Q: What are the differences between VL10.1 and VL10?
A: The VL10.1 linestage preamplifier is an improved version over VL10. The VL10.1 is built on top of the foundation from VL10 with several improvements. The improvements include the use of wideband MOSFET current source, enhanced precision DC regulated power supply, new types of capacitors and resistors. The result is a better overall sounding preamplifier.
Q: How is the Wideband Unity Balanced Amplifier (WUBA) being used in this line amplifier VL10.1 different from the conventional design?
A: A fully balanced amplifier will cancel out the noises and distortions picked up by the audio cables caused by electromagnetic interferences. The WUBA is a patented design that allows a vacuum tube amplifier to be operated in a fully balanced condition, from the input to the output in only a single stage. The WUBA is a single gain stage wideband balanced differential amplifier design that contains no load resistors, no buffers, no followers and no global negative feedback. Hence, the purity of the musical signals can be faithfully preserved.
Q: Is the line amplifier VL10.1 phase non-inverting?
A: Yes. The output signals are in phase with respect to the input signals at the XLR receptacle. The pin configuration of the XLR receptacle is given as follows: pin-1 is ground; pin-2 is +VE and pin-3 is –VE signals.
Q: What is the break-in time for a new VL10.1?
A: The VL10.1 has been gone through a mild break-in at the factory. When you power it up the first time, it should sound reasonably well. But it may take about 50 to 100 hours before it completely breaks in. However, it is not advised to turn on the amplifier continuously all day. It is recommended to turn it off for one hour after it is operated for 3 to 4 hours.
Q: Do I need to bias the tubes of the VL10.1?
A: Unlike most power amplifiers, line amplifiers such as VL10.1 do not require to manually bias the tubes.
Q: Can I swap the tubes within the line amplifier VL10.1?
A: It is not recommended to swap any 6H30. The three 6H30s in each channel have been tested so that they work best in the current positions in terms of noise level and operating voltages.
Q: Why can some noises be heard from loudspeakers when tapping the chassis of VL10.1?
A: This is so called microphonic effect due to vibration of the grid winding. The 6H30 is frame grid twin triodes with large frame structure so as to increase transconductance, voltage gain and to reduce plate impedance. The 6H30 exhibits a little more microphonics compared with non-frame grid audio tubes such as 12AX7, 12AU7 and 6SN7, etc. But the microphonics do not affect the sound in normal operation.
Q: Can I place the VL10.1 inside a Hi-fi cabinet?
A: It is recommended not to place the VL10.1 inside a Hi-fi cabinet. Otherwise, it will cause the temperature of the VL10.1 getting too high. This will shorten the life of VL10.1. If the VL10.1 must be placed inside a Hi-fi cabinet, measures should be taken to ensure the ventilation openings of the VL10.1 are not obstructed and the distance between the VL10 and enclosure is at least greater than 80mm. The cabinet doors should be opened. And the lid of the vacuum tubes compartment must be removed.
Q: Can I remove the lid of the vacuum tubes compartment all time?
A: Removing the vacuum tube compartment lid can improve heat ventilation. However, cautions should be taken to ensure no objects falling into the compartment and the safety instructions given in this manual are strictly followed.
