Goede buizenversterkers zijn ook wel strak te krijgen van 20Hz tot 20khz.
Hoger en lager hoef je toch niet, dat hoor je toch niet.
"Vacuum tubes are the more linear and require less feedback
Tubes are voltage amplifiers as opposed to transistors which are current amplification devices. As a consequence, tubes are a more linear amplification technology, requiring less overall negative feedback to make the circuit linear. Negative feedback re-injects a sample of the amplifier’s output signal back into the input, 180 degrees out of phase, in an attempt to reduce amplifier non-linearity and distortion. In practice, negative feedback tends to slow the amplifier down and sucks the emotion and life out of the music. High feedback designs usually sound sterile, boring and lifeless, while low or zero feedback designs provide for a more immediate and natural sound. Depending on technology and type of the used output device, transistor amplifiers generally require the use of over 40dB of local loop or global negative feedback."
En:
"Vacuum tubes – Advantages
Highly linear without negative feedback, specially some small-signal types
Clipping is smooth, which is widely considered more musical than transistors
Tolerant of overloads and voltage spikes
Characteristics highly independent of temperature, greatly simplifies biasing
Wider dynamic range than typical transistor circuits, thanks to higher operating voltages
Device capacitances vary only slightly with signal voltages
Capacitive coupling can be done with low-value, high-quality film capacitors
Circuit designs tend to be simpler than semiconductor equivalents
Operation is usually in Class A or AB, which minimizes crossover distortion
Output transformer in power amp protects speaker from tube failure
Maintenance tends to be easier because user can replace tubes
Vacuum tubes – Disadvantages
Bulky, hence less suitable for portable products
High operating voltages required
High power consumption, needs heater supply
Generate lots of waste heat
Lower power efficiency than transistors in small-signal circuits
Low-cost glass tubes are physically fragile
More prone to microphonics than semiconductors, especially in low-level stages
Cathode electron-emitting materials are used up in operation, resulting in shorter lifetimes (typically 1-5 years for power tubes)
High-impedance devices that usually need a matching transformer for low impedance loads, like speakers
Usually higher cost than equivalent transistors
Transistors – Advantages
Usually lower cost than tubes, especially in small-signal circuits
Smaller than equivalent tubes
Can be combined in one die to make integrated circuit
Lower power consumption than equivalent tubes, especially in small-signal circuits
Less waste heat than equivalent tubes
Can operate on low-voltage supplies, greater safety, lower component costs, smaller clearances
Matching transformers not required for low-impedance loads
Usually more physical ruggedness than tubes (depends on chassis construction)
Transistors – Disadvantages
Tendency toward higher distortion than equivalent tubes
Complex circuits and considerable negative feedback required for low distortion
Sharp clipping, in a manner widely considered non-musical, due to considerable negative feedback commonly used
Device capacitances tend to vary with applied voltages
Large unit-to-unit variations in key parameters, such as gain and threshold voltage
Stored-charge effects add signal delay, which complicates high-frequency and feedback amplifier design
Device parameters vary considerably with temperature, complicating biasing and raising the possibility of thermal runaway
Cooling is less efficient than with tubes, because lower operating temperature is required for reliability
Power MOSFETs have high input capacitances that very with voltage
Class B totem-pole circuits are common, which can result in crossover distortion
Less tolerant of overloads and voltage spikes than tubes
Nearly all transistor power amplifiers have directly-coupled outputs and can damage speakers, even with active protection
Capacitive coupling usually requires high-value electrolytic capacitors, which give inferior performance at audio-frequency extremes
Greater tendency to pick up radio frequency interference, due to rectification by low-voltage diode junctions or slew-rate effects
Maintenance more difficult; devices are not easily replaced by user
Older transistors and ICs often unavailable after 20 years, making replacement difficult or impossible"
[Reactie gewijzigd door Tourmaline op 22 juli 2024 23:56]