Audio-GD - Master 1 Vacuum Valve (Single Ended Tube Preamplifier)
Master 1 Vacuum Valve preamplifier's design is not one of a kind!
It is the purest vacuum valve design possible, even the power supply has been built around tubes. Only DALE resistors, SOLEN capacitors and vacuum valves are used.
Due to its unique design the SN ratio has been boost up to 98dB on normal listening volume.
So, its sound may have some different than some vacuum valve units you have ever listened with.
Sound is transpant, detailed and dynamic while the musical tube sound is preserved.
All active components have a nonlinear character, it cannot be perfect in all states. During the design of the unit, the most optimal performance of components has been considered.
The output level is best at around 2V, although its maximum output rate is over 15V.
Traditionally the audio-gd boards are mirrored, however vacuum valve is having same boards for left and right channel to guarantee both channels have exact same specifications and behavior.
The power filtering caps and signal couple caps are SOLEN film capacitors. Vacuum valves are selected by Audio-GD after a lot of tests and over 15 years of experience.
We misadvise uses to change any component to keep the unit a perfect match on musical and precise soundstage.
Master 1 Vacuum Valve has 11DB gain which nowadays is sufficient due to higher output levels of sources. The volume control runs evenly smooth.
Current mode volume control system
Traditionally volume controls are either potentiometers ore digital volume controls. Both are degradation of sound quality, specially where everything counts like this vacuum valve preamplifier.
Master 1 Vacuum uses a current mode volume control: The signal only goes through a resistor then feed to the next stage. Without going through a volume control port. This design was published already in 2005 by Mr. Kingwa the founder of Audio-GD.
Master 1 Vacuum has 95DdB volume control range, below volume step 0-15 the volume increases just a few dB Above volume setting 15, the increase is 0.75dB with every step, resulting in a smooth and precise volume control adjustment.
To avoid any noise can be picked-up, the volume control board has been shielded by a thick copper enclosure.
Master 1 Vacuum Valve remote control is included and has a luxury metal aluminum finish. Functions available are volume; source selection and mute.
Vacuum valves are nonlinear components, when the input signal level gets higher, the distortion will increase and both the low and high output signal level will cause the distortion to increase.
This design has a dual volume control system to improve and bring down the distortion to a minimum possible.
To deliver strong output, there are two vacuum valves placed in parallel, run as buffers after the second and last volume control port.
Transparency and detailed music
With Master 1 Vacuum design will amplify a 1mV output detail signal up to ten times, then through the second volume port attenuation back to 1mV again.
This operation seems complex but it has mainly advantages:
Gain the weak signal up to ten times, far away from the noise level to avoid the signal be affected by the noise level.
Attenuation the signal from 10 mV back to 1mV; the noise, part of the signal also goes down. For example, if the signal attenuation is down to 20x times, the music signal goes back from 20mV to 1mV; while the e.g. 0.5mV noise has been reduced by 20 times too, to 0.025mV. This results in a much better S/N ratio.
The S/N is performs excellent on the lower (normal listening) volumes signal reproduction will result in a more detailed sound therefore. This normal listening volume is between volume 30-50, in this area the Master 1 Vacuum Valve S/N is over 98dB.