2SA1837/2SC4793 Matching Yield?

[jkeny]

I'm looking for 6 complimentary matched pairs of these transistors & I wondered had anybody here got experience in matching these? Approx how many pair matches could I expect from 20 of each?

This is for the Bias function in a Steve Dunlap Krill amp so I need 6 pairs for 2 monoblock amps.

[AndrewT]

what your tolerance on matching parameters? 10% or 1% or something completely different?

What do you need to match? hFE or Vbe or both hFE and Vbe @ one specific current over over a range of currents?

If you're only matching Vbe to +-10mV then a batch of 20 will probably give you 6pairs. If you change your tolerance to +-1mV at two currents the yield is likely to drop, you might get 1pair or 6pairs, it's down to luck.

If you want to match hFE to 10% at one current, again a batch of 20 is likely to yield 6 pairs.

The tighter the tolerance and the more parameters that must be matched the lower the yield.