Quote:
Originally Posted by PaoloJM
Most of the earlier amps used valve rectifiers which introduce that same sag feel, exept they do it for the power valves too, so it has an even greater effect/affect (never sure which, so there's both!!).
Valve rectifiers have an internal resistance, using around 100/200 ohms depending on the type, and drop voltage proportional to the current drawn just the same.
If the vintage amps had used a power resistor choke and a vlave rectifier the amp would have sagged like old ladies boobs!!
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JCM 800 and 1959/1987 both had solid state rectifiers AND a choke. The choke contributes to limiting sag but not in the same way as a rectifier or filter capacitors. The chokes attempts to keep the current steady. That's not the same thing as what the rectifier or filter caps try to do.
Voltage sag can contribute to the overall compression of the amp at high volume. A proper choke will keep current demand high, which in turn can contribute to sag wen the amp is pushed hard.