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Symphonic Designs Tube Amplifier
Why Tubes?
Tube amplifiers have long been known to produce high quality very clear and powerful sound. The downfall has always been the heat produced as well as the cost of replacing the hard to find vacuum tubes. These factors led to the conversion to digitally produced sound of usually lower quality by transistors in 1947. Until that time all electronics were based on the thermionic valve or vacuum tube. Vacuum tubes are desirable for sound output devices as they are capable of very high frequency response ranges and modest gain or transconductance.
Advantages of Vacuum Tubes:
- Very linear, making them viable to use them in low distortion circuits with little or no negative feedback
- Extremely high input impedance
- Vacuum tubes can dissipate large amounts of heat. For this reason valves remained the only viable technology for very high power, and especially high power/high voltage applications.
- Electrically very robust and can tolerate overloads for long periods which would destroy normal transistor systems in milliseconds. In the worst case a failed tube can simply be unplugged and replaced by the user.
Disadvantages of valves
- Significantly larger than equivalent solid-state transistors
- Vacuum tube audio equipment is normally heavy because of the weight of transformers.
- Vacuum tubes may have a shorter working life than solid state parts due to various failure mechanisms, although this should not be overstated; many valve types typically have operation lives in the tens of thousands of hours and an indefinite shelf life (many 60 year old tubes are still in regular use).
- Larger power requirements as stated above the use of a transformer is required.
Introducing the SD-VTA1B18X2
Let's continue on to its specifications.