Primaluna Evo 400 Valve Power Amplifier

Primaluna Evo 400 Valve Power Amplifier

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Key info

The EVO 400 stereo/mono (can be run as a stereo power amplifier or as mono power amplifiers) power amplifier uses the largest chassis in the EVO power amplifier range to house the largest Toriodal and output transformers that are used in the EVO series. These transformers are the largest and highest specification that PrimaLuna use. The EVO 400 also offers XLR and RCA connections.

All specifications

Physical characteristics
Weight 34.1 kg
Dimensions (HxWxD) 203.2 X 386.08 X 403.86 mm
Technical specifications
Power output Power: Stereo Ultra-linear 70 watts x 2 (EL34) (8Ω, 1% THD), Power: Stereo Triode 38 watts x 2 (EL34) (8Ω, 1% THD), Power: Mono Ultra-linear 140 watts (EL34) (8Ω, 1% THD), Power: Mono Triode 82 watts (EL34) (8Ω, 1% THD)
THD < 0.1% @ 1W < 2% @ Rated Power
Frequency response 9Hz-60kHz +/- 1dB 8Hz-70kHz +/- 3dB
S/N Ratio 95 dB, 105 dBA
Input sensitivity 1100 mV
Input impedance 100kΩ
Output Impedance 4, 8, & 16 Ω (stereo) 2, 4, & 8 Ω (mono)
Maximum power consumption 470 watts (EL34) 480 watts (KT88) 540 watts (KT120) 550 watts (KT150)
Tubes 6 - 12AU7, 8 - EL34
Analog inputs 1x Stereo RCA 1x Stereo XLR

The EVO 400 can be operated in ultra-linear or triode mode (remote switchable) and uses 6 x 12AU7 and 8 x EL34 valves. The EVO 400 has a healthy output  of 70 watts per channel in ultra-linear or 38 watts per channel triode mode in stereo configuration. If used in mono configuration then output is 140 watts in ultra-linear or 82 watts in triode mode (remote switchable).

Remote controlled triode / ultra linear switching

Do you have some classic rock albums you used to love so much that have now ended up left on the shelf, unplayed for years? How about jazz or classical recordings from the 60’s? Every audiophile has albums that they used to play, but stopped because they are harsh, brittle, or bright. There is a solution.

Triode and Single Ended Triode (SET) amps are popular for their warmer, fuller, and easy to settle into sound. But triode amps have limitations! Ultra-linear has more extension on the top and bottom, not to mention greater power. They have greater “pop” with a bigger difference between light and dark, and loud and soft. Having triode only can be a little limiting.

The best option is to have both triode and ultra-linear. PrimaLuna engineers in Holland designed an ingenious circuit that lets you change from triode to ultra-linear with a push of a button on the supplied remote control. No need to get up and stop the music. Make an instant comparison while you listen and choose what you like best for that song or album.

Ac offset killer – a PrimaLuna exclusive

AC Offset Killer is about goose bumps. The ones you get when music comes out of a background so quiet, you may say to yourself “Just how is this possible?” PrimaLuna custom winds their own massive toroidal power transformers that are low in hum and EMI. But they wanted more. PrimaLuna`s engineers designed the AC Offset Killer to lower transformer noise to a place no other manufacturer dreams of going, regardless of how bad your electricity is. The result? Sense of space. Texture. The resonance of an acoustic guitar or violin string that seems to trail on forever. The AC Offset Killer will amaze you.

Custom toroidal power transformer

Power transformers generate two types of noise, magnetic and acoustic. That’s why toroidal power transformers are used in the very best audio products. Compared to standard transformers, toroids radiate about 1/10 the magnetic field that pollutes music and obscures detail. Additionally, the absence of an air gap typically means toroids have an 8:1 reduction of acoustic noise. As transformers are the most expensive components in any audio product, manufacturers will even house cheaper C-core and EI-core transformers in an outboard power supply box with an umbilical cable rather than upgrade to an expensive toroid. The increased cost is significant, but PrimaLuna doesn’t cut corners. All PrimaLuna products use massive, potted toroidal transformers. PrimaLuna transformers are enclosed in a metal housing and then potted in a non-microphonic resin to further reduce noise and to protect the windings from moisture and deterioration forever.

Custom Super-wide-bandwidth output transformers

Output transformers are the most important part of any tube amplifier. They determine how low the bass will reach and how high the top end goes. 250 watts of power will have no top and bottom extension if the output transformers don’t have the bandwidth. PrimaLuna use lower power to extend tube life, and bandwidth to give you slam. Transformers are the most expensive components in an amplifier, so manufacturers save money by using ‘off the shelf’ units available on the market. PrimaLuna output transformers are custom designed, wound in house, and massive. One reason why no other brand sounds like a PrimaLuna. “The flat tops and bottoms of these square waves correlate with the amplifier’s extended low frequency response; PrimaLuna’s output transformers are of excellent quality.” -John Atkinson, Stereophile Magazine.

Adaptive autobias

What most companies call Auto Bias is actually “Cathode Bias”- A commonly used method that is cheap to make, and often found in guitar amps, but also high end audio amps. It reduces the available power of the amp and runs the tubes hard, meaning shorter tube life and failures via “shorts”.

PrimaLuna’s Adaptive AutoBias is a true, smart technology employing an array of sensors to monitor tubes and make adjustments seamlessly in real time. More important, it is the ONLY circuit of its kind that is truly “adaptive” by addressing “tube pinch off” at higher volumes, therefore reducing distortion by over 50% and greatly extending tube life. Adaptive AutoBias is completely passive and NOT in the signal path. The result is low to no maintenance, long tube life, and the lowest possible distortion for amazing sound.

Adaptive AutoBias also provides unparalleled flexibility by allowing use of almost any tube on the market today. It even has a fine tuning switch for EL-34 and KT88/KT120/KT150 tube types.

Point to point wiring w/swiss made wire

You spend a lot of money on interconnects. So why have the signal go right from the RCA jacks or loudspeaker terminals into circuit boards with copper traces so thin you can hardly see them? What’s high-end about that?

PrimaLuna employs Point to Point Wiring on all products. The entire signal path, including resistors and capacitors, is painstakingly hand wired with heavy-gauge cable by craftsman.

EVO 300 and EVO 400 models use Swiss made, silver plated, oxygen free continuous crystal (OCC) copper with a Teflon dielectric in the critical signal path for superior signal speed and increased clarity.

Takman resistors

Easy to identify through their pink colour, these premium resistors from Japan are popular with those who rebuild and upgrade their gear. “Modders” love TAKMAN for their low noise, linearity, and musicality.

Bad tube indicator

PrimaLuna engineers wanted to make owning a tube amp so simple you would have no excuse not to have your tube dreams come true.

If a tube fails, Adaptive AutoBias will instantly put the amplifier into protection mode so no parts can get damaged. A red LED will light up in front of the tube that needs replacing. Simply plug in another tube, and listen. No guess work. No smoking amp. No getting out the soldering iron or dropping your amp off at UPS.

Smartwatts – extended tube life

Tube life is simply a matter of how hard you run the tubes. That’s it. The only way to extend tube life is to run them as close to zero as you possible can, making sure it is not so low you go into crossover distortion. The life of a tube will depend on two things: Plate and screen voltage.

If the plate and screen voltage is high, you are more likely to get tube shorts when you turn the amp on and you get cathode stripping which greatly effects the cathodes ability to spit out electrons. Manufacturers that run the hell out of tubes to pump up their power ratings will never tell you what voltages they use. They’ll say it’s “proprietary” as if it’s some secret sauce. There is no such thing. But if they told you that they used 575, 600, or even 625 volts you probably wouldn’t buy. PrimaLuna proudly tell you their tubes run at just about 417 volts for the plates and screens.

PrimaLuna runs their output tubes at a minimum dissipation without going into crossover distortion. When you look at PrimaLuna amps, they provide less power from each tube. With KT-120’s as an example, a PrimaLuna will give you only 21 watts per tube. So running a pair of them you get 42 watts. That’s a lot of power, but the demands per tube are a fraction of some manufacturers that give you 100 watts from a pair of KT-120’s. It’s a cheap way to get big power, and it’s cheap. In fact, free. To get more power the right way is expensive. It requires bigger transformers, sockets, wiring, resistors, capacitors, and the tubes to do it. Which is exactly what PrimaLuna did. But they didn’t stop there.

Primaluna amps are perfect. But your system may not be

Ask any seasoned tube-head what the most musical output tube is and they will most certainly declare it the EL34. Other amp manufacturers would love to use it. Only PrimaLuna, through our proprietary output transformer designs, can give you EL34 midrange beauty with top-end air that goes on forever. And, bass extension with so much slam, our amps are used to power subwoofers.

However, every system is different. What if you bought a loudspeaker with bass that overloads the room? Or, that is too dark? Or, too bright? What if you just want to have fun trying the different colours of sound from a vast pallet of tubes? With other manufacturers’ products, you’re stuck. They’re a one trick pony. How are you going to fine tune your sound? Buy some different cables?!

With PrimaLuna, you get to choose. Go for it. 6L6G, 6L6GC, 7581A, EL34, EL37, 6550, KT66, KT77, KT88, KT90, KT120 (not KT150). A future proof design, PrimaLuna is compatible with NEW tube types not even thought of today!

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