affected the high frequencies in that region as well. The mute switch does not reduce the level significantly (I just turned down the volume).

I liked the separate mono/stereo channel switches. Push in the switch for the left channel and that channel comes through both the left and right speakers. Push in the right channel switch and the right channel is heard through both speakers. Push them both in and it is mono through both channels.

Listening

Together the Fet Valve EC preamp and Omega III 440hc amplifier revealed transparent, detailed and highly dynamic music. Bass was very deep and there was zero harshness. Examples: On jazz music, instruments were realistic sounding and I noticed a lot of resolution and space around them. On the Chesky Records CD of Johnny Frigo's Debut of A Legend (JD119), violin tone was excellent, and the Van Alstine pair revealed an accurate sense of location on all the instruments, including drums and bass.

On the Rickie Lee Jones' self titled debut (Warner Bros. 32962), the cut 'Night Train" contains a very natural finger squeak on the guitar strings that was not lost in the mix, as I have heard it through other components.

I really liked the sound of the cello on the CD, Duos for Violin and Cello (Second Hearing GS 9009). The instrument was very full-bodied as is a live cello.

For kick drum and bass, I sampled Los Lobos' Kiko (Slash Warner Bros. 9-26786-2). The bass was definitely powerful and tight through the Omega III 440hc. The Fet Valve EC preamp did contribute a certain "warmness" to the bass when compared to the solid-state preamp - more on that later.

The Omega III 440hc offers way more power than I was willing to sample wide open but it is nice to have that kind of power on hand if necessary. Within the confines of my home studio/listening room, the pair did not blur the sound when played uncomfortably loud. When paired with other components, the Van Alstine products were just as competent. When playing the Fet Valve EC preamp with the Legacy amp, the detail of the Johnny Frigo CD was obvious.

A lot of my listening also was done through the all-tube Super Pas Three preamp. It was generally similar to the Fet Valve EC. On solo or quartet classical music, they sound alike - except the Fet Valve EC revealed more fine detail. The big difference came when playing more demanding recordings. The Fet Valve EC produces big drum whacks of symphonies with less thickness and tighter control than the Super Pas Three. The same was true for bass rock and pop music. In fact, the Van Alstine Fet Valve EC preamp seemed to be at ease playing any type of music.

Comparing the Fet Valve EC to the conrad-johnson PF2-L that I reviewed last issue was a bit more difficult. That also is a fine preamp and very revealing and detailed, imparting no harshness. The PF2-L, on both amps, seemed to have a tad tighter bass than the Van Alstine, which was a little warmer. Also, there were some recordings where the c-j sounded a smidgen more detailed. But then on other kinds of music, such as a couple of trumpet recordings, the c-j sometimes was a bit thinner sounding. This comparison impression does not affect my high regard for either preamp. They are both great products.

The EC's phono section provided realistic sound from my direct-to-disc records and Mobile Fidelity vinyl versions of Muddy Waters and John Hiatt. The phono preamp was as quiet as the one in the Super Pas Three, but the EC's overall bass capability was the difference to my ears.

Lastly, the headphone amp. I am not an extensive user of headphones - too confining. I use them when recording, but not for extended listening. But the Fet Valve EC headphone provided clean audio through my Sony MDR-V6. However, the preamp output cannot be muted to listen to the headphones only. You'll have to shut off the amp to listen to headphones.

As for the amplifiers, I didn't hear any huge difference between the Omega III and the Legacy. Both were detailed, relayed very deep bass material and did not fatigue my ears. Solid-state amps are rapidly catching up to tubes in the last area - especially at higher prices. The only difference that I noticed was that the Legacy sometimes sounded brighter in the treble region. But I did not notice this on all recordings. Overall, however, the Omega III 440hc sounded very good - definitely in the high-end audiophile league, but several hundreds dollars less than the Legacy and other state-of-the art amplifiers.

The Omega III 440hc does have one attribute that I have not ever heard in another amplifier: a melodic power-down noise. When I shut off the amp, it was quiet for about 10 seconds, then came this electronic, bird-like noise that lasted for about five seconds. Van Alstine said that the noise is the small signal regulated power supplys shutting down at about 0.02 watts output, that the anomaly is not harmful, and that eliminating it was not worth the cost of adding a muting circuit.

In any case, the noise did not occur during power-on or during operation, and was of no significance to me.

Conclusion

Overall, the made-in-USA Van Alstine Fet Valve EC preamplifier and Omega III 440hc are excellent products. The preamp embodies the latest advances in solid-state and tube technology, loads of control features, and exemplary sound quality. Likewise, the Omega III 440hc gives you a lot of watts per-buck with both a transparent and an easy-to-listen-to character.

Combine the high degree of product quality and reasonable price - with Frank Van Alstine's one-on-one service - and the result is a winning combination. Highly recommended.

For more information, contact Audio by Van Alstine at (651) 890 3517 or 2665 Brittany Lane, Woodbury, MN 55125 or e-mail to avahifi@aol.com.

Associated Equipment

Audio by Van Alstine Super Pas Three preamp, conrad johnson PF2-L preamp, Legacy high-current amplifier, Boston Acoustics A-200 loudspeakers, Denon DCD-1015 CD player, Luxman PD-264 turntable, Audio-Technica ML-150 phono cartridge, Esoteric Audio and Monster Cable interconnects, AlphaCore Goertz MI speaker cable and Sony MDR-V6 headphone.

Products: Fet Valve EC Preamplifier, Omega 440hc Amplifier