There is a lot of good audio amplifier designer-engineers out there but I've always found little talk about Gerald Stanley's designs and contribution to the audio industry through the years he was at Crown International. He holds a large amount of patents on his deisgns. A true innovator in amplifier design and incredible knowledge of semi conductors. Crown would never achieved the success that they did if he wasn't around. A very humble quiet man who always gave credit to other people working at Crown
Four of his patents I most like is the Class AB+B, Grounded Bridge, JTS -ODEP (transistor protection scheme) and the Opposed Current Converter (class I)
Class AB+B in a three deep darlington. The pre-driver and drivers are high speed fT and carry the bias and the tranistors are in class AB mode. The last outputs are lower fT but more durable able to carry the higher current demands. High open loop gain, maximum negative feedback (overall and nested) used to reduce distortion to very low numbers. (Crown DC300). Gerald was using as much negative feedback as possible before any other designer could to get these low distortion numbers and low output impedance (made Crown famous for high damping factors)
Grounded Bridge to get maxumum voltage swing in a smaller package and less parts used. Clever use of the power transfomer not using the ground but creating a floating ground that varies on the sine wave. (inverting when wave goes high or low) moving the ground in proportion. Jim Wordinger also had much input to develop this circuit into the Micro-tech and Macro-Tech designs.
Then came JTS and later ODEP to protect the outputs. A very clever design which made the amplifiers (M600, Micro-tech, Macro-tech, Studio reference) very reliable.
Class I came about in the mid 90's when class D was coming into the commercial pro market. At the time Crown were not happy with the amount of distortion that class D was creating so they Gerald came up with his own design called Opposed Current Convertor Class I. This was released into the Crown K series which has a linear Transformer power supply but utilized the first version of the Class I. In its most simplest form... Where the high and low side switch on and off at the same time into inductors for zero output but vary each sides switching time to create current into a load. A really clever deisgn. This design is still in use in Crowns most recent flagship amplifiers and a Mark Levinson model.
Crown found you never needed very high slew rates (marketing race in some companies) Helped to dispel the TIM SID theory that was hot topic in the late 70's, even coming out with a paper on it by Gerald and Dave McLaughlin (very hard to find on the net) High focus on IMD than THD and a strong believer in using negative feedback to make amplfiers linear as possible
I do think we one Gerald much gratitude on amplifier development.
Four of his patents I most like is the Class AB+B, Grounded Bridge, JTS -ODEP (transistor protection scheme) and the Opposed Current Converter (class I)
Class AB+B in a three deep darlington. The pre-driver and drivers are high speed fT and carry the bias and the tranistors are in class AB mode. The last outputs are lower fT but more durable able to carry the higher current demands. High open loop gain, maximum negative feedback (overall and nested) used to reduce distortion to very low numbers. (Crown DC300). Gerald was using as much negative feedback as possible before any other designer could to get these low distortion numbers and low output impedance (made Crown famous for high damping factors)
Grounded Bridge to get maxumum voltage swing in a smaller package and less parts used. Clever use of the power transfomer not using the ground but creating a floating ground that varies on the sine wave. (inverting when wave goes high or low) moving the ground in proportion. Jim Wordinger also had much input to develop this circuit into the Micro-tech and Macro-Tech designs.
Then came JTS and later ODEP to protect the outputs. A very clever design which made the amplifiers (M600, Micro-tech, Macro-tech, Studio reference) very reliable.
Class I came about in the mid 90's when class D was coming into the commercial pro market. At the time Crown were not happy with the amount of distortion that class D was creating so they Gerald came up with his own design called Opposed Current Convertor Class I. This was released into the Crown K series which has a linear Transformer power supply but utilized the first version of the Class I. In its most simplest form... Where the high and low side switch on and off at the same time into inductors for zero output but vary each sides switching time to create current into a load. A really clever deisgn. This design is still in use in Crowns most recent flagship amplifiers and a Mark Levinson model.
Crown found you never needed very high slew rates (marketing race in some companies) Helped to dispel the TIM SID theory that was hot topic in the late 70's, even coming out with a paper on it by Gerald and Dave McLaughlin (very hard to find on the net) High focus on IMD than THD and a strong believer in using negative feedback to make amplfiers linear as possible
I do think we one Gerald much gratitude on amplifier development.
