Fet Valve 400R Hybrid Amplifier 200 Watts Per Channel.. Product #: Amp-Fet-400R based on 0 reviews
Regular price: $2,699.00 $2,699.00

Fet Valve 400R Hybrid Amplifier


Circuits: Fet Valve R Series
Chassis: Full Size AVA chassis 17 x 13 x 7
Switchable RCA/XLR Option +$300
Silver Premium Faceplate +$300
240V Wiring +$55
or call 651.330.9871

A lower powered version of the amazing Fet Valve 600R amplifier.

The Fet Valve 400R shares the same hybrid design of the Fet Valve 600R that blends the best of vacuum tube and solid state technologies. There is no compromise in sound in the Fet Valve 400R. There is no compromise is parts in the Fet Valve 400R. There is no compromise in quality in the Fet Valve 400R.

The only difference is that the Fet Valve 400R produces 200 Watts per channel. For those not needing to drive the most inefficient speakers, the Fet Valve 400R is an excellent choice.

Standard configuration includes gold plated machined RCA input jacks, 5-way gold plated speaker jacks, external speaker fuses. XLR balanced input jacks, or switchable RCA/XLR input jacks are optional.

The chassis is 17" wide, 13" deep, 7" high. The faceplate is our rugged double anodized black faceplate. We also offer a thick double anodized silver faceplate with a push button power switch and modern LED power lamp at additional cost. Shipping weight 38 pounds.


By far the most important innovation is our capability now to offer high powered audio amplifiers with pure analog, high current, high power, high speed regulated output circuit power supplies. The Fet Valve amplifiers output power supply rails sit solid as a rock, unvarying at all between idle and clipping under all musical demands.

Now when the music signal says "do it" you can hear an amplifier that actually "does it" rather than one that "almost" does it as the supply rails sag and vary under load. The rubber is gone, the dynamics and transients are astonishing, and the clarity, without edge or grain or glare, is pure. For good reason "R" stands for regulated output supplies, for reality, and right too.

Not only do the output circuits have regulated power supplies, each 12AT7 tube has three independent regulated power supplies, one for each plate, and a third for the filament/heater. The high power, high current power mos-fet in the output driver patented transimpedance amplifier also has a separate regulated power supply. There are ten regulated power supplies in all, five for each channel. You have never experienced an amplifier with these capabilities before, and when you do, nothing else will suffice.

Our power supply features a high current shielded toroid power transformer capable of providing ample power for all the regulators. The amps are dead quiet and play music from a deep black background.

The Fet Valve 400R operates with standard 120 Volt power, has an IEC power jack, and includes a polarized 120V power cord. For international use a 240 Volt (50-60 Hz.) option is available at additional cost.

Our single ended mos-fet/hybrid vacuum tube design used in the Fet Valve 400R sounds so real because it lets the audio gain parts each work in optimum environments. Vacuum tubes are great at manipulating voltages -- you can play with 200+ volt signals where transistors would go up in smoke and flames. So, we use vacuum tubes for all voltage manipulations; however, vacuum tubes cannot drive difficult loads. They have very limited output current and get in big trouble trying to drive feedback loops, stray internal capacitance, and connection cables, so, we don't let our tubes see any loads at all. They operate in an idealized mode amplifying voltages only, and do it perfectly.

Power mos-fets are super current amplifiers. They control great gobs of current without stress, and when properly selected and used, they perform without needing external compensation, thermal tracking circuits, or VI limiting and protect circuits. So we use all power mos-fets for current amplification duties. There is simply no roughness or compression in Fet Valve amplifiers.

The tubes are run under their maximum rating so that they provide long life and reliability. The output transistors are double-die lateral mos-fets that are extremely reliable and rugged. The lateral mos-fet transistors have a very fast slew rate, low distortion, and very high bandwidth that actually extends way beyond human hearing. The mos-fet transistors are not susceptible to thermal runaway, a significant issue plaguing bipolar transistor power amplifiers.

The Fet Valve 400R produces 200 watts per channel, 20 to 20 kHz into 8 ohms at less than 0.01% THD. Eight double-die output transistors, standard on the Fet Valve 400R, handle challenging speaker loads (2 Ohm loads and up).

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