Hi Andrew,
I'm afraid that is not possible to produce an exceptional sounding output stage in class B with a single pair of power transistors.
Put as many as possible in parallel, matched by Vbe and hfe, and biased at optimal class B current. It will give you a pure class A sound for normally listening levels and transients in class B without to much high harmonics.
If i had to use only one pair of output transistors, that amp will be only class A. For this situation, i'll match them for hfe only - as close as possible, 5-10%
Mihai
I'm afraid that is not possible to produce an exceptional sounding output stage in class B with a single pair of power transistors.
Put as many as possible in parallel, matched by Vbe and hfe, and biased at optimal class B current. It will give you a pure class A sound for normally listening levels and transients in class B without to much high harmonics.
If i had to use only one pair of output transistors, that amp will be only class A. For this situation, i'll match them for hfe only - as close as possible, 5-10%
Mihai
I assume that your are using D. Self's definition of ClassB here rather than the normal ClassAB where the quiescent Vre~=15mV to 25mV on the output stage emitter resistors.roender said:
Is there a way to correct this setting up voltage to take account of the internal emitter resistance that we builders have no access to, to take measurements?
sparkle said:Roender - thanks...hmmm...maybe to go on those 25 pieces in Digikey and buy them.... that way i will have more room to pair them...it is a better price than in Jameco ... arround 2.5USD....
o.k. it is done
i wil do it this way - at digikey....
Digikey's price is for 225 pieces, not 25.
I asked the product line manager from On Semi what was the difference between the "0" series parts and the original ones. Here's what he had to say:
"The only difference between the NJL0302/0281 parts and the NJL1302/3281
parts is the transistor die. The NJL0302/0281 parts use a smaller die.
This provides a lower cost alternative for customers who may not need
the higher power."
Hope this helps.
"The only difference between the NJL0302/0281 parts and the NJL1302/3281
parts is the transistor die. The NJL0302/0281 parts use a smaller die.
This provides a lower cost alternative for customers who may not need
the higher power."
Hope this helps.
Thank you Charles.
Smaller die is no necessary a bad thing. This imply a smaller Cob, high ft, high linearity at lower currents and of course smaller SOA. It is a good think if you use many transistor in parallel in order to achieve as much as possible class A and also properly biased class B.
Mihai
Smaller die is no necessary a bad thing. This imply a smaller Cob, high ft, high linearity at lower currents and of course smaller SOA. It is a good think if you use many transistor in parallel in order to achieve as much as possible class A and also properly biased class B.
Mihai
I would, although a bit late for you, probably.
http://www.diyaudio.com/forums/showthread.php?postid=1745010#post1745010
Cheers Ernst
http://www.diyaudio.com/forums/showthread.php?postid=1745010#post1745010
Cheers Ernst
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