You're pulling my leg aren't you?
Get away with you! You're pulling my leg! How? Why? What logic supports that?
Originally Posted by Zemlya
The really challenging parts of the audio system are not the electronics, but anything that involves mechanical components, that is, moving parts: microphones, pickups, turntables/arms and loudspeakers. That's because all mechanical system have billions of variables, none of which can be perfectly optimised - the end result is just a compromise. Amplifiers have variables too, but the designer's 'room for manoeuvre' is exceedingly limited. The mechanical designer starts with a completely blank canvass: the amplifier designer doesn't because he has dangerous voltages and reliability to consider which means that the circuitry has to take a certain shape or the amp will fail, catch fire or (worse?) destroy the speakers. The actual difference between mechanical systems can be very significant indeed (as we know with loudspeakers, musical instruments and cars but the actual difference, at a circuit functionality level between amps of the same Class technology (A, AB, B etc.) is insignificant. All amp designers have to follow design rules and electrical safety* considerations. Mechanical designers have no rules to obey because there are no dangerous voltages and few if any safety issues. Amplifier designers are constrained by a straight jacket called physics, safety and durability. The mechanical designer can do whatever he fancies.
If anyone really believes that the home amplifier is the golden heart of the hi-fi chain then it's as barmy a saying that the engine management system (black box computer) that controls the car engine timing is more important for a smooth ride than the suspension, gearbox, wheels, engine and seats. It just doesn't make any sense at all. When and where did this ludicrous notion slip into the open minds of the hifi consumer?
An analogy between amplifier designer and nuclear engineer: there are so many safety and durability issues of paramount importance that both are obliged to use standard, proven, reliable parts - even though each may in his dreams, conceive exotic solutions he just cannot use them. Hence, despite the fancy case work, underneath the skin, they are functionally identical.
We on the inside know this to be the truth. You on the outside may chose to substitute fantasies for the facts. I could be saying the same thing in twenty years, you still wouldn't believe me.
* as we found when exporting active speakers to the USA, UK insurers heavily load the annual public liability premium when they're made aware of exports of powered equipment. This means that the amplifier designer is highly constrained by the materials, clearances, insulation, grounding and even selection of components which is why, functionally, lift the lid and you'll see the same circuitry replicated over and over again across amp models and brands. If the insurers mandate 'UL', Underwiter's Labs approval (look for the UR backwards printed symbol on the equipment) - it means that they have scrutinised every single resistor, transistor, capacitor, IC, circuit board, tie wrap, connector, plug, socket, cable, transformer and wiring right down to the smallest part, and demanded that they are individually UL approved. That's creates a shallow pool of approved parts that the amp designer can draw on because it costs money for suppliers to get those piece parts through the UL approval process. Again, the amp designer is working in a highly constricted environment. The amp has to be designed to rarely break down and fail. That means the input > output concept is rigidly defined. He just doesn't have the freedom to create a 'sonic personality' because there are no components that can be added-in to do that.
Alan A. Shaw
Harbeth Audio UK