Is the Cyrus I a relative of the SymAsym?
SymAsym5 - Project
or are they too far apart to be considered similar?
SymAsym5 - Project
or are they too far apart to be considered similar?
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Hi Andrew,
Nope, and you should know this.
The Cyrus 1 predates the SymAsym by a number of years, and the front end is completely different. The Cyrus 1 is a quasi-complimentary output as well.
-Chris
Nope, and you should know this.
The Cyrus 1 predates the SymAsym by a number of years, and the front end is completely different. The Cyrus 1 is a quasi-complimentary output as well.
-Chris
Yes, there are differences.
But the circuit topology looks very similar.
Exclude the quasi complementary and look at the rest.
It uses a version of EF followers on the two collector loads and feeds the two signals to the long tail pair which is loaded with a mirror and the unused leg has the same cascode referenced to audio ground.
Cyrus even uses the two 150pF comp to ground as the SymAsym.
But the circuit topology looks very similar.
Exclude the quasi complementary and look at the rest.
It uses a version of EF followers on the two collector loads and feeds the two signals to the long tail pair which is loaded with a mirror and the unused leg has the same cascode referenced to audio ground.
Cyrus even uses the two 150pF comp to ground as the SymAsym.
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Hi Andrew,
The very next version of this amplifier used a full complimentary output stage, so you might want to dig that schematic up.
The input stage to the Vas connection is bog standard, except they did the same thing with both phases. The long tailed pair is only loaded with the resistor and emitter follower. The emitter follower is loaded with the current mirror. The magic in that differential input stage is the CFP arrangement. The diff pair itself does receive two signals, input signal and feedback signal just like any other amplifier of this type.
This schematic predates the SymAsym by over a decade. This amplifier was at issue 7 in April of 1988. The first began production in May of 1984. The design and prototypes predates that. So there is enough separation in time between the SymAsym and the Cyrus One that I doubt there was any direct cross-pollination. Besides, those diagrams merely resemble the more general layout of an amplifier.
-Chris 🙂
-Chris
The very next version of this amplifier used a full complimentary output stage, so you might want to dig that schematic up.
The input stage to the Vas connection is bog standard, except they did the same thing with both phases. The long tailed pair is only loaded with the resistor and emitter follower. The emitter follower is loaded with the current mirror. The magic in that differential input stage is the CFP arrangement. The diff pair itself does receive two signals, input signal and feedback signal just like any other amplifier of this type.
This schematic predates the SymAsym by over a decade. This amplifier was at issue 7 in April of 1988. The first began production in May of 1984. The design and prototypes predates that. So there is enough separation in time between the SymAsym and the Cyrus One that I doubt there was any direct cross-pollination. Besides, those diagrams merely resemble the more general layout of an amplifier.
Which is very likely what this general design needs, and it's very likely more luck than management. 150 pF is a very common 10% value in the series when you stock parts. I'm not surprised about this appearing in two amplifiers that are broadly similar in design.
-Chris 🙂
-Chris
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