"Without sacrificing performance",how???
megajocke said:Did anyone else notice that the Rth(j-c), power dissipation, thermal derating and maximum power dissipation don't add upp for many of the ONSemi plastic parts? (MJL21193, MJL3281...)
Rth(j-c) is stated as 0.7K/W and thermal derating as 1.43W/K. This would suggest a power rating of 180W. Or a typo as this is the same values as stated for the 250W metal cans.
Strange is that the mjw3281a datasheet says 0.625K/W (this works out to 200W) but the MJL3281 in the bigger TO264 says 0.7K/W. I have a hard time believing that the smaller package has better thermal properties...
I wonder too what is the advantage of TO3-P vs. TO247. Maybe it is cheaper in some way. Or maybe it's just the japanese transistor looks they are after
ozonek said:Any update from ONSEMI regarding to the TO3-P vs TO247/TO264 package's thermal resistance?
Here in China a local hi-fi magazine reviewed in a recent issue the new NJW0302/0281, NJW1302/3281 and some other popular output BJT. To my surprise, NJW0203/0281 was ranked 1st based on some subjective listening tests and NJW1302/3281 was ranked 2nd. Has anyone compared the NJW series with the older MJLs, any difference in performance?
ozonek said:Thanks K-amp for reply. From the info on the magazine, they only change the output BJTs and adjust idle current to same value. Seems no adjustment was done on the VA stage, so higher loading caused by Cob on 3281/1302 is possible for some audible effects then..
BTW, comparing high early voltage (less Ic change due to Vce change, as in 21193/21194 series) with sustained beta (less hfe down with current increase, as in 3281/1302 series) which factor is more important for linearly amplifying analog signals? Need some comment on this..thanks
Sigurd Ruschkow said:Ozonek -
that is interesting information. I am using the NJW0302/0281 in a class A amplifier running about 1.5A idle bias current, and like how it sounds.
Could you let us know what the other BJTs were?
and what the magazine is called and in what issue the test was made?
If not using triple darlington output then the higher and more linear (at low currents) beta of the sustained-beta types will be more useful for minimizing VAS loading.
When using a triple darlington this doesn't have as big importance.