Audio-GD – Vacuum HE1 MK3 – Regenerative PSU Tube Preamplifier

REVIEWS

VACUUM HE1 MK3 

This special design has more special features. The S / N ratio is designed to reach 98dB at normal listening level. Therefore, the sound experience will differ from all other vacuum valves you have been listening to most likely. When listening you might expect the typical “tube”; thick, slow and warm sound.  When listening to this preamplifier you will experience a transparent detailed and dynamic sound with the typical tube musicality.

Except for the vacuum valves which only have 3 months warranty, the preamplifier itself has our standard 2 year and 10-year repair warranty policy. We recommend to renew the vacuum valves after 5000 hours, (Every day 3 hours, it is around 5 years). After replacement around 150 hours burn in is advised.

SUMMARY

• Integrated regenerative power supply
• HE1 Single Ended model Tube amplifier consist of 8 vacuum valves
• HE1 Balanced model Tube amplifier consist of 10 vacuum valves
• Listening volume S/N Ratio up to 98 dB
• Vacuum rectifier has implemented. Zero silicon elements in signal and tube power circuits
• Equipped with SOLEN film caps
• Vacuum valves powered with AC voltage
• Luxury Aluminium Remote Control included

REGENERATIVE POWER SUPPLY

An integrated regenerative power supply is a proprietary electric generator built into the unit to avoid any noise from main power and deliver ultra-low noise and clean AC wave to feed the preamp

It will regenerate the main power and block noise from the power line, this way the preamp is able to reproduce the most neutral and analog sound you can imagine.

First a transformer converts main voltage. DC conversion is done by class A PSUs power supplies.

A discrete balanced regenerative wave generator produces the new ultra-low noise wave form at 400Hz. The 400Hz frequency was chosen because they have better efficiency compared to traditional 50Hz and at this frequency, 400Hz, it will boost the sound to reproduce real and pleasant analog sound.

The balanced gain amps with powerful output stages are driving the regenerative transformers to produce the extreme clean AC power. The extreme regenerated clean AC power is send to separate class A PSUs power supplies for both left and right channel.

The discrete class-A DC power supply with high input impedance will avoid any noise and allow the amplifier stages to have low output impedance at very high speed and linear at frequency spectrum.

DESIGN

While we designed this preamplifier unit, we have chosen the most optimal area of the components used.Active components have A nonlinear character, they are not perfect in the hole spectrum but have its sweet spot. Realizing most power amps input sensitivity is around 1V and preamplifier output level will work best when its output is at 10V output. This tube preamplifier has its sweet spot around 2V output level, its maximum is over 15V though.

The frequency band has been adjusted to obtain the best sound and long term listening. The preamplifier consists of two identical PCB’s, one for left and one for right. Not built in mirror like our solid-state equipment because vacuum valves do not allow such design without impact on the sound.

The power caps and signal coupling caps are all premium grade SOLEN film capacitors. The vacuum valves chosen are selected based on best combination of different types and models We have over 15 years’ experience designing and building vacuum vale amplifiers. We do not advise users to change or replace components even if they have good DIY skills to preserve best match on musical and precise performance.
The total gain is 11dB which will allow the user to control the volume smooth and gradually.

LOW DISTORTION

Vacuum valves are nonlinear components. This means when the input signal increases the distortion will increase and variation in low and high signal level will again increase distortion.To reduce distortion on the tube preamplifier a dual volume control ports was implemented. The first port placed at the preamp input reduces the input level, this will avoid high input level to increase distortion. The second port is placed on the gain tube output, to select and apply the sweet spot of the vacuum valve.To obtain stronger output ability two vacuum valves are put in parallel and function buffers after the second volume control port.

HIGH PRECISION VOLUME CONTROL

Volume control consist of relay-controlled attenuators. Fully-independent, fully-balanced stereo volume controls. The volume controls feature consist of high-precision 0.05% tolerance film resistors and golden contact relays. Buffered inputs and outputs.There 4 channels volume boards are built in the unit to achieve ultimate balanced volume control. They are controlled by a digital signal controlling the high quality relays switching the precision resistors in analog area.

Quality of volume control is very important in balanced applications . It have to effectuate the four channels to work as synchronous as possible to keep the balanced signal in perfect shape. In traditional volume controls the balanced output will introduce distortion which will negatively influence sound quality and performance and might even get worse than a single ended setup and waste the advantages of balanced designed solution.