The vacuum tube gradually decreases the number of thermo-electrons during the long-term operation and reduces the gain. If the tube is near the end of its life, it means that the tube is weak enough to prevent proper operation. The tube used for the Prelude 3.1 is a military high-reliability tube and the tube life is approximately 10,000 hours, and it can be used for 10 years in 4 hours operation every day.
Two of the front tubes are front-end tubes, and the top of the tube is touchable by hand, but the middle body is hot. The two vacuum tubes behind are the output driver tubes and the middle body is very hot. Take care with your hand as it can cause burns. If the tube gets water, it will be broken by temperature difference. If the tube accidentally breaks or cracks, the inside of the glass tube surface turns white. If this happens, be sure to disconnect the power cord and receive the A / S for safety.
In the case of an integrated amplifier or a power amplifier, a somewhat longer preheating time is required due to the characteristics of the output tube, but since the tube used in Prelude 3.1 is a voltage amplifying tube and a low-power driver tube, the preheating of the tube is shorter than 3 minutes. In particular, it adopts military high-reliability tube, and the operation time is fast. After 30 seconds, the sound is heard after the power is turned on, and the preheating time reaches the normal value within 3 minutes. For example, even in the case of a semiconductor op-amp, the semiconductor maker's data sheet indicates that warm-up time is about 3-4 minutes. Even if you preheat the Prelude 3.1 for over an hour, it is hard to detect the sound change significantly. Of course, it's okay to keep it on for a whole day or a week. Instead, children or pets need special protection around them.
It is recommended to aging for 50-100 hours after purchasing a new one. If you listen to it for one or two hours a day for a month, the tube will age naturally. Technically speaking, it is because the filament is ignited for the appropriate time, the irregular thermal emission is constant, and the tube is settled into a stable state.
In general, vacuum tube amplifiers are dominated by expensive vintage casings produced in 1930-60. In the case of vacuum tubes manufactured before 1960, if the vacuum tube pin is highly corrosive and connected to the socket for a long time, corrosion will proceed quickly if the current flows. If intermittent sound noise occurs due to bad contact of the vacuum tube socket, it is necessary to clean the vacuum tube pin. The vacuum tube used for all amplifiers manufactured by Analog Design is a modern military building of Russian Military produced in 70-90 years. Particularly, since the pin part of the vacuum tube is nickel plated, the contact resistance is designed to be small. If vacuum tube insertion is frequent, the socket may become loose and contact failure may occur, so it is not necessary to perform frequent cleaning.
Prelude 3.1 has been carefully selected for the best vacuum tube, and is finished after perfect inspection such as Gain, Transconductance, Matched Pair, Noise. Those who like the vintage tendency can exchange the old tube with the classic tube, but it is not recommended because the overall characteristics are rather high compared to the high price and anti-vibration measures such as microphonic are needed. A matched pair is recommended if you want to replace it with a replaceable tube. A tube with the same amplification factor ensures stereo balance.
Turn on & off
Repeatedly turning on and off the power can cause the filament to be stressed and shorten its service life. If you turn off the power and turn off the power after 1 minute, there is no problem in the vacuum tube. Except for damage to the vacuum tube due to user's carelessness, we will replace the vacuum tube free of charge to the Prelude 3.1 first owner.
The power consumption of the Prelude 3.1 is 40 watts and the monthly power is 40 watts x 8 hours x 30 days = 9.6kw /Hour , when used for 8 hours every day.
This is quoted from ADLAB articles.