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matched dual transistors - input pair - MAT12 / SSM2212

If you cascoded them the voltage limit wouldn't be a problem. There were a number of amps in Elector Magazine in the 80's that used them like that that were well regarded. I've got some of the DIP version and some LM394 which are similar. The Hackernap however is recommended to have a specific degree of mis-match to its input pair just as its Naim brethren did. Do they offer a matched PNP pair like the old MAT03?

John
 
Naim never had a mismatched pair, they went to great (and tedious) lengths to make sure they were matched.
 
Is that so MJS. I wonder why we went to such lengths to ensure a specific degree of mis-match to the input differential pair for the Hackernaps then? Or am I using the wrong terminology and confusing matching with balancing?

John
 
There is a difference between matching transistor pairs for Vbe, or hfe. 'Matched pairs' are for the former (because it is crucial for many precision uses; and no solid-state design should ever depend on 'beta' - hfe ...and that said..: )

...The selection for hfe, borrowed iirc from LesW, was ever the hack to get acceptable dc-offset results given the grossly-oversized R value in one leg of the LTP (that provides drive to the VAS stage) - the resistor that also provides so much of the characteristic Nap (& NAP- alike) output thd harmonic spectrum.
 
I never went in for the LTP hfe mismatch. I just could not see any reason to do this, the impedances in the base circuits are equal at 27K!

The oversized collector resistor in the LTP has amost no effect on dc offset according to my experiments.
 
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