On Feb 7, 2025, at 3:37?PM, Mike M <groups@...> wrote:

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From the data sheets here are the absolute Max Voltages. As you can see the 2SC3357 has lower VCBO and VCEO:

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????? 2SC5551??? 2SC3357

VCBO??? 40???????? 20

VCEO??? 30???????? 12

VEBO? ?? 2??? ? ??? 3

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Measuring on an LZ1AQ amp with 2SC3357 operating at 12V, here are the max voltages over all four transistors:

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???? Measured?? Margin

VCBO?? 5.5?????? 14.5

VCEO?? 6.2??????? 5.8

VEBO?? 0.743??? ? 2.257

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So for the LZ1AQ design the 2SC3357 operates with plenty of margin.

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Mike M