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Old 30th January 2013, 12:53 AM   #8271
Salas is offline Salas  Greece
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OK
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Old 30th January 2013, 12:58 AM   #8272
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The yellow graph is a 2SJ74 with a little less Idss then the green graph 2SK170 so part of the missmatch comes from the Idss difference. On the other hand you can see that the yellow curve has a steeper bend. 2SJ74 have higher Gm with the same amount of idle then the 2SK170.
From graph 3 post 8266 you see that the 2SK170 needs less Vds to go into saturation.
That will allow the 2SK170 to work on a voltage as low as 3V to be linear.
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Old 30th January 2013, 01:55 PM   #8273
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Today i measured 2SA1015GR, 2SC1815GR and the 2SA970GR, 2SC2240GR pair.
The 2SA1015, 2SC1815 are good to about 6mA so somewhat better then 2N4401, 4403.
The 2SA970, 2SC2240 is really awesome. Very nice up to 12V, the maximum i can measure.
See the curves of the PNP 2SA970. Very high early voltage. That is the major problem in PNP but here it is fine.
I would say that the good reputation of Japanese audio transistors compared to the European counterparts is deserved, at least at high current.
The picture is taken with the snipping tool. Thanks Frans for that idea.
I had something called Snaggit some years ago that did the same but now that feature comes for free with newer versions of windows.
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Old 30th January 2013, 01:56 PM   #8274
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Actually above 8mA it gets a bit worse but not much.
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Old 30th January 2013, 03:49 PM   #8275
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Your 970/2240 are GR or BL hfe class?
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Old 30th January 2013, 03:57 PM   #8276
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GR, as i remember Hfe was around 200.
I will buy more of those also in BL.
I think they are among the best. Rbb`is around 30 Ohm i think so there are some that get lower but paralleling will do the trick.
I am still searching for very low Rbb´ones that are also complimentary.
So far the Sanyos come closest-
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Old 30th January 2013, 04:43 PM   #8277
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The 970/2240BL I got measure in the high 300s to early 400s @ 2.5mA. Lowest Rbb TO-92s I got are 2SC2545E Hitachi at 530 average hFe.
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Old 30th January 2013, 05:03 PM   #8278
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Maybe this thread needs some attention Lowest noise BJT transistor?
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Old 30th January 2013, 05:37 PM   #8279
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I got some Hitachis too. The are really great but not made any more.
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Old 30th January 2013, 10:31 PM   #8280
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I measured some more candidates. The Zetex medium power SMDs do well up to 7mA. The picture shows the PNP, always the achilles heel.
I have also a surprising find : our old BC140, BC160.
Very high early voltage on the PNP and very symmetrical.
Actually here i did a little trick. The PNP had Hfe of 170 and the NPN over 300 so i adjusted the base current until they match. With this trick you can cancel distortion when the values are known. Matched for Hfe this gives a very good pair. I know from the 80th that they have decent low Rbb´too. Grundig used them in their MC heads, so did Stan Curtis and a friend of mine, a physicist. Some selection for noise is necessary here. I know that from the physicist so they do not come easy but when they play, they play just fine.
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File Type: jpg BC140 BC160.JPG (166.0 KB, 144 views)
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